Ionic Conductive, Antidrying, and Flexible Organohydrogels Suitable for Pressure Sensors and Gas Sensors

Abstract

In recent years, hydrogels have become excellent optional materials for flexible sensors due to their high stretchability and biocompatibility. However, the instabilities of hydrogels including the tendency to dry out and the poor reusability seriously limit their applications. Herein, a double-network (DN) organohydrogel is derived by regulating the mechanical property, conductivity, and antidrying characteristic of the poly (acrylamide-co-acrylic acid) (P(AM-co-AA)) hydrogel. Specifically, the ionic coordination (CO2LFeIII) is imported as the secondary cross-link to strengthen the mechanical property, and LiCl in ethylene glycol (EG) solution enhances the conductivity and antidrying characteristics simultaneously. Benefiting from these improvements of material characteristics, the iontronic pressure sensor assembled from the DN organohydrogel demonstrates excellent performances such as a high sensitivity, fast response/recovery characteristic at different frequencies, and remarkable fatigue resistance. These properties also enable physiological signal detections in diverse scenarios. At the same time, with the help of abundant functional groups in the double network and solvent, the organohydrogel exhibits practical NH3 sensing performances including high response, strong gas selectivity, and excellent long-term stability, paving the way toward broader multiscene applications of hydrogels.