NaCl-zwitterion enhanced chitosan-based hydrogels with super compressibility, conductivity, and stretchability as...

Conductive hydrogels, combining flexibility with electrical conductivity, are ideal for flexible strain/pressure sensors, yet integrating high toughness, sensitivity, and conductivity remains challenging. This study fabricates a multifunctional hydrogel using methacrylated chitosan (CSMA) and acrylamide (AM) as the matrix, innovatively incorporating anhydrous betaine (Bet) