Drones are the sexy, mysterious tech craze that are often a butt of a joke, a vague solution or an ominous threat. But no matter how flashy, good technology should still solve concrete problems.
Robots clean rivers and sort waste, monitor ecosystems, and inspect renewable-energy infrastructure. But even the greenest robot has an environmental footprint.
EPFL engineers have designed acoustic cavities that convert sound waves into thrust, propelling small robots and ultralight aerial vehicles without on-board actuators or electronics.