This illustration shows a 3D printed heart ventricle engineered with fiber-infused ink. Credit: Harvard SEAS

By Kat J. McAlpine / SEAS Communications

Over the last decade, advances in 3D printing have unlocked new possibilities for bioengineers to build heart tissues and structures. Their goals include creating better in vitro platforms for discovering new therapeutics for heart disease, the leading cause of death in the United States, responsible for about one in every five deaths nationally, and using 3D-printed cardiac tissues to evaluate which treatments might work best in individual patients. A more distant aim is to fabricate implantable tissues that can heal or replace faulty or diseased structures inside a patient’s heart.

In a paper published in Nature Materials, researchers from Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering at Harvard University report the development of a new hydrogel ink infused with gelatin fibers that enables 3D printing of a functional heart ventricle that mimics beating like a human heart. They discovered the fiber-infused gel (FIG) ink allows heart muscle cells printed in the shape of a ventricle to align and beat in coordination like a human heart chamber.

“People have been trying to replicate organ structures and functions to test drug safety and efficacy as a way of predicting what might happen in the clinical setting,” says Suji Choi, research associate at SEAS and first author on the paper. But until now, 3D printing techniques alone have not been able to achieve physiologically-relevant alignment of cardiomyocytes, the cells responsible for transmitting electrical signals in a coordinated fashion to contract heart muscle.

“We started this project to address some of the inadequacies in 3D printing of biological tissues.”

– Kevin “Kit” Parker

The innovation lies in the addition of fibers within a printable ink. “FIG ink is capable of flowing through the printing nozzle but, once the structure is printed, it maintains its 3D shape,” says Choi. “Because of those properties, I found it’s possible to print a ventricle-like structure and other complex 3D shapes without using extra support materials or scaffolds.”

This video shows the spontaneous beating of a 3D-printed heart muscle. Credit: Harvard SEAS.

To create the FIG ink, Choi leveraged a rotary jet spinning technique developed in the lab of Kevin “Kit” Parker, Ph.D. that fabricates microfiber materials using an approach similar to the way cotton candy is spun. Postdoctoral researcher and Wyss Lumineer Luke MacQueen, a co-author on the paper, proposed the idea that fibers created by the rotary jet spinning technique could be added to an ink and 3D printed. Parker is a Wyss Associate Faculty member and the Tarr Family Professor of Bioengineering and Applied Physics at SEAS.

“When Luke developed this concept, the vision was to broaden the range of spatial scales that could be printed with 3D printers by dropping the bottom out of the lower limits, taking it down to the nanometer scale,” Parker says. “The advantage of producing the fibers with rotary jet spinning rather than electrospinning” – a more conventional method for generating ultrathin fibers – “is that we can use proteins that would otherwise be degraded by the electrical fields in electrospinning.”

Using the rotary jet to spin gelatin fibers, Choi produced a sheet of material with a similar appearance to cotton. Next, she used sonification – sound waves – to break that sheet into fibers about 80 to 100 micrometers long and about 5 to 10 micrometers in diameter. Then, she dispersed those fibers into a hydrogel ink.

“This concept is broadly applicable – we can use our fiber-spinning technique to reliably produce fibers in the lengths and shapes we want.”

– Suji Choi

The most difficult aspect was troubleshooting the desired ratio between fibers and hydrogel in the ink to maintain fiber alignment and the overall integrity of the 3D-printed structure.

As Choi printed 2D and 3D structures using FIG ink, the cardiomyocytes lined up in tandem with the direction of the fibers inside the ink. By controlling the printing direction, Choi could therefore control how the heart muscle cells would align.

The tissue-engineered 3D ventricle model. Credit: Harvard SEAS

When she applied electrical stimulation to 3D-printed structures made with FIG ink, she found it triggered a coordinated wave of contractions in alignment with the direction of those fibers. In a ventricle-shaped structure, “it was very exciting to see the chamber actually pumping in a similar way to how real heart ventricles pump,” Choi says.

As she experimented with more printing directions and ink formulas, she found she could generate even stronger contractions within ventricle-like shapes.

“Compared to the real heart, our ventricle model is simplified and miniaturized,” she says. The team is now working toward building more life-like heart tissues with thicker muscle walls that can pump fluid more strongly. Despite not being as strong as real heart tissue, the 3D-printed ventricle could pump 5-20 times more fluid volume than previous 3D-printed heart chambers.

The team says the technique can also be used to build heart valves, dual-chambered miniature hearts, and more.

“FIGs are but one tool we have developed for additive manufacturing,” Parker says. “We have other methods in development as we continue our quest to build human tissues for regenerative therapeutics. The goal is not to be tool driven – we are tool agnostic in our search for a better way to build biology.”

Additional authors include Keel Yong Lee, Sean L. Kim, Huibin Chang, John F. Zimmerman, Qianru Jin, Michael M. Peters, Herdeline Ann M. Ardoña, Xujie Liu, Ann-Caroline Heiler, Rudy Gabardi, Collin Richardson, William T. Pu, and Andreas Bausch.

This work was sponsored by SEAS; the National Science Foundation through the Harvard University Materials Research Science and Engineering Center (DMR-1420570, DMR-2011754); the National Institutes of Health and National Center for Advancing Translational Sciences (UH3HL141798, 225 UG3TR003279); the Harvard University Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Coordinated Infrastructure Network (NNCI) which is supported by the National Science Foundation (ECCS-2025158, S10OD023519); and the American Chemical Society’s Irving S. Sigal Postdoctoral Fellowships.

• PAPER – Fibre-infused gel scaffolds guide cardiomyocyte alignment in 3D-printed ventricles. Suji Choi, Keel Yong Lee, Sean L. Kim, Luke A. MacQueen, Huibin Chang, John F. Zimmerman, Qianru Jin, Michael M. Peters, Herdeline Ann M. Ardoña, Xujie Liu, Ann-Caroline Heiler, Rudy Gabardi, Collin Richardson, William T. Pu, Andreas R. Bausch and Kevin Kit Parker. Nat. Mater. 22, 1039–1046 (2023). https://doi.org/10.1038/s41563-023-01611-3

If you had asked Adama Sesay as a child what she wanted to be when she grew up, the answer would have been a doctor, an architect, and a firefighter. Now a Senior Engineer specializing in sensors and microsystems, you may think she’s gone in a completely different direction, but by following the passions that led her to those ideas – science, design, and saving lives – she’s found a career she loves. At the Wyss, Adama is a member of the Advanced Technology Team and works on a wide range of projects that span from sensor-integrated Organ Chips to make drugs safer to an enzyme that converts sugar to fiber to make food healthier, while simultaneously leading the Women’s Health Catalyst. Learn more about Adama and her work in this month’s Humans of the Wyss.

What projects are you involved with?

I specialize in biosensing, microfluidics, and microsystems, and my projects span over quite a diverse area. The first project I’ve been managing is a BARDA project, which is a federally funded project looking at integrating sensors to measure biomarkers like cytokines, from a lymph node tissue model, or a lymphoid follicle (LF) Chip. In this project, I’ve mostly concentrated on the instrumentation side, providing the actual hardware (which is a sort of sensor-integrated cartridge) and retrofitting it into a commercial Organ Chip system.

Adama Sesay, Senior Engineer II. Credit: Wyss Institute at Harvard University

Then I have another project where we’re developing an enzyme-encapsulated particle that reduces sugar in food once it’s consumed, converting it to dietary fiber. Basically, this would be a “smart food” ingredient, where the enzyme is only activated once you consume it. That way, the food tastes the same, but the actual amount of sugar your body metabolizes is lower.

I’m working on a third project where we are developing and microfabricating a microfluidic Blood Clotting Chip to study clotting time for patients that have mesothelioma, a cancer caused by exposure to asbestos. We’re collaborating with Massachusetts General Hospital and Boston Children’s Hospital.

What are biosensors, microfluidics, and microsystems?

A biosensor is a device that combines a biological component with a sensor transducer and can measure a biological or chemical reaction by producing signals to indicate the concentration of the analyte, or component of interest, in the monitored sample. Microfluidics refers to a system that has small channels that can move and deliver low volumes of fluid. The concept is that fabrication-wise, a microfluidic channel is anything that has dimensions in the micrometer range. The advantage of microfluidics is that you can deliver very low volumes to different areas and manipulate those flows a classic example is a an Organ Chip. A microsystem device in this context takes it a bit further and is the integration of sensors, microfluidics, and application. The three are a closely integrated package.

What real-world problems do these projects address?

With the BARDA project, we can use the LF Chips to monitor the immune system’s reaction to different types of drugs. We can use patient samples to get time resolved data about the inflammation response. In addition to helping screen drugs for safety, this could help us determine which therapies can be used on immuno-compromised patients or what a vaccine response will be in a certain population.

This illustration demonstrates the structure of the LF Chip that Adama is working on. Credit: Wyss Institute at Harvard University

The sugar fiber project will help address America’s ever-growing problems with obesity and diabetes. Despite these issues, there is a big food industry here that relies on refined sugars, especially high fructose corn syrup. In addition to those other issues, high fructose diets contribute to metabolic syndrome. Plus, the American diet is low in fiber. We started this project looking at how to make food more enjoyable while also being responsible. Our enzyme encapsulation will hopefully address diabetes and metabolic syndrome, while increasing fiber, which will make people’s gut microbiomes healthier.

We hope to use the Blood Clotting Chip to understand the clotting time and the thrombosis factors of mesothelioma. It can also be used as a diagnostic tool. Understanding a patient’s blood clotting factor is essential when they go into surgery, even beyond those suffering from this disease. This became even more apparent to me recently when my father needed to have emergency surgery, but they had to wait until he could be off blood thinners for a period of time. If we could use this as a diagnostic test, surgeons would know when a patient’s clotting factor was such that they were ready for surgery.

What is your specific role on the team?

I’m a Senior Engineer here and part of the Advanced Technology Team, I lead the biosensing, microfluidics, and microsystems effort at the Wyss. I am also responsible for the microfabrication room and efforts, and work closely with Pawan Jolly, who is the lead on sensors. That entails but is not limited to research project management, writing funding proposals, mentorship, and overseeing relationships with internal and external collaborator.

How are you helping to advance women’s health at the Wyss?

One of my biggest interests at the moment is to build up the Women’s Health Catalyst. In a place like the Wyss that’s looking at unmet needs, it’s natural that we have quite a lot of projects already in our pipeline dedicated to women’s health because therapeutics and diagnostics specifically aimed at women’s health issues are one of the biggest unmet clinical needs in the world. All this work is being done within our existing Focus Areas. Many of our researchers are incredibly dedicated to increasing our knowledge and finding real-world solutions.

Adama and the other speakers at the Wyss’ event celebrating Women at the Intersection of Science and Art on International Women’s Day. Credit: Wyss Institute at Harvard University

So, right now we’re aiming to coalesce all these projects to bring together our brilliant scientists, clinicians, and technology teams to advance research and make drugs and devices to help people. We aim to be able to highlight these projects to attract external collaborators to work with our Wyss technology translation engine, and one day become a world-class beacon where people want to come and really make advances in women’s health.

How are you helping to bridge the gap between academia and industry at the Wyss?

I have a diverse group of researchers on my team including biologists, biotechnologists, biomedical engineers, and mechanical engineers who look at challenges very differently, while I look at the industrial need and see how we can translate the science into something to address the gaps. I think what it boils down to is facilitating the communication between scientists and engineers on the research side and translating that acquired knowledge into know-how, services, and products on the business and industrial sides.

“I think what it boils down to is facilitating the communication between scientists and engineers on the research side and translating that acquired knowledge into know-how, services, and products on the business and industrial sides.”

– Adama Sesay

For example, if I’m designing a diagnostic device, I will listen to the scientists about how the fundamental biology works in their system and use my experience in sensor development, microsystems, and developing point-of-care devices to speak to more practically minded engineers about how to build the device, finding a common language between the two. Then, we need to communicate why this device is useful to a business audience in order to successfully commercialize it.

What brought you to the Wyss?

I wanted to be in a place that was busy doing what I had been doing for a while in Europe, which is translational science. The first place on my wish list was the Wyss Institute. I loved the work going on here; the organs-on-chips and the translational nature of the place. It’s quite unique in its structure. So, I got in touch with people working here, especially in Donald Ingber’s lab, and I was lucky that there was a position open when I applied.

Members of Don Ingber’s lab, including Adama, at the Wyss Retreat in 2022. Credit: Wyss Institute at Harvard University

How has your previous work experience shaped your approach to your work today?

Starting with my master’s and Ph.D., much of my work has focused on technology transfer. It’s shaped my approach to work because it has taught me to talk to different people, bring various viewpoints and skills together, really listen to where the problems are, and find solutions. I think sometimes, especially earlier in your career, it’s easy to think that your idea is brilliant, but at the end of the day, it might be a great technology that’s hard to translate into a product. I’ve learned that you need to take your ego out of it, listen, and find the best way forward, even if it isn’t your way. Having a critical mass of new knowledge around you means you’ll always be at the forefront; you just have to be open to trying new things and making the sum of the parts better than the individual pieces.

What is your biggest piece of advice for an academic scientist looking to translate their technology?

“Maintain a level of curiosity and wonder. Be prepared to keep on improving and learning.”

– Adama Sesay

Maintain a level of curiosity and wonder. Be prepared to keep on improving and learning. Don’t be discouraged if you get knocked back, because even if your first approach doesn’t work, it’s because you go through that and you’re willing to get back up again that you will succeed.

What inspired you to get into this field?

If you had asked me what I wanted to be when I was a kid, I would always say a doctor, an architect, or a firefighter. A doctor because I really liked science and I didn’t know there was anything else out there other than that. My parents were in the medical field, so I thought that was it. An architect because I liked art, and I love buildings. I thought architecture was the practical way to apply that. I was unaware there was a profession called an engineer. And a firefighter because I enjoy being active and I thought they were so heroic. I just admired them.

I realized very quickly that none of those things were exactly for me, but I followed the passions that led me to those ideas – science, design, and saving lives – and by doing what I love I found my way to a career in translational research focused on sensors and microsystems. If you really enjoy what you do, it doesn’t feel like a job.

What continues to motivate you?

Making a difference and working with a great team in an amazing work environment. I think that knowing that the people I’m working alongside are truly having an impact, even if they’re not on my project directly, is very inspiring. It makes me feel that I’m a part of something that can cause positive change in my lifetime.

“I think that knowing that the people I’m working alongside are truly having an impact, even if they’re not on my project directly, is very inspiring. It makes me feel that I’m a part of something that can cause positive change in my lifetime.”

– Adama Sesay

When not at the Wyss, how do you like to spend your time?

I like roller skating. I started playing my clarinet again, which I used to do when I was a teenager, and that’s given me a lot of joy. I also like watching films. My favorite recent films have been Everything, Everywhere, All at Once and The Woman King. Everything, Everywhere, All at Once manages to be light while also touching some quite thought-provoking concepts. I love the types of films that you can spend time talking about. The Woman King, while it has faced some criticism for being inaccurate, opens a dialogue about African history on a world stage between individuals whom audiences in the west have never known or even wondered about it. Although some of these discussions might be uncomfortable, at least people are beginning to have them. Again, I like a film that starts a conversation.

What’s something unique about you that someone wouldn’t know from your resume?

My mother suffered from Alzheimer’s disease, and it finally took her this past Christmas. In her memory, my sister and I are working towards building a smart city in her village in Sierra Leone. To do this, we’re raising awareness and funding to build an agricultural school for women and empower them to harvest crops based on new technology that’s sustainable and appropriate for the land, given that it’s a wildlife sanctuary area, and create businesses from farming. Hopefully, by next year we can start working on the curriculum for the school. We’re putting a lot of work into this, but we think it’s a great way to honor our mother’s legacy and enable women to get out of poverty and become future entrepreneurs.

What does it feel like to be working towards translating cutting-edge technology that has the potential to have a real and significant impact on people’s lives and society?

It feels great to be part of such a dynamic environment. I think as an engineer and a technology transfer specialist, it’s the best of all worlds. I’m lucky enough to have worked at some exceptional institutes in some amazing countries, but the Wyss is quite special in that we have a critical mass of world-class, high-impact projects ripe for translation. I’m in my fifth year now and it’s been a great ride so far. I’m looking forward to what comes next.

MyoExo integrates a series of sensors into a wearable device capable of detecting slight changes in muscle strain and bulging, enabling it to measure and track the symptoms of Parkinson’s disease. Credit: Oluwaseun Araromi

By Matthew Goisman/SEAS Communications

Nearly one million people in the United States live with Parkinson’s disease. The degenerative condition affects the neurons in the brain that produce the neurotransmitter dopamine, which can impact motor function in multiple ways, including muscle tremors, limb rigidity and difficulty walking.

There is currently no cure for Parkinson’s disease, and current treatments are limited by a lack of quantitative data about the progress of the disease.

MyoExo, a translation-focused research project based on technology developed at the Harvard John A. Paulson School of Engineering (SEAS) and the Wyss Institute for Biologically Inspired Engineering, aims to provide that data. The team is refining the technology and starting to develop a business plan as part of the Harvard Innovation Lab’s venture program. The MyoExo wearable device aims to not only provide a remote monitoring device for patients at-home setting but also be sensitive enough to aid early diagnostics of Parkinson’s disease.

“This is a disease that’s affecting a lot of people and it seems like the main therapeutics that tackle this have not changed significantly in the past several decades,” said Oluwaseun Araromi, Research Associate in Materials Science and Mechanical Engineering at SEAS and the Wyss Institute.

The MyoExo technology consists of a series of wearable sensors, each one capable of detecting slight changes in muscle strain and bulging. When integrated into a wearable device, the data can provide what Araromi described as “muscle-centric physiological signatures.”

“The enabling technology underlying this is a sensor that detects small changes in the shape of an object,” he said. “Parkinson’s disease, especially in its later stages, really expresses itself as a movement disorder, so sensors that can detect shape changes can also detect changes in the shape of muscle as people move.”

MyoExo emerged from research done in the Harvard Biodesign Lab of Conor Walsh, the Paul A. Maeder Professor of Engineering and Applied Sciences, and the Microrobotics Lab of Rob Wood, the Charles River Professor of Engineering and Applied Sciences at SEAS. Araromi, Walsh and Wood co-authored a paper on their research into resilient wearable sensors in November 2020, around the same time the team began to focus on medical applications of the technology.

“If we had these hypersensitive sensors in something that a person was wearing, we could detect how their muscles were bulging,” Walsh said. “That was more application-agnostic. We didn’t know exactly where that would be the most important, and I credit Seun and our Wyss collaborators for being the ones to think about identifying Parkinson’s applications.”

Araromi sees the MyoExo technology as having value for three major stakeholders: the pharmaceutical industry, clinicians and physicians, and patients. Pharmaceutical companies could use data from the wearable system to quantify their medications’ effect on Parkinson’s symptoms, while clinicians could determine if one treatment regimen is more effective than another for a specific patient. Patients could use the system to track their own treatment, whether that’s medication, physical therapy, or both.

“Some patients are very incentivized to track their progress,” Araromi said. “They want to know that if they were really good last week and did all of the exercises that they were prescribed, their wearable device would tell them their symptomatology has reduced by 5% compared to the week before. We envision that as something that would really encourage individuals to keep and adhere to their treatment regiments.”

MyoExo’s sensor technology is based on research conducted in the Harvard Biodesign Lab of Conor Walsh and the Microrobotics Lab of Rob Wood at SEAS, and further developed through the Wyss Institute for Biologically Inspired Engineering and Harvard Innovation Labs venture program. Credit: Oluwaseun Araromi

Araromi joined SEAS and the Wyss Institute as a postdoctoral researcher in 2016, having earned a Ph.D in mechanical engineering from the University of Bristol in England and completed a postdoc at the Swiss Federal Institute of Technology Lausanne.

His interest in sensor technology made him a great fit for research spanning the Biodesign and Microrobotics labs, and his early work included helping develop an exosuit to aid with walking.

“I was initially impressed with Seun’s strong background in materials, transduction and physics,” Walsh said. “He really understood how you’d think about creating novel sensors with soft materials. Seun’s really the translation champion for the project in terms of driving forward the technology, but at the same time trying to think about the need in the market, and how we demonstrate that we can meet that.”

The technology is currently in the human testing phase to demonstrate proof of concept detection of clinically-relevant metrics with support from the Wyss Institute Validation Project program. Araromi wants to show that the wearable device can quantify the difference between the muscle movements of someone with Parkinson’s and someone without. From there, the goal is to demonstrate that the device can quantify whether a person has early- or late-stage symptoms of the disease, as well as their response to treatment.

“We are evaluating our technology and validating our technical approach, making sure that as it’s currently constructed, even in this crude form, we can get consistent data and results,” Araromi said. “We’re doing this in a small pilot phase, such that if there are issues, we can fix those issues, and then expand to a larger population where we would test our device on more individuals with Parkinson’s disease. That should really convince ourselves and hopefully the community that we are able to reach a few key technical milestones, and then garner more interest and potentially investment and partnership.”

AI-designed (C-shaped) organisms push loose stem cells (white) into piles as they move through their environment. Credit: Douglas Blackiston and Sam Kriegman

By Joshua Brown, University of Vermont Communications

To persist, life must reproduce. Over billions of years, organisms have evolved many ways of replicating, from budding plants to sexual animals to invading viruses.

Now scientists at the University of Vermont, Tufts University, and the Wyss Institute for Biologically Inspired Engineering at Harvard University have discovered an entirely new form of biological reproduction—and applied their discovery to create the first-ever, self-replicating living robots.

The same team that built the first living robots (“Xenobots,” assembled from frog cells—reported in 2020) has discovered that these computer-designed and hand-assembled organisms can swim out into their tiny dish, find single cells, gather hundreds of them together, and assemble “baby” Xenobots inside their Pac-Man-shaped “mouth”—that, a few days later, become new Xenobots that look and move just like themselves.

And then these new Xenobots can go out, find cells, and build copies of themselves. Again and again.

“With the right design—they will spontaneously self-replicate,” says Joshua Bongard, Ph.D., a computer scientist and robotics expert at the University of Vermont who co-led the new research.

The results of the new research were published in the Proceedings of the National Academy of Sciences.

Into the Unknown

In a Xenopus laevis frog, these embryonic cells would develop into skin. “They would be sitting on the outside of a tadpole, keeping out pathogens and redistributing mucus,” says Michael Levin, Ph.D., a professor of biology and director of the Allen Discovery Center at Tufts University and co-leader of the new research. “But we’re putting them into a novel context. We’re giving them a chance to reimagine their multicellularity.” Levin is also an Associate Faculty member at the Wyss Institute.

As Pac-man-shaped Xenobot “parents” move around their environment, they collect loose stem cells in their “mouths” that, over time, aggregate to create “offspring” Xenobots that develop to look just like their creators. Credit: Doug Blackiston and Sam Kriegman

And what they imagine is something far different than skin. “People have thought for quite a long time that we’ve worked out all the ways that life can reproduce or replicate. But this is something that’s never been observed before,” says co-author Douglas Blackiston, Ph.D., the senior scientist at Tufts University and the Wyss Institute who assembled the Xenobot “parents” and developed the biological portion of the new study.

“This is profound,” says Levin. “These cells have the genome of a frog, but, freed from becoming tadpoles, they use their collective intelligence, a plasticity, to do something astounding.” In earlier experiments, the scientists were amazed that Xenobots could be designed to achieve simple tasks. Now they are stunned that these biological objects—a computer-designed collection of cells—will spontaneously replicate. “We have the full, unaltered frog genome,” says Levin, “but it gave no hint that these cells can work together on this new task,” of gathering and then compressing separated cells into working self-copies.

“These are frog cells replicating in a way that is very different from how frogs do it. No animal or plant known to science replicates in this way,” says Sam Kriegman, Ph.D., the lead author on the new study, who completed his Ph.D. in Bongard’s lab at UVM and is now a post-doctoral researcher at Tuft’s Allen Center and Harvard University’s Wyss Institute for Biologically Inspired Engineering.

On its own, the Xenobot parent, made of some 3,000 cells, forms a sphere. “These can make children but then the system normally dies out after that. It’s very hard, actually, to get the system to keep reproducing,” says Kriegman. But with an artificial intelligence program working on the Deep Green supercomputer cluster at UVM’s Vermont Advanced Computing Core, an evolutionary algorithm was able to test billions of body shapes in simulation—triangles, squares, pyramids, starfish—to find ones that allowed the cells to be more effective at the motion-based “kinematic” replication reported in the new research.

“We asked the supercomputer at UVM to figure out how to adjust the shape of the initial parents, and the AI came up with some strange designs after months of chugging away, including one that resembled Pac-Man,” says Kriegman. “It’s very non-intuitive. It looks very simple, but it’s not something a human engineer would come up with. Why one tiny mouth? Why not five? We sent the results to Doug and he built these Pac-Man-shaped parent Xenobots. Then those parents built children, who built grandchildren, who built great-grandchildren, who built great-great-grandchildren.” In other words, the right design greatly extended the number of generations.

Kinematic replication is well-known at the level of molecules—but it has never been observed before at the scale of whole cells or organisms.

An AI-designed “parent” organism (C shape; red) beside stem cells that have been compressed into a ball (“offspring”; green). Credit: Douglas Blackiston and Sam Kriegman

“We’ve discovered that there is this previously unknown space within organisms, or living systems, and it’s a vast space,” says Bongard. “How do we then go about exploring that space? We found Xenobots that walk. We found Xenobots that swim. And now, in this study, we’ve found Xenobots that kinematically replicate. What else is out there?”

Or, as the scientists write in the Proceedings of the National Academy of Sciences study: “life harbors surprising behaviors just below the surface, waiting to be uncovered.”

Responding to Risk

Some people may find this exhilarating. Others may react with concern, or even terror, to the notion of a self-replicating biotechnology. For the team of scientists, the goal is deeper understanding.

“We are working to understand this property: replication. The world and technologies are rapidly changing. It’s important, for society as a whole, that we study and understand how this works,” says Bongard. These millimeter-sized living machines, entirely contained in a laboratory, easily extinguished, and vetted by federal, state and institutional ethics experts, “are not what keep me awake at night. What presents risk is the next pandemic; accelerating ecosystem damage from pollution; intensifying threats from climate change,” says UVM’s Bongard. “This is an ideal system in which to study self-replicating systems. We have a moral imperative to understand the conditions under which we can control it, direct it, douse it, exaggerate it.”

Bongard points to the COVID epidemic and the hunt for a vaccine. “The speed at which we can produce solutions matters deeply. If we can develop technologies, learning from Xenobots, where we can quickly tell the AI: ‘We need a biological tool that does X and Y and suppresses Z,’ —that could be very beneficial. Today, that takes an exceedingly long time.” The team aims to accelerate how quickly people can go from identifying a problem to generating solutions—”like deploying living machines to pull microplastics out of waterways or build new medicines,” Bongard says.

“We need to create technological solutions that grow at the same rate as the challenges we face,” Bongard says.

And the team sees promise in the research for advancements toward regenerative medicine. “If we knew how to tell collections of cells to do what we wanted them to do, ultimately, that’s regenerative medicine—that’s the solution to traumatic injury, birth defects, cancer, and aging,” says Levin. “All of these different problems are here because we don’t know how to predict and control what groups of cells are going to build. Xenobots are a new platform for teaching us.”

