Anti-drying and recyclable polyvinyl alcohol/xanthan gum hydrogels based on a novel binary solvent for capacitive sensors

Conductive hydrogels hold great promise for wearable sensors due to their flexibility, biocompatibility, and customizability. However, issues such as poor environmental stability, water loss, and insufficient mechanical properties have hindered their broader application. In this study, we introduce a novel polyvinyl alcohol (PVA) hydrogel reinforced with xanthan gum (XG) and a solketal-water binary solvent, creating an interpenetrating network with exceptional performance. XG serves as a toughening agent, enhancing the hydrogel's toughness from 0.09 MJm −3 to 5.82 MJm −3 compared to conventional PVA hydrogels. Solketal significantly improves moisture retention and freeze resistance, allowing the hydrogel to retain less than 20 % water loss over days at moderate humidity and to autonomously absorb moisture under high humidity conditions. Incorporating polydopamine (PDA) and NaCl further improves recyclability and conductivity, achieving a gauge factor of 2.54 and enabling reshaping with retained performance after multiple cycles. This eco-friendly, cost-effective hydrogel functions as a versatile strain and capacitive sensor, accurately detecting human motion and writing patterns, showcasing potential for wearable electronics and environmental monitoring. Our work fundamentally advances the field by balancing mechanical, electrical, and environmental stability properties in a multifunctional hydrogel, overcoming limitations of prior literature.