Chemically Crosslinked Antifreezing Ionic Conductive Hydrogels for Flexible Wearable Strain Sensors

Conductive hydrogels exhibit great potential for wearable strain sensors. However, traditional conductive hydrogels tend to freeze at low temperatures, drastically reducing both electrical and mechanical performance, thus limiting their cryogenic applications. In this work, poly(acrylic acid)/ethylene glycol/zinc trifluoromethanesulfonate (PAA/EG/Zn(CF 3 SO 3 ) 2 ) antifreeze conductive hydrogels were prepared via free‐radical polymerization with acrylic acid (AA) as monomer, ethylene glycol (EG) as cryoprotectant, zinc trifluoromethanesulfonate (Zn(CF 3 SO 3 ) 2 ) as conductive filler, ammonium persulfate (APS) as initiator, and N,N′‐methylenebisacrylamide (MBA) as crosslinking agent. The PAA/EG/Zn(CF 3 SO 3 ) 2 (9 wt.%) hydrogel demonstrates excellent antifreezing and electrical conductivity, retaining conductivity after 24‐h freezing at −23°C. Concomitantly, this hydrogel demonstrates superb mechanical properties, exceptional fatigue tolerance, sustained moisture retention, autonomous self‐repair function, tissue adhesion efficacy, and tissue biocompatibility. At 500% tensile strain, the PAA/EG/Zn(CF 3 SO 3 ) 2 hydrogel (9 wt.%) exhibits a high gauge factor (GF = 6.82), negligible hysteresis, and ultrafast response/recovery times. When assembled into a wearable strain sensor, it can precisely monitor both large‐scale joint movements and subtle physiological motions such as frowning and swallowing. This antifreezing conductive hydrogel exhibits significant potential for flexible wearable electronics.