The scientists behind the Xenobots participated in a live panel discussion on December 1, 2021 to discuss the latest developments in their research. Credit: Wyss Institute at Harvard University

• PUBLICATION – Kinematic self-replication in reconfigurable organisms. Sam Kriegman, Douglas Blackiston, Michael Levin, and Josh Bongard, Proceedings of the National Academy of Sciences Dec 2021, 118 (49) e2112672118; DOI: 10.1073/pnas.2112672118

Most people associate the term “wearable” with a fitness tracker, smartwatch, or wireless earbuds. But what if cutting-edge biotechnology were integrated into your clothing, and could warn you when you were exposed to something dangerous?

A team of researchers from the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Massachusetts Institute of Technology has found a way to embed synthetic biology reactions into fabrics, creating wearable biosensors that can be customized to detect pathogens and toxins and alert the wearer.

The team has integrated this technology into standard face masks to detect the presence of the SARS-CoV-2 virus in a patient’s breath. The button-activated mask gives results within 90 minutes at levels of accuracy comparable to standard nucleic acid-based diagnostic tests like polymerase chain reactions (PCR). The achievement is reported in Nature Biotechnology.

The wFDCF face mask can be integrated into any standard face mask. The wearer pushes a button on the mask that releases a small amount of water into the system, which provides results within 90 minutes. Credit: Wyss Institute at Harvard University

“We have essentially shrunk an entire diagnostic laboratory down into a small, synthetic biology-based sensor that works with any face mask, and combines the high accuracy of PCR tests with the speed and low cost of antigen tests,” said co-first author Peter Nguyen, Ph.D., a Research Scientist at the Wyss Institute. “In addition to face masks, our programmable biosensors can be integrated into other garments to provide on-the-go detection of dangerous substances including viruses, bacteria, toxins, and chemical agents.”

Taking cells out of the equation

The SARS-CoV-2 biosensor is the culmination of three years of work on what the team calls their wearable freeze-dried cell-free (wFDCF) technology, which is built upon earlier iterations created in the lab of Wyss Core Faculty member and senior author Jim Collins. The technique involves extracting and freeze-drying the molecular machinery that cells use to read DNA and produce RNA and proteins. These biological elements are shelf-stable for long periods of time and activating them is simple: just add water. Synthetic genetic circuits can be added to create biosensors that can produce a detectable signal in response of the presence of a target molecule.

The researchers first applied this technology to diagnostics by integrating it into a tool to address the Zika virus outbreak in 2015. They created biosensors that can detect pathogen-derived RNA molecules and coupled them with a colored or fluorescent indicator protein, then embedded the genetic circuit into paper to create a cheap, accurate, portable diagnostic. Following their success embedding their biosensors into paper, they next set their sights on making them wearable.

These flexible, wearable biosensors can be integrated into fabric to create clothing that can detect pathogens and environmental toxins and alert the wearer via a companion smartphone app. Credit: Wyss Institute at Harvard University

“Other groups have created wearables that can sense biomolecules, but those techniques have all required putting living cells into the wearable itself, as if the user were wearing a tiny aquarium. If that aquarium ever broke, then the engineered bugs could leak out onto the wearer, and nobody likes that idea,” said Nguyen. He and his teammates started investigating whether their wFDCF technology could solve this problem, methodically testing it in more than 100 different kinds of fabrics.

Then, the COVID-19 pandemic struck.

Pivoting from wearables to face masks

“We wanted to contribute to the global effort to fight the virus, and we came up with the idea of integrating wFDCF into face masks to detect SARS-CoV-2. The entire project was done under quarantine or strict social distancing starting in May 2020. We worked hard, sometimes bringing non-biological equipment home and assembling devices manually. It was definitely different from the usual lab infrastructure we’re used to working under, but everything we did has helped us ensure that the sensors would work in real-world pandemic conditions,” said co-first author Luis Soenksen, Ph.D., a Postdoctoral Fellow at the Wyss Institute.

The team called upon every resource they had available to them at the Wyss Institute to create their COVID-19-detecting face masks, including toehold switches developed in Core Faculty member Peng Yin’s lab and SHERLOCK sensors developed in the Collins lab. The final product consists of three different freeze-dried biological reactions that are sequentially activated by the release of water from a reservoir via the single push of a button.

The first reaction cuts open the SARS-CoV-2 virus’ membrane to expose its RNA. The second reaction is an amplification step that makes numerous double-stranded copies of the Spike-coding gene from the viral RNA. The final reaction uses CRISPR-based SHERLOCK technology to detect any Spike gene fragments, and in response cut a probe molecule into two smaller pieces that are then reported via a lateral flow assay strip. Whether or not there are any Spike fragments available to cut depends on whether the patient has SARS-CoV-2 in their breath. This difference is reflected in changes in a simple pattern of lines that appears on the readout portion of the device, similar to an at-home pregnancy test.

When SARS-CoV-2 particles are present, the wFDCF system cuts a molecular bond that changes the pattern of lines that form in the readout strip, similar to an at-home pregnancy test. Credit: Wyss Institute at Harvard University

The wFDCF face mask is the first SARS-CoV-2 nucleic acid test that achieves high accuracy rates comparable to current gold standard RT-PCR tests while operating fully at room temperature, eliminating the need for heating or cooling instruments and allowing the rapid screening of patient samples outside of labs.

“This work shows that our freeze-dried, cell-free synthetic biology technology can be extended to wearables and harnessed for novel diagnostic applications, including the development of a face mask diagnostic. I am particularly proud of how our team came together during the pandemic to create deployable solutions for addressing some of the world’s testing challenges,” said Collins, Ph.D., who is also the Termeer Professor of Medical Engineering & Science at MIT.

Beyond the COVID-19 pandemic

The Wyss Institute’s wearable freeze-dried cell-free (wFDCF) technology can quickly diagnose COVID-19 from virus in patients’ breath, and can also be integrated into clothing to detect a wide variety of pathogens and other dangerous substances. Credit: Wyss Institute at Harvard University

The face mask diagnostic is in some ways the icing on the cake for the team, which had to overcome numerous challenges in order to make their technology truly wearable, including capturing droplets of a liquid substance within a flexible, unobtrusive device and preventing evaporation. The face mask diagnostic omits electronic components in favor of ease of manufacturing and low cost, but integrating more permanent elements into the system opens up a wide range of other possible applications.

In their paper, the researchers demonstrate that a network of fiber optic cables can be integrated into their wFCDF technology to detect fluorescent light generated by the biological reactions, indicating detection of the target molecule with a high level of accuracy. This digital signal can be sent to a smartphone app that allows the wearer to monitor their exposure to a vast array of substances.

“This technology could be incorporated into lab coats for scientists working with hazardous materials or pathogens, scrubs for doctors and nurses, or the uniforms of first responders and military personnel who could be exposed to dangerous pathogens or toxins, such as nerve gas,” said co-author Nina Donghia, a Staff Scientist at the Wyss Institute.

The team is actively searching for manufacturing partners who are interested in helping to enable the mass production of the face mask diagnostic for use during the COVID-19 pandemic, as well as for detecting other biological and environmental hazards.

“This team’s ingenuity and dedication to creating a useful tool to combat a deadly pandemic while working under unprecedented conditions is impressive in and of itself. But even more impressive is that these wearable biosensors can be applied to a wide variety of health threats beyond SARS-CoV-2, and we at the Wyss Institute are eager to collaborate with commercial manufacturers to realize that potential,” said Don Ingber, M.D., Ph.D., the Wyss Institute’s Founding Director. Ingber is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, and Professor of Bioengineering at the Harvard John A. Paulson School of Engineering and Applied Sciences.

Additional authors of the paper include Nicolaas M. Angenent-Mari and Helena de Puig from the Wyss Institute and MIT; former Wyss and MIT member Ally Huang who is now at Ampylus; Rose Lee, Shimyn Slomovic, Geoffrey Lansberry, Hani Sallum, Evan Zhao, and James Niemi from the Wyss Institute; and Tommaso Galbersanini from Dreamlux.

This research was supported by the Defense Threat Reduction Agency under grant HDTRA1-14-1-0006, the Paul G. Allen Frontiers Group, the Wyss Institute for Biologically Inspired Engineering, Harvard University, Johnson & Johnson through the J&J Lab Coat of the Future QuickFire Challenge award, CONACyT grant 342369 / 408970, and MIT-692 TATA Center fellowship 2748460.

• PAPER – Wearable materials with embedded synthetic biology sensors for biomolecule detection. Peter Q. Nguyen, Luis R. Soenksen, Nina M. Donghia, Nicolaas M. Angenent-Mari, Helena de Puig, Ally Huang, Rose Lee, Shimyn Slomovic, Tommaso Galbersanini, Geoffrey Lansberry, Hani M. Sallum, Evan M. Zhao, James B. Niemi and James J. Collins. Nat Biotechnol (2021).

The laser steering device is able to trace complex trajectories such as an exposed wire as well as a word within geometrical shapes. Credit: Wyss Institute at Harvard University

A microrobotic opto-electro-mechanical device able to steer a laser beam with high speed and a large range of motion could enhance the possibilities of minimally invasive surgeries

By Benjamin Boettner

Minimally invasive surgeries in which surgeons gain access to internal tissues through natural orifices or small external excisions are common practice in medicine. They are performed for problems as diverse as delivering stents through catheters, treating abdominal complications, and performing transnasal operations at the skull base in patients with neurological conditions.

The ends of devices for such surgeries are highly flexible (or “articulated”) to enable the visualization and specific manipulation of the surgical site in the target tissue. In the case of energy-delivering devices that allow surgeons to cut or dry (desiccate) tissues, and stop internal bleeds (coagulate) deep inside the body, a heat-generating energy source is added to the end of the device. However, presently available energy sources delivered via a fiber or electrode, such as radio frequency currents, have to be brought close to the target site, which limits surgical precision and can cause unwanted burns in adjacent tissue sections and smoke development.

Laser technology, which already is widely used in a number of external surgeries, such as those performed in the eye or skin, would be an attractive solution. For internal surgeries, the laser beam needs to be precisely steered, positioned and quickly repositioned at the distal end of an endoscope, which cannot be accomplished with the currently available relatively bulky technology.

Responding to an unmet need for a robotic surgical device that is flexible enough to access hard to reach areas of the G.I. tract while causing minimal peripheral tissue damage, Researchers at the Wyss Institute and Harvard SEAS have developed a laser steering device that has the potential to improve surgical outcomes for patients. Credit: Wyss Institute at Harvard University

Now, robotic engineers led by Wyss Associate Faculty member Robert Wood, Ph.D., and postdoctoral fellow Peter York, Ph.D., at Harvard University’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School for Engineering and Applied Science (SEAS) have developed a laser-steering microrobot in a miniaturized 6×16 millimeter package that operates with high speed and precision, and can be integrated with existing endoscopic tools. Their approach, reported in Science Robotics, could help significantly enhance the capabilities of numerous minimally invasive surgeries.

This collage shows a prototype of the laser steering device creating a star trajectory at 5000 mm/s. Credit: Wyss Institute at Harvard University

In this multi-disciplinary approach, we managed to harness our ability to rapidly prototype complex microrobotic mechanisms…provide clinicians with a non-disruptive solution that could allow them to advance the possibilities of minimally invasive surgeries in the human body with life-altering or potentially life-saving impact.

Robert Wood

“To enable minimally invasive laser surgery inside the body, we devised a microrobotic approach that allows us to precisely direct a laser beam at small target sites in complex patterns within an anatomical area of interest,” said York, the first and corresponding author on the study and a postdoctoral fellow on Wood’s microrobotics team. “With its large range of articulation, minimal footprint, and fast and precise action, this laser-steering end-effector has great potential to enhance surgical capabilities simply by being added to existing endoscopic devices in a plug-and-play fashion.”

The team needed to overcome the basic challenges in design, actuation, and microfabrication of the optical steering mechanism that enables tight control over the laser beam after it has exited from an optical fiber. These challenges, along with the need for speed and precision, were exacerbated by the size constraints – the entire mechanism had to be housed in a cylindrical structure with roughly the diameter of a drinking straw to be useful for endoscopic procedures.

“We found that for steering and re-directing the laser beam, a configuration of three small mirrors that can rapidly rotate with respect to one another in a small ‘galvanometer’ design provided a sweet spot for our miniaturization effort,” said second author Rut Peña, a mechanical engineer with micro-manufacturing expertise in Wood’s group. “To get there, we leveraged methods from our microfabrication arsenal in which modular components are laminated step-wise onto a superstructure on the millimeter scale – a highly effective fabrication process when it comes to iterating on designs quickly in search of an optimum, and delivering a robust strategy for mass-manufacturing a successful product.”

The microrobotic laser-steering end-effector (on the right) can be used as a fitted add-on accessory for existing endoscopic systems (on the left) for use in minimally invasive surgery. Credit: Wyss Institute at Harvard University

The team demonstrated that their laser-steering end-effector, miniaturized to a cylinder measuring merely 6 mm in diameter and 16 mm in length, was able to map out and follow complex trajectories in which multiple laser ablations could be performed with high speed, over a large range, and be repeated with high accuracy.

To further show that the device, when attached to the end of a common colonoscope, could be applied to a life-like endoscopic task, York and Peña, advised by Wyss Clinical Fellow Daniel Kent, M.D., successfully simulated the resection of polyps by navigating their device via tele-operation in a benchtop phantom tissue made of rubber. Kent also is a resident physician in general surgery at the Beth Israel Deaconess Medical Center.

“In this multi-disciplinary approach, we managed to harness our ability to rapidly prototype complex microrobotic mechanisms that we have developed over the past decade to provide clinicians with a non-disruptive solution that could allow them to advance the possibilities of minimally invasive surgeries in the human body with life-altering or potentially life-saving impact,” said senior author Wood, Ph.D., who also is the Charles River Professor of Engineering and Applied Sciences at SEAS.

The laser steering device performing a colonoscope demo in a life-size model of the colon. Credit: Wyss Institute at Harvard University

Wood’s microrobotics team together with technology translation experts at the Wyss Institute have patented their approach and are now further de-risking their medical technology (MedTech) as an add-on for surgical endoscopes.

“The Wyss Institute’s focus on microrobotic devices and this new laser-steering device developed by Robert Wood’s team working across disciplines with clinicians and experts in translation will hopefully revolutionize how minimally invasive surgical procedures are carried out in a number of disease areas,” said Wyss Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, and Professor of Bioengineering at SEAS.

The study was funded by the National Science Foundation under award #CMMI-1830291, and the Wyss Institute for Biologically Inspired Engineering.

• PUBLICATION – Microrobotic laser steering for minimally invasive surgery Peter A. York, Rut Peña, Daniel Kent and Robert J. Wood. Science Robotics, 6(50).

Bluebots are fish-shaped robots that can coordinate their movements in three dimensions underwater, rather than the two dimensions previously achieved by Kilobots. Credit: Harvard SEAS

By Leah Burrows / SEAS Communications

Schools of fish exhibit complex, synchronized behaviors that help them find food, migrate, and evade predators. No one fish or sub-group of fish coordinates these movements, nor do fish communicate with each other about what to do next. Rather, these collective behaviors emerge from so-called implicit coordination — individual fish making decisions based on what they see their neighbors doing.

This type of decentralized, autonomous self-organization and coordination has long fascinated scientists, especially in the field of robotics.

Now, a team of researchers at Harvard’s Wyss Institute and John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed fish-inspired robots that can synchronize their movements like a real school of fish, without any external control. It is the first time researchers have demonstrated complex 3D collective behaviors with implicit coordination in underwater robots.

“Robots are often deployed in areas that are inaccessible or dangerous to humans, areas where human intervention might not even be possible,” said Florian Berlinger, a Ph.D. Candidate at the Wyss Institute and SEAS and first author of the paper. “In these situations, it really benefits you to have a highly autonomous robot swarm that is self-sufficient. By using implicit rules and 3D visual perception, we were able to create a system that has a high degree of autonomy and flexibility underwater where things like GPS and WiFi are not accessible.”

The research is published in Science Robotics.

The fish-inspired robotic swarm, dubbed Blueswarm, was created in the lab of Wyss Associate Faculty member Radhika Nagpal, Ph.D., who is also the Fred Kavli Professor of Computer Science at SEAS. Nagpal’s lab is a pioneer in self-organizing systems, from their 1,000 robot Kilobot swarm to their termite-inspired robotic construction crew.

However, most previous robotic swarms operated in two-dimensional space. Three-dimensional spaces, like air and water, pose significant challenges to sensing and locomotion.

To overcome these challenges, the researchers developed a vision-based coordination system in their fish robots based on blue LED lights. Each underwater robot, called a Bluebot, is equipped with two cameras and three LED lights. The on-board, fisheye-lens cameras detect the LEDs of neighboring Bluebots and use a custom algorithm to determine their distance, direction and heading. Based on the simple production and detection of LED light, the researchers demonstrated that the Blueswarm could exhibit complex self-organized behaviors, including aggregation, dispersion, and circle formation.

These fish-inspired robots can synchronize their movements without any outside control. Based on the simple production and detection of LED light, the robotic collective exhibits complex self-organized behaviors, including aggregation, dispersion, and circle formation. Credit: Harvard University’s Self-organizing Systems Research Group

“Each Bluebot implicitly reacts to its neighbors’ positions,” said Berlinger. “So, if we want the robots to aggregate, then each Bluebot will calculate the position of each of its neighbors and move towards the center. If we want the robots to disperse, the Bluebots do the opposite. If we want them to swim as a school in a circle, they are programmed to follow lights directly in front of them in a clockwise direction.”

The researchers also simulated a simple search mission with a red light in the tank. Using the dispersion algorithm, the Bluebots spread out across the tank until one comes close enough to the light source to detect it. Once the robot detects the light, its LEDs begin to flash, which triggers the aggregation algorithm in the rest of the school. From there, all the Bluebots aggregate around the signaling robot.

Blueswarm, a Harvard Wyss- and SEAS-developed underwater robot collective, uses a 3D vision-based coordination system and 3D locomotion to coordinate the movements of its individual Bluebots autonomously, mimicking the behavior of schools of fish. Credit: Harvard SEAS

“Our results with Blueswarm represent a significant milestone in the investigation of underwater self-organized collective behaviors,” said Nagpal. “Insights from this research will help us develop future miniature underwater swarms that can perform environmental monitoring and search in visually-rich but fragile environments like coral reefs. This research also paves a way to better understand fish schools, by synthetically recreating their behavior.”

The research was co-authored by Melvin Gauci, Ph.D., a former Wyss Technology Development Fellow. It was supported in part by the Office of Naval Research, the Wyss Institute for Biologically Inspired Engineering, and an Amazon AWS Research Award.

• PUBLICATION – Implicit coordination for 3D underwater collective behaviors in a fish-inspired robot swarm. Florian Berlinger, Melvin Gauci and Radhika Nagpal. Science Robotics, 6(50).

Graduate student Moritz Graule demonstrates a fabric arm sleeve with embedded sensors. The sensors detect the small changes in the Graule’s forearm muscle through the fabric. Such a sleeve could be used in everything from virtual reality simulations and sportswear to clinical diagnostics for neurodegenerative diseases like Parkinson’s Disease. Credit: Oluwaseun Araromi/Harvard SEAS

By Leah Burrows / SEAS communications

Newly engineered slinky-like strain sensors for textiles and soft robotic systems survive the washing machine, cars and hammers.

Think about your favorite t-shirt, the one you’ve worn a hundred times, and all the abuse you’ve put it through. You’ve washed it more times than you can remember, spilled on it, stretched it, crumbled it up, maybe even singed it leaning over the stove once. We put our clothes through a lot and if the smart textiles of the future are going to survive all that we throw at them, their components are going to need to be resilient.

Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering have developed an ultra-sensitive, seriously resilient strain sensor that can be embedded in textiles and soft robotic systems. The research is published in Nature.

“Current soft strain gauges are really sensitive but also really fragile,” said Oluwaseun Araromi, Ph.D., a Research Associate in Materials Science and Mechanical Engineering at SEAS and the Wyss Institute and first author of the paper. “The problem is that we’re working in an oxymoronic paradigm — highly sensitivity sensors are usually very fragile and very strong sensors aren’t usually very sensitive. So, we needed to find mechanisms that could give us enough of each property.”

In the end, the researchers created a design that looks and behaves very much like a Slinky.

“A Slinky is a solid cylinder of rigid metal but if you pattern it into this spiral shape, it becomes stretchable,” said Araromi. “That is essentially what we did here. We started with a rigid bulk material, in this case carbon fiber, and patterned it in such a way that the material becomes stretchable.”

The pattern is known as a serpentine meander, because its sharp ups and downs resemble the slithering of a snake. The patterned conductive carbon fibers are then sandwiched between two pre-strained elastic substrates. The overall electrical conductivity of the sensor changes as the edges of the patterned carbon fiber come out of contact with each other, similar to the way the individual spirals of a slinky come out of contact with each other when you pull both ends. This process happens even with small amounts of strain, which is the key to the sensor’s high sensitivity.

A close-up view of the sensor’s patterned conductive carbon fibers. The fibers are sandwiched between two prestrained elastic substrates. The overall electrical conductivity of the sensor changes as the edges of the patterned carbon fiber come out of contact with each other. Credit: James Weaver/Harvard SEAS

Unlike current highly sensitive stretchable sensors, which rely on exotic materials such as silicon or gold nanowires, this sensor doesn’t require special manufacturing techniques or even a clean room. It could be made using any conductive material.

The researchers tested the resiliency of the sensor by stabbing it with a scalpel, hitting it with a hammer, running it over with a car, and throwing it in a washing machine ten times. The sensor emerged from each test unscathed. To demonstrate its sensitivity, the researchers embedded the sensor in a fabric arm sleeve and asked a participant to make different gestures with their hand, including a fist, open palm, and pinching motion. The sensors detected the small changes in the subject’s forearm muscle through the fabric and a machine learning algorithm was able to successfully classify these gestures.

“These features of resilience and the mechanical robustness put this sensor in a whole new camp,” said Araromi.

Such a sleeve could be used in everything from virtual reality simulations and sportswear to clinical diagnostics for neurodegenerative diseases like Parkinson’s Disease. Harvard’s Office of Technology Development has filed to protect the intellectual property associated with this project.

“The combination of high sensitivity and resilience are clear benefits of this type of sensor,” said senior author Robert Wood, Ph.D., Associate Faculty member at the Wyss Institute, and the Charles River Professor of Engineering and Applied Sciences at SEAS. “But another aspect that differentiates this technology is the low cost of the constituent materials and assembly methods. This will hopefully reduce the barriers to get this technology widespread in smart textiles and beyond.”

This ultra-sensitive resilient strain sensor can be embedded in textiles and soft robotic systems. Credit: Oluwaseun Araromi/Harvard SEAS

“We are currently exploring how this sensor can be integrated into apparel due to the intimate interface to the human body it provides,” says co-author and Wyss Associate Faculty member Conor Walsh, Ph.D., who also is the Paul A. Maeder Professor of Engineering and Applied Sciences at SEAS. “This will enable exciting new applications by being able to make biomechanical and physiological measurements throughout a person’s day, not possible with current approaches.”

The combination of high sensitivity and resilience are clear benefits of this type of sensor. But another aspect that differentiates this technology is the low cost of the constituent materials and assembly methods. This will hopefully reduce the barriers to get this technology widespread in smart textiles and beyond.

Robert Wood

The research was co-authored by Moritz A. Graule, Kristen L. Dorsey, Sam Castellanos, Jonathan R. Foster, Wen-Hao Hsu, Arthur E. Passy, James C. Weaver, Senior Staff Scientist at SEAS and Joost J. Vlassak, the Abbott and James Lawrence Professor of Materials Engineering at SEAS. It was funded through the university’s strategic research alliance with Tata. The 6-year, $8.4M alliance was established in 2016 to advance Harvard innovation in fields including robotics, wearable technologies, and the internet of things (IoT).

• PUBLICATION – Ultra-sensitive and resilient compliant strain gauges for soft machines. Oluwaseun A. Araromi, Moritz A. Graule, Kristen L. Dorsey, Sam Castellanos, Jonathan R. Foster, Wen-Hao Hsu, Arthur E. Passy, Joost J. Vlassak, James C. Weaver, Conor J. Walsh and Robert J. Wood. Nature, vol. 587, pp. 219-224 (2020)

A team led by Wyss Associate Faculty member Paolo Bonato, Ph.D., found in a recent study that wearable technology is suitable to accurately track motor recovery of individuals with brain injuries and thus allow clinicians to choose more effective interventions and to improve outcomes. Credit: Shutterstock/Dmytro Zinkevych

By Tim Sullivan / Spaulding Rehabilitation Hospital Communications

A group based out of the Spaulding Motion Analysis Lab at Spaulding Rehabilitation Hospital published “Enabling Precision Rehabilitation Interventions Using Wearable Sensors and Machine Learning to Track Motor Recovery” in the newest issue of Nature Digital Medicine. The aim of the study is to lay the groundwork for the design of “precision rehabilitation” interventions by using wearable technologies to track the motor recovery of individuals with brain injury.

The study found that the technology is suitable to accurately track motor recovery and thus allow clinicians to choose more effective interventions and to improve outcomes. The study was a collaborative effort under students and former students connected to the Motion Analysis Lab under faculty mentorship.

Paolo Bonato, Ph.D., Director of the Spaulding Motion Analysis Lab and senior author on the study said, “By providing clinicians precise data will enable them to design more effective interventions to improve the care we deliver. To have so many of our talented young scientists and researchers from our lab collaborate to create this meaningful paper is especially gratifying for all of our faculty who support our ongoing research enterprise.” Bonato is also an Associate Faculty member at Harvard’s Wyss Institute for Biologically Inspired Engineering.

Catherine Adans-Dester, P.T., Ph.D., a member of Dr. Bonato’s team served as lead author on the manuscript. “The need to develop patient-specific interventions is apparent when one considers that clinical studies often report satisfactory motor gains only in a portion of participants, which suggests that clinical outcomes could be improved if we had better tools to develop patient-specific interventions. Data collected using wearable sensors provides clinicians with the opportunity to do so with little burden on clinicians and patients,” said Dr. Adans-Dester. The approach proposed in the paper relied on machine learning-based algorithms to derive clinical score estimates from wearable sensor data collected during functional motor tasks. Sensor-based score estimates showed strong agreement with those generated by clinicians.

By providing clinicians precise data will enable them to design more effective interventions to improve the care we deliver

Paolo Bonato

The results of the study demonstrated that wearable sensor data can be used to derive accurate estimates of clinical scores utilized in the clinic to capture the severity of motor impairments and the quality of upper-limb movement patterns. In the study, the upper-limb Fugl-Meyer Assessment (FMA) scale was used to generate clinical scores of the severity of motor impairments, and the Functional Ability Scale (FAS) was used to generate clinical scores of the quality of movement. Wearable sensor data (i.e., accelerometer data) was collected during the performance of eight functional motor tasks taken from the Wolf-Motor Function Test, thus providing a sample of gross arm movements and fine motor control tasks. Machine learning-based algorithms were developed to derive accurate estimates of the FMA and FAS clinical scores from the sensor data. A total of 37 study participants (16 stroke survivors and 21 traumatic brain injury survivors) participated in the study.

Involved in the study in addition to Dr. Bonato and Dr. Adans-Dester were Nicolas Hankov, Anne O’Brien, Gloria Vergara-Diaz, Randie Black-Schaffer, MD, Ross Zafonte, DO, from the Harvard Medical School Department of Physical Medicine & Rehabilitation at Spaulding Rehabilitation Hospital, Boston MA, USA, Jennifer Dy Department of Electrical and Computer Engineering, Northeastern University, Boston MA, and Sunghoon I. Lee of the College of Information and Computer Sciences, University of Massachusetts Amherst, Amherst MA.

