High tough, self‐adhesive, conductive double network hydrogel for flexible strain sensors

Abstract The application of adhesive conductive hydrogel materials in flexible sensors has been extensively studied. However, existing adhesive hydrogel sensor materials have problems such as poor adhesion, low conductivity, and difficulty in balancing mechanical and adhesive properties, which limit their practical applications. In this study, we propose a simple and economical method to fabricate double‐network hydrogels for flexible strain sensors by dissolving acrylamide (AM), chitosan (CS), polyethylene glycol (PEG) and gelatin (Gel) in a mixed solvent of deionized water and a food‐grade phosphate. The prepared AM/CS/PEG/Gel (ACPG) hydrogel exhibits excellent toughness (maximum stress of 154 kPa, maximum elongation of 2256%), self‐adhesiveness (maximum adhesion strength to wood of 17.2 kPa), and high conductivity (2.33 S/m). Compared with similar adhesive hydrogels, the conductivity of ACPG hydrogel is significantly improved. Therefore, ACPG hydrogel can be used as an ideal material for flexible sensors, and has broad application potential in wearable devices and human‐computer interaction.