Inspired by the Hydrophilic Nature of Squid Muscles: Constructing High-Performance Anti-fatigue Polymeric Hydrogel...

Polymeric hydrogel artificial muscles (PHAMs) are popular in flexible electro-mechano-chemically responsive actuation research but suffer from performance degradation and structural damage with repeated use, limiting their potential applications. Inspired by the highly anti-fatigue squid muscles, this study enhanced PHAMs by introducing different hydrophilic polymeric substances, creating hydrophilic PHAMs with improved output force stability, response speed, and fatigue resistance under both single- and multi-cycle conditions. The results showed that the modified polymeric hydrogel, combining sodium alginate, κ-Carrageenan, and L-Sodium Lactate, increased the ionic conductivity and water absorption of the polymeric hydrogel network, achieving a maximum output force density (ρ_f·max, mN/g) of 22.45 mN/g and extending the working life (T, s) to 9775 s, 4.23 times longer than the original. Polymeric hydrogels synthesized with polyacrylamide (PAM) enhanced the hydrogel network structure by leveraging the extended molecular chains to envelop and increasing cross-linking points, thereby forming a more stable network structure. This structural configuration markedly improved PHAM performance, as evidenced by a reduction in the peak difference attenuation rate of output force density (τ_ρp, %) to -12.09% and a notable enhancement in electro-actuated anti-fatigue performance. This study offers an effective strategy for the development of high-performance, significantly anti-fatigue PHAM actuators.