• PUBLICATION – Nature Digital Medicine: Enabling precision rehabilitation interventions using wearable sensors and machine learning to track motor recovery.

Minimally invasive laparoscopic surgery, in which a surgeon uses tools and a tiny camera inserted into small incisions to perform operations, has made surgical procedures safer for both patients and doctors over the last half-century. Recently, surgical robots have started to appear in operating rooms to further assist surgeons by allowing them to manipulate multiple tools at once with greater precision, flexibility, and control than is possible with traditional techniques. However, these robotic systems are extremely large, often taking up an entire room, and their tools can be much larger than the delicate tissues and structures on which they operate.

The mini-RCM is controlled by three linear actuators (mini-LAs) that allow it to move in multiple dimensions and help correct hand tremors and other disturbances during teleoperation. Credit: Wyss Institute at Harvard University

A collaboration between Wyss Associate Faculty member Robert Wood, Ph.D. and Robotics Engineer Hiroyuki Suzuki of Sony Corporation has brought surgical robotics down to the microscale by creating a new, origami-inspired miniature remote center of motion manipulator (the “mini-RCM”). The robot is the size of a tennis ball, weighs about as much as a penny, and successfully performed a difficult mock surgical task, as described in a recent issue of Nature Machine Intelligence.

“The Wood lab’s unique technical capabilities for making micro-robots have led to a number of impressive inventions over the last few years, and I was convinced that it also had the potential to make a breakthrough in the field of medical manipulators as well,” said Suzuki, who began working with Wood on the mini-RCM in 2018 as part of a Harvard-Sony collaboration. “This project has been a great success.”

A mini robot for micro tasks

To create their miniature surgical robot, Suzuki and Wood turned to the Pop-Up MEMS manufacturing technique developed in Wood’s lab, in which materials are deposited on top of each other in layers that are bonded together, then laser-cut in a specific pattern that allows the desired three-dimensional shape to “pop up,” as in a children’s pop-up picture book. This technique greatly simplifies the mass-production of small, complex structures that would otherwise have to be painstakingly constructed by hand.

The team created a parallelogram shape to serve as the main structure of the robot, then fabricated three linear actuators (mini-LAs) to control the robot’s movement: one parallel to the bottom of the parallelogram that raises and lowers it, one perpendicular to the parallelogram that rotates it, and one at the tip of the parallelogram that extends and retracts the tool in use. The result was a robot that is much smaller and lighter than other microsurgical devices previously developed in academia.

The mini-LAs are themselves marvels in miniature, built around a piezoelectric ceramic material that changes shape when an electrical field is applied. The shape change pushes the mini-LA’s “runner unit” along its “rail unit” like a train on train tracks, and that linear motion is harnessed to move the robot. Because piezoelectric materials inherently deform as they change shape, the team also integrated LED-based optical sensors into the mini-LA to detect and correct any deviations from the desired movement, such as those caused by hand tremors.

Steadier than a surgeon’s hands

To mimic the conditions of a teleoperated surgery, the team connected the mini-RCM to a Phantom Omni device, which manipulated the mini-RCM in response to the movements of a user’s hand controlling a pen-like tool. Their first test evaluated a human’s ability to trace a tiny square smaller than the tip of a ballpoint pen, looking through a microscope and either tracing it by hand, or tracing it using the mini-RCM. The mini-RCM tests dramatically improved user accuracy, reducing error by 68% compared to manual operation – an especially important quality given the precision required to repair small and delicate structures in the human body.

After the mini-RCM’s success on the tracing test, the researchers then created a mock version of a surgical procedure called retinal vein cannulation, in which a surgeon must carefully insert a needle through the eye to inject therapeutics into the tiny veins at the back of the eyeball. They fabricated a silicone tube the same size as the retinal vein (about twice the thickness of a human hair), and successfully punctured it with a needle attached to the end of the mini-RCM without causing local damage or disruption.

In addition to its efficacy in performing delicate surgical maneuvers, the mini-RCM’s small size provides another important benefit: it is easy to set up and install and, in the case of a complication or electrical outage, the robot can be easily removed from a patient’s body by hand.

“The Pop-Up MEMS method is proving to be a valuable approach in a number of areas that require small yet sophisticated machines, and it was very satisfying to know that it has the potential to improve the safety and efficiency of surgeries to make them even less invasive for patients,” said Wood, who is also the Charles River Professor of Engineering and Applied Sciences at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS).

The researchers aim to increase the force of the robot’s actuators to cover the maximum forces experienced during an operation, and improve its positioning precision. They are also investigating using a laser with a shorter pulse during the machining process, to improve the mini-LAs’ sensing resolution.

“This unique collaboration between the Wood lab and Sony illustrates the benefits that can arise from combining the real-world focus of industry with the innovative spirit of academia, and we look forward to seeing the impact this work will have on surgical robotics in the near future,” said Wyss Institute Founding Director Don Ingber, M.D., Ph.D., who is also the the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, and Professor of Bioengineering at SEAS.

• PUBLICATION – Nature Machine Intelligence: Origami-inspired miniature manipulator for teleoperated microsurgery
• WYSS TECHNOLOGY: Pop-Up MEMS: Origami-Inspired Micromanufacturing

The newly designed HAMR-Jr alongside its predecessor, HAMR-VI. HAMR-Jr is only slightly bigger in length and width than a penny, making it one of the smallest yet highly capable, high-speed insect-scale robots. Credit: Kaushik Jayaram/Harvard SEAS

This itsy-bitsy robot can’t climb up the waterspout yet but it can run, jump, carry heavy payloads and turn on a dime. Dubbed HAMR-JR, this microrobot developed by researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and Harvard’s Wyss Institute for Biologically Inspired Engineering, is a half-scale version of the cockroach-inspired Harvard Ambulatory Microrobot or HAMR.

About the size of a penny, HAMR-JR can perform almost all of the feats of its larger-scale predecessor, making it one of the most dexterous microrobots to date.

“Most robots at this scale are pretty simple and only demonstrate basic mobility,” said Kaushik Jayaram, Ph.D., a former postdoctoral fellow at SEAS and the Wyss Institute, and first author of the paper. “We have shown that you don’t have to compromise dexterity or control for size.”

Jayaram is currently an Assistant Professor at the University of Colorado, Boulder.

The research was presented virtually at the International Conference on Robotics and Automation (ICRA 2020) this week.

One of the big questions going into this research was whether or not the pop-up manufacturing process used to build previous versions of HAMR and other microbots, including the RoboBee, could be used to build robots at multiple scales — from tiny surgical bots to large-scale industrial robots.

PC-MEMS (short for printed circuit microelectromechanical systems) is a fabrication process in which the robot’s components are etched into a 2D sheet and then popped out in its 3D structure. To build HAMR-JR, the researchers simply shrunk the 2D sheet design of the robot — along with the actuators and onboard circuitry — to recreate a smaller robot with all the same functionalities.

“The wonderful part about this exercise is that we did not have to change anything about the previous design,” said Jayaram. “We proved that this process can be applied to basically any device at a variety of sizes.”

HAMR-JR comes in at 2.25 centimeters in body length and weighs about 0.3 grams — a fraction of the weight of an actual penny. It can run about 14 body lengths per second, making it not only one of the smallest but also one of the fastest microrobots.

Scaling down does change some of the principles governing things like stride length and joint stiffness, so the researchers also developed a model that can predict locomotion metrics like running speeds, foot forces, and payload based on a target size. The model can then be used to design a system with the required specifications.

“This new robot demonstrates that we have a good grasp on the theoretical and practical aspects of scaling down complex robots using our folding-based assembly approach,” said co-author Robert Wood, Ph.D., Charles River Professor of Engineering and Applied Sciences in SEAS and Core Faculty Member of the Wyss Institute.

This research was co-authored by Jennifer Shum, Samantha Castellanos and E. Farrell Helbling, Ph.D. This research was supported by the Defense Advanced Research Projects Agency (DARPA) and the Wyss Institute.

• WYSS TECHNOLOGY: HAMR: Versatile Crawling Microrobot
• PUBLICATION – IEEE International Conference on Robotics and Automation 2020: Scaling down an insect-size microrobot, HAMR-VI into HAMR-Jr

Using a robot to disrupt the gait cycle of participants, researchers discovered that feedforward mechanisms controlled by the cerebellum and feedback mechanisms controlled at the spinal level determine how the nervous system responds to robot-induced changes in step length. Credit: Wyss Institute at Harvard University

Many of us aren’t spending much time outside lately, but there are still many obstacles for us to navigate as we walk around: the edge of the coffee table, small children, the family dog. How do our brains adjust to changes in our walking strides? Researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Motion Analysis Laboratory at Spaulding Rehabilitation Hospital used robots to try to answer that question, and discovered that mechanisms in both the cerebellum and the spinal cord determine how the nervous system responds to robot-induced changes in step length. The new study is published in the latest issue of Scientific Reports, and points the way toward improving robot-based physical rehabilitation programs for patients.

“Our understanding of the neural mechanisms underlying locomotor adaptation is still limited. Specifically, how behavioral, functional, and physiological processes work in concert to achieve adaptation during locomotion has remained elusive to date,” said Paolo Bonato, Ph.D., an Associate Faculty member of the Wyss Institute and Director of the Spaulding Motion Analysis Lab who led the study. “Our goal is to create a better understanding of this process and hence develop more effective clinical interventions.”

For the study, the team used a robot to induce two opposite unilateral mechanical perturbations to human subjects as they were walking that affected their step length over multiple gait cycles. Electrical signals recorded from muscles were collected and analyzed to determine how muscle synergies (the activation of a group of muscles to create a specific movement) change in response to perturbation. The results revealed a combination of feedforward control signals coming from the cerebellum and feedback-driven control signals arising in the spinal cord during adaptation. The relative side-specific contributions of the two processes to motor-output adjustments, however, depended on which type of perturbation was delivered. Overall, the observations provide evidence that, in humans, both descending and afferent drives project onto the same spinal interneuronal networks that encode locomotor muscle synergies.

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These results mirror previous observations from animal studies, strongly suggesting the presence of a defined population of spinal interneurons regulating muscle coordination that can be accessed by both cortical and afferent drives in humans. “Our team hopes to build on this work to develop new approaches to the design of robot-assisted gait rehabilitation procedures targeting specific descending- and afferent-driven responses in muscle synergies in the coming year,” said Bonato.

• PUBLICATION – Scientific Reports: Robot-Driven Locomotor Perturbations Reveal Synergy-Mediated, Context-Dependent Feedforward and Feedback Mechanisms of Adaptation

Of all the cool things about octopuses (and there are a lot), their arms may rank among the coolest.

Two-thirds of an octopus’s neurons are in its arms, meaning each arm literally has a mind of its own. Octopus arms can untie knots, open childproof bottles, and wrap around prey of any shape or size. The hundreds of suckers that cover their arms can form strong seals even on rough surfaces underwater.

Imagine if a robot could do all that.

Researchers have developed an octopus-inspired robot can grip, move, and manipulate a wide range of objects. Credit: Elias Knubben, Zhexin Xie, August Domel, and Li Wen

Researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS) and colleagues from Beihang University have developed an octopus-inspired soft robotic arm that can grip, move, and manipulate a wide range of objects. Its flexible, tapered design, complete with suction cups, gives the gripper a firm grasp on objects of all shapes, sizes and textures — from eggs to smartphones to large exercise balls.

“Most previous research on octopus-inspired robots focused either on mimicking the suction or the movement of the arm, but not both,” said co-first author August Domel, Ph.D., a Postdoctoral Scholar at Stanford University and former graduate student at the Wyss Institute and Harvard. “Our research is the first to quantify the tapering angles of the arms and the combined functions of bending and suction, which allows for a single small gripper to be used for a wide range of objects that would otherwise require the use of multiple grippers.”

The research is published in Soft Robotics.

The researchers began by studying the tapering angle of real octopus arms and quantifying which design for bending and grabbing objects would work best for a soft robot. Next, the team looked at the layout and structure of the suckers (yes, that is the scientific term) and incorporated them into the design.

“We mimicked the general structure and distribution of these suckers for our soft actuators,” said co-first author Zhexin Xie, Ph.D., a graduate student at Beihang University. “Although our design is much simpler than its biological counterpart, these vacuum-based biomimetic suckers can attach to almost any object.”

Xie is the co-inventor of the Festo Tentacle Gripper, which is the first fully integrated implementation of this technology in a commercial prototype.

The soft robot is controlled with two valves, one to apply pressure for bending the arm and one for a vacuum that engages the suckers. By changing the pressure and vacuum, the arm can attach to any object, wrap around it, carry it, and release it. Credit: Bertoldi Lab/Harvard SEAS

Researchers control the arm with two valves, one to apply pressure for bending the arm and one as a vacuum that engages the suckers. By changing the pressure and vacuum, the arm can attach to an object, wrap around it, carry it, and release it.

The researchers successfully tested the device on many different objects, including thin sheets of plastic, coffee mugs, test tubes, eggs, and even live crabs. The tapered design also allowed the arm to squeeze into confined spaces and retrieve objects.

“The results from our study not only provide new insights into the creation of next-generation soft robotic actuators for gripping a wide range of morphologically diverse objects, but also contribute to our understanding of the functional significance of arm taper angle variability across octopus species,” said Katia Bertoldi, Ph.D., an Associate Faculty member of the Wyss Institute who is also the William and Ami Kuan Danoff Professor of Applied Mechanics at SEAS, and co-senior author of the study.

This research was also co-authored by James Weaver from the Wyss Institute, Ning An and Connor Green from Harvard SEAS, Zheyuan Gong, Tianmiao Wang, and Li Wen from Beihang University, and Elias M. Knubben from Festo SE & Co. It was supported in part by the National Science Foundation under grant DMREF-1533985 and Festo Corporate’s project division.

• PUBLICATION – Soft Robotics: Octopus Arm-Inspired Tapered Soft Actuators with Suckers for Improved Grasping

The Wyss Institute’s and SEAS robotics team built different models of the soft actuator powered RoboBee. Shown here is a four-wing, two actuator, and an eight-wing, four-actuator RoboBee model the latter of which being the first soft actuator-powered flying microrobot that is capable of controlled hovering flight. Credit: Harvard Microrobotics Lab/Harvard SEAS

The sight of a RoboBee careening towards a wall or crashing into a glass box may have once triggered panic in the researchers in the Harvard Microrobotics Laboratory at the Harvard John A. Paulson School of Engineering and Applied Science (SEAS), but no more.

Researchers at SEAS and Harvard’s Wyss Institute for Biologically Inspired Engineering have developed a resilient RoboBee powered by soft artificial muscles that can crash into walls, fall onto the floor, and collide with other RoboBees without being damaged. It is the first microrobot powered by soft actuators to achieve controlled flight.

“There has been a big push in the field of microrobotics to make mobile robots out of soft actuators because they are so resilient,” said Yufeng Chen, Ph.D., a former graduate student and postdoctoral fellow at SEAS and first author of the paper. “However, many people in the field have been skeptical that they could be used for flying robots because the power density of those actuators simply hasn’t been high enough and they are notoriously difficult to control. Our actuator has high enough power density and controllability to achieve hovering flight.”

The research is published in Nature.

To solve the problem of power density, the researchers built upon the electrically-driven soft actuators developed in the lab of David Clarke, Ph.D., the Extended Tarr Family Professor of Materials at SEAS. These soft actuators are made using dielectric elastomers, soft materials with good insulating properties that deform when an electric field is applied.

By improving the electrode conductivity, the researchers were able to operate the actuator at 500 Hertz, on par with the rigid actuators used previously in similar robots.

Another challenge when dealing with soft actuators is that the system tends to buckle and become unstable. To solve this challenge, the researchers built a lightweight airframe with a piece of vertical constraining thread to prevent the actuator from buckling.

The soft actuators can be easily assembled and replaced in these small-scale robots. To demonstrate various flight capabilities, the researchers built several different models of the soft actuator-powered RoboBee. A two-wing model could take off from the ground but had no additional control. A four-wing, two-actuator model could fly in a cluttered environment, overcoming multiple collisions in a single flight.

“One advantage of small-scale, low-mass robots is their resilience to external impacts,” said Elizabeth Farrell Helbling, Ph.D., a former graduate student at SEAS and a coauthor on the paper. “The soft actuator provides an additional benefit because it can absorb impact better than traditional actuation strategies. This would come in handy in potential applications such as flying through rubble for search and rescue missions.”

An eight-wing, four-actuator model demonstrated controlled hovering flight, the first for a soft-actuator-powered flying microrobot.

Next, the researchers aim to increase the efficiency of the soft-powered robot, which still lags far behind more traditional flying robots.

“Soft actuators with muscle-like properties and electrical activation represent a grand challenge in robotics,” says Wyss Institute Core Faculty member Robert Wood, Ph.D., who also is the Charles River Professor of Engineering and Applied Sciences in SEAS and senior author of the paper. “If we could engineer high performance artificial muscles, the sky is the limit for what robots we could build.”

Harvard’s Office of Technology Development has protected the intellectual property relating to this project and is exploring commercialization opportunities.

This paper was also co-authored by Huichan Zhao, Jie Mao, Pakpong Chirarattananon, Nak-seung, and Patrick Hyun. It supported in part by the National Science Foundation.

• WYSS TECHNOLOGY: Autonomous Flying Microrobots (RoboBees)
• WYSS TECHNOLOGY: Pop-Up MEMS
• PUBLICATION – Nature: Controlled flight of a microrobot powered by soft artificial muscles

What would it take to transform a flat sheet into a human face? How would the sheet need to grow and shrink to form eyes that are concave into the face and a convex nose and chin that protrude?

How to encode and release complex curves in shape-shifting structures is at the center of research led by the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and Harvard’s Wyss Institute of Biologically Inspired Engineering.

Over the past decade, theorists and experimentalists have found inspiration in nature as they have sought to unravel the physics, build mathematical frameworks, and develop materials and 3D and 4D-printing techniques for structures that can change shape in response to external stimuli.

However, complex multi-scale curvature has remained out of reach.

A portrait of Carl Friedrich Gauss painted by Christian Albrecht Jensen in 1840. The researchers generated a 3D surface via an artificial intelligence algorithm. The ribs in the different layers of the lattice are programmed to grow and shrink in response to a change in temperature, mapping the curves of Gauss’ face. Images courtesy of Lori Sanders/Harvard SEAS

Now, researchers have created the most complex shape-shifting structures to date — lattices composed of multiple materials that grow or shrink in response to changes in temperature. To demonstrate their technique, team printed flat lattices that shape morph into a frequency-shifting antenna or the face of pioneering mathematician Carl Friedrich Gauss in response to a change in temperature.

The research is published in the Proceedings of the National Academy of Sciences.

“Form both enables and constrains function,” said L Mahadevan, Ph.D., the de Valpine Professor of Applied Mathematics, and Professor of Physics and Organismic and Evolutionary Biology at Harvard. “Using mathematics and computation to design form, and a combination of multi-scale geometry and multi-material printing to realize it, we are now able to build shape-shifting structures with the potential for a range of functions.”

“Together, we are creating new classes of shape-shifting matter,” said Jennifer A. Lewis, Sc.D., the Hansjörg Wyss Professor of Biologically Inspired Engineering at Harvard. “Using an integrated design and fabrication approach, we can encode complex ‘instruction sets’ within these printed materials that drive their shape-morphing behavior.”

Lewis is also a Core Faculty member of the Wyss Institute.

To create complex and doubly-curved shapes — such as those found on a face — the team turned to a bilayer, multimaterial lattice design.

“The open cells of the curved lattice give it the ability to grow or shrink a lot, even if the material itself undergoes limited extension,” said co-first author Wim M. van Rees, Ph.D., who was a postdoctoral fellow at SEAS and is now an Assistant Professor at MIT.

To achieve complex curves, growing and shrinking the lattice on its own isn’t enough. You need to be able to direct the growth locally.

“That’s where the materials palette that we’ve developed comes in,” said J. William Boley, Ph.D., a former postdoctoral fellow at SEAS and co-first author of the paper. “By printing materials with different thermal expansion behavior in pre-defined configurations, we can control the growth and shrinkage of each individual rib of the lattice, which in turn gives rise to complex bending of the printed lattice both within and out of plane.” Boley is now an Assistant Professor at Boston University.

The researchers used four different materials and programmed each rib of the lattice to change shape in response to a change in temperature. Using this method, they printed a shape-shifting patch antenna, which can change resonant frequencies as it changes shape.

To showcase the ability of the method to create a complex surface with multiscale curvature, the researchers printed the face of the 19th century mathematician who laid the foundations of differential geometry: Carl Friederich Gauss. Images courtesy of Lori Sanders/Harvard SEAS

To showcase the ability of the method to create a complex surface with multiscale curvature, the researchers decided to print a human face. They chose the face of the 19th century mathematician who laid the foundations of differential geometry: Carl Friederich Gauss. The researchers began with a 2D portrait of Gauss, painted in 1840, and generated a 3D surface using an open-source artificial intelligence algorithm. They then programmed the ribs in the different layers of the lattice to grow and shrink, mapping the curves of Gauss’ face.

This inverse design approach and multimaterial 4D printing method could be extended to other stimuli-responsive materials and be used to create scalable, reversible, shape-shifting structures with unprecedented complexity.

“Application areas include, soft electronics, smart fabrics, tissue engineering, robotics and beyond,” said Boley.

“This work was enabled by recent advances in posing and solving geometric inverse problems combined with 4D-printing technologies using multiple materials. Going forward, our hope is that this multi-disciplinary approach for shaping matter will be broadly adopted,” said Mahadevan.

This research was co-authored by Charles Lissandrello, Mark Horenstein, Ryan Truby, and Arda Kotikian. It was supported by the National Science Foundation and Draper Laboratory.

A new ultra-soft gripper developed at the Wyss Institute and Baruch College uses fettuccini-like silicone “fingers” inflated with water to gently but firmly grasp jellyfish and release them without harm, allowing scientists to safely interact with these delicate creatures in their own habitats. Credit: Anand Varma

Now, a new technology developed by researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (SEAS), and Baruch College at CUNY offers a novel solution to that problem in the form of an ultra-soft, underwater gripper that uses hydraulic pressure to gently but firmly wrap its fettuccini-like fingers around a single jellyfish, then release it without causing harm. The gripper is described in a new paper published in Science Robotics.

“Our ultra-gentle gripper is a clear improvement over existing deep-sea sampling devices for jellies and other soft-bodied creatures that are otherwise nearly impossible to collect intact,” said first author Nina Sinatra, Ph.D., a former graduate student in the lab of Robert Wood at the Wyss Institute. “This technology can also be extended to improve underwater analysis techniques and allow extensive study of the ecological and genetic features of marine organisms without taking them out of the water.”

The gripper’s six “fingers” are composed of thin, flat strips of silicone with a hollow channel inside bonded to a layer of flexible but stiffer polymer nanofibers. The fingers are attached to a rectangular, 3D-printed plastic “palm” and, when their channels are filled with water, curl in the direction of the nanofiber-coated side. The fingers each exert an extremely low amount of pressure – about 0.0455 kPA, or less than one-tenth of the pressure of a human’s eyelid on their eye. By contrast, current state-of-the-art soft marine grippers, which are used to capture delicate but more robust animals than jellyfish, exert about 1 kPA.

First author Nina Sinatra, Ph.D. tests the ultra-soft gripper on a jellyfish at the New England Aquarium. Credit: Anand Varma

The researchers fitted their ultra-gentle gripper to a specially created hand-held device and tested its ability to grasp an artificial silicone jellyfish in a tank of water to determine the positioning and precision required to collect a sample successfully, as well as the optimum angle and speed at which to capture a jellyfish. They then moved on to the real thing at the New England Aquarium, where they used the grippers to grab swimming moon jellies, jelly blubbers, and spotted jellies, all about the size of a golf ball.

The gripper was successfully able to trap each jellyfish against the palm of the device, and the jellyfish were unable to break free from the fingers’ grasp until the gripper was depressurized. The jellyfish showed no signs of stress or other adverse effects after being released, and the fingers were able to open and close roughly 100 times before showing signs of wear and tear.

“Marine biologists have been waiting a long time for a tool that replicates the gentleness of human hands in interacting with delicate animals like jellyfish from inaccessible environments,” said co-author David Gruber, Ph.D., who is a Professor of Biology and Environmental Science at Baruch College, CUNY and a National Geographic Explorer. “This gripper is part of an ever-growing soft robotic toolbox that promises to make underwater species collection easier and safer, which would greatly improve the pace and quality of research on animals that have been under-studied for hundreds of years, giving us a more complete picture of the complex ecosystems that make up our oceans.”

The ultra-soft gripper is the latest innovation in the use of soft robotics for underwater sampling, an ongoing collaboration between Gruber and Wyss Founding Core Faculty member Robert Wood, Ph.D. that has produced the origami-inspired RAD sampler and multi-functional “squishy fingers” to collect a diverse array of hard-to-capture organisms, including squids, octopuses, sponges, sea whips, corals, and more.

“Soft robotics is an ideal solution to long-standing problems like this one across a wide variety of fields, because it combines the programmability and robustness of traditional robots with unprecedented gentleness thanks to the flexible materials used,” said Wood, who is the co-lead of the Wyss Institute’s Bioinspired Soft Robotics Platform, the Charles River Professor of Engineering and Applied Sciences at SEAS, and a National Geographic Explorer.

“At the Wyss Institute we are always asking, ‘How can we make this better?’ I am extremely impressed by the ingenuity and out-of-the-box thinking that Rob Wood and his team have applied to solve a real-world problem that exists in the open ocean, rather than in the laboratory. This could help to greatly advance ocean science,” said Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School, the Vascular Biology Program at Boston Children’s Hospital, and Professor of Bioengineering at SEAS.

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The team is continuing to refine the ultra-soft gripper’s design, and aims to conduct studies that evaluate the jellyfishes’ physiological response to being held by the gripper, to more definitively prove that they do not cause the animals stress. Wood and Gruber are also co-Principal Investigators of the Schmidt Ocean Institute’s “Designing the Future” project, and will be further testing their various underwater robots on an upcoming expedition aboard the research ship Falkor in 2020.

Additional authors of the paper are Clark Teeple, Daniel Vogt, M.S., and Kevin Kit Parker, Ph.D. from the Wyss Institute and Harvard SEAS. Parker is a Founding Core Faculty member of the Wyss Institute and the Tarr Family Professor of Bioengineering and Applied Physics at SEAS. The research was supported by the National Science Foundation, The Harvard University Materials Research Science and Engineering Center, The National Academies Keck Futures Initiative, and the National Geographic Society.

• PUBLICATION – Science Robotics: Ultragentle manipulation of delicate structures using a soft robotic gripper

The light-weight versatile exosuit assists hip extension during uphill walking and at different running speeds in natural terrain. Credit: Wyss Institute at Harvard University

Between walking at a leisurely pace and running for your life, human gaits can cover a wide range of speeds. Typically, we choose the gait that allows us to consume the least amount of energy at a given speed. For example, at low speeds, the metabolic rate of walking is lower than that of running in a slow jog; vice versa at high speeds, the metabolic cost of running is lower than that of speed walking.

