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Diagram Illustrating the Acid?Responsive Energy Storage and Release Mechanism of Bioinspired Polyurethane Woven Artificial Muscle Nanofibers (By Figdraw).AbstractPolyurethane (PU) is a traditional chemical known for its chemical stability and mechanical performance. Inspired by the similarity between the formation and breakage of chemical coordination bonds and the energy storage and release of muscle fibers, muscle?like electrostatically spun fibers with acid?responsive energy storage and release were prepared by introducing bio?inspired elastic energy storage groups and bio?active degradation groups (PU?BPY?Fe) in the main chain of PU, taking advantage of the good mechanical properties of PU. The fabricated electrospinning film PU?BPY?Fe can respond to external stimulation, which generated high strain (32?MPa), stretch of 206%, outperforming the nanofiber membrane before stimulation, similar and even higher than the biological muscles. The variable mechanical properties and elastic energy storage capacity of PU?BPY?Fe were attributed to the reversible hydrogen bonding and the destabilization of metal coordination bonds (Fe3+ to Fe2+) within the material under acidic stimulation. Cytotoxicity testing of the synthesized fibers indicated a degree of biocompatibility, suggesting potential for in vivo applications. This method of storing and releasing elastic energy was demonstrated and has endowed the PU?BPY?Fe with stimuli?responsibility and muscle?like mechanical properties, which may inspire the design of soft muscles materials for robots and tissue engineering applications.