Self-Healable, Self-Adhesive\nand Degradable MXene-Based\nMultifunctional Hydrogel for Flexible Epidermal Sensors

Abstract

Conductive hydrogels have garnered significant interest\nin the\nrealm of wearable flexible sensors due to their close resemblance\nto human tissue, wearability, and precise signal acquisition capabilities.\nHowever, the concurrent attainment of an epidermal hydrogel sensor\nincorporating reliable self-healing capabilities, biodegradability,\nrobust adhesiveness, and the ability to precisely capture subtle electrophysiological\nsignals poses a daunting and intricate challenge. Herein, an innovative\nMXene-based composite hydrogel (PBM hydrogel) with exceptional self-healing,\nself-adhesive, and versatile functionality is engineered through the\nintegration of conductive MXene nanosheets into a well-structured\npoly(vinyl alcohol) (PVA) and bacterial cellulose (BC) hydrogel three-dimensional\n(3D) network, utilizing multiple dynamic cross-linking synergistic\nrepeated freeze–thaw strategy. The hydrogel harnesses the presence\nof dynamically reversible borax ester bonds and multiple hydrogen\nbonds between its constituents, endowing it with rapid self-healing\nefficiency (97.8%) and formidable self-adhesive capability. The assembled\nPBM hydrogel epidermal sensor possesses a rapid response time (10\nms) and exhibits versatility in detecting diverse external stimuli\nand human movements such as vocalization, handwriting, joint motion,\nMorse code signals, and even monitoring infusion status. Additionally,\nthe PBM hydrogel sensor offers the added advantage of swift degradation\nin phosphate-buffered saline solution (within a span of 56 days) and\nH₂O₂ solution (in just 53 min), maintaining\nan eco-friendly profile devoid of any environmental pollution. This\nwork lays the groundwork for possible uses in electronic skins, interactions\nbetween humans and machines, and the monitoring of individualized\nhealthcare.