Researchers in academic and industry labs have previously developed robotic devices for rehabilitation and other areas of life that can either assist walking or running, but no untethered portable device could efficiently do both. Assisting walking and running with a single device is challenging because of the fundamentally different biomechanics of the two gaits. However, both gaits have in common an extension of the hip joint, which starts around the time when the foot comes in contact with the ground and requires considerable energy for propelling the body forward.

As reported today in Science, a team of researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS), and the University of Nebraska Omaha now has developed a portable exosuit that assists with gait-specific hip extension during both walking and running. Their lightweight exosuit is made of textile components worn at the waist and thighs, and a mobile actuation system attached to the lower back which is controlled by an algorithm that can robustly detect the transition from walking to running and vice versa.

The team first showed that the exosuit worn by users in treadmill-based indoor tests, on average, reduced their metabolic costs of walking by 9.3% and of running by 4% compared to when they were walking and running without the device. “We were excited to see that the device also performed well during uphill walking, at different running speeds and during overground testing outside, which showed the versatility of the system,” said Conor Walsh, Ph.D., who led the study. Walsh is a Core Faculty member of the Wyss Institute, the Gordon McKay Professor of Engineering and Applied Sciences at SEAS, and Founder of the Harvard Biodesign Lab. “While the metabolic reductions we found are modest, our study demonstrates that it is possible to have a portable wearable robot assist more than just a single activity, helping to pave the way for these systems to become ubiquitous in our lives,” said Walsh.

The hip exosuit was developed as part of the Defense Advanced Research Projects Agency (DARPA)’s former Warrior Web program and is the culmination of years of research and optimization of the soft exosuit technology by the team. A previous multi-joint exosuit developed by the team could assist both the hip and ankle during walking, and a medical version of the exosuit aimed at improving gait rehabilitation for stroke survivors is now commercially available in the US and Europe, via a collaboration with ReWalk Robotics.

The team’s most recent hip-assisting exosuit is designed to be simpler and lighter weight compared to their past multi-joint exosuit. It assists the wearer via a cable actuation system. The actuation cables apply a tensile force between the waist belt and thigh wraps to generate an external extension torque at the hip joint that works in concert with the gluteal muscles. The device weighs 5kg in total with more than 90% of its weight located close to the body’s center of mass. “This approach to concentrating the weight, combined with the flexible apparel interface, minimizes the energetic burden and movement restriction to the wearer,” said co-first-author Jinsoo Kim, a SEAS graduate student in Walsh’s group. “This is important for walking, but even more so for running as the limbs move back and forth much faster.” Kim shared the first-authorship with Giuk Lee, Ph.D., a former postdoctoral fellow on Walsh’s team and now Assistant Professor at Chung-Ang University in Seoul, South Korea.

A major challenge the team had to solve was that the exosuit needed to be able to distinguish between walking and running gaits and change its actuation profiles accordingly with the right amount of assistance provided at the right time of the gait cycle.

To explain the different kinetics during the gait cycles, biomechanists often compare walking to the motions of an inverted pendulum and running to the motions of a spring-mass system. During walking, the body’s center of mass moves upward after heel-strike, then reaches maximum height at the middle of the stance phase to descend towards the end of the stance phase. In running, the movement of the center of mass is opposite. It descends towards a minimum height at the middle of the stance phase and then moves upward towards push-off.

“We took advantage of these biomechanical insights to develop our biologically inspired gait classification algorithm that can robustly and reliably detect a transition from one gait to the other by monitoring the acceleration of an individual’s center of mass with sensors that are attached to the body,” said co-corresponding author Philippe Malcolm, Ph.D., Assistant Professor at University of Nebraska Omaha. “Once a gait transition is detected, the exosuit automatically adjusts the timing of its actuation profile to assist the other gait, as we demonstrated by its ability to reduce metabolic oxygen consumption in wearers.”

In ongoing work, the team is focused on optimizing all aspects of the technology, including further reducing weight, individualizing assistance and improving ease of use. “It is very satisfying to see how far our approach has come,” said Walsh, “and we are excited to continue to apply it to a range of applications, including assisting those with gait impairments, industry workers at risk of injury performing physically strenuous tasks, or recreational weekend warriors.”

The team’s portable exosuit is made of textile components worn at the waist and thighs, and a mobile actuation system attached to the lower back which uses an algorithm that robustly predicts transitions between walking and running gaits. Credit: Wyss Institute at Harvard University

“This breakthrough study coming out of the Wyss Institute’s Bioinspired Soft Robotics platform gives us a glimpse into a future where wearable robotic devices can improve the lives of the healthy, as well as serve those with injuries or in need of rehabilitation,” said Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School, the Vascular Biology Program at Boston Children’s Hospital, and Professor of Bioengineering at SEAS.

Other authors on the study are past and present members of Walsh’s team, including data analyst Roman Heimgartner; Research Fellow Dheepak Arumukhom Revi; Control Engineer Nikos Karavas, Ph.D.; Functional Apparel Designer Danielle Nathanson; Robotics Engineer Ignacio Galiana, Ph.D.; Robotics Engineer Asa Eckert-Erdheim; Electromechanical Engineer Patrick Murphy; Engineer David Perry; Software Engineer Nicolas Menard, and graduate student Dabin Kim Choe. The study was funded by the Defense Advanced Research Projects Agency’s Warrior Web Program, the National Science Foundation and Harvard’s Wyss Institute for Biologically Inspired Engineering.

• WYSS TECHNOLOGY: Soft Exosuits
• PUBLICATION – Science: Reducing the metabolic rate of walking and running with a versatile, portable exosuit

Changes to the Robobee — including an additional pair of wings and improvements to the actuators and transmission ratio — made the vehicle more efficient and allowed the addition of solar cells and an electronics panel. This Robobee is the first to fly without a power cord and is the lightest, untethered vehicle to achieve sustained flight. Credit: Harvard Microrobotics Lab/Harvard SEAS

By Leah Burrows

In the Harvard Microrobotics Lab, on a late afternoon in August, decades of research culminated in a moment of stress as the tiny, groundbreaking Robobee made its first solo flight.

Graduate student Elizabeth Farrell Helbling, Ph.D.’19, and postdoctoral fellow Noah T. Jafferis, Ph.D. from Harvard’s Wyss Institute for Biologically Inspired Engineering, the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), and the Graduate School of Arts and Sciences caught the moment on camera.

Helbling, who has worked on the project for six years, counted down: “Three, two, one, go.”

The bright halogens switched on and the solar-powered Robobee launched into the air. For a terrifying second, the tiny robot, still without on-board steering and control, careened towards the lights.

Off camera, Helbling exclaimed and cut the power. The Robobee fell dead out of the air, caught by its Kevlar safety harness.

“That went really close to me,” Helbling said, with a nervous laugh.

“It went up,” Jafferis, who has also worked on the project for about six years, responded excitedly from the high-speed camera monitor where he was recording the test.

And with that, Harvard University’s Robobee reached its latest major milestone — becoming the lightest vehicle ever to achieve sustained untethered flight.

“This is a result several decades in the making,” said Robert Wood, Ph.D., Core Faculty member of the Wyss Institute, the Charles River Professor of Engineering and Applied Sciences at SEAS, and principle investigator of the Robobee project. “Powering flight is something of a Catch-22 as the tradeoff between mass and power becomes extremely problematic at small scales where flight is inherently inefficient.  It doesn’t help that even the smallest commercially available batteries weigh much more than the robot. We have developed strategies to address this challenge by increasing vehicle efficiency, creating extremely lightweight power circuits, and integrating high efficiency solar cells.”

The milestone is described in Nature.

To achieve untethered flight, this latest iteration of the Robobee underwent several important changes, including the addition of a second pair of wings. “The change from two to four wings, along with less visible changes to the actuator and transmission ratio, made the vehicle more efficient, gave it more lift, and allowed us to put everything we need on board without using more power,” said Jafferis. (The addition of the wings also earned this Robobee the nickname X-Wing, after the four-winged starfighters from Star Wars.)

That extra lift, with no additional power requirements, allowed the researchers to cut the power cord — which has kept the Robobee tethered for nearly a decade — and attach solar cells and an electronics panel to the vehicle.

The solar cells, the smallest commercially available, weigh 10 milligrams each and get 0.76 milliwatts per milligram of power when the sun is at full intensity. The Robobee X-Wing needs the power of about three Earth suns to fly, making outdoor flight out of reach for now. Instead, the researchers simulate that level of sunlight in the lab with halogen lights. The solar cells are connected to an electronics panel under the bee, which converts the low voltage signals of the solar array into high voltage drive signals needed to control the actuators. The solar cells sit about three centimeters above the wings, to avoid interference.

In all, the final vehicle, with the solar cells and electronics, weights 259 milligrams (about a quarter of a paper clip) and uses about 120 milliwatts of power, which is less power than it would take to light a single bulb on a string of LED Christmas lights.

“When you see engineering in movies, if something doesn’t work, people hack at it once or twice and suddenly it works. Real science isn’t like that,” said Helbling. “We hacked at this problem in every which way to finally achieve what we did. In the end, it’s pretty thrilling.” The researchers will continue to hack away, aiming to bring down the power and add on-board control to enable the Robobee to fly outside.

To achieve untethered flight, the latest iteration of the Robobee underwent several important changes, including the addition of a second pair of wings. (Video courtesy of the Harvard Microrobotics Lab/Harvard SEAS)

“Over the life of this project we have sequentially developed solutions to challenging problems, like how to build complex devices at millimeter scales, how to create high-performance millimeter-scale artificial muscles, bioinspired designs, and novel sensors, and flight control strategies,” said Wood. “Now that power solutions are emerging, the next step is onboard control. Beyond these robots, we are excited that these underlying technologies are finding applications in other areas such as minimally-invasive surgical devices, wearable sensors, assistive robots, and haptic communication devices – to name just a few.”

Harvard has developed a portfolio of intellectual property (IP) related to the fabrication process for millimeter-scale devices. This IP, as well as related technologies, can be applied to microrobotics, medical devices, consumer electronics and a wide range of complex electromechanical systems. Harvard’s Office of Technology Development is exploring opportunities for commercial impact in these fields.

This research was co-authored by Michael Karpelson, Ph.D., Staff Electrical Engineer on the Institute’s Advanced Technology Team. It was supported by the National Science Foundation and the Office of Naval Research.

Root is controlled using an iPad app that has three different levels of coding, allowing students as young as four years old to learn the fundamentals of programming. Credit: Wyss Institute at Harvard University

iRobot Corp. announced its acquisition of Root Robotics, Inc., whose educational Root coding robot got its start as a summer research project at the Wyss Institute for Biologically Inspired Engineering in 2011 and subsequently developed into a robust learning tool that is being used in over 500 schools to teach children between the ages of four and twelve how to code in an engaging, intuitive way. iRobot plans to incorporate the Root robot into its growing portfolio of educational robot products, and continue the work of scaling up production and expanding Root’s programming content that began when Root Robotics was founded by former Wyss Institute members in 2017.

The Root robot can be programmed to perform a variety of actions based on what students draw on a whiteboard, including avoid obstacles, play music, and flash its lights. Credit: Wyss Institute at Harvard University

“We’re honored that we got to see a Wyss Institute technology go from its earliest stages to where we are today, with the opportunity to make a gigantic impact on the world,” said Zivthan Dubrovsky, former Bioinspired Robotics Platform Lead at the Wyss Institute and co-founder of Root Robotics who is now the General Manager of Educational Robots at iRobot. “We’re excited to see how this new chapter in Root’s story can further amplify our mission of making STEM education accessible to students of any age in any classroom around the world.”

Root began in the lab of Wyss Core Faculty Member and Bioinspired Robotics Platform co-lead Radhika Nagpal, Ph.D., who was investigating the idea of robots that could climb metal structures using magnetic wheels. “Most whiteboards in classrooms are backed with metal, so I thought it would be wonderful if a robot could automatically erase the whiteboard as I was teaching – ironically, we referred to it as a ‘Roomba^® for whiteboards,’ because many aspects were directly inspired by iRobot’s Roomba at the time,” said Nagpal, who is also the Fred Kavli Professor of Computer Science at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS). “Once we had a working prototype, the educational potential of this robot was immediately obvious. If it could be programmed to detect ink, navigate to it, and erase it, then it could be used to teach students about coding algorithms of increasing complexity.”

That prototype was largely built by Raphael Cherney, first as a Research Engineer in Nagpal’s group at Harvard in 2011, and then beginning in 2013 when he was hired to work on developing Root full-time along with Dubrovsky and other members of the Wyss Institute. “When Raphael and Radhika pitched me the idea of Root, I fell in love with it immediately,” said Dubrovsky. “My three daughters were all very young at the time and I wanted them to have exposure to STEM concepts like coding and engineering, but I was frustrated by the lack of educational systems that were designed for children their age. The idea of being able to create that for them was really what motivated me to throw all my weight behind the project.”

Under Cherney and Dubrovsky’s leadership, Root’s repertoire expanded to include drawing shapes on the whiteboard as it wheeled around, navigating through obstacles drawn on the whiteboard, playing music, and more. The team also developed Root’s coding interface, which has three levels of increasing complexity that are designed to help students from preschool to high school easily grasp the concepts of programming and use them to create their own projects. “The tangible nature of a robot really brings the code to life, because the robot is ‘real’ in a way that code isn’t – you can watch it physically carrying out the instructions that you’ve programmed into it,” said Cherney, who co-founded Root Robotics and is now a Principal Systems Engineer at iRobot. “It helps turn coding into a social activity, especially for kids, as they learn to work in teams and see coding as a fun and natural thing to do.”

Over the next three years the team iterated on Root’s prototype and began testing it in classrooms in and around Boston, getting feedback from students and teachers to get the robot closer to its production-ready form. “Robots are very hard to build, and the support we had from the Wyss Institute let us do it right, instead of just fast,” said Cherney. “We were able to develop Root from a prototype to a product that worked in schools and was doing what we envisioned, and the whole process was much smoother than it would have been if we had just been a team working in a garage.”

By 2016, they felt ready for commercialization. They ran a Kickstarter^® campaign as a market test to see if they had a viable consumer business, and raised nearly $400,000 from almost 2,000 backers, far exceeding their target of $250,000. Buoyed by this vote of confidence from potential customers, Dubrovsky and Cherney left the Wyss Institute in the summer of 2017 to co-found Root Robotics with Nagpal serving as Scientific Advisor and $2.5 million in seed funds, and a license from Harvard’s Office of Technology Development. While most of their time at the Wyss Institute was spent getting the robot right, the company focused on getting the content of Root’s programming app up to par, setting up a classroom in their office and inviting students to come try out the robot, then updating their content with insights learned from those experiences.

Once they achieved their vision for three different levels of programming targeting students of different ages, they shipped Root robots to their Kickstarter backers and made it available for purchase on their website in September 2018. Since then, over a million coding projects have been run on the Root app. “What’s been most rewarding for me personally is seeing my kids take Root to their classrooms and show their teachers and their peers what they’ve been able to make a robot do. Getting to see them problem-solve and iterate and then achieve something they’re proud of is priceless,” said Dubrovsky. “I’ve been pleasantly surprised by seeing people come up with new things to do with the robot that we never thought of,” added Cherney. “The way it seems to immediately unlock creativity is beautiful and inspiring.”

Root Robotics co-founders Raphael Cherney (left) and Zee Dubrovsky (center) are joining iRobot’s Educational Robotics division. Root started as a project in the lab of Wyss Faculty member Radhika Nagpal (right). Credit: Wyss Institute at Harvard University

“One of the things that really attracted us to Root was that it was designed as an education product from the ground up, which fits perfectly with our own deep passion for using robots as a way of turbo charging STEM education,” said Colin Angle, chairman and CEO of iRobot. “The Root robot has tremendous value as a tool for teaching students not only coding, but also concepts of AI, engineering and autonomous robots, all of which are very important for our future.”

Nagpal is still sometimes floored by the fact that what started as an idea for a simple whiteboard-erasing robot ended up developing into such a robust teaching tool. “Without the Wyss Institute, I would not have even thought to try and commercialize this idea,” she said. “It supported an amazing team of engineers in creating and testing Root over several years, which allowed us to be able to raise the funds to launch the company with a product that was so well-developed that it now has the potential to really scale up and make a big difference in the world.”

“Root Robotics is one of the great success stories to come out of the Wyss Institute, partially because of how quickly the team recognized its potential impact and focused on de-risking it both technically and commercially,” said Wyss Founding Director Donald Ingber, M.D., Ph.D. “It was fantastic to see Root take root at the Institute, and we are immensely proud of them and their ability to develop a technology that can truly bring about positive change in our world by targeting children who are the creators and visionaries of tomorrow.” Ingber is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at SEAS.

• WYSS TECHNOLOGY: Root – A robot to empower the next generation of coders

With this motivation, a team of roboticists at Harvard’s Wyss Institute for Biologically Inspired Engineering has developed a robot that can autonomously drive interlocking steel sheet piles into soil. The structures that it builds could function as retaining walls or check dams for erosion control. The study will be presented at the upcoming 2019 IEEE International Conference on Robotics and Automation.

Romu, the Wyss Institute’s sheet pile driving robot has been extensively tested in a sandbox in the laboratory. Credit: Wyss Institute at Harvard University

Conventional sheet pile driving processes are extremely energy intensive. Only a fraction of the weight of typical heavy machinery is used for applying downward force. The Wyss team’s “Romu” robot, on the other hand, is able to leverage its own weight to drive sheet piles into the ground. This is made possible by each of its four wheels being coupled to a separate linear actuator, which also allows it to adapt to uneven terrain and ensure that piles are driven vertically. From a raised position, Romu grips a sheet pile and then lowers its chassis, pressing the pile into the soil with the help of an on-board vibratory hammer. By gripping the pile again at a higher position and repeating this process, the robot can drive a pile much taller than its own range of vertical motion. After driving a pile to sufficient depth, Romu advances and installs the next pile such that it interlocks with the previous one, thereby forming a continuous wall. Once it has used all of the piles it carries, it may return to a supply cache to restock.

The study grew out of previous work at the Wyss Institute on teams or swarms of robots for construction applications. In work inspired by mound-building termites, Core Faculty member Radhika Nagpal and Senior Research Scientist Justin Werfel designed an autonomous robotic construction crew called TERMES, whose members worked together to build complex structures from specialized bricks. Further work by Werfel and researcher Nathan Melenbrink explored strut-climbing robots capable of building cantilevering truss structures, addressing applications like bridges. However, neither of these studies addressed the challenge of anchoring structures to the ground. The Romu project began as an exploration of methods for automated site preparation and installation of foundations for the earlier systems to build on; as it developed, the team determined that such interventions could also be directly applicable to land restoration tasks in remote environments.

The robot is designed to drive interlocking sheet piles into granular soils like sand on a beach. Credit: Wyss Institute at Harvard University

“In addition to tests in the lab, we demonstrated Romu operating on a nearby beach,” said Melenbrink. “This kind of demonstration can be an icebreaker for a broader conversation around opportunities for automation in construction and land management. We’re interested in engaging with experts in related fields who might see potential benefit for the kind of automated interventions we’re developing.”

The researchers envision large numbers of Romu robots working together as a collective or swarm. They demonstrated in computer simulations that teams of Romu robots could make use of environmental cues like slope steepness in order to build walls in effective locations, making efficient use of limited resources. “The swarm approach gives advantages like speedup through parallelism, robustness to the loss of individual robots, and scalability for large teams,” said Werfel. “By responding in real-time to the conditions they actually encounter as they work, the robots can adapt to unexpected or changing situations, without needing to rely on a lot of supporting infrastructure for abilities like site surveying, communication, or localization.”

“The name Terramanus ferromurus (Romu) is a nod to the concept of ‘machine ecology’ in which autonomous systems can be introduced into natural environments as new participants, taking specific actions to complement and promote human environmental stewardship,” said Melenbrink. In the future, the Terramanus “genus” could be extended by additional robots carrying out different tasks to protect or restore ecosystem services. Based on their findings, the team now is interested in investigating interventions ranging from groundwater retention structures for supporting agriculture in arid regions, to responsive flood barrier construction for hurricane preparedness. Future versions of the robot could perform other interventions such as spraying soil-binding agents or installing silt fencing, such that a family of these robots could act to stabilize soil in a wide range of situations.

In many scenarios for environmental protection or restoration, the opportunity for action is limited by the availability of human labor and by site access for heavy machinery. Smaller, more versatile construction machines could provide a solution. “Clearly, the needs of many degraded landscapes are not being met with the currently available tools and techniques,” said Melenbrink. “Now, 100 years after the dawn of the heavy equipment age, we’re asking whether there might be more resilient and responsive ways to approach land management and restoration.”

“This sheet pile driving robot with its demonstrated ability to perform in a natural setting signals a path on which the Wyss Institute’s robotics and swarm robotics capabilities can be brought to bear on both natural and man-made environments where conventional machinery, man power limitations, or cost is inadequate to prevent often disastrous consequences. This robot also could address disaster situations where walling off dangerous chemical spills or released radioactive fluids makes it difficult or impossible for humans to intervene,” said Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at HMS and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at SEAS.

The toggle gripper holding a screwdriver. Credit: Daniel Preston / Harvard University

A soft robot, attached to a balloon and submerged in a transparent column of water, dives and surfaces, then dives and surfaces again, like a fish chasing flies. Soft robots have performed this kind of trick before. But unlike most soft robots, this one is made and operated with no hard or electronic parts. Inside, a soft, rubber computer tells the balloon when to ascend or descend. For the first time, this robot relies exclusively on soft digital logic.

In the last decade, soft robots have surged into the metal-dominant world of robotics. Grippers made from rubbery silicone materials are already used in assembly lines: Cushioned claws handle delicate fruit and vegetables like tomatoes, celery, and sausage links or extract bottles and sweaters from crates. In laboratories, the grippers can pick up slippery fish, live mice, and even insects, eliminating the need for more human interaction.

Soft robots already require simpler control systems than their hard counterparts. The grippers are so compliant, they simply cannot exert enough pressure to damage an object and without the need to calibrate pressure, a simple on-off switch suffices. But until now, most soft robots still rely on some hardware: Metal valves open and close channels of air that operate the rubbery grippers and arms, and a computer tells those valves when to move.

Now, researchers have built a soft computer using just rubber and air. “We’re emulating the thought process of an electronic computer, using only soft materials and pneumatic signals, replacing electronics with pressurized air,” says Daniel J. Preston, first author on a paper published in PNAS and a postdoctoral researcher working with George Whitesides, a Founding Core Faculty member of Harvard’s Wyss Institute for Biologically Inspired Engineering, and the Woodford L. and Ann A. Flowers University Professor at Harvard University’s Department of Chemistry and Chemical Biology.

To make decisions, computers use digital logic gates, electronic circuits that receive messages (inputs) and determine reactions (outputs) based on their programming. Our circuitry isn’t so different: When a doctor strikes a tendon below our kneecap (input), the nervous system is programmed to jerk (output).

Preston’s soft computer mimics this system using silicone tubing and pressurized air. To achieve the minimum types of logic gates required for complex operations—in this case, NOT, AND, and OR—he programmed the soft valves to react to different air pressures. For the NOT logic gate, for example, if the input is high pressure, the output will be low pressure. With these three logic gates, Preston says, “you could replicate any behavior found on any electronic computer.”

The bobbing fish-like robot in the water tank, for example, uses an environmental pressure sensor (a modified NOT gate) to determine what action to take. The robot dives when the circuit senses low pressure at the top of the tank and surfaces when it senses high pressure at depth. The robot can also surface on command if someone pushes an external soft button.

Robots built with only soft parts have several benefits. In industrial settings, like automobile factories, massive metal machines operate with blind speed and power. If a human gets in the way, a hard robot could cause irreparable damage. But if a soft robot bumps into a human, Preston says, “you wouldn’t have to worry about injury or a catastrophic failure.” They can only exert so much force.

But soft robots are more than just safer: They are generally cheaper and simpler to make, light weight, resistant to damage and corrosive materials, and durable. Add intelligence and soft robots could be used for much more than just handling tomatoes. For example, a robot could sense a user’s temperature and deliver a soft squeeze to indicate a fever, alert a diver when the water pressure rises too high, or push through debris after a natural disaster to help find victims and offer aid.

Soft robots can also venture where electronics struggle: High radiative fields, like those produced after a nuclear malfunction or in outer-space, and inside Magnetic Resonance Imaging (MRI) machines. In the wake of a hurricane or flooding, a hardy soft robot could manage hazardous terrain and noxious air. “If it gets run over by a car, it just keeps going, which is something we don’t have with hard robots,” Preston says.

Preston and colleagues are not the first to control robots without electronics. Other research teams have designed microfluidic circuits, which can use liquid and air to create nonelectronic logic gates. One microfluidic oscillator helped a soft octopus-shaped robot flail all eight arms.

Yet, microfluidic logic circuits often rely on hard materials like glass or hard plastics, and they use such thin channels that only small amounts of air can move through at a time, slowing the robot’s motion. In comparison, Preston’s channels are larger—close to one millimeter in diameter—which enables much faster air flow rates. His air-based grippers can grasp an object in a matter of seconds.

Microfluidic circuits are also less energy efficient. Even at rest, the devices use a pneumatic resistor, which flows air from the atmosphere to either a vacuum or pressure source to maintain stasis. Preston’s circuits require no energy input when dormant. Such energy conservation could be crucial in emergency or disaster situations where the robots travel far from a reliable energy source.

The soft, pneumatic robots also offer an enticing possibility: Invisibility. Depending on which material Preston selects, he could design a robot that is index-matched to a specific substance. So, if he chooses a material that camouflages in water, the robot would appear transparent when submerged. In the future, he and his colleagues hope to create autonomous robots that are invisible to the naked eye or even sonar detection. “It’s just a matter of choosing the right materials,” he says.

For Preston, the right materials are elastomers or rubbers. While other fields chase higher power with machine learning and artificial intelligence, the Whitesides team turns away from the mounting complexity. “There’s a lot of capability there,” Preston says, “but it’s also good to take a step back and think about whether or not there’s a simpler way to do things that gives you the same result, especially if it’s not only simpler, it’s also cheaper.”

This biocompatible sensor is made from a non-toxic, highly conductive liquid solution that could be used in diagnostics, therapeutics, human-computer interfaces, and virtual reality. Credit: Harvard SEAS

Harvard University researchers have developed a soft, non-toxic wearable sensor that unobtrusively attaches to the hand and measures the force of a grasp and the motion of the hand and fingers.

The research was published in Advanced Functional Materials and is a collaboration between the Wyss Institute for Biologically Inspired Engineering, The Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), Beth Israel Deaconess Medical Center, and Boston Children’s Hospital.

One novel element of the sensor is a non-toxic, highly conductive liquid solution.

“We have developed a new type of conductive liquid that is no more dangerous than a small drop of salt water,” said Siyi Xu, a graduate student at SEAS and first author of the paper. “It is four times more conductive than previous biocompatible solutions, leading to cleaner, less noisy data.”

The sensing solution is made from potassium iodide, which is a common dietary supplement, and glycerol, which is a common food additive. After a short mixing period, the glycerol breaks the crystal structure of potassium iodide and forms potassium cations (K+) and iodide ions (I-), making the liquid conductive. Because glycerol has a lower evaporation rate than water, and the potassium iodide is highly soluble, the liquid is both stable across a range of temperatures and humidity levels, and highly conductive.

“Previous biocompatible soft sensors have been made using sodium chloride-glycerol solutions but these solutions have low conductivities, which makes the sensor data very noisy, and it also takes about 10 hours to prepare,” said Xu. “We’ve shortened that down to about 20 minutes and get very clean data.”

