A frost-resistant and self-healing enhanced hydrogel for wearable sensors and electronic skin

Abstract

Recent progress in hydrogel engineering has concentrated on the creation of multifunctional materials tailored for the advancement of next-generation wearable electronic devices. This study presents an anti-freezing, self-healing hydrogel engineered by integrating lithium bis(trifluoromethane)sulfonimide (LiTFSI) into a copolymer network of acrylamide (AM) and N-[tris(hydroxymethyl)methyl] acrylamide (THMA). The triple hydrogen-bond network endows the hydrogel with a fracture strain of 1023%, a tensile strength of 103.8 kPa and a toughness of 501.6 kJ m⁻³. LiTFSI suppresses water crystallization while enhancing ionic conductivity. As a strain-sensing element, the material achieves a Gauge Factor (GF) of 9.09 with a 107 ms response and a 104 ms recovery time. It maintains reliable performance throughout 300 cyclic tests, enabling precise tracking of physiological motions and other complex movements. Its inherent adhesive properties and autonomous self-healing capabilities highlighted its potential applications in prosthetics, human–machine interfaces, and wearables designed for extreme environments. This minimalist ternary hydrogel integrates anti-freezing, self-healing, and sensing capabilities while enhancing electrical performance, thereby significantly improving applicability in complex environments.