Ultrastretchable, Self-Healable, and Wearable Epidermal Sensors Based on Ultralong Ag Nanowires Composited Binary-Networked Hydrogels

Stretchable and biocompatible flexible electronic devices are essential to meet the increasing demands of complex and multifunctional personal healthcare systems. To detect various external stimuli, noninvasively epidermal sensors with reliable and sustainable performances are desirable. Herein, ultrastretchable, self-healable, and wearable epidermal sensors based on ultralong Ag nanowires (AgNWs) composited binary-networked hydrogels are fabricated. The flexible hydrogel sensors can monitor dynamic strains in a wide range (4-3000%), realize high healing efficiency (94.3%) and strong adhesiveness, which is attributed to the strong covalent bond and reversible physical interaction structured binary-network. The ultralong AgNWs network remains in direct contact under strain, ensures a rapid response to external stimuli. The strong interactions between polymer matrix and the nanowires endow the hydrogel sensors excellent sensitivity (gauge factor of 4.59) within a wide sensing range (0-850%). The cycling stability of the hydrogel sensors is further improved by the composition of AgNWs, presenting negligible degradation both on tension and compression. Based on the advantageous performances, the flexible stain sensors can differentiate complicated human motions and realize phonation recognition precisely, showing promising application in next-generation wearable epidermal sensors with ultrabroad working range and high sensitivity.