Safe, soft sensors on the top and tip of the index finger detect the movements, strain and force of the finger while performing different activities, such as flexing and extending the finger and picking up weights and boxes. Credit: Harvard SEAS

The design of the sensors also takes the need of children into account. Rather than a bulky glove, the silicon-rubber sensor sits on top of the finger and on the finger pad.

“We often see that children who are born early or who have been diagnosed with early developmental disorders have highly sensitive skin,” said Eugene Goldfield, Ph.D., coauthor of the study, and Associate Faculty Member of the Wyss Institute at Harvard University and an Associate Professor in the Program in Behavioral Sciences at Boston Children’s Hospital and Harvard Medical School. “By sticking to the top of the finger, this device gives accurate information while getting around the sensitively of the child’s hand.”

Goldfield is the Principal investigator of the Flexible Electronics for Toddlers project at the Wyss Institute, which designs modular robotic systems for toddlers born prematurely and at risk for cerebral palsy.

Goldfield and his colleagues currently study motor function using the Motion Capture Lab at SEAS and Wyss. While motion capture can tell a lot about movement, it cannot measure force, which it critical to diagnosing neuromotor and cognitive developmental disabilities.

“Early diagnosis is the name of the game when it comes to treating these developmental disabilities and this wearable sensor can give us a lot of advantages not currently available,” said Goldfield.

This paper only tested the device on adult hands. Next, the researchers plan to scale down the device and test it on the hands of children.

“The ability to quantify complex human motions gives us an unprecedented diagnostic tool,” says senior author Robert Wood, Ph.D., Founding Core Faculty Member of the Wyss Institute and the Charles River Professor of Engineering and Applied Sciences at SEAS. “The focus on the development of motor skills in toddlers presents unique challenges for how to integrate many sensors into a small, lightweight, and unobtrusive wearable device. These new sensors solve these challenges – and if we can create wearable sensors for such a demanding task, we believe that this will also open up applications in diagnostics, therapeutics, human-computer interfaces, and virtual reality.”

This research was also authored by SEAS researcher Daniel M. Vogt; Wyss Institute researchers Wen-Hao Hsu, John Osborne, Timothy Walsh, Jonathan R. Foster, Sarah K. Sullivan, and Andreas Rousing; and Beth Israel Deaconess Medical Center researcher Vincent C. Smith. It was supported by the National Institutes of Health.

PUBLICATION – Advanced Functional Materials : Biocompatible Soft Fluidic Strain and Force Sensors for Wearable Devices
WYSS TECHNOLOGY – “Flexi-mitts”for tracking neurodevelopment in very low birth weight premature infants

Jet engines can have up to 25,000 individual parts, making regular maintenance a tedious task that can take over a month per engine. Many components are located deep inside the engine and cannot be inspected without taking the machine apart, adding time and costs to maintenance. This problem is not only confined to jet engines, either; many complicated, expensive machines like construction equipment, generators, and scientific instruments require large investments of time and money to inspect and maintain.

HAMR-E uses electroadhesive pads on its feet and a special gait pattern to climb on vertical, inverted, and curved surfaces, like the inside of this jet engine. Credit: Wyss Institute at Harvard University

Researchers at Harvard University’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS) have created a micro-robot whose electroadhesive foot pads, origami ankle joints, and specially engineered walking gait allow it to climb on vertical and upside-down conductive surfaces, like the inside walls of a commercial jet engine. The work is reported in Science Robotics.

“Now that these robots can explore in three dimensions instead of just moving back and forth on a flat surface, there’s a whole new world that they can move around in and engage with,” said first author Sébastien de Rivaz, a former Research Fellow at the Wyss Institute and SEAS who now works at Apple. “They could one day enable non-invasive inspection of hard-to-reach areas of large machines, saving companies time and money and making those machines safer.”

The new robot, called HAMR-E (Harvard Ambulatory Micro-Robot with Electroadhesion), was developed in response to a challenge issued to the Harvard Microrobotics Lab by Rolls-Royce, which asked if it would be possible to design and build an army of micro-robots capable of climbing inside parts of its jet engines that are inaccessible to human workers. Existing climbing robots can tackle vertical surfaces, but experience problems when trying to climb upside-down, as they require a large amount of adhesive force to prevent them from falling.

The team based HAMR-E on one of its existing micro-robots, HAMR, whose four legs enable it to walk on flat surfaces and swim through water. While the basic design of HAMR-E is similar to HAMR, the scientists had to solve a series of challenges to get HAMR-E to successfully stick to and traverse the vertical, inverted, and curved surfaces that it would encounter in a jet engine.

First, they needed to create adhesive foot pads that would keep the robot attached to the surface even when upside-down, but also release to allow the robot to “walk” by lifting and placing its feet. The pads consist of a polyimide-insulated copper electrode, which enables the generation of electrostatic forces between the pads and the underlying conductive surface. The foot pads can be easily released and re-engaged by switching the electric field on and off, which operates at a voltage similar to that required to move the robot’s legs, thus requiring very little additional power. The electroadhesive foot pads can generate shear forces of 5.56 grams and normal forces of 6.20 grams – more than enough to keep the 1.48-gram robot from sliding down or falling off its climbing surface. In addition to providing high adhesive forces, the pads were designed to be able to flex, thus allowing the robot to climb on curved or uneven surfaces.

HAMR-E is small but mighty, and could one day carry instruments and cameras to inspect small spaces. Credit: Wyss Institute at Harvard University

The scientists also created new ankle joints for HAMR-E that can rotate in three dimensions to compensate for rotations of its legs as it walks, allowing it to maintain its orientation on its climbing surface. The joints were manufactured out of layered fiberglass and polyimide, and folded into an origami-like structure that allows the ankles of all the legs to rotate freely, and to passively align with the terrain as HAMR-E climbs.

Finally, the researchers created a special walking pattern for HAMR-E, as it needs to have three foot pads touching a vertical or inverted surface at all times to prevent it from falling or sliding off. One foot releases from the surface, swings forward, and reattaches while the remaining three feet stay attached to the surface. At the same time, a small amount of torque is applied by the foot diagonally across from the lifted foot to keep the robot from moving away from the climbing surface during the leg-swinging phase. This process is repeated for the three other legs to create a full walking cycle, and is synchronized with the pattern of electric field switching on each foot.

When HAMR-E was tested on vertical and inverted surfaces, it was able to achieve more than one hundred steps in a row without detaching. It walked at speeds comparable to other small climbing robots on inverted surfaces and slightly slower than other climbing robots on vertical surfaces, but was significantly faster than other robots on horizontal surfaces, making it a good candidate for exploring environments that have a variety of surfaces in different arrangements in space. It is also able to perform 180-degree turns on horizontal surfaces.

HAMR-E also successfully maneuvered around a curved, inverted section of a jet engine while staying attached, and its passive ankle joints and adhesive foot pads were able to accommodate the rough and uneven features of the engine surface simply by increasing the electroadhesion voltage.

This iteration of HAMR-E is the first and most convincing step towards showing that this approach to a centimeter-scale climbing robot is possible, and that such robots could in the future be used to explore any sort of infrastructure, including buildings, pipes, engines, generators, and more

ROBERT WOOD

The team is continuing to refine HAMR-E, and plans to incorporate sensors into its legs that can detect and compensate for detached foot pads, which will help prevent it from falling off of vertical or inverted surfaces. HAMR-E’s payload capacity is also greater than its own weight, opening the possibility of carrying a power supply and other electronics and sensors to inspect various environments. The team is also exploring options for using HAMR-E on non-conductive surfaces.

“This iteration of HAMR-E is the first and most convincing step towards showing that this approach to a centimeter-scale climbing robot is possible, and that such robots could in the future be used to explore any sort of infrastructure, including buildings, pipes, engines, generators, and more,” said corresponding author Robert Wood, Ph.D., who is a Founding Core Faculty member of the Wyss Institute as well as the Charles River Professor of Engineering and Applied Sciences at SEAS.

“While academic scientists are very good at coming up with fundamental questions to explore in the lab, sometimes collaborations with industrial scientists who understand real-world problems are required to develop innovative technologies that can be translated into useful products. We are excited to help catalyze these collaborations here at the Wyss Institute, and to see the breakthrough advances that emerge,” said Wyss Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children’s Hospital, and Professor of Bioengineering at SEAS.

This study is co-authored by Benjamin Goldberg, Ph.D., Neel Doshi, Kaushik Jayaram, Ph.D., and Jack Zhou from the Wyss Institute and Harvard SEAS.

Support for this research was contributed by the Wyss Institute for Biologically Inspired Engineering at Harvard University, Rolls-Royce, and the US Army Research Office.

The multi-joint soft exosuit consists of textile apparel components worn at the waist, thighs and calves that guide mechanical forces from an optimized mobile actuation system attached to a rucksack via cables to the ankle and hip joints. In addition, a new tuning method helps personalize the exosuit’s effects to wearers’ specific gaits. Credit: Harvard Biodesign Lab

In the future, smart textile-based soft robotic exosuits could be worn by soldiers, fire fighters and rescue workers to help them traverse difficult terrain and arrive fresh at their destinations so that they can perform their respective tasks more effectively. They could also become a powerful means to enhance mobility and quality of living for people suffering from neurodegenerative disorders and for the elderly.

Conor Walsh’s team at the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has been at the forefront of developing different soft wearable robotic devices that support mobility by applying mechanical forces to critical joints of the body, including at the ankle or hip joints, or in the case of a multi-joint soft exosuit both. Because of its potential for relieving overburdened solders in the field, the Defense Advanced Research Projects Agency (DARPA) funded the team’s efforts as part of its former Warrior Web program.

While the researchers have demonstrated that lab-based versions of soft exosuits can provide clear benefits to wearers, allowing them to spend less energy while walking and running, there remains a need for fully wearable exosuits that are suitable for use in the real world.

Now, in a study reported in the proceedings of the 2018 IEEE International Conference on Robotics and Automation (ICRA), the team presented their latest generation of a mobile multi-joint exosuit, which has been improved on all fronts and tested in the field through long marches over uneven terrain. Using the same exosuit in a second study published in the Journal of NeuroEngineering and Rehabilitation (JNER), the researchers developed an automatic tuning method to customize its assistance based on how an individual’s body is responding to it, and demonstrated significant energy savings.

The multi-joint soft exosuit consists of textile apparel components worn at the waist, thighs, and calves. Through an optimized mobile actuation system worn near the waist and integrated into a military rucksack, mechanical forces are transmitted via cables that are guided through the exosuit’s soft components to ankle and hip joints. This way, the exosuit adds power to the ankles and hips to assist with leg movements during the walking cycle.

“We have updated all components in this new version of the multi-joint soft exosuit: the apparel is more user-friendly, easy to put on and accommodating to different body shapes; the actuation is more robust, lighter, quieter and smaller; and the control system allows us to apply forces to hips and ankles more robustly and consistently,” said David Perry, a co-author of the ICRA study and a Staff Engineer on Walsh’s team. As part of the DARPA program, the exosuit was field-tested in Aberdeen, MD, in collaboration with the Army Research Labs, where soldiers walked through a 12-mile cross-country course.

“We previously demonstrated that it is possible to use online optimization methods that by quantifying energy savings in the lab automatically individualize control parameters across different wearers. However, we needed a means to tune control parameters quickly and efficiently to the different gaits of soldiers at the Army outside a laboratory,” said Walsh, Ph.D., Core Faculty member of the Wyss Institute, the John L. Loeb Associate Professor of Engineering and Applied Sciences at SEAS, and Founder of the Harvard Biodesign Lab.

In the JNER study, the team presented a suitable new tuning method that uses exosuit sensors to optimize the positive power delivered at the ankle joints. When a wearer begins walking, the system measures the power and gradually adjusts controller parameters until it finds those that maximize the exosuit’s effects based on the wearer’s individual gait mechanics. The method can be used as a proxy measure for elaborate energy measurements.

“We evaluated the metabolic parameters in the seven study participants wearing exosuits that underwent the tuning process and found that the method reduced the metabolic cost of walking by about 14.8% compared to walking without the device and by about 22% compared to walking with the device unpowered,” said Sangjun Lee, the first author of both studies and a Graduate Student with Walsh at SEAS.

“These studies represent the exciting culmination of our DARPA-funded efforts. We are now continuing to optimize the technology for specific uses in the Army where dynamic movements are important; and we are exploring it for assisting workers in factories performing strenuous physical tasks,” said Walsh. “In addition, the field has recognized there is still a lot to understand on the basic science of co-adaptation of humans and wearable robots. Future co-optimization strategies and new training approaches could help further enhance individualization effects and enable wearers that initially respond poorly to exosuits to adapt to them as well and benefit from their assistance”.

“This research marks an important point in the Wyss Institute’s Bioinspired Soft Robotics Initiative and its development of soft exosuits in that it opens a path on which robotic devices could be adopted and personalized in real world scenarios by healthy and disabled wearers,” said Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at HMS and the Vascular Biology Program at Boston Children’s Hospital, and Professor of Bioengineering at SEAS.

Additional members of Walsh’s team were authors on either or both studies. Nikos Karavas, Ph.D., Brendan T. Quinlivan, Danielle Louise Ryan, Asa Eckert-Erdheim, Patrick Murphy, Taylor Greenberg Goldy, Nicolas Menard, Maria Athanassiu, Jinsoo Kim, Giuk Lee, Ph.D., and Ignacio Galiana, Ph.D., were authors on the ICRA study; and Jinsoo Kim, Lauren Baker, Andrew Long, Ph.D., Nikos Karavas, Ph.D., Nicolas Menard, and Ignacio Galiana, Ph.D., on the JNER study. The studies, in addition to DARPA’s Warrior Web program, were funded by Harvard’s Wyss Institute and SEAS.

• WYSS TECHNOLOGY – Soft Exosuits
• PUBLICATION – Journal of NeuroEngineering and Rehabilitation: Autonomous multi-joint soft exosuit with augmentation-power-based control parameter tuning reduces energy cost of loaded walking
• PUBLICATION – 2018 IEEE International Conference on Robotics and Automation (ICRA): Autonomous Multi-Joint Soft Exosuit for Assistance with Walking Overground

Credit: Wyss Institute Harvard

Manipulating delicate tissues such as blood vessels during difficult surgeries, or gripping fragile organisms in the deep sea presents a challenge to surgeons and researchers alike. Roboticists have made inroads into this problem by developing soft actuators on the microscale that are made of elastic materials and, through the expansion or contraction of embedded active components, can change their shapes to gently handle objects without damaging them. However, the specific designs and materials used for their fabrication so far still limit their range of motion and the strength they can exert at scales on which surgeons and researchers would like to use them.

“The fabrication of soft micro-actuators is currently facing two main limitations: the reinforcement layers that direct bending often increase the overall size of the device,” explained Nina Sinatra, a Graduate Student working with Wyss Institute Core Faculty members Robert Wood, Ph.D., and Kevin Kit Parker, Ph.D., at Harvard’s Wyss Institute for Biologically Inspired Engineering and the Harvard Paulson School of Engineering and Applied Sciences (SEAS). “Also, bending micro-actuators in different ways, such as with twisting motions, thus far required that the geometry of the actuator had to be re-designed.”

Now, researchers led by Wood and Parker at the Wyss Institute and SEAS, including Sinatra, have joined their forces to create a new type of soft micro-actuator that can be fabricated using simple shapes and geometries, to exhibit greater toughness and different bend or bend-twist motions. As reported in the Journal of Micromechanics and Microengineering, the team for the first time achieved this feat by combining two very different fabrication approaches and materials with complementary functions.

This video explains how two fabrication techniques, soft lithography and rotary jet spinning of nanofibers, are combined to create a new type of micro-actuator for the manipulation of small fragile objects in challenging environments. Credit: Wyss Institute at Harvard University

“At the start of the project, we hypothesized that we could extend the toughness and bending capabilities of soft micro-actuators simply by reinforcing them with a thin layer of a nanofiber network,” said Sinatra, the study’s first author.

To test this idea, the team first used soft lithography to fabricate the micro-actuator’s elastic component as a thin, elongated shape with a rectangular cross-section. The flexible polymer polydimethylsiloxane (PDMS) was used for this component because of its elastic and chemical properties and compatibility with many biomedical and industrial applications. Soft lithography is a layered fabrication technique that is widely deployed to create diverse micro-scale structures from soft elastomeric materials with the help of stamps, molds, or masks. Choosing to manufacture the micro-actuator layer-by-layer also allowed them to embed a hollow channel along one side, which, in the finished design, can be pressurized with air or liquid to trigger the micro-actuator’s motions.

For the micro-actuator’s nanofiber component, the team took advantage of a rotary jet spinning (RJS) technique previously developed by Parker’s group to create nanofibers from biological materials in an ongoing effort to manufacture regenerating heart valves for patients in need. In RJS, a rotating nozzle extrudes a solution of proteins or polymers that solidify as thin nanofibers; to fabricate nanofabrics for soft micro-actuators, the team used solutions of strong and stretchable synthetic polymers such as nylon and polyurethane. They collected the extruded nanofibers in aligned sheets and bonded laser-cut sections of the sheets to the side opposite of the channel in the soft PDMS component. As the channel is pressurized, the nanofabric will reinforce one side of the actuator and preferentially induce bending toward this direction. This step completed the final composite micro-actuator.

With one end of the actuator free and the other end fixed to a pressure source, the team found their original hypothesis confirmed: the composite soft micro-actuators were 2.3 times tougher than control micro-actuators made of PDMS alone and capable of withstanding pressures almost 26% higher. “By varying the nanofiber orientation and incising angled patterns into nanofiber sheets, we could program bend-twist motions into the soft micro-actuators, which widens our design space and the usability of these micro-devices significantly,” said Sinatra. The resulting micro-actuators are the slimmest soft pneumatic devices to achieve a more complex bending-twisting motion, which point to the potential for unprecedented delicate manipulation on the microscale.

“This new prototype of nanofiber-enforced soft micro-actuators is a compelling starting point for real-world applications that, interfacing this new actuator design with other tools, can facilitate micromanipulation of various fragile objects in challenging environments,” said Wood, who also is the Charles River Professor of Engineering and Applied Sciences at SEAS.

• PUBLICATION – Journal of Micromechanics and Microengineering: Nanofiber-reinforced soft fluidic micro-actuators
• WYSS TECHNOLOGY – Flexible force sensors for microrobotics

A new fabrication process enables the creation of soft robots at the millimeter scale with features on the micrometer scale as shown here with the example of a small soft robotic peacock spider with moving body parts and colored eyes and abdomens. Credit: Wyss Institute at Harvard University

Roboticists are envisioning a future in which soft, animal-inspired robots can be safely deployed in difficult-to-access environments, such as inside the human body or in spaces that are too dangerous for humans to work, in which rigid robots cannot currently be used. Centimeter-sized soft robots have been created, but thus far it has not been possible to fabricate multifunctional flexible robots that can move and operate at smaller size scales.

A team of researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering, Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), and Boston University now has overcome this challenge by developing an integrated fabrication process that enables the design of soft robots on the millimeter scale with micrometer-scale features. To demonstrate the capabilities of their new technology, they created a robotic soft spider – inspired by the millimeter-sized colorful Australian peacock spider – from a single elastic material with body-shaping, motion, and color features. The study is published in Advanced Materials.

“The smallest soft robotic systems still tend to be very simple, with usually only one degree of freedom, which means that they can only actuate one particular change in shape or type of movement,” said Sheila Russo, Ph.D., co-author of the study. Russo helped initiate the project as a Postdoctoral Fellow in Robert Wood’s group at the Wyss Institute and SEAS and now is Assistant Professor at Boston University. “By developing a new hybrid technology that merges three different fabrication techniques, we created a soft robotic spider made only of silicone rubber with 18 degrees of freedom, encompassing changes in structure, motion, and color, and with tiny features in the micrometer range.”

Wood, Ph.D., is a Core Faculty member and co-leader of the Bioinspired Soft Robotics platform at the Wyss Institute and the Charles River Professor of Engineering and Applied Sciences at SEAS. “In the realm of soft robotic devices, this new fabrication approach can pave the way towards achieving similar levels of complexity and functionality on this small scale as those exhibited by their rigid counterparts. In the future, it can also help us emulate and understand structure-function relationships in small animals much better than rigid robots can,” he said.

In their Microfluidic Origami for Reconfigurable Pneumatic/Hydraulic (MORPH) devices, the team first used a soft lithography technique to generate 12 layers of an elastic silicone that together constitute the soft spider’s material basis. Each layer is precisely cut out of a mold with a laser-micromachining technique, and then bonded to the one below to create the rough 3D structure of the soft spider.

Key to transforming this intermediate structure into the final design is a pre-conceived network of hollow microfluidic channels that is integrated into individual layers. With a third technique known as injection induced self-folding, pressurized one set of these integrated microfluidic channels with a curable resin from the outside. This induces individual layers, and with them also their neighboring layers, to locally bend into their final configuration, which is fixed in space when the resin hardens. This way, for example, the soft spider’s swollen abdomen and downward-curved legs become permanent features.

“We can precisely control this origami-like folding process by varying the thickness and relative consistency of the silicone material adjacent to the channels across different layers or by laser-cutting at different distances from the channels. During pressurization, the channels then function as actuators that induce a permanent structural change,” said first and corresponding author Tommaso Ranzani, Ph.D., who started the study as a Postdoctoral Fellow in Wood’s group and now also is Assistant Professor at Boston University.

The remaining set of integrated microfluidic channels were used as additional actuators to colorize the eyes and simulate the abdominal color patterns of the peacock spider species by flowing colored fluids; and to induce walking-like movements in the leg structures. “This first MORPH system was fabricated in a single, monolithic process that can be performed in few days and easily iterated in design optimization efforts,” said Ranzani.

“The MORPH approach could open up the field of soft robotics to researchers who are more focused on medical applications where the smaller sizes and flexibility of these robots could enable an entirely new approach to endoscopy and microsurgery,” said Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at HMS and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at SEAS.

Additional authors on the study are Nicholas Bartlett, a Graduate Student on Wood’s team and Michael Wehner, Ph.D., a former Postdoctoral Fellow with Wood, who know is Assistant Professor at University of California Santa Cruz. The study was funded by Harvard’s Wyss Institute, the Defense Advanced Research Project Agency (DARPA), and a National Defense Science and Engineering Graduate Fellowship.

PUBLICATION – Advanced Materials: Increasing the Dimensionality of Soft Microstructures through Injection‐Induced Self‐Folding

his fully 3D-printed version of the grippers includes “fingernails” on the ends of the fingers to help pick up organisms that are sitting on hard surfaces, as well as mesh extensions between the fingers to keep samples secure. Credit: Wyss Institute at Harvard University

The deep ocean – dark, cold, under high pressure, and airless – is notoriously inhospitable to humans, yet it teems with organisms that manage to thrive in its harsh environment. Studying those creatures requires specialized equipment mounted on remotely operated vehicles (ROVs) that can withstand those conditions in order to collect samples. This equipment, designed primarily for the underwater oil and mining industries, is clunky, expensive, and difficult to maneuver with the kind of control needed for interacting with delicate sea life. Picking a delicate sea slug off the ocean floor with these tools is akin to trying to pluck a grape using pruning shears.

Now, a multidisciplinary group of engineers, marine biologists, and roboticists has developed an alternative sampling device that is soft, flexible, and customizable, allowing scientists to gently grab different types of organisms from the sea without damaging them, and 3D-print modifications to the device overnight without the need to return to a land-based laboratory. The research is reported in PLOS One.

“When interacting with soft, delicate underwater creatures, it makes the most sense for your sampling equipment to also be soft and gentle,” said co-author Rob Wood, Ph.D., a Founding Core Faculty member of the Wyss Institute who is also the Charles River Professor of Engineering and Applied Sciences at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). “It’s only recently that the field of soft robotics has developed to the point where we can actually build robots that can grasp these animals reliably and harmlessly.”

The “soft gripper” devices the team designed have anywhere from two to five “fingers” made of polyurethane and other squishy materials that open and close via a low-pressure hydraulic pump system that uses seawater to drive their movement. The grippers themselves are attached to a wooden ball that is held and manipulated using an ROV’s existing, hard claw-like tools, controlled by a human operator on the ship to which the ROV is tethered.

A modified version of the gripper with only two fingers can perform both a “power grasp” for holding large objects and a “pinch grasp” for holding small objects, much like a human hand. Credit: Wyss Institute at Harvard University

The team deployed their latest iteration of the soft grippers on a voyage aboard the Schmidt Ocean Institute’s R/V Falkor in the remote Phoenix Islands Protected Area in the South Pacific. Such an isolated environment meant that obtaining new parts for the grippers would be nearly impossible, so they brought two 3D printers for creating new components on-the-fly.

“Being on a ship for a month meant that we had to be able to make anything we needed, and it turns out that the 3D printers worked really well for doing that on the boat. We had them running almost 24/7, and we were able to take feedback from the ROV operators about their experience using the soft grippers and make new versions overnight to address any problems,” said Daniel Vogt, M.S., a Research Engineer at the Wyss Institute who is the first author of the paper.

The soft grippers were able to grab sea slugs, corals, sponges, and other marine life much more effectively and with less damage than traditional underwater sampling tools. Based on input from the ROV operators, the team 3D-printed “fingernail” extensions that could be added to the gripper’s fingers to help them get underneath samples that were sitting on hard surfaces. A flexible mesh was also added to each finger to help keep samples contained within the fingers’ grip. Another, two-fingered version of the grippers was also created based on ROV pilots’ familiarity with controlling existing two-fingered graspers, and their request that the two fingers be able to hold samples with both a “pinch” grasp (for small objects) and a “power” grasp (for large objects).

The team is continuing to develop the grippers, hoping to add sensors that can indicate to the ROV operator when the grippers come into contact with an organism, “feel” how hard or soft it is, and take other measurements. Ultimately, their goal is to be able to capture sea creatures in the deep ocean and obtain full physical and genetic data without taking them out of their native habitats.

“Being able to 3D-print variations of these soft robots within hours to safely interact with different types of sea life has the potential to revolutionize the way marine biology fieldwork is done,” said co-corresponding author David Gruber, Ph.D., who is a 2017-2018 Radcliffe Fellow, National Geographic Explorer, and Professor of Biology and Environmental Science at Baruch College, CUNY.

“New technologies are continually enabling us to overcome the limitations of old technologies, which all too often are simply accepted as the status quo and never challenged,” said Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at HMS and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at SEAS. “3D printing and soft robotics technologies are now allowing the processes of design and iteration to happen on-site rather than in the lab, making it faster, easier, and cheaper to create solutions to existing problems.”

Additional authors of the paper include Kaitlyn Becker and Mortiz Graule from the Wyss Institute and Harvard SEAS, Brennan Phillips, Ph.D. from the University of Rhode Island, Randi Rotjan, Ph.D. from Boston University, Timothy Shank, Ph.D. from Woods Hole Oceanographic Institution, and Erik Cordes, Ph.D. from Temple University.

The research was supported by the National Oceanographic and Atmospheric Association, the Schmidt Ocean Institute, the National Science Foundation, the National Academy of Sciences, the PIPA Conservation Trust, the PIPA Scientific Committee, and the Wyss Institute at Harvard University.

