Preparation and Sensing Application of Polyacrylamide/Polyvinyl Alcohol-Based Conductive Hydrogels

A dual-network hydrogel was prepared by copolymerization and freeze-thaw cycles using acrylamide (AM), sulfobetaine methacrylate (SBMA), and polyvinyl alcohol (PVA). The hydrogel was immersed in an inorganic salt solution (glycerol/water) containing sodium citrate (Na₃Cit) to form the P(AM-co-SBMA)/PVA-Cit ionically conductive hydrogel. The composition and structure of the hydrogel were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. Mechanical properties and adhesion performance were tested using a universal testing machine, and the strain-sensing capability was evaluated by simultaneous electrical resistance measurement during tensile stretching. The hydrogel exhibits excellent mechanical properties, adhesive properties, water retention, and conductivity. Its maximum elongation and ionic conductivity reach 940% and 1.83 S/m, respectively, with a tensile strength of 1.75 MPa and an adhesion strength of 27 kPa. As a flexible strain sensor, the hydrogel demonstrates excellent tensile strain sensitivity (gauge factor (GF): 3.021), rapid response, and stable electrical signal output.