Conductive Self-Healing\nNanocomposite Hydrogel Skin\nSensors with Antifreezing and Thermoresponsive Properties

Abstract

With growing\ninterest in flexible and wearable devices, the demand for nature-inspired\nsoft smart materials, especially intelligent hydrogels with multiple\nperceptions toward external strain and temperatures to mimic the human\nskin, is on the rise. However, simultaneous achievement of intelligent\nhydrogels with skin-compatible performances, including good transparency,\nappropriate mechanical properties, autonomous self-healing ability,\nmultiple mechanical/thermoresponsiveness, and retaining flexibility\nat subzero temperatures, is still challenging and thus limits their\napplication as skinlike devices. Here, conductive nanocomposite hydrogels\n(NC gels) were delicately designed and prepared via gelation of oligo­(ethylene\nglycol) methacrylate (OEGMA)-based monomers in a glycerol–water\ncosolvent, where inorganic clay served as the physical cross-linker\nand provided conductive ions. The resultant NC gels exhibited good\nconductivity (∼3.32 × 10^–4 S cm^–1, akin to biological muscle tissue) and an autonomously\nself-healing capacity (healing efficiency reached 84.8%). Additionally,\nsuch NC gels displayed excellent flexibility and responded well to\nmultiple strain/temperature external stimuli and subtle human motions\nin a wide temperature range (from −20 to 45 °C). These\ndistinguished properties would endow such NC gels significant applications\nin fields of biosensors, human–machine interfaces, and soft\nrobotics.