A High Environmentally Stable Ionic Hydrogel for Pressure‐Temperature Bimodal Passive Flexible Tactile Sensor

Abstract

Ionic hydrogels‐derived flexible tactile sensors, referred to as “ionic skin”, have attracted significant attention due to their bionic perception behavior of human skin. Up to now, in addition to their favorable stretchability and sensitivity, the requirements for the practical application, such as high environmental suitability and optimal decoupling sensing capabilities, have become the focus of attention in ionic flexible tactile devices. Herein, in this study, a novel poly(vinyl alcohol) (PVA)/poly(vinyl alcohol) (PEG)/glycerol/ionic liquids (IL) ‐ thermochromic microcapsules (TCPs) (PPGIL‐TCPs) ionic hydrogel is developed and exhibits exceptional water retention (>90% after 7 days) and frost resistance (<−70 °C), alongside the excellent flexibility and conductivity, wherein the cross‐linked PVA/PEG networks constitute the robust matrix, the IL supplies the environmental suitability and acts as the active origin of sensing signals, the Glycerol mitigates the adverse effects of ILs on mechanical properties while synergistically improves the environmental stability, and the TCPs part imparts the thermo‐responsive discoloration ability. Accordingly, the derived flexible sensor displays the bimodal passive pressure sensing and temperature visualization capabilities with the uncoupled output signals, which can be employed to generate distinct signals to identify the path of applied pressure, enabling array configurations with minimal signal output channels. This work will inspire the development of next‐generation ionic bionic sensing systems.