Preparation of ion-conductive hydrogels with chemically crosslinked networks for flexible wearable sensors

Conductive hydrogels have a wide range of applications in cutting-edge fields such as flexible wearable sensors and smart electronic devices. However, traditional conductive hydrogels generally possess inferior mechanical properties, insufficient fracture resistance, and poor electrical conductivity. Complex and changeable application scenarios impose higher requirements on the comprehensive performance of hydrogels, including conductivity, mechanical properties, and sensitivity. To solve the above-mentioned problems, in this work, ion-conductive hydrogels with chemically crosslinked networks of potassium polyacrylate/zinc trifluoromethanesulfonate (PAAK/Zn(CF3SO3)2) conductive hydrogels were prepared by free-radical polymerization. Potassium polyacrylate (PAAK) was used as the matrix, zinc trifluoromethanesulfonate (Zn(CF3SO3)2) as the conductive filler, N, N’-methylenebisacrylamide (MBA) as the cross-linking agent, and ammonium persulfate (APS) as the initiator. The incorporation of Zn(CF3SO3)2 endows the hydrogel with excellent conductivity and significantly enhances its mechanical strength. At a Zn(CF3SO3)2 concentration of 4.5 wt.%, the PAAK/Zn(CF3SO3)2 conductive hydrogel exhibits outstanding mechanical properties, electrical conductivity, fatigue resistance, adhesion properties, swelling capacity, water retention capability, self-healing properties, and sensitivity. These superior characteristics make it suitable for stable monitoring of subtle human movements such as finger flexion in wearable sensors, demonstrating the significant potential applications in the field of flexible electronics.