PUBLICATION – PLOS One: Shipboard design and fabrication of custom 3D-printed soft robotic manipulators for the investigation of delicate deep-sea organisms

When HAMR needs to sink, its footpads emit a high voltage to break the water surface tension. This process is called electrowetting, which is the reduction of the contact angle between a material and the water surface under an applied voltage. This change of contact angle makes it easier for objects to break the water surface. (Credit: Yufeng Chen, Neel Doshi, and Benjamin Goldberg/Harvard University)

By Leah Burrows

In nature, cockroaches can survive underwater for up to 30 minutes. Now, a robotic cockroach can do even better. Harvard’s Ambulatory Microrobot, known as HAMR, can walk on land, swim on the surface of water, and walk underwater for as long as necessary, opening up new environments for this little bot to explore.

This next generation HAMR uses multifunctional foot pads that rely on surface tension and surface tension-induced buoyancy when HAMR needs to swim but can also apply a voltage to break the water surface when HAMR needs to sink. This process is called electrowetting, which is the reduction of the contact angle between a material and the water surface under an applied voltage. This change of contact angle makes it easier for objects to break the water surface.

Moving on the surface of water allows a microrobot to evade submerged obstacles and reduces drag. Using four pairs of asymmetric flaps and custom designed swimming gaits, HAMR robo-paddles on the water surface to swim. Inspired by the gait of a diving beetle, the researchers exploited the unsteady interaction between the robot’s passive flaps and the surrounding water to effectively swim forward and turn.

“This research demonstrates that microrobotics can leverage small-scale physics — in this case surface tension — to perform functions and capabilities that are challenging for larger robots,” said Kevin Chen, Ph.D., a postdoctoral fellow at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and first author of the paper.

The most recent research is published in the journal Nature Communications.

“HAMR’s size is key to its performance,” said Neel Doshi, graduate student at SEAS and co-author of the paper. “If it were much bigger, it would be challenging to be support the robot with surface tension and if it were much smaller, the robot would need a lot more force to break it.”

HAMR weighs 1.65 grams (about as much as a large paper clip), can carry 1.44 grams of additional payload without sinking and can paddle its legs with a frequency up to 10 Hz. It’s coated in Parylene to keep it from shorting under water.

Once below the surface of the water, HAMR uses the same gait to walk as it does on dry land and is just as mobile. Getting out of the water, however, is an enormous challenge. The water’s surface tension force is twice HAMR’s weight and the induced torque causes a dramatic increase of friction on the robot’s hind legs. The researchers stiffened the robot’s transmission and installed soft pads to the robot’s front legs to increase payload capacity and redistribute friction during climbing. Finally, walking up a modest incline, the robot is able break out of the water’s hold.

Havard’s Ambulatory Microrobot (HAMR) joins the Robobee (right) as a microrobot that can transition between air and water (Credit: Yufeng Chen, Neel Doshi, and Benjamin Goldberg/Harvard University)

“This robot nicely illustrates some of the challenges and opportunities with small-scale robots,” said senior author Robert Wood, Ph.D., Core Faculty member at the Wyss Institute for Biologically Inspired Engineering and the Charles River Professor of Engineering and Applied Sciences at Harvard’s Paulson School of Engineering and Applied Sciences. “Shrinking brings opportunities for increased mobility – such as walking on the surface of water – but also challenges since the forces that we take for granted at larger scales can start to dominate at the size of an insect.”

Next, the researchers hope to further improve HAMR’s locomotion and find a way to return to land without a ramp, perhaps incorporating gecko-inspired adhesives or impulsive jumping mechanisms.

This research was co-authored by Benjamin Goldberg and Hongqiang Wang, Ph.D.. It was supported by the Wyss Institute for Biologically Inspired Engineering, the Harvard John A. Paulson School of Engineering and Applied Science, and the Office of Naval Research’s Defense University Research Instrumentation Program.

• WYSS TECHNOLOGY – Versatile Ambulatory Microrobots
• PUBLICATION – Nature Communications: Controllable water surface to underwater transition through electrowetting in a hybrid terrestrial-aquatic microrobot

The open ocean is the largest and least explored environment on Earth, estimated to hold up to a million species that have yet to be described. However, many of those organisms are soft-bodied – like jellyfish, squid, and octopuses – and are difficult to capture for study with existing underwater tools, which all too frequently damage or destroy them. Now, a new device developed by researchers at Harvard University’s Wyss Institute, John A. Paulson School of Engineering and Applied Sciences (SEAS), and Radcliffe Institute for Advanced Study safely traps delicate sea creatures inside a folding polyhedral enclosure and lets them go without harm using a novel, origami-inspired design. The research is reported in Science Robotics.

The rotary actuated dodecahedron (RAD) sampler has five origami-inspired “petals” arranged around a central point that fold up to safely capture marine organisms, like this jellyfish. Credit: Wyss Institute at Harvard University

“We approach these animals as if they are works of art: would we cut pieces out of the Mona Lisa to study it? No – we’d use the most innovative tools available. These deep-sea organisms, some being thousands of years old, deserve to be treated with a similar gentleness when we’re interacting with them,” said collaborating author David Gruber, Ph.D., who is a 2017-2018 Radcliffe Fellow, National Geographic Explorer, and Professor of Biology and Environmental Science at Baruch College, CUNY.

The idea to apply folding properties to underwater sample collection began in 2014 when first author Zhi Ern Teoh, Ph.D., took a class from Chuck Hoberman, M.S., a Wyss Associate Faculty Member and Pierce Anderson Lecturer in Design Engineering at the Harvard Graduate School of Design, about creating folding mechanisms through computational means. “I was building microrobots by hand in graduate school, which was very painstaking and tedious work, and I wondered if there was a way to fold a flat surface into a three-dimensional shape using a motor instead,” said Teoh, a former Postdoctoral Fellow at the Wyss Institute in the lab of Robert Wood, Ph.D.; he is now an engineer at Cooper Perkins.

A fellow member of the Wood lab at the time, Brennan Phillips, Ph.D. – now Assistant Professor of Ocean Engineering at the University of Rhode Island – saw Teoh’s designs and suggested he adapt it to capture sea creatures, which are notoriously difficult to grab with existing underwater equipment that is largely designed for the rough work of ocean mining and construction.

The device that Teoh built consists of five identical 3D-printed polymer “petals” attached to a series of rotating joints that are linked together to form a scaffold. When a single motor applies a torque to the point where the petals meet, it causes the entire structure to rotate about its joints and fold up into a hollow dodecahedron (like a twelve-sided, almost-round box), earning it the name of Rotary Actuated Dodecahedron (RAD). The folding is entirely directed by the design of the joints and the shape of the petals themselves; no other input is required.

The team tested the RAD sampler at Mystic Aquarium in Mystic, Conn., and successfully collected and released moon jellyfish underwater. After making modifications to the sampler so it could withstand open ocean conditions, they then mounted it on an underwater remotely-operated vehicle (ROV) provided by the Monterey Bay Aquarium Research Institute (MBARI) in Monterey, Calif., and tested it in the field at depths of 500-700 m (1,600-2,300 ft) using the ROV’s manipulator arm and human-controlled joystick to operate the sampler. The team was able to capture soft organisms like squid and jellyfish within their natural habitats, and release them without harm.

First author Zhi Ern Teoh tests the RAD sampler, mounted on the ROV Ventana, before its deployment into the Pacific Ocean at Monterey Canyon, California. Credit: Wyss Institute at Harvard University

“The RAD sampler design is perfect for the difficult environment of the deep ocean because its controls are very simple, so there are fewer elements that can break. It’s also modular, so if something does break, we can simply replace that part and send the sampler back down into the water,” said Teoh. “This folding could also be well-suited to be used in space, which is similar to the deep ocean in that it’s a low-gravity, inhospitable environment that makes operating any device challenging.”

Teoh and Phillips are currently working on a more rugged version of the RAD sampler for use in heavier-duty underwater tasks, like marine geology, while Gruber and Wood are focusing on further refining the sampler’s more delicate abilities. “We’d like to add cameras and sensors to the sampler so that, in the future, we can capture an animal, collect lots of data about it like its size, material properties, and even its genome, and then let it go, almost like an underwater alien abduction,” said Gruber.

“Our group’s collaboration with the marine biology community has opened the door for the fields of soft robotics and origami-inspired engineering to apply those technologies to solve problems in an entirely different discipline, and we are excited to see the ways in which this synergy creates novel solutions,” said Wood, who is a Founding Core Faculty member of the Wyss Institute, the Charles River Professor of Engineering and Applied Sciences at SEAS, and also a National Geographic Explorer.

“Collaboration across disciplines is a defining feature of the Wyss Institute, and this work exemplifies how new innovations can emerge when scientists from vastly different fields start communicating with each other,” said Don Ingber, M.D., Ph.D., the Founding Director of the Wyss Institute who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children’s Hospital, as well as a Professor of Bioengineering at SEAS.

Phillips is currently an Assistant Professor of Ocean Engineering at the University of Rhode Island. Additional authors of the paper include Kaitlyn Becker, Griffin Whittredge, and James Weaver, Ph.D. from the Wyss Institute and SEAS.

This research was supported by the National Science Foundation and the National Academy of Sciences.

• PUBLICATION – Science Robotics: Rotary-actuated folding polyhedrons for midwater investigation of delicate marine organisms

As the vacuum is applied to the flexible material, it becomes stiff and able to support the weight of the drone. Credit: Yashraj Narang

Even octopuses understand the importance of elbows. When these squishy, loose-limbed cephalopods need to make a precise movement — such as guiding food into their mouth — the muscles in their tentacles contract to create a temporary revolute joint. These joints limit the wobbliness of the arm, enabling more controlled movements.

Now, researchers from the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have shown how a multi-layered structure can allow robots to mimic the octopus’ kinematics, creating and eliminating joints on command. The structure can also allow robots to rapidly change their stiffness, damping, and dynamics.

The research is published in two papers in Advanced Functional Materials and IEEE Robotics and Automation Letters.

“This research helps bridge the gap between soft robotics and traditional rigid robotics,” said Yashraj Narang, first author of both studies and graduate student at SEAS. “We believe that this class of technology may foster a new generation of machines and structures that cannot simply be classified as soft or rigid.”

When a vacuum is applied, the layers of flexible material becomes stiff and can hold arbitrary shapes, and be molded into additional forms. Credit: Yashraj Narang/Harvard SEAS

The structure is surprisingly simple, consisting of multiple layers of flexible material wrapped in a plastic envelope and connected to a vacuum source. When the vacuum is off, the structure behaves exactly as you would expect, bending, twisting and flopping without holding shape. But when a vacuum is applied, it becomes stiff and can hold arbitrary shapes, and it can be molded into additional forms.

This transition is the result of a phenomenon called laminar jamming, in which the application of pressure creates friction that strongly couples a group of flexible materials.

“The frictional forces generated by the pressure act like glue,” said Narang. “We can control the stiffness, damping, kinematics, and dynamics of the structure by changing the number of layers, tuning the pressure applied to it, and adjusting the spacing between multiple stacks of layers.”

The research team, which included Wyss Associate Faculty member Robert Howe, Ph.D., the Abbott and James Lawrence Professor of Engineering at SEAS; Joost Vlassak, Ph.D., the Abbott and James Lawrence Professor of Materials Engineering at SEAS; and Alperen Degirmenci, a SEAS graduate student, extensively modeled the mechanical behavior of laminar jamming to better control its capabilities.

Next, they built real-world devices using the structures, including a two-fingered gripper that, without a vacuum, could wrap around and hold onto large objects and, with a vacuum, could pinch and hold onto small objects about the size of a marble.

The researchers also demonstrated the structure’s capabilities as shock absorbers by attaching them to a drone as a landing gear. The team tuned the stiffness and damping of the structures to absorb the impact of landing.

The structure is a proof-of-concept that could have many applications in the future, from surgical robots to wearable devices and flexible speakers.

“Our work has explained the phenomenon of laminar jamming and shown how it can provide robots with highly versatile mechanical behavior,” said Howe, who is the senior author of the paper. “We believe that this technology will eventually lead to robots that can change state between soft, continuous devices that can safely interact with humans, and rigid, discrete devices that can meet the demands of industrial automation.”

 This research was supported in part by the National Science Foundation.

A Bayesian optimization method that integrates the metabolic costs in wearers of this hip-assisting exosuit enabled the individualized fine-tuning of assistive forces. Credit: Ye Ding/Harvard University

When it comes to soft, assistive devices — like the exosuit being designed by the Harvard Biodesign Lab — the wearer and the robot need to be in sync. But every human moves a bit differently and tailoring the robot’s parameters for an individual user is a time-consuming and inefficient process.

Now, researchers from the Wyss Institute for Biologically Inspired Engineering and the Harvard John A. Paulson School of Engineering and Applied and Sciences (SEAS) have developed an efficient machine learning algorithm that can quickly tailor personalized control strategies for soft, wearable exosuits.

The research is described in Science Robotics.

“This new method is an effective and fast way to optimize control parameter settings for assistive wearable devices,” said Ye Ding, a Postdoctoral Fellow at SEAS and co-first author of the research. “Using this method, we achieved a huge improvement in metabolic performance for the wearers of a hip extension assistive device.”

When humans walk, we constantly tweak how we move to save energy (also known as metabolic cost).

“Before, if you had three different users walking with assistive devices, you would need three different assistance strategies,” said Myunghee Kim, Ph.D., postdoctoral research fellow at SEAS and co-first author of the paper. “Finding the right control parameters for each wearer used to be a difficult, step-by-step process because not only do all humans walk a little differently but the experiments required to manually tune parameters are complicated and time consuming.”

The researchers, led by Conor Walsh, Ph.D., Core Faculty member at the Wyss Institute and the John L. Loeb Associate Professor of Engineering and Applied Sciences, and Scott Kuindersma, Ph.D., Assistant Professor of Engineering and Computer Science at SEAS, developed an algorithm that can cut through that variability and rapidly identify the best control parameters that work best  for minimizing the energy used for walking.

The researchers used so-called human-in-the-loop optimization, which uses real-time measurements of human physiological signals, such as breathing rate, to adjust the control parameters of the device. As the algorithm honed in on the best parameters, it directed the exosuit on when and where to deliver its assistive force to improve hip extension. The Bayesian Optimization approach used by the team was first report in a paper last year in PLOS ONE.

The combination of the algorithm and suit reduced metabolic cost by 17.4 percent compared to walking without the device. This was a more than 60 percent improvement compared to the team’s previous work.

“Optimization and learning algorithms will have a big impact on future wearable robotic devices designed to assist a range of behaviors,” said Kuindersma. “These results show that optimizing even very simple controllers can provide a significant, individualized benefit to users while walking. Extending these ideas to consider more expressive control strategies and people with diverse needs and abilities will be an exciting next step.” 

“With wearable robots like soft exosuits, it is critical that the right assistance is delivered at the right time so that they can work synergistically with the wearer,” said Walsh. “With these online optimization algorithms, systems can learn how do achieve this automatically in about twenty minutes, thus maximizing benefit to the wearer.”

Next, the team aims to apply the optimization to a more complex device that assists multiple joints, such as hip and ankle, at the same time.

“In this paper, we demonstrated a high reduction in metabolic cost by just optimizing hip extension,” said Ding. “This goes to show what you can do with a great brain and great hardware.”

This research was supported by the Defense Advanced Research Projects Agency, Warrior Web Program, Harvard’s Wyss Institute for Biologically Inspired Engineering, and the Harvard John A. Paulson School of Engineering and Applied Science.

• PUBLICATION – Science Robotics: Human-in-the-loop optimization of hip assistance with a soft exosuit during walking

This soft robotic gripper is the result of a platform technology developed by Harvard researchers to create soft robots with embedded sensors that can sense inputs as diverse as movement, pressure, touch, and temperature. Credit: Ryan L. Truby/Harvard University

Researchers at Harvard University have built soft robots inspired by nature that can crawl, swim, grasp delicate objects and even assist a beating heart, but none of these devices has been able to sense and respond to the world around them.

That’s about to change.

Inspired by our bodies’ sensory capabilities, researchers at the Wyss Institute for Biologically Inspired Engineering and the Harvard John A. Paulson School of Engineering and Applied Sciences have developed a platform for creating soft robots with embedded sensors that can sense movement, pressure, touch, and even temperature.

The research is published in Advanced Materials.

“Our research represents a foundational advance in soft robotics,” said Ryan Truby, first author of the paper and recent Ph.D. graduate at SEAS. “Our manufacturing platform enables complex sensing motifs to be easily integrated into soft robotic systems.”

Integrating sensors within soft robots has been difficult in part because most sensors, such as those used in traditional electronics, are rigid.  To address this challenge, the researchers developed an organic ionic liquid-based conductive ink that can be 3D printed within the soft elastomer matrices that comprise most soft robots.

“To date, most integrated sensor/actuator systems used in soft robotics have been quite rudimentary,” said Michael Wehner, former Postdoctoral Fellow at SEAS and co-author of the paper. “By directly printing ionic liquid sensors within these soft systems, we open new avenues to device design and fabrication that will ultimately allow true closed loop control of soft robots.”

Wehner is now an Assistant Professor at the University of California, Santa Cruz.

To fabricate the device, the researchers relied on an established 3D printing technique developed in the lab of Jennifer Lewis, Sc.D., Core Faculty Member of the Wyss Institute and the Hansjörg Wyss Professor of Biologically Inspired Engineering at SEAS. The technique — known as embedded 3D printing — seamlessly and quickly integrates multiple features and materials within a single soft body.

“This work represents the latest example of the enabling capabilities afforded by embedded 3D printing – a technique pioneered by our lab,” said Lewis.

“The function and design flexibility of this method is unparalleled,” said Truby. “This new ink combined with our embedded 3D printing process allows us to combine both soft sensing and actuation in one integrated soft robotic system.”

To test the sensors, the team printed a soft robotic gripper comprised of three soft fingers or actuators. The researchers tested the gripper’s ability to sense inflation pressure, curvature, contact, and temperature. They embedded multiple contact sensors, so the gripper could sense light and deep touches.

“Soft robotics are typically limited by conventional molding techniques that constrain geometry choices, or, in the case of commercial 3D printing, material selection that hampers design choices,” said Robert Wood, Ph.D., Core Faculty Member of the Wyss Institute and the Charles River Professor of Engineering and Applied Sciences at SEAS, and co-author of the paper.  “The techniques developed in the Lewis Lab have the opportunity to revolutionize how robots are created — moving away from sequential processes and creating complex and monolithic robots with embedded sensors and actuators.”

Next, the researchers hope to harness the power of machine learning to train these devices to grasp objects of varying size, shape, surface texture, and temperature.

The research was coauthored by Abigail Grosskopf, Daniel Vogt and Sebastien Uzel. It was supported it part by through Harvard MRSEC and Harvard’s Wyss Institute for Biologically Inspired Engineering.

• PUBLICATION – Advanced Materials: Soft Somatosensitive Actuators via Embedded 3D Printing

This soft robot is made using kirigami — an ancient Japanese paper craft that relies on cuts, rather than origami folds, to change the properties of a material. As the robot stretches, the kirigami is transformed into a 3D-textured surface. Credit: Ahmad Rafsanjani/Harvard SEAS

Who needs legs? With their sleek bodies, snakes can slither up to 14 miles-per-hour, squeeze into tight spaces, scale trees, and swim. How do they do it? It’s all in the scales. As a snake moves, its scales grip the ground and propel the body forward — similar to how crampons help hikers establish footholds in slippery ice. This so-called “friction-assisted locomotion” is possible because of the shape and positioning of snake’s scales.

Now, a team of researchers from the Wyss Institute at Harvard University and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has developed a soft robot that uses those same principles of locomotion to crawl without any rigid components. The soft robotic scales are made using kirigami — an ancient Japanese paper craft that relies on cuts, rather than origami folds, to change the properties of a material.  As the robot stretches, the flat kirigami surface is transformed into a 3D-textured surface, which grips the ground just like snake skin.

The research is published in Science Robotics.

“There has been a lot of research in recent years into how to fabricate these kinds of morphable, stretchable structures,” said Ahmad Rafsanjani, Ph.D., a postdoctoral fellow at SEAS and first author of the paper. “We have shown that kirigami principles can be integrated into soft robots to achieve locomotion in a way that is simpler, faster, and cheaper than most previous techniques.”

The researchers started with a simple, flat plastic sheet. Using a laser cutter, they embedded an array of centimeter-scale cuts, experimenting with different shapes and sizes. Once the sheet was cut, the researchers wrapped it around a tube-like elastomer actuator, which expands and contracts with air like a balloon.

When the actuator expands, the kirigami cuts pop out, forming a rough surface that grips the ground. When the actuator deflates, the cuts fold flat, propelling the crawler forward.

Wyss and Harvard researchers have built a fully untethered, soft robot, with integrated on-board control, sensing, actuation and power supply packed into a tiny tail. Credit: Ahmad Rafsanjani/Harvard SEAS

The researchers built a fully untethered robot, with its integrated on-board control, sensing, actuation, and power supply all packed into a tiny tail. They tested it crawling throughout Harvard’s campus.

The team experimented with various-shaped cuts, including triangular, circular, and trapezoidal. They found that trapezoidal cuts — which most closely resemble the shape of snake scales —gave the robot a longer stride.

“We show that the locomotive properties of these kirigami-skins can be harnessed by properly balancing the cut geometry and the actuation protocol,” said Rafsanjani. “Moving forward, these components can be further optimized to improve the response of the system.”

“We believe that our kirigami-based strategy opens avenues for the design of a new class of soft crawlers,” said the paper’s senior author Katia Bertoldi, Ph.D., an Associate Faculty member of the Wyss Institute and the William and Ami Kuan Danoff Professor of Applied Mechanics at SEAS. “These all-terrain soft robots could one day travel across difficult environments for exploration, inspection, monitoring, and search and rescue missions, or perform complex, laparoscopic medical procedures.”

This research was co-authored by Yuerou Zhang; Bangyuan Liu, a visiting student in the Bertoldi lab; and Shmuel M. Rubinstein, Ph.D., Associate Professor of Applied Physics at SEAS. It was supported by the National Science Foundation.

• PUBLICATION – Science Robotics: Kirigami skins make a simple soft actuator crawl

Completely unfolded, the milliDelta with 15 mm-by-15 mm-20 mm roughly compares to a cent piece, and uses piezoelectric actuators, and flexural joints in its three arms to control high-frequency movements of a stage on top. Credit: Wyss Institute at Harvard University

Because of their high precision and speed, Delta robots are deployed in many industrial processes, including pick-and-place assemblies, machining, welding and food packaging. Starting with the first version developed by Reymond Clavel for a chocolate factory to quickly place chocolate pralines in their packages, Delta robots use three individually controlled and lightweight arms that guide a platform to move fast and accurately in three directions. The platform is either used as a stage, similar to the ones being used in flight simulators, or coupled to a manipulating device that can, for example, grasp, move, and release objects in prescribed patterns. Over time, roboticists have designed smaller and smaller Delta robots for tasks in limited workspaces, yet shrinking them further to the millimeter scale with conventional manufacturing techniques and components has proven fruitless.

Reported in Science Robotics, a new design, the milliDelta robot, developed by Robert Wood’s team at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS) overcomes this miniaturization challenge. By integrating their microfabrication technique with high-performance composite materials that can incorporate flexural joints and bending actuators, the milliDelta can operate with high speed, force, and micrometer precision, which make it compatible with a range of micromanipulation tasks in manufacturing and medicine.

In 2011, inspired by pop-up books and origami, Wood’s team developed a micro-fabrication approach that enables the assembly of robots from flat sheets of composite materials. Pop-up MEMS (short for “microelectromechanical systems”) manufacturing has since been used for the construction of dynamic centimeter-scale machines that can simply walk away, or, as in the case of the RoboBee, can fly. In their new study, the researchers applied their approach to develop a Delta robot measuring a mere 15 mm-by-15 mm-by-20 mm.

“The physics of scaling told us that bringing down the size of Delta robots would increase their speed and acceleration, and pop-up MEMS manufacturing with its ability to use any material or combination of materials seemed an ideal way to attack this problem,” said Wood, who is a Core Faculty member at the Wyss Institute and co-leader of its Bioinspired Robotics platform. Wood is also the Charles River Professor of Engineering and Applied Sciences at SEAS. “This approach also allowed us to rapidly go through a number of iterations that led us to the final milliDelta.”

The milliDelta design incorporates a composite laminate structure with embedded flexural joints that approximate the more complicated joints found in large scale Delta robots. “With the help of an assembly jig, this laminate can be precisely folded into a millimeter-scale Delta robot. The milliDelta also utilizes piezoelectric actuators, which allow it to perform movements at frequencies 15 to 20 times higher than those of other currently available Delta robots,” said first-author Hayley McClintock, a Wyss Institute Staff Researcher on Wood’s team.

In addition, the team demonstrated that the milliDelta can operate in a workspace of about seven cubic millimeters and that it can apply forces and exhibit trajectories that, together with its high frequencies, could make it ideal for micromanipulations in industrial pick-and-place processes and microscopic surgeries such as retinal microsurgeries performed on the human eye.

The work by Wood’s team demonstrating the enhanced speed and control of their milliDelta robot at the millimeter scale opens entirely new avenues of development for industrial and medical robots, which are currently beyond the reach of existing technologies. Donald Ingber

Putting the milliDelta’s potential for microsurgeries and other micromanipulations to a first test, the researchers explored their robot as a hand tremor-cancelling device. “We first mapped the paths that the tip of a toothpick circumscribed when held by an individual, computed those, and fed them into the milliDelta robot, which was able to match and cancel them out,” said co-first author Fatma Zeynep Temel, Ph.D., a SEAS Postdoctoral Fellow in Wood’s team. The researchers think that specialized milliDelta robots could either be added on to existing robotic devices, or be developed as standalone devices like, for example, platforms for the manipulation of cells in research and clinical laboratories.

“The work by Wood’s team demonstrating the enhanced speed and control of their milliDelta robot at the millimeter scale opens entirely new avenues of development for industrial and medical robots, which are currently beyond the reach of existing technologies. It’s yet another example of how our Bioinspired Robotics platform is leading the way into the future,” said Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at HMS and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at SEAS.

Other authors on the study are Neel Doshi, a SEAS Graduate Student, and Je-sung Koh, Ph.D., a former Postdoctoral Fellow on Wood’s Wyss Institute/SEAS team and now Assistant Professor at Ajou University in Korea. The work was funded by Harvard’s Wyss Institute for Biologically Inspired Engineering and a National Defense Science and Engineering Graduate Fellowship.

• PUBLICATION – Science Robotics: The milliDelta: A high-bandwidth, high-precision, millimeter-scale Delta robot

This programmable DNA nanorobot ‘patrols’ the bloodstream and releases its payload of drugs in response to the presence of its target, much like the body’s white blood cells. Credit: Wyss Institute at Harvard University

DNA has often been compared to an instruction book that contains the information needed for a living organism to function, its genes made up of distinct sequences of the nucleotides A, G, C, and T echoing the way that words are composed of different arrangements of the letters of the alphabet. DNA, however, has several advantages over books as an information-carrying medium, one of which is especially profound: based on its nucleotide sequence alone, single-stranded DNA can self-assemble, or bind to complementary nucleotides to form a complete double-stranded helix, without human intervention. That would be like printing the instructions for making a book onto loose pieces of paper, putting them into a box with glue and cardboard, and watching them spontaneously come together to create a book with all the pages in the right order.

But just as paper can also be used to make origami animals, cups, and even the walls of houses, DNA is not limited to its traditional purpose as a passive repository of genetic blueprints from which proteins are made – it can be formed into different shapes that serve different functions, simply by controlling the order of As, Gs, Cs, and Ts along its length. A group of scientists at the Wyss Institute for Biologically Inspired Engineering at Harvard University is investigating this exciting property of DNA molecules, asking, “What types of systems and structures can we build with them?”

