A self-healing and environmental stable fully physical crosslinked double-network ion hydrogel sensor

Conductive hydrogels with adjustable mechanical properties, good flexibility, and high sensitivity are considered to be promising and reliable materials for next-generation wearable devices. To enhance the mechanical properties of hydrogels, double-network (DN) strategy was always brought in hydrogel preparation. However, chemical crosslinks in DN hydrogel will lead to lack self-recovery properties and biocompatibility. Thus, we developed a fully physical crosslinked DN gel by a large quantities of metal chelation and hydrogen bonds by adding ions in mixture of gum arabic (GA) and copolymer polymerized by acrylamide (AM), acrylic acid (AA), and N-Methylolacrylamide (NMAM). This hydrogel (we named GPFE gel) exhibited excellent mechanical properties such as superb tensile strain (2340%), tensile strength (198 KPa), and high toughness (1.59 MJ/m³). Besides, benefiting from the large number of hydrogen bonds brought by the introduction of EG, GPFE gel also showed intriguing self-healing property (97.0% healing efficiency after 2 h), adhesive property (both in the air and underwater), and environmental stablity (could be used normally at –20 °C). Wearable flexible sensors prepared directly from GPFE gel can sensitively monitor both daily activities and slight physiological movements, exhibiting high sensitivity (GF = 2.16) and a wide strain detection window (to eleven times the original length). Therefore, the prepared GPFE gel as a high-performance wearable flexible sensor in this study shows tremendous potential applications in a complex environment.

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