Poly(vinyl alcohol)/polyacrylamide double-network ionic conductive hydrogel strain sensor with high sensitivity and high elongation at break

As a soft material with biocompatibility and stimulation response, ionic conductive hydrogel-based wearable strain sensors show great potential across a wide spectrum of engineering disciplines, but their mechanical toughness is limited in practical applications. In this study, freeze-thawing techniques were utilized to fabricate double-network hydrogels of poly(vinyl alcohol)/polyacrylamide (PVA/PAM) with both covalent and physical cross-linking networks. These double-network hydrogels demonstrate excellent mechanical performance, with an elongation at break of 2253% and tensile strength of 268.2 kPa. Simultaneously, they also display a high sensitivity (Gage factor, GF = 2.32 at 0%–200% strain), achieve a rapid response time of 368 ms without the addition of extra conductive fillers or ions, stable signal transmission even after multiple cycles, and fast response to human motion detection.