Environment-Resistant\nOrganohydrogel-Based Sensor\nEnables Highly Sensitive Strain, Temperature, and Humidity Responses

Abstract

Conductive\nhydrogels have been extensively used in wearable skin\nsensors owing to their outstanding flexibility, tissuelike compliance,\nand biocompatibility. However, the dehydration and embrittlement of\nhydrogels can result in sensitivity loss or even invalidation, restraining\ntheir wearable applications in external environments, especially at\nlow temperatures and in arid environments. Herein, an environment-resistant\norganohydrogel is developed for multifunctional sensors. A double-network\norganohydrogel based on hyaluronic acid and poly­(acrylic acid-<i>co</i>-acrylamide) is developed, and glycerol is introduced\ninto the organohydrogel network via a solvent displacement strategy.\nOwing to the water-locking effects of glycerol and tough polymeric\nbackbone, the resultant organohydrogel not only exhibits stable tensibility\nbut also maintains excellent flexibility and stable conductivity with\nthe environment-resistant properties, including freezing resistance\nagainst −30 °C and moisture retention at 4% relative humidity\nin a high temperature of 60 °C. Moreover, a series of organohydrogel-based\nsensors and an array device are developed to achieve highly sensitive\nstrain, temperature, and humidity responses and exhibit a high gauge\nfactor of 10.79 in the strain-sensitive test. This work develops a\nuniversal ionic skin based on organohydrogels to be applied to wearable\nsensors for health monitoring.