Multifunctional Organohydrogel-Based Ionic Skin for Capacitance and Temperature Sensing toward Intelligent Skin-like Devices

The ionic conducting hydrogel has attracted tremendous attention in fabricating flexible artificial skin-like devices. However, there are still unsolved challenges in hydrogel-based ionic skins, such as poor fulfillment of stretchability and compliance and weak interface interaction, as well as single sensory function. Herein, a high-performance organohydrogel-based ionic skin is facilely fabricated through one-step UV-initiated polymerization, in the presence of a polyacrylamide/cellulose nanofibril (PAAm/CNF) hybrid skeleton, a tannic acid (TA)-functionalized interface, and electrolytes (NaCl) dissolved in a glycerol–water binary solvent network. The design strategy demonstrates a profound synergistic effect of interpenetrating networks and interbonding structure in improving ultrastretchability (up to 1430%), suitable Young’s modulus (≈23 kPa), and high ionic conductivity (2.7 S m–1). Inspired by the adhesive mechanism of catechol groups in the mussel foot proteins, the TA component provides a durable interfacial contact (self-adhesiveness ≈ 103 N m–1) and unexpected UV-blocking capability (efficiency >99.9%). Moreover, by introducing a glycerol/water solvent system, the organohydrogel achieves desirable environmental stability. Furthermore, benefiting from the superior mechanical response and thermal perception capacities, our ionic skin can be assembled as capacitance sensors for real-life motion monitoring as well as thermistors for dynamic temperature detection.