Re-foldable origami-inspired bidirectional twisting of artificial muscles reproduces biological motion

Recent advances in soft-matter artificial muscles enable machines, especially robots, to reproduce muscle-like actuation of biological organisms, yet there remain substantial and persistent challenges to develop advanced artificial muscles capable of mimicking flexible, controllable, and versatile biological motions. Here, we introduce re-foldable origami strategy into artificial muscles that can use different pre-programmed crease patterns to achieve multimode morphing. Re-foldable square-twist artificial muscles derived from re-foldable square-twist origami is demonstrated, where different twisting directions of re-foldable square-twist artificial muscles are induced through differences in torsional resistance resulting from applying vacuum power on two chambers in sequence. Re-foldable squire-twist artificial muscles can exhibit a complex compound motion coupling twisting, bending, and contraction motions into one, allowing them to flexibly and vividly mimic versatile biological motions by a single muscle or multimuscle combination (like "building bricks"), including hand grasping, bicep stretching, and the bidirectional twisting of the neck, wrist, or ankle.