Enhancing Fatigue-Resistant Electrical Actuation and Energy Dissipation in Squid-Inspired Gel Bionic Artificial Muscles (GBAMs) Using Covalently Cross-Linked Polyacrylamide for Superior Stability

Gel bionic artificial muscles (GBAMs) are promising flexible electric actuators, but their poor fatigue-resistant electrical actuation limits practical use. This study enhanced squid-inspired GBAMs by creating a 3D interpenetrating network with covalently cross-linked polyacrylamide (PAM), sodium alginate, and κ-carrageenan, improving their electrical actuation and fatigue resistance. Using 0.12 g of PAM, the GBAM showed a 26% increase in an electroactuation force density of 21.56 mN/g and a 2.5 times longer operating life of 5830 s. In cyclic tests, the peak difference of the electroactuation force density and response speed decay rates decreased by -12.76% and -93.59%, respectively. The elastic modulus increased by 79% to 14.41 MPa, and after 100 stretching cycles, no cracks appeared, unlike the control group (uncross-linked), which fractured after 55 cycles. The fatigue threshold after 10,000 cycles was 287.2 J/m², 64% higher than the control group, yet lower than its fracture energy of 612.9 J/m². The specific capacitance was 719.1 nF/cm², the resistance was 1.71 Ω, the specific energy was 84.38 A·J/g, and the energy density was 11.99 J. Furthermore, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectra confirmed PAM's effective cross-linking, which inhibited phase separation in sodium alginate and κ-Carrageenan mixtures, enhanced network uniformity, and improved ionic migration and fatigue resistance. This resulted in GBAMs with stable electrical actuation and excellent fatigue resistance, meeting practical needs and offering new development insights.