Sensitive Wearable Strain Sensor Based on a Self-Doped Conductive Hydrogel

Conductive hydrogels have been widely applied to develop flexible and wearable sensors. Classic conductive polymers such as poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) exhibit high conductivity and biocompatibility, but their intrinsic insolubility may affect the establishment of conductive pathways, thereby further impeding the enhancement of both electrical and mechanical properties. In this study, a self-doped highly conductive poly(3,4-ethylenedioxythiophene) sulfonate (PEDOT-S) solution was obtained by photopolymerization, avoiding the introduction of iron ions. Following this, we developed a double network (DN) hydrogel system from poly(vinyl alcohol) and polyacrylamide via a freezing–thawing approach, combining with PEDOT-S as conductive agent. The hydrogel exhibited robust mechanical strength, adhesive capability, and remarkable conductive sensitivity. As a strain sensor, the conductive hydrogel can be used to detect body motion and vocal cord vibrations, providing promising potential for application in flexible and wearable devices.