Tough, Self-Healing, Antifatigue, Self-Adhesive Conductive Hydrogel via Inorganic Hybrid Cross-Linking

Conductive hydrogels are ideal materials for flexible sensors because of their inherent flexibility, tunable mechanical properties, high conductivity, and operational stability. These properties facilitate the seamless control of smart devices through simple gestures or muscle movements. However, most conductive hydrogels cannot simultaneously achieve high toughness and high conductivity, significantly limiting their practical applicability in flexible sensors. Herein, poly(2-acrylamido-2-methylpropanesulfonate-lithium- co -acrylamide)/graphene oxide/silicon dioxide (P(AMPSLi- co -AM)/GO/SiO 2 ) conductive hydrogels were prepared utilizing acrylamide (AM) and 2-acrylamide-2-methylpropanesulfonatelithium (AMPSLi) as monomers, and vinyl triethoxysilane (VTES) as silicon source via in situ free radical copolymerization and sol–gel method in the presence of GO. Within this system, GO served as both a conductive filler and a physical cross-linker, whereas vinyl-SiO 2 functioned as a chemical cross-linker and a reinforcing filler. The P(AMPSLi- co -AM)/GO/SiO 2 conductive hydrogel demonstrates outstanding mechanical properties, including a tensile stress of 203.89 kPa, an elongation at break of 528.94%, and an ultrahigh compressive strength of 1175.58 kPa. It also exhibits remarkable toughness (>400 kJ/m 3 ), excellent fatigue resistance, strong self-adhesion, and rapid self-healing capability. The incorporation of Li + ions and GO imparts high electrical conductivity (greater than 0.85 S/m) to the hydrogel. A flexible strain sensor fabricated from this hydrogel shows high sensitivity with a gauge factor of up to 2.268, along with an instantaneous response, outstanding stability, repeatability under cyclic loading, and reliable long-term detection of various human physiological and motion signals. These combined characteristics indicate that the P(AMPSLi- co -AM)/GO/SiO 2 hydrogel is a promising candidate for wearable health monitoring devices.