Energy harvesting and storage using highly durable Biomass-Based artificial muscle fibers via shape memory effect

This study presents the development of novel artificial muscle fibers from biomass-derived polylactic acid (PLA) and thermoplastic polyurethane (TPU), demonstrating multifunctional properties, including shape memory, energy harvesting, and storage, and offering a sustainable alternative to traditional actuators. The optimized TPU/PLA 4:6 conjugate fiber demonstrates exceptional shape fixity (99.83 %) and shape recovery (99.36 %), with outstanding cyclic durability, retaining over a 98.3 % recovery ratio after fifty consecutive cycles. The fibers exhibit a specific work output of 5.230 J g^–1 and can lift weights over 56,000 times their own, significantly outperforming conventional artificial muscle fibers. Twisting (240 turns m⁻¹) and 2-ply configurations enhance tensile strength by 4.18 times compared to untreated shape memory fibers, highlighting their mechanical robustness. The TPU/PLA fibers also generate significant piezoelectric energy directly during the shape memory effect, emphasizing their dual functionality in actuation and energy harvesting. Energy production is significantly higher in the longitudinal direction than in the perpendicular direction, with an open circuit voltage of 488 mV and a short circuit current of 6.28 μA, demonstrating efficient energy generation during deformation and shape recovery. Additionally, CNT-coated fibers display efficient energy storage with a specific capacitance of 42.18 μF cm^–1 and retain 90.8 % of their initial capacitance after 1,000 cycles, confirming their durability in repeated applications.