They’ve decided to build robots.

At first glance, there might not seem to be much similarity between a strand of DNA and, say, a Roomba or Rosie the Robot from The Jetsons. “Looking at DNA versus a modern-day robot is like comparing a piece of string to a tractor trailer,” says Wyss Faculty member Wesley Wong, Ph.D., Assistant Professor of Biological Chemistry and Molecular Pharmacology (BCMP) at Harvard Medical School (HMS) and Investigator at Boston Children’s Hospital. Despite the vast difference in their physical form, however, robots and DNA share the ability to be programmed to complete a specific function – robots with binary computer code, DNA molecules with their nucleotide sequences.

Recognizing that commonality, the Wyss Institute created the cross-disciplinary Molecular Robotics Initiative in 2016, which brings together researchers with experience in the disparate disciplines of robotics, molecular biology, and nanotechnology to collaborate and help inform each other’s work to solve the fields’ similar challenges. Wong is a founding member of the Initiative, along with Wyss Faculty members William Shih, Ph.D., Professor of BCMP at HMS and Dana-Farber Cancer Institute; Peng Yin, Ph.D., Professor of Systems Biology at HMS; and Radhika Nagpal, Ph.D., Fred Kavli Professor of Computer Science at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS); as well as other Wyss scientists and support staff.

“We’re not used to thinking about molecules inside cells doing the same things that computers do. But they’re taking input from their environment and performing actions in response – a gene is either turned on or off, a protein channel is either open or closed, etc. – in ways that can resemble what computer-controlled systems do,” says Shih. “Molecules can do a lot of things on their own that robots usually have trouble with (move autonomously, self-assemble, react to the environment, etc.), and they do it all without needing motors or an external power supply,” adds Wyss Founding Director Don Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at HMS and the Vascular Biology Program at Boston Children’s Hospital, as well as a Professor of Bioengineering at SEAS. “Programmable biological molecules like DNA have almost limitless potential for creating transformative nanoscale devices and systems.”

Molecular Robotics capitalizes on the recent explosion of technologies that read, edit, and write DNA (like next-generation sequencing and CRISPR) to investigate the physical properties of DNA and its single-stranded cousin RNA. “We essentially treat DNA not only as a genetic material, but as an incredible building block for creating molecular sensors, structures, computers, and actuators that can interact with biology or operate completely separately,” says Tom Schaus, M.D., Ph.D., a Staff Scientist at the Wyss Institute and Molecular Robotics team member.

Many of the early projects taking advantage of DNA-based self-assembly were static structures.  These include DNA “clamshell” containers that can be programmed to snap open and release their contents in response to specific triggers, and DNA “bricks” whose nucleotide sequences allow their spontaneous assembly into three-dimensional shapes, like tiny Lego bricks that put themselves together to create sculptures automatically. Many of these structures are three-dimensional, and some incorporate as many as 10,000 unique DNA strands in a single complete structure.

The reliable specificity of DNA and RNA (where A always binds with T or U, C always with G) allows for not only the construction of static structures, but also the programming of dynamic systems that sense and respond to environmental cues, as seen in traditional robotics. For example, Molecular Robotics scientists have created a novel, highly controllable mechanism that automatically builds new DNA sequences from a mixture of short fragments in vitro. It utilizes a set of hairpin-shaped, covalently-modified DNA strands with a single-stranded “overhang” sequence dangling off one end of the hairpin. The overhang sequence can bind to a complementary free-floating fragment of DNA (a “primer”) and act as a template for its extension into a double-stranded DNA sequence. The hairpin ejects the new double strand and can then be re-used in subsequent reactions to produce multiple copies of the new strand.

Such extension reactions can be programmed to occur only in the presence of signal molecules, such as specific RNA sequences, and can be linked together to create longer DNA product strands through “Primer Exchange Reactions” (PER). PER can in turn be programmed to enzymatically cut and destroy particular RNA sequences, record the order in which certain biochemical events happen, or generate components for DNA structure assembly.

PER reactions can also be combined into a mechanism called “Autocycling Proximity Recording” (APR), which records the geometry of nano-scale structures in the language of DNA. In this instance, unique DNA hairpins are attached to different target molecules in close proximity and, if any two targets are close enough together, produce new pieces of DNA containing the molecular identities (“names”) of those two targets, allowing the shape of the underlying structure to be determined by sequencing that novel DNA.

Another tool, called “toehold switches,” can be used to exert complex and precise control over the machinery inside living cells. Here, a different, RNA-based hairpin is designed to “open” when it binds to a specific RNA molecule, exposing a gene sequence in its interior that can be translated into a protein that then performs some function within the cell. These synthetic circuits can even be built with logic-based sequences that mimic the “AND,” “OR,” and “NOT” system upon which computer languages are based, which prevents the hairpin from opening and its gene from being translated except under very specific conditions.

Such an approach could induce cells that are deficient in a given protein to produce more of it, or serve as a synthetic immune system that, when it detects a given problem in the cell, produces a toxin that kills it to prevent it from spreading an infection or becoming cancerous. [toeholds] “Because we have a thorough understanding of DNA and RNA’s properties and how their bases pair together, we can use that simple machinery to design complex circuits that allow us to precisely interact with the molecular world,” says Yin. “It’s an ability that has been dreamed about for a long time, and now, we’re actually making it a reality.”

The potential applications of that ability are seemingly endless. In addition to the previously mentioned tools, Molecular Robotics researchers have created loops of DNA attached to microscopic beads to create “calipers” that can both measure the size, structure, and stiffness of other molecules, and form the basis of inexpensive protein recognition tests. Another advance is folding single-stranded DNA into molecular origami to create molecular structures, rather than traditional double-stranded DNA. Some academic projects are already moving into the commercial sector. These include a low-cost alternative to super-resolution microscopy that can image up to 100 different molecular targets in a single sample (DNApaint), as well as a multiplexed imaging technique that integrates fluorescent probes into self-folding DNA structures and enables simultaneous visualization of ultra-rare DNA and/or RNA molecules.

One of the major benefits of engineering molecular machines is that they’re tiny, so it’s relatively easy to create a large amount of them to complete any one task (for example, circulating through the body to detect any rogue cancer DNA). Getting simple, individual molecules to interact with each other to achieve a more complex, collective task (like relaying the information that cancer has been found), however, is a significant challenge, and one that the roboticists in Molecular Robotics are tackling at the macroscopic scale with inch-long “Kilobots.”

Taking cues from colonies of insects like ants and bees, Wyss researchers are developing swarms of robots that are themselves limited in function but can form complex shapes and complete tasks by communicating with each other via reflected infrared light. The insights gained from studies with the Kilobots are likely to be similar to those needed to solve similar problems when trying to coordinate molecular robots made of DNA.

“In swarm robotics, you have multiple robots that explore their environment on their own, talk to each other about what they find, and then come to a collective conclusion. We’re trying to replicate that with DNA but it’s challenging because, as simple as Kilobots are, they’re brilliant compared to DNA in terms of computational power,” says Justin Werfel, Ph.D., a Senior Research Scientist at the Wyss Institute and director of the Designing Emergence Laboratory at Harvard. “We’re trying to push the limits of these really dumb little molecules to get them to behave in sophisticated, collective ways – it’s a new frontier for DNA nanotechnology.”

Given the magnitude of the challenge and the short time the Molecular Robotics Initiative has existed, it is already making significant progress, with more than two dozen papers published and two companies (Ultivue and NuProbe) founded around its insights and discoveries. It may take years of creative thinking, risk taking, and swapping ideas across the members’ different expertise areas before a molecule of DNA is able to achieve the same task on the nanoscale that a robot can do on the human scale, but the team is determined to see it happen.

“Our vision with Molecular Robotics is to solve hard problems humanity currently faces using smaller, simpler tools, like a single loop of DNA or a single Kilobot that can act cooperatively en masse, instead of bigger, more complex ones that are harder to develop and become useless should any one part fail,” says Wong. “It’s an idea that definitely goes against the current status quo, and we’re lucky enough to be pursuing it here at the Wyss Institute, which brings together people with common goals and interests to create new things that wouldn’t exist otherwise.”

Click on the links below to explore research from the Molecular Robotics Initiative.

1. Researchers at Harvard’s Wyss Institute Develop DNA Nanorobot to Trigger Targeted Therapeutic Responses
2. A 100-fold leap to GigaDalton DNA nanotech
3. Autonomously growing synthetic DNA strands
4. High-fidelity recording of molecular geometry with DNA “nanoscopy”
5. Programming cells with computer-like logic
6. Democratizing high-throughput single molecule force analysis
7. Single-stranded DNA and RNA origami go live
8. Capturing ultrasharp images of multiple cell components at once
9. A self-organizing thousand-robot swarm
10. Discrete Molecular Imaging

Origami-inspired artificial muscles are capable of lifting up to 1,000 times their own weight, simply by applying air or water pressure. Credit: Shuguang Li / Wyss Institute at Harvard University

Soft robotics has made leaps and bounds over the last decade as researchers around the world have experimented with different materials and designs to allow once rigid, jerky machines to bend and flex in ways that mimic and can interact more naturally with living organisms. However, increased flexibility and dexterity has a trade-off of reduced strength, as softer materials are generally not as strong or resilient as inflexible ones, which limits their use.

Now, researchers at the Wyss Institute at Harvard University and MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have created origami-inspired artificial muscles that add strength to soft robots, allowing them to lift objects that are up to 1,000 times their own weight using only air or water pressure, giving much-needed strength to soft robots. The study is published this week in Proceedings of the National Academy of Sciences (PNAS).

“We were very surprised by how strong the actuators [aka, “muscles”] were. We expected they’d have a higher maximum functional weight than ordinary soft robots, but we didn’t expect a thousand-fold increase. It’s like giving these robots superpowers,” says Daniela Rus, Ph.D., the Andrew and Erna Viterbi Professor of Electrical Engineering and Computer Science at MIT and one of the senior authors of the paper.

“Artificial muscle-like actuators are one of the most important grand challenges in all of engineering,” adds  Rob Wood, Ph.D., corresponding author of the paper and Founding Core Faculty member of the Wyss Institute, who is also the Charles River Professor of Engineering and Applied Sciences at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS). “Now that we have created actuators with properties similar to natural muscle, we can imagine building almost any robot for almost any task.”

Each artificial muscle consists of an inner “skeleton” that can be made of various materials, such as a metal coil or a sheet of plastic folded into a certain pattern, surrounded by air or fluid and sealed inside a plastic or textile bag that serves as the “skin.” A vacuum applied to the inside of the bag initiates the muscle’s movement by causing the skin to collapse onto the skeleton, creating tension that drives the motion. Incredibly, no other power source or human input is required to direct the muscle’s movement; it is determined entirely by the shape and composition of the skeleton.

“One of the key aspects of these muscles is that they’re programmable, in the sense that designing how the skeleton folds defines how the whole structure moves. You essentially get that motion for free, without the need for a control system,” says first author Shuguang Li, Ph.D., a Postdoctoral Fellow at the Wyss Institute and MIT CSAIL. This approach allows the muscles to be very compact and simple, and thus more appropriate for mobile or body-mounted systems that cannot accommodate large or heavy machinery.

Artificial muscle-like actuators are one of the most important grand challenges in all of engineering. Robert Wood

“When creating robots, one always has to ask, ‘Where is the intelligence – is it in the body, or in the brain?’” says Rus. “Incorporating intelligence into the body (via specific folding patterns, in the case of our actuators) has the potential to simplify the algorithms needed to direct the robot to achieve its goal. All these actuators have the same simple on/off switch, which their bodies then translate into a broad range of motions.”

The team constructed dozens of muscles using materials ranging from metal springs to packing foam to sheets of plastic, and experimented with different skeleton shapes to create muscles that can contract down to 10% of their original size, lift a delicate flower off the ground, and twist into a coil, all simply by sucking the air out of them.

The structural geometry of artificial muscle skeleton determines the muscle’s motion. Credit: Shuguang Li / Wyss Institute at Harvard University

Not only can the artificial muscles move in many ways, they do so with impressive resilience. They can generate about six times more force per unit area than mammalian skeletal muscle can, and are also incredibly lightweight; a 2.6-gram muscle can lift a 3-kilogram object, which is the equivalent of a mallard duck lifting a car. Additionally, a single muscle can be constructed within ten minutes using materials that cost less than $1, making them cheap and easy to test and iterate.

These muscles can be powered by a vacuum, a feature that makes them safer than most of the other artificial muscles currently being tested. “A lot of the applications of soft robots are human-centric, so of course it’s important to think about safety,” says Daniel Vogt, M.S., co-author of the paper and Research Engineer at the Wyss Institute. “Vacuum-based muscles have a lower risk of rupture, failure, and damage, and they don’t expand when they’re operating, so you can integrate them into closer-fitting robots on the human body.”

“In addition to their muscle-like properties, these soft actuators are highly scalable. We have built them at sizes ranging from a few millimeters up to a meter, and their performance holds up across the board,” Wood says. This feature means that the muscles can be used in numerous applications at multiple scales, such as miniature surgical devices, wearable robotic exoskeletons, transformable architecture, deep-sea manipulators for research or construction, and large deployable structures for space exploration.

The team was even able to construct the muscles out of the water-soluble polymer PVA, which opens the possibility of robots that can perform tasks in natural settings with minimal environmental impact, as well as ingestible robots that move to the proper place in the body and then dissolve to release a drug. “The possibilities really are limitless. But the very next thing I would like to build with these muscles is an elephant robot with a trunk that can manipulate the world in ways that are as flexible and powerful as you see in real elephants,” Rus says.

“The actuators developed through this collaboration between the Wood laboratory at Harvard and Rus group at MIT exemplify the Wyss’ approach of taking inspiration from nature without being limited by its conventions, which can result in systems that not only imitate nature, but surpass it,” says the Wyss Institute’s Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at HMS and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at SEAS.

This research was funded by the Defense Advanced Research Projects Agency (DARPA), the National Science Foundation (NSF), and the Wyss Institute for Biologically Inspired Engineering.

• PUBLICATION – PNAS: Fluid-driven origami-inspired artificial muscles

New, hybrid RoboBee can fly, dive into water, swim, propel itself back out of water, and safely land. The RoboBee is retrofitted with four buoyant and a central gas collection chamber. Once the RoboBee swims to the surface, an electrolytic plate in the chamber converts water into oxyhydrogen, a combustible gas fuel. Credit: Wyss Institute at Harvard University

We’ve seen RoboBees that can fly, stick to walls, and dive into water. Now, get ready for a hybrid RoboBee that can fly, dive into water, swim, propel itself back out of water, and safely land.

New floating devices allow this multipurpose air-water microrobot to stabilize on the water’s surface before an internal combustion system ignites to propel it back into the air.

This latest-generation RoboBee, which is 1,000 times lighter than any previous aerial-to-aquatic robot, could be used for numerous applications, from search-and-rescue operations to environmental monitoring and biological studies.

The research is described in Science Robotics. It was led by a team of scientists from the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). 

“This is the first microrobot capable of repeatedly moving in and through complex environments,” says Yufeng Chen, Ph.D., currently a Postdoctoral Fellow at the Wyss Institute who was a graduate student in the Microrobotics Lab at SEAS when the research was conducted and is the first author of the paper. “We designed new mechanisms that allow the vehicle to directly transition from water to air, something that is beyond what nature can achieve in the insect world.”

Designing a millimeter-sized robot that moves in and out of water has numerous challenges. First, water is 1,000 times denser than air, so the robot’s wing flapping speed will vary widely between the two mediums. If the flapping frequency is too low, the RoboBee can’t fly. If it’s too high, the wing will snap off in the water.

By combining theoretical modeling and experimental data, the researchers found the Goldilocks combination of wing size and flapping rate, scaling the design to allow the bee to operate repeatedly in both air and water. Using this multimodal locomotive strategy, the robot to flaps its wings at 220 to 300 hertz in air and nine to 13 hertz in water.

Another major challenge the team had to address: at the millimeter scale, the water’s surface might as well be a brick wall. Surface tension is more than 10 times the weight of the RoboBee and three times its maximum lift. Previous research demonstrated how impact and sharp edges can break the surface tension of water to facilitate the RoboBee’s entry, but the question remained: How does it get back out again?

To solve that problem, the researchers retrofitted the RoboBee with four buoyant outriggers — essentially robotic floaties — and a central gas collection chamber. Once the RoboBee swims to the surface, an electrolytic plate in the chamber converts water into oxyhydrogen, a combustible gas fuel.

“Because the RoboBee has a limited payload capacity, it cannot carry its own fuel, so we had to come up with a creative solution to exploit resources from the environment,” says Elizabeth Farrell Helbling, graduate student in the Microrobotics Lab and co-author of the paper. “Surface tension is something that we have to overcome to get out of the water, but is also a tool that we can utilize during the gas collection process.”

The gas increases the robot’s buoyancy, pushing the wings out of the water, and the floaties stabilize the RoboBee on the water’s surface. From there, a tiny, novel sparker inside the chamber ignites the gas, propelling the RoboBee out of the water. The robot is designed to passively stabilize in air, so that it always lands on its feet.

“By modifying the vehicle design, we are now able to lift more than three times the payload of the previous RoboBee,” says Chen. “This additional payload capacity allowed us to carry the additional devices including the gas chamber, the electrolytic plates, sparker, and buoyant outriggers, bringing the total weight of the hybrid robot to 175 miligrams, about 90mg heavier than previous designs. We hope that our work investigating tradeoffs like weight and surface tension can inspire future multi-functional microrobots – ones that can move on complex terrains and perform a variety of tasks.”

Because of the lack of onboard sensors and limitations in the current motion-tracking system, the RoboBee cannot yet fly immediately upon propulsion out of water but the team hopes to change that in future research.

“The RoboBee represents a platform where forces are different than what we – at human scale – are used to experiencing,” says Wyss Core Faculty Member Robert Wood, Ph.D., who is also the Charles River Professor of Engineering and Applied Sciences at Harvard and senior author of the paper. “While flying the robot feels as if it is treading water; while swimming it feels like it is surrounded by molasses. The force from surface tension feels like an impenetrable wall. These small robots give us the opportunity to explore these non-intuitive phenomena in a very rich way.”

The paper was co-authored by Hongqiang Wang, Ph.D., Postdoctoral Fellow at the Wyss Institute and SEAS; Noah Jafferis, Ph.D., Postdoctoral Fellow at the Wyss Institute; Raphael Zufferey, Postgraduate Researcher at Imperial College, London; Aaron Ong, Mechanical Engineer at the University of California, San Diego and former member of the Microrobotics Lab; Kevin Ma, Ph.D., Postdoctoral Fellow at the Wyss Institute; Nicholas Gravish, Ph.D., Assistant Professor at the University of California, San Diego and former member of the Microrobotics Lab; Pakpong Chirarattananon, Ph.D., Assistant Professor at the City University of Hong Kong and former member of the Microrobotics Lab; and Mirko Kovac, Ph.D., Senior Lecturer at Imperial College, London and former member of the Microrobotics Lab and Wyss Institute. It was supported by the National Science Foundation and the Wyss Institute for Biologically Inspired Engineering.

• PUBLICATION – Science Robotics: A biologically inspired, flapping-wing, hybrid aerial-aquatic microrobot
• WYSS TECHNOLOGY – Autonomous Flying Microrobots (RoboBees)

The face of the father of quantum physics, Max Planck, emerges from a flat disk. In each state, the colors show the growth factors of the top (left) and bottom (right) layer, and the thin black lines indicate the direction of growth. The top layer is viewed from the front, and the bottom layer is viewed from the back, to highlight the complexity of the geometries. Credit: Harvard SEAS

Nature has a way of making complex shapes from a set of simple growth rules. The curve of a petal, the swoop of a branch, even the contours of our face are shaped by these processes. What if we could unlock those rules and reverse engineer nature’s ability to grow an infinitely diverse array of shapes?

Scientists from Harvard’s Wyss Institute for Biologically Inspired Engineering and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have done just that. In a paper published in the Proceedings of the National Academy of Sciences, the team demonstrates a technique to grow any target shape from any starting shape.

“Architect Louis Sullivan once said that ‘form ever follows function’,” said L. Mahadevan, Ph.D., Associate Faculty member at the Wyss Institute and the Lola England de Valpine Professor of Applied Mathematics, of Organismic and Evolutionary Biology and of Physics and senior author of the study. “But if one took the opposite perspective, that perhaps function should follow form, how can we inverse design form?”

In previous research, the Mahadevan group used experiments and theory to explain how naturally morphing structures — such as Venus flytraps, pine cones and flowers — changed their shape in the hopes of one day being able to control and mimic these natural processes. And indeed, experimentalists have begun to harness the power of simple, bioinspired growth patterns. For example, in 2016, in a collaboration with the group of Jennifer Lewis, a Wyss Institute Core Faculty member and the Hansjörg Wyss Professor of Biologically Inspired Engineering at SEAS, the team printed a range of structures that changed its shape over time in response to environmental stimuli.

“The challenge was how to do the inverse problem,” said Wim van Rees, Ph.D., a postdoctoral fellow at SEAS and first author of the paper. “There’s a lot of research on the experimental side but there’s not enough on the theoretical side to explain what’s actually happening. The question is, if I want to end with a specific shape, how do I design my initial structure?”

Inspired by the growth of leaves, the researchers developed a theory for how to pattern the growth orientations and magnitudes of a bilayer, two different layers of elastic materials glued together that respond differently to the same stimuli. By programming one layer to swell more and/or in a different direction than the other, the overall shape and curvature of the bilayer can be fully controlled. In principle, the bilayer can be made of any material, in any shape, and respond to any stimuli from heat to light, swelling, or even biological growth.

The team unraveled the mathematical connection between the behavior of the bilayer and that of a single layer.

“We found a very elegant relationship in a material that consists of these two layers,” said van Rees. “You can take the growth of a bilayer and write its energy directly in terms of a curved monolayer.”

That means that if you know the curvatures of any shape you can reverse engineer the energy and growth patterns needed to grow that shape using a bilayer.

“This kind of reverse engineering problem is notoriously difficult to solve, even using days of computation on a supercomputer,” said Etienne Vouga, Ph.D., former postdoctoral fellow in the group and now an Assistant Professor of Computer Science at the University of Texas at Austin. “By elucidating how the physics and geometry of bilayers are intimately coupled, we were able to construct an algorithm that solves the needed growth pattern in seconds, even on a laptop, no matter how complicated the target shape.”

A snapdragon flower petal starting from a cylinder. In each state, the colors show the growth factors of the top (left) and bottom (right) layer, and the thin black lines indicate the direction of growth. The top layer is viewed from the front, and the bottom layer is viewed from the back, to highlight the complexity of the geometries. Credit: Harvard SEAS

The researchers demonstrated the system by modeling the growth of a snapdragon flower petal from a cylinder, a topographical map of the Colorado river basin from a flat sheet and, most strikingly, the face of Max Planck, one of the founders of quantum physics, from a disk.

“Overall, our research combines our knowledge of the geometry and physics of slender shells with new mathematical algorithms and computations to create design rules for engineering shape,” said Mahadevan. “It paves the way for manufacturing advances in 4-D printing of shape-shifting optical and mechanical elements, soft robotics as well as tissue engineering.”

The researchers are already collaborating with experimentalists to try out some of these ideas.

This research was funded in part by the Swiss National Science Foundation and the US National Science Foundation.

• PUBLICATION – PNAS: Growth patterns for shape-shifting elastic bilayers

SEM images of the hybrid soft pop-up actuators. The image has been colored in post processing to differentiate between the soft (in yellow) and the rigid structure (in blue). Credit: Wyss Institute at Harvard University

By Leah Burrows, SEAS Communications

Flexible endoscopes can snake through narrow passages to treat difficult to reach areas of the body. However, once they arrive at their target, these devices rely on rigid surgical tools to manipulate or remove tissue. These tools offer surgeons reduced dexterity and sensing, limiting the current therapeutic capabilities of the endoscope.

Now, researchers from the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a hybrid rigid-soft robotic arm for endoscopes with integrated sensing, flexibility, and multiple degrees of freedom. This arm — built using a manufacturing paradigm based on pop-up fabrication and soft lithography — lies flat on an endoscope until it arrives at the desired spot, then pops up to assist in surgical procedures.

The research is described in Advanced Materials Technologies.

Soft robots are so promising for surgical applications because they can match the stiffness of the body, meaning they won’t accidentally puncture or tear tissue. However, at small scales, soft materials cannot generate enough force to perform surgical tasks.

“At the millimeter scale, a soft device becomes so soft that it can’t damage tissue but it also can’t manipulate the tissue in any meaningful way,” said Tommaso Ranzani, Ph.D., a Postdoctoral Fellow at the Wyss Institute and SEAS and coauthor of the paper. “That limits the application of soft microsystems for performing therapy. The question is, how can we develop soft robots that are still able to generate the necessary forces without compromising safety.”

Inspired by biology, the team developed a hybrid model that used a rigid skeleton surrounded by soft materials. The manufacturing method drew on previous work in origami-inspired, pop-up fabrication developed by Robert Wood, Ph.D., who coauthored the paper and is a Core Faculty Member of the Wyss Institute and the Charles River Professor of Engineering and Applied Sciences at SEAS.

Soft pop-up arm performing tissue counter-traction during an ex-vivo test on a porcine stomach. Credit: Harvard University

Previous pop-up manufacturing techniques — such as those used with the RoboBees — rely on actuation methods that require high voltages or temperatures to operate, something that wouldn’t be safe in a surgical tool directly manipulating biological tissues and organs.

So, the team integrated soft actuators into the pop-up system.

“We found that by integrating soft fluidic microactuators into the rigid pop-up structures, we could create soft pop-up mechanisms that increased the performance of the actuators in terms of the force output and the predictability and controllability of the motion,” said Sheila Russo, Ph.D., Postdoctoral Fellow at the Wyss Institute and SEAS and lead author of the paper. “The idea behind this technology is basically to obtain the best of both worlds by combining soft robotic technologies with origami-inspired rigid structures. Using this fabrication method, we were able to design a device that can lie flat when the endoscope is navigating to the surgical area, and when the surgeon reaches the area they want to operate on, they can deploy a soft system that can safely and effectively interact with tissue.”

The soft actuators are powered by water. They are connected to the rigid components with an irreversible chemical bond, without the need of any adhesive. The team demonstrated the integration of simple capacitive sensing that can be used to measure forces applied to the tissue and to give the surgeon a sense of where the arm is and how it’s moving. The fabrication method allows for bulk manufacturing, which is important for medical devices, and allows for increased levels of complexity for more sensing or actuation. Furthermore, all materials used are biocompatible.

The arm is also equipped with a suction cup — inspired by octopus tentacles — to safely interact with tissue. The team tested the device ex vivo, simulating a complicated endoscopic procedure on pig tissue. The arm successfully manipulated the tissue safely.

“The ability to seamlessly integrate gentle yet effective actuation into millimeter-scale deployable mechanisms fits naturally with a host of surgical procedures,” said Wood. “We are focused on some of the more challenging endoscopic techniques where tool dexterity and sensor feedback are at a premium and can potentially make the difference between success and failure.”

Multi-articulated soft pop-up robotic arm. Concept of the system (left): An endoscope navigating in the GI tract and detail of the arm mounted at the tip of the endoscope. Soft pop-up arm (right) performing tissue counter-traction during an ex-vivo test on a porcine stomach. Credit: Harvard University

The researchers demonstrated that the device could be scaled down to 1 millimeter, which would allow it to be used in even tighter endoscopic procedures, such as in lungs or the brain.

