Self-Healable Conductive Hydrogels with High Stretchability and Ultralow Hysteresis for Soft Electronics

Abstract

Stretchable sensors based on conductive hydrogels haveattractedconsiderable attention for wearable electronics. However, their practicalapplications have been limited by the low sensitivity, high hysteresis,and long response times of the hydrogels. In this study, we developedhigh-performance poly-(vinyl alcohol) (PVA)/poly-(3,4-ethylenedioxythiophene):poly-(styrenesulfonate)(PEDOT:PSS) based hydrogels post-treated with NaCl, which showed excellentmechanical properties, fast electrical response, and ultralow hysteresisproperties. The hydrogels also demonstrated excellent self-healingproperties with electrical and mechanical properties comparable tothose of the original hydrogel and more than 150% elongation at breakafter the self-healing process. The high performance of the optimizedhydrogels was attributed to the enhanced intermolecular forces betweenthe PVA matrix and PEDOT:PSS, the favorable conformational changeof the PEDOT chains, and an increase in localized charges in the hydrogelnetworks. The hydrogel sensors were capable of tracking large humanmotion and subtle muscle action in real time with high sensitivity,a fast response time (0.88 s), and low power consumption (<180 mu W). Moreover, the sensor was able to monitor human respirationdue to chemical changes in the hydrogel. These highly robust, stretchable,conductive, and self-healing PVA/PEDOT:PSS hydrogels, therefore, showgreat application potential as wearable sensors for monitoring humanactivity.