Elastic-sheathed artificial muscle fibers delivering natural muscle-like resilient actuation for robotics and wearables

Natural muscles feature resilient actuation, but currently developed artificial muscle fibers do not. The main challenge is serious plastic elongation, especially when artificial muscle fibers are operated at heavy loads, significantly limiting their applications. We report a resilient artificial muscle fiber that deploys an elastic sheath. The sheath enables full lengthwise recovery of the coiled artificial muscle fiber straightened at 375% strain. This muscle fiber produces natural muscle-like resilient actuation, which features elastic elongation when bearing heavy loads and consistent contractions at load-balanced muscle lengths. Two muscle fibers connected in an antagonistic structure, amounting to ∼8% of the weight of an electrical rudder system, efficiently control the flight attitude of a commercial ornithopter. An adaptive pressure band based on these muscle fibers provides rhythmic pressure to prevent venous diseases. Such resilient muscle fibers can offer important potential in robotics and wearable technologies that require high durability and adaptability.