Next, the researchers hope to test the device in vivo.

“Our technology paves the way to design and develop smaller, smarter, softer robots for biomedical applications,” said Russo.

The paper was coauthored by Conor Walsh, Ph.D., a Core Faculty Member of the Wyss Institute and the John L. Loeb Associate Professor of Engineering and Applied Sciences at SEAS.

The research was supported by the DARPA “Atoms to Product” program and the Wyss Institute for Biologically Inspired Engineering.

Publication: Advanced Materials Technologies: An Additive Millimeter-Scale Fabrication Method for Soft Biocompatible Actuators and Sensors

A magnetic folding robot arm can grasp and bend thanks to its pattern of origami-inspired folds and a wireless electromagnetic field. Credit: Wyss Institute at Harvard University

The traditional Japanese art of origami transforms a simple sheet of paper into complex, three-dimensional shapes through a very specific pattern of folds, creases, and crimps. Folding robots based on that principle have emerged as an exciting new frontier of robotic design, but generally require onboard batteries or a wired connection to a power source, making them bulkier and clunkier than their paper inspiration and limiting their functionality.

A team of researchers at the Wyss Institute for Biologically Inspired Engineering and the John A. Paulson School of Engineering and Applied Sciences (SEAS) at Harvard University has created battery-free folding robots that are capable of complex, repeatable movements powered and controlled through a wireless magnetic field.

“Like origami, one of the main points of our design is simplicity,” says co-author Je-sung Koh, Ph.D., who conducted the research as a Postdoctoral Fellow at the Wyss Institute and SEAS and is now an Assistant Professor at Ajou University in South Korea. “This system requires only basic, passive electronic components on the robot to deliver an electric current—the structure of the robot itself takes care of the rest.”

The research team’s robots are flat and thin (resembling the paper on which they’re based) plastic tetrahedrons, with the three outer triangles connected to the central triangle by hinges, and a small circuit on the central triangle. Attached to the hinges are coils made of a type of metal called shape-memory alloy (SMA) that can recover its original shape after deformation by being heated to a certain temperature. When the robot’s hinges lie flat, the SMA coils are stretched out in their “deformed” state; when an electric current is passed through the circuit and the coils heat up, they spring back to their original, relaxed state, contracting like tiny muscles and folding the robots’ outer triangles in toward the center. When the current stops, the SMA coils are stretched back out due to the stiffness of the flexure hinge, thus lowering the outer triangles back down.

The power that creates the electrical current needed for the robots’ movement is delivered wirelessly using electromagnetic power transmission, the same technology inside wireless charging pads that recharge the batteries in cell phones and other small electronics. An external coil with its own power source generates a magnetic field, which induces a current in the circuits in the robot, thus heating the SMA coils and inducing folding. In order to control which coils contract, the team built a resonator into each coil unit and tuned it to respond only to a very specific electromagnetic frequency. By changing the frequency of the external magnetic field, they were able to induce each SMA coil to contract independently from the others.

“Not only are our robots’ folding motions repeatable, we can control when and where they happen, which enables more complex movements,” explains lead author Mustafa Boyvat, Ph.D., also a Postdoctoral Fellow at the Wyss Institute and SEAS.

Just like the muscles in the human body, the SMA coils can only contract and relax: it’s the structure of the body of the robot — the origami “joints” — that translates those contractions into specific movements. To demonstrate this capability, the team built a small robotic arm capable of bending to the left and right, as well as opening and closing a gripper around an object. The arm is constructed with a special origami-like pattern to permit it to bend when force is applied, and two SMA coils deliver that force when activated while a third coil pulls the gripper open. By changing the frequency of the magnetic field generated by the external coil, the team was able to control the robot’s bending and gripping motions independently.

There are many applications for this kind of minimalist robotic technology; for example, rather than having an uncomfortable endoscope put down their throat to assist a doctor with surgery, a patient could just swallow a micro-robot that could move around and perform simple tasks, like holding tissue or filming, powered by a coil outside their body. Using a much larger source coil — on the order of yards in diameter — could enable wireless, battery-free communication between multiple “smart” objects in an entire home. The team built a variety of robots — from a quarter-sized flat tetrahedral robot to a hand-sized ship robot made of folded paper — to show that their technology can accommodate a variety of circuit designs and successfully scale for devices large and small. “There is still room for miniaturization. We don’t think we went to the limit of how small these can be, and we’re excited to further develop our designs for biomedical applications,” Boyvat says.

“When people make micro-robots, the question is always asked, ‘How can you put a battery on a robot that small?’ This technology gives a great answer to that question by turning it on its head: you don’t need to put a battery on it, you can power it in a different way,” says corresponding author Rob Wood, Ph.D., a Core Faculty member at the Wyss Institute who co-leads its Bioinspired Robotics Platform and the Charles River Professor of Engineering and Applied Sciences at SEAS.

“Medical devices today are commonly limited by the size of the batteries that power them, whereas these remotely powered origami robots can break through that size barrier and potentially offer entirely new, minimally invasive approaches for medicine and surgery in the future,” says Wyss Founding Director Donald Ingber, who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children’s Hospital, as well as a Professor of Bioengineering at Harvard’s School of Engineering and Applied Sciences.

The research paper was published in Science Robotics.

The Harvard team’s exosuit is a wearable robot that directly targets the ankle joints and is made of functional textiles, cable-based actuation and a biologically-inspired control system. In this version, actuation, electronics and battery units (shown on the left) have been off-boarded to better allow the researchers to quantify the exosuit’s energy-saving potential in healthy wearers. Credit: Wyss Institute at Harvard University

Last year, Harvard’s soft exosuit team provided first proof-of-concept results showing that its wearable robot could lower energy expenditure in healthy people walking with a load on their back. Made of functional textiles, cable-based actuation and a biologically-inspired control system, the exosuit targets specific leg joints – instead of the full leg – and delivers assistance that is synchronized with the wearer’s walking mechanics in individuals ranging from people that carry heavy loads to people that are disabled by stroke or other health complications.

The team is led by Conor Walsh, a Wyss Institute Core Faculty member, John L. Loeb Associate Professor of Engineering and Applied Sciences at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Founder of the Harvard Biodesign Lab.

But the question still remained. What is the effect of increasing assistance levels on the overall energy savings to wearers? These savings are the result of the energy spared due to the assistive force provided to the ankle motions, and this must be balanced with the additional energy expended by the wearer when carrying the exosuit’s mass.

Now, in a new study published as the cover article in Science Robotics, Walsh’s multidisciplinary team of roboticists, engineers, biomechanics experts and apparel designers isolated the beneficial effects of the exosuit. By removing the actuation, electronics and battery units, leaving only the exosuit’s light wearable textiles and pulling cables, the researchers were able to calculate the impact on the wearers’ joints. The study is selected as the cover article of the issue.

“In a test group of seven healthy wearers, we clearly saw that the more assistance provided to the ankle joints, the more energy the wearers could save with a maximum reduction of almost 23% compared to walking with the exosuit powered-off,” said Walsh. “To our knowledge, this is the highest relative reduction in energy expenditure observed to date with a tethered exoskeleton or exosuit.”

Interestingly, the team found that wearers significantly adapted their gait with increasing levels of assistance. The changes were most significant at the ankle joint but also at the hip as the exosuit included straps coupling the assistance from the back of the lower legs to the front of the hip in a beneficial manner.

“Other studies had reported that there can be an energy transfer between the ankle and other joints. However, by having a textile couple the ankle and hip with our soft exosuit, may have amplified this effect, contributing to the considerable energy savings we found,” said Brendan Quinlivan, a graduate student working with Walsh and one of the two first-authors on the study.

The exosuit’s soft textiles strategically position the actuating cables that assist with the ankle motion at the back of the lower legs and, through additional straps, transfer energy produced at the ankle to the front of the hip to also assist with the gait’s hip motion. Credit: Wyss Institute at Harvard University

The authors acknowledge that future studies are now required to compare the effects of fully body-worn versions of the exosuit, with the weight of the actuation and battery carried by the wearer, to walking with normal clothes to better quantify the true impact of the technology.

“This study represents another major step forward along a path that will bring this new type of ‘wearable robot’ into the marketplace where it will help soldiers and workers, as well as patients with disabilities,” said Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Professor of Bioengineering at Harvard SEAS.“The results from this study will help us find a sweet spot between the added system weight and the amount of force applied to achieve maximum benefits in energy expenditure in wearers. Defining these interdependencies in healthy people will ultimately also help us design versions suitable for people with gait abnormalities,” said Sangjun Lee, who also is a graduate student in Walsh’s team and a co-first author of the study.

The multi-disciplinary study was supported by the Wyss Institute for Biologically Inspired Engineering, the Harvard John A. Paulson School of Engineering and Applied Sciences, the Defense Advanced Research Projects Agency (DARPA)’s Warrior Web Program, the National Science Foundation, a Samsung Scholarship, the São Paulo Research Foundation and the Robert Bosch Stiftung.

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In this image, VAMPs are shown actuated and cut open in cross section. The cross section shows the inner chambers that collapse when vacuum is applied. Credit: Wyss Institute at Harvard University.

To make robots more cooperative and have them perform tasks in close proximity to humans, they must be softer and safer. A new actuator developed by a team led by George Whitesides, Ph.D. — who is a Core Faculty member at Harvard’s Wyss Institute for Biologically Inspired Engineering and the Woodford L. and Ann A. Flowers University Professor of Chemistry and Chemical Biology in Harvard University’s Faculty of Arts and Sciences (FAS) – generates movements similar to those of skeletal muscles using vacuum power to automate soft, rubber beams.

Like real muscles, the actuators are soft, shock absorbing, and pose no danger to their environment or humans working collaboratively alongside them or the potential future robots equipped with them. The work was reported June 1 in the journal Advanced Materials Technologies.

“Functionally, our actuator models the human bicep muscle,” said Whitesides, who is also a Director of the Kavli Institute for Bionano Science and Technology at Harvard University. “There are other soft actuators that have been developed, but this one is most similar to muscle in terms of response time and efficiency.”

Whitesides’ team took an unconventional approach to its design, relying on vacuum to decrease the actuator’s volume and cause it to buckle. While conventional engineering would consider bucking to be a mechanical instability and a point of failure, in this case the team leveraged this instability to develop VAMPs (vacuum-actuated muscle-inspired pneumatic structures). Whereas previous soft actuators rely on pressurized systems that expand in volume, VAMPs mimic true muscle because they contract, which makes them an attractive candidate for use in confined spaces and for a variety of purposes.

The actuator — comprising soft rubber or ‘elastomeric’ beams — is filled with small, hollow chambers of air like a honeycomb. By applying vacuum the chambers collapse and the entire actuator contracts, generating movement. The internal honeycomb structure can be custom tailored to enable linear, twisting, bending, or combinatorial motions.

VAMPs are functionally modeled after the human bicep, similar to the biological muscle in terms of response time and efficiency. Credit: Wyss Institute at Harvard University

“Having VAMPs built of soft elastomers would make it much easier to automate a robot that could be used to help humans in the service industry,” said the study’s first author Dian Yang, who was a graduate researcher pursuing his Ph.D. in Engineering Sciences at Harvard during the time of the work, and is now a Postdoctoral Researcher.

The team envisions that robots built with VAMPs could be used to assist the disabled or elderly, to serve food, deliver goods, and perform other tasks related to the service industry. What’s more, soft robots could make industrial production lines safer, faster, and quality control easier to manage by enabling human operators to work in the same space.

Although a complex control system has not yet been developed for VAMPs, this type of actuation is easy to control due to its simplicity: when vacuum is applied, VAMPs will contract. They could be used as part of a tethered or untethered system depending on environmental or performance needs. Additionally, VAMPs are designed to prevent failure — even when damaged with a 2mm hole, the team showed that VAMPs will still function. In the event that major damage is caused to the system, it fails safely.

“It can’t explode, so it’s intrinsically safe,” said Whitesides.

Here, a VAMPs lifts a 500 gram weight with ease. Credit: Wyss Institute at Harvard University

Whereas other actuators powered by electricity or combustion could cause damage to humans or their surroundings, loss of vacuum pressure in VAMPs would simply render the actuator motionless.

“These self-healing, bioinspired actuators bring us another step closer to being able to build entirely soft-bodied robots, which may help to bridge the gap between humans and robots and open entirely new application areas in medicine and beyond,” said Wyss Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Boston Children’s Hospital Vascular Biology Program, as well as Professor of Bioengineering at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS).

In addition to Whitesides and Yang, other authors on the study included: Mohit S. Verma, Ph.D.,(FAS); Ju-Hee So, Ph.D., (FAS); Bobak Mosadegh, Ph.D., (Wyss, FAS); Christoph Keplinger, Ph.D., (FAS); Benjamin Lee (FAS); Fatemeh Khashai (FAS); Elton Lossner (FAS), and Zhigang Suo, Ph.D., (SEAS, Kavli Institute).

Source: Wyss Institute

By Leah Burrows, SEAS Communications

In a recent article in Science, Harvard roboticists demonstrate that their flying microrobots, nicknamed the RoboBees, can now perch during flight to save energy — like bats, birds or butterflies.

“Many applications for small drones require them to stay in the air for extended periods,” said Moritz Graule, first author of the paper, who was a student researcher at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering at Harvard University at the time the study was conducted. “Unfortunately, smaller drones run out of energy quickly. We want to keep them aloft longer without requiring too much additional energy.”

The team found inspiration in nature and simple science.

“A lot of different animals use perching to conserve energy,” said co-author Kevin Ma, Ph.D., a Postdoctoral Researcher at SEAS and the Wyss Institute. “But the methods they use to perch, like sticky adhesives or latching with talons, are inappropriate for a paperclip-size microrobot, as they either require intricate systems with moving parts or high forces for detachment.”

Instead, the team turned to electrostatic adhesion — the same basic science that causes a static-charged sock to cling to a pant leg or a balloon to stick to a wall.

When you rub a balloon on a wool sweater, the balloon becomes negatively charged. If the charged balloon is brought close to a wall, its negative charge forces some of the wall’s electrons away, leaving the surface positively charged. The attraction between opposite charges then causes the balloon to stick to the wall.

“In the case of the balloon, however, the charges dissipate over time, and the balloon will eventually fall down,” said Graule. “In our system, a small amount of energy is constantly supplied to maintain the attraction.”

The RoboBee, initially pioneered at the Harvard Microrobotics Lab, has now been updated to include an electrode patch and a foam mount that absorbs shock. The new perching components weigh 13.4 mg, bringing the total weight of the robot to about 100mg — similar to the weight of a real bee. The robot takes off and flies normally. When the electrode patch is supplied with a charge, it can stick to almost any surface, from glass to wood to a leaf. To detach, the power supply is simply switched off.

“One of the biggest advantages of this system is that it doesn’t cause destabilizing forces during disengagement, which is crucial for a robot as small and delicate as ours,” said Graule.

The patch requires about 1000 times less power to perch than it does to hover, offering to dramatically extend the operational life of the robot. Reducing the robot’s power requirements is critical for the researchers, as they work to integrate onboard batteries on untethered RoboBees.

“The use of adhesives that are controllable without complex physical mechanisms, are low power, and can adhere to a large array of surfaces is perfect for robots that are agile yet have limited payload — like the RoboBee,” added Robert Wood, Ph.D., Charles River Professor of Engineering and Applied Sciences at SEAS and a Core Faculty member at the Wyss Institute, and senior author of the study. “When making robots the size of insects, simplicity and low power are always key constraints.”

Right now, the RoboBee can only perch under overhangs and on ceilings, as the electrostatic patch is attached to the top of the vehicle. Next, the team hopes to change the mechanical design so that the robot can perch on any surface.

“There are more challenges to making a robust, robotic landing system but this experimental result demonstrates a very versatile solution to the problem of keeping flying microrobots operating longer without quickly draining power,” said Ma.

References:

The paper was coauthored by Pakpong Chirarattananon, Sawyer B. Fuller, Noah Jafferis, Matthew Spenko and Roy Kornbluh. The research was funded by the National Science Foundation, the Wyss Institute for Biologically Inspired Engineering, and the Swiss Study Foundation.

The Wyss Solution: Root
Recognizing the remarkable power of using robots as learning tools, a team of researchers at the Wyss Institute has developed a new educational robot, Root, and accompanying programming environment, Square, to engage students with coding from an early age, retain their interest, and guide the growth of their coding skills. The system is designed to be as intuitive and approachable as any tablet app, providing a framework easy for teachers to understand and comfortable for young students to use.

The robot, Root, is designed to fit into every classroom. It operates on whiteboards by driving on the vertical surface magnetically and — using dry-erase markers — draws, erases, and responds to lines drawn on the board. This ability to interact with the robot simply by drawing opens up potential for a broad range of unique instructional activities and games.

The programming environment, Square, provides a sliding framework in which students can program the robot at different levels of proficiency — from a blocks-based graphical environment designed for beginners and early elementary school students, up to a traditional text-based environment for older students or intermediate coders — with the unique ability to toggle and automatically translate a program from displaying in any of the multiple levels. In this way, it helps support the transition to more advanced concepts and coding processes. The interface meets students at their individual level and evolves with them as their skills develop.

Root requires no special set up to begin operating on the whiteboard at the front of the a classroom. Unlike structured websites that teach coding as an individual activity based on exercises with unique solutions, the classroom environment is ideal for using multiple Root robots at the same time, providing opportunities for peer-to-peer learning and more freeform creativity. Coding with robots is an inherently dynamic experience; robot, environment, and students all react to each other, stimulating students to come up with diverse solutions and challenges together. Furthermore, robots have been shown to have a powerful appeal to all ages and demographics, making interactions and relationships with them far more compelling than images confined to a computer screen.

Root hardware features:

Magnetic — Root can drive vertically on any metal-backed whiteboard or be used on the ground, a desk, or any flat surface
Position and direction sensing — Root uses feedback from its wheel encoders, gyroscope, and accelerometer to drive accurate distances and angles
Color scanner — Root can recognize and respond to the colors of lines it drives over with its 32 color sensors array
Bumpers & touch surface — Root can respond to the physical world when it comes into contact with something through its two front bumpers or four capacitive touch keys on its top
Lift & drop mechanisms — Root controls a dry-erase marker and eraser to draw or erase markings on whiteboard surface
Ambient light sensors — Root perceives and can orient towards light sources in the room
Light and sound output — Root has 15 multicolor LEDs and a speaker that can be used to provide feedback on the robot’s state
Expansion port — Root can be customized with new hardware enhancements, mounted magnetically on its surface and interfaced directly with the robot’s microcontroller

Square interface features:

Multi-level programming — Scoreable coding experiences that start with simple elements and scale to full text programming, all within the same iOS environment
Real-time interactive environment — No compiling necessary; programs written in Square are executed in real time. Programming the natural way that students respond and think on the fly, users can flexibly adapt a program while it is running to pause, step, or add instructions at any time
Real-time sensor values — Giving users constant access to what the robot sees and knows promotes agent-based thinking and facilitates the debugging of robot programs
Event-based rules — Priorities and designated interruption can be used in a natural way to let the robot take actions in response to real-world conditions and events
iOS ready — Square will first be available for download in the Apple App Store for use with any Bluetooth Low Energy iPad
iOS sensors — Root can use and react to sensors on the host iOS device, enabling advanced interactions between the robot and the user
Applications manager — Students can learn from, modify, create, share, and access an unlimited number of new activities and functions through a network of sharing programs and loading other users’ data

The Wyss team is currently seeking the right curriculum and translation partners to help put Root coding robots in every classroom.

Contact
Root was made possible by funding from the Wyss Institute, and by the dedicated work of Raphael Cherney (Research Associate) who leads the effort and designed the robot, Julián da Silva Gillig (Research Associate) who leads the creation of Square, Hani Sallum (Wyss ATT Staff), Justin Werfel (Wyss Sr Staff Scientist), Zivthan Dubrovsky (Wyss ATT Lead), Todd Rose (Wyss Institute Associate Faculty), and Radhika Nagpal (Wyss Institute Core Faculty).

For more information, please contact Zivthan Dubrovsky .

Source: Wyss Institute at Harvard University

In the Disruptive Podcast series, Terrence McNally speaks directly with Wyss Institute researchers, exploring what motivates them and how they envision our future as might be impacted by their disruptive technologies. In part 3 of the Disruptive: Bioinspired Robotics episode, Wyss Core Faculty Member Conor Walsh discusses how a wearable robotic exosuit or soft robotic glove could assist people with mobility impairments, as well as how the goal to create real-world applications drives his research approach.

Walsh is the founder of the Harvard Biodesign Lab, which brings together researchers from the engineering, industrial design, apparel, clinical and business communities to develop new technologies and translate them to industrial partners. His research focuses on applying disruptive technologies to the development of robotic devices for augmenting and restoring human performance. His current research interests include new approaches to design, manufacture and control of wearable robotic devices and characterizing their performance through biomechanical and physiological studies.

He leads a team of researchers on the DARPA Warrior Web project to develop a soft exosuit that can assist with locomotion that can perform small levels of assistance to a wearer. The exosuit’s function is based on a detailed understanding of human walking and is soft and pliable, unlike traditional exoskeletons that use rigid components. The long term goal is to develop fully portable wearable robots to assist the disabled and able-bodied and further the scientific understanding of how humans interact with such machines.

Source: Wyss Institute at Harvard University

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See all the latest robotics news on Robohub, or sign up for our weekly newsletter.

Source: Wyss Institute at Harvard University

In the Disruptive Podcast series, Terrence McNally speaks directly with Wyss Institute researchers, exploring what motivates them and how they envision our future as might be impacted by their disruptive technologies. In part 2 of the Disruptive: Bioinspired Robotics episode, Wyss Founding Core Faculty Member Robert Wood discusses new manufacturing techniques that are enabling popup and soft robots.

Wood is developing biologically inspired aerial and terrestrial microrobots, soft-bodied robots, and “printable” robots. His current research interests include new micro- and meso-scale manufacturing techniques, fluid mechanics of low Reynolds number flapping wings, control of sensor-limited and computation-limited systems, active soft materials, and morphable soft-bodied robots. He leads a team of over 40 researchers on the National Science Foundation (NSF) “RoboBees” project to develop coordinated colonies of autonomous robotic bees.

His group is also building agile ambulatory robots that are inspired by insects and centipedes. The long-term goal is to create a swarm of robotic insects capable of performing important tasks, such as search and rescue, hazardous environmental explorations, and pollination. Wood is collaborating with a diverse set of researchers at the Wyss who are exploring soft-bodied autonomous robots and soft devices for human-robot interaction and rehabilitation. One of these projects, called “Second Skin,” is a system in which sensing, actuation, and control mechanisms are embedded in soft devices that can be worn by patients with neuromuscular disorders to help them regain function. Wood is also working on novel manufacturing processes for “printable robots” with the goal of automating robot development and creating new methods for rapid prototyping complex electromechanical devices.

Source: Wyss Institute at Harvard University

In the Disruptive Podcast series, Terrence McNally speaks directly with Wyss Institute researchers, exploring what motivates them and how they envision our future as might be impacted by their disruptive technologies. In part 1 of the Disruptive: Bioinspired Robotics podcast episode, Wyss Founding Core Faculty Member Radhika Nagpal discusses swarm collectives, as well as the challenges faced by women in the engineering and computer science fields.

Nagpal is developing programming paradigms that enable new types of robotic systems to mimic the collective behaviors of living creatures. Inspired by bee swarms and termite colonies, she is applying nature’s approach to decentralized cooperation to engineer new collective systems that meet real-world challenges. Biological systems, from embryos to social insects, depend upon the coordinated behavior of large numbers of individual agents to achieve highly complex outcomes — termites build skyscrapers and embryonic cells develop into healthy babies. Nagpal is building new types of distributed systems — from multi-modular robots and robot swarms, to vast sensor networks — that have similar capabilities.

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See all the latest robotics news on Robohub, or sign up for our weekly newsletter.

By Leah Burrows | SEAS Communications

Engineers have been trying to design functional aerial-aquatic vehicles for decades with little success. The biggest challenge is conflicting design requirements: aerial vehicles require large airfoils like wings or sails to generate lift while underwater vehicles need to minimize surface area to reduce drag.

To solve this, engineers at the Harvard John A. Paulson School of Engineering and Applied Science (SEAS) and the Wyss Institute for Biologically Inspired Engineering at Harvard University took a clue from puffins. The birds with flamboyant-colored beaks are one of nature’s most adept hybrid locomotors, employing similar flapping motions to propel themselves through air as well as through water to dive for fish.

“Through various theoretical, computational and experimental studies, we found that the mechanics of flapping propulsion are actually very similar in air and in water,” said Kevin Chen, a graduate student in the Harvard Microrobotics Lab at SEAS. “In both cases, the wing is moving back and forth. The only difference is the speed at which the wing flaps.”

RoboBee: From Aerial to Aquatic from Wyss Institute on Vimeo.

Applying this in the lab, the team of researchers at SEAS and Wyss have demonstrated the first flying, swimming, insect-like robot — paving the way for future duel aerial aquatic robotic vehicles. The aerial-aquatic robot is an adaptation of the previously developed “RoboBee”, a microrobot smaller than a paperclip that flies and hovers like an insect, flapping its tiny, nearly invisible wings 120 times per second.

The new research was presented recently in a paper at the International Conference on Intelligent Robots and Systems in Germany, where first author Chen accepted the award for best student paper. The paper was co-authored by SEAS/Wyss graduate student Farrell Helbling, SEAS/Wyss postdoctoral fellows Nick Gravish and Kevin Ma, and Robert J. Wood, who is the founder of the Harvard Microrobotics Lab, the Charles River Professor of Engineering and Applied Sciences at SEAS, and a Core Faculty Member at the Wyss Institute.

In order to make the transition from air to water, the team first had to solve the problem of surface tension. The RoboBee, designed in Wood’s lab, is so small and lightweight that it cannot break the surface tension of the water. To overcome this hurdle, the RoboBee hovers over the water at an angle, momentarily switches off its wings, and crashes unceremoniously into the water in order to sink.

Next, the team had to account for water’s increased density. “Water is almost 1,000 times denser than air and would snap the wing off the RoboBee if we didn’t adjust its flapping speed,” said Helbling, the paper’s second author.

The team lowered the wing speed from 120 flaps per second to nine but kept the flapping mechanisms and hinge design the same. A swimming RoboBee changes its direction by adjusting the stroke angle of the wings, the same way it does in air. Like a flying version, it is still tethered to a power source. The team prevented the RoboBee from shorting by using deionized water and coating the electrical connections with glue.

While this RoboBee can move seamlessly from air to water, it cannot yet transition from water to air. Solving that design challenge is the next phase of the research, according to Chen.

“What is really exciting about this research is that our analysis of flapping-wing locomotion is not limited to insect-scaled vehicles,” said Chen. “From millimeter-scaled insects to meter-scaled fishes and birds, flapping locomotion spans a range of sizes. This strategy has the potential to be adapted to larger aerial-aquatic robotic designs.”

“Bioinspired robots, such as the RoboBee, are invaluable tools for a host of interesting experiments — in this case on the fluid mechanics of flapping foils in different fluids,” said Wood. “This is all enabled by the ability to construct complex devices that faithfully recreate some of the features of organisms of interest.”

This research was funded by the National Science Foundation and the Wyss Institute for Biologically Inspired Engineering.