Multifunctional Ion-Conductive Hydrogels with Self-Healing, Antifreeze, and Water-Retention Capabilities for Robust Wearable Sensing

Abstract

Conductive hydrogels have attracted attention in wearable electronics due to their softness, biocompatibility, and ionic conductivity. Yet, challenges such as poor signal stability, limited environmental tolerance, and mechanical fragility hinder broader application. Here, we report a multifunctional ionically conductive hydrogel (Li-gel) synthesized via a two-step process, featuring a PVA/PAAm dual-network crosslinked with dynamic boronate ester bonds and doped with lithium chloride (LiCl). The hydrogel demonstrates ambient self-healing capability, restoring up to 80% of its mechanical strength, and achieves high ionic conductivity (1.1 S/m) through LiCl-mediated ion transport. LiCl also depresses the freezing point to -13.5 ℃ and enhances water retention, enabling >90% mass recovery after thermal dehydration and strong resistance to ambient water loss. Li-gel exhibits excellent transparency (>90%) and adheres firmly to skin, glass, and plastic, supporting robust interface stability. Strain-sensing tests yield a gauge factor of 2.00 at 100% strain, with rapid response, frequency adaptability, and high durability over 1000 cycles. Altogether, Li-gel combines mechanical resilience, environmental adaptability, and sensing reliability, offering a promising platform for next-generation wearable sensors.