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

Abstract Conductive hydrogels have attracted enormous attention in wearable electronic devices due to considerable flexibility and similarity with human skin. However, the majority of hydrogels were fabricated by one-pot process and were completely homogeneous, which limited the response to electrical signals. In this paper, we propose a simple strategy to obtain asymmetrical polyacrylic acid/chitosan@silver nanowires (PAA/CS@AgNWs) hydrogels, namely, depositing AgNWs layer by dropping AgNWs dispersions in ethanol on PAA/CS hydrogel prepared via one-pot process. Ethanol diffused into the hydrogel and endowed the upper surface with wrinkle structure. Besides, the inevitable conductivity difference between hydrogel itself and AgNWs further enhanced the sensitivity, leading to the ultra-high gauge factor (GF = 191.2, 7413, 18720). The adhesion of the hydrogel not only improved the adaptability to skin, but also the fastness of AgNWs. Reliable application performance (flexibility, self-healing, dry resistance and adhesion) and excellent electrical signal response (ultra-high sensitivity, identification, repetition and stability) indicated the potential applications in motion detection, gesture recognition and health monitoring.