Adhesive conductive hydrogels with wrinkled Janus surface and ultra-high sensitivity used as strain sensors

Conductive hydrogels have attracted enormous attention in wearable electronic devices due to considerable flexibility and similarity with human skin. Since the majority of hydrogels were fabricated by one-pot method alone and the conductivity change under strain was caused by the slight shape change and the fixed conductive path, further improvement of the sensitivity is hard. Thus, we cast the silver nanowires (AgNW) in ethanol solvent on the upper surface of polyacrylic acid/chitosan (PAA/CS) hydrogels prepared by one-pot method to obtain asymmetrical PAA/CS@AgNW hydrogels. As the construction of conductive surface, the ethanol gradually diffused into the hydrogel and caused the upper surface with ideal wrinkle structure. Thanks to the dual-effect of the design, the sensitivity was greatly enhanced with the ultra-high gauge factor (GF = 191.2, 7413, 18,720) at different pressure ranges. A series of reliable application performance (flexibility, self-healing, dry resistance and adhesion) and excellent electrical signal response (ultra-high sensitivity, identification, repetition and stability) was tested and indicated the potential applications in motion detection, gesture recognition and health monitoring.