In designing materials for artificial muscles, the goals are to find those that will combine high strokes, high efficiency, long cycle life, low hysteresis, and low cost. In the latest issue of Science, Haines et al. show that this is possible. Twisting high-strength, readily available polymer fibers, such as those used for fishing lines or sewing thread, to the point where they coil up, allowed construction of highly efficient actuators that could be triggered by a number of stimuli.

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