Dual-Mode Sensing Elastomer Arrays: Integrating Temperature Visualization and Digitization in Liquid-Free Ionic Networks

The advancement of wearable electronics demands flexible conductors that overcome the limitations of existing ionic materials, such as dehydration in hydrogels and leakage in ionogels. In contrast to these conventional systems, this work introduces a liquid-free ionic conductive elastomer (ICE) designed with a covalent/noncovalent network architecture. This unique liquid-free design not only circumvents the inherent issues of evaporation and leakage but also enables robust elasticity (560% strain), autonomous self-healing (89% efficiency in 16 h), and tunable ionic conductivity (up to 3.5 × 10–5 S/m). More importantly, we go beyond single-mode sensing by integrating thermochromic microcapsules (triggered at 28 °C, 45 °C, 65 °C) into the ICE matrix to create a dual-mode sensor array capable of simultaneous digital sensing and spatial temperature visualization. The synergistic network composed of poly(lipoic acid), poly(2-(N-3-sulfopropyl-N,N-dimethylammonium) ethyl methacrylate), and 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][DCA]) ionic liquid facilitates dynamic hydrogen bonding and electrostatic interactions, granting exceptional resilience across a broad temperature range (25–120 °C) and strong adhesion to biological tissues. As a strain sensor, the ICE exhibits high sensitivity (gauge factor = 1.36 at 0–100% strain), fast response/recovery (210/100 ms), and durability (>2500 cycles). The embedded thermochromic elements provide reversible, real-time colorimetric feedback, i.e., gradient transitions from a multicolor pattern to a uniform yellow color when the temperature exceeds a set threshold. This dual functionality allows the sensor to quantitatively track joint movements (fingers, wrists, knees) through resistance changes while intuitively mapping heat exposure for application in smart wearables for injury prevention during human-computer interactions. Our scalable strategy offers a versatile platform for multifunctional sensing systems.