Dual-Ion Synergy Achieves Megapascal Strength and High Conductivity in Wearable Hydrogel Sensors

As three-dimensional crosslinked polymer networks with high water content, conductive hydrogels show great potential for applications in flexible wearable electronics, health monitoring, and related fields, owing to their biocompatibility, stretchability, self-healing capability, and tactile sensing performance. However, conventional hydrogels often suffer from limited mechanical strength and low ionic conductivity, highlighting the need to develop hydrogel-based sensors that combine high toughness, sensitivity, and excellent electrical performance. In this work, we developed a dual-ion-regulated double-network hydrogel composed of polyvinyl alcohol (PVA), sodium acrylate, acrylic acid, MTAC, and lithium chloride via a facile one-pot method. By introducing dual cations (Na + and Li + ), we established electrostatic interactions and coordination bonds within the network, which—together with dynamically reversible hydrogen bonds—resulted in a crosslinked structure that provides outstanding mechanical and conductive properties. This dual-cation (Na + /Li + ) regulation strategy synergistically enhanced the hydrogel’s elongation at break (1001%), tensile strength (1.2 MPa), and toughness (7.24 MJ/m 3 ), while also achieving high electrical conductivity (8.4 mS/cm) and excellent sensing sensitivity (gauge factor = 6.44). As a strain sensor, the hydrogel effectively monitors both large-scale and subtle human motions, including limb movements, pulse, and facial expressions, demonstrating its strong potential for health monitoring and human–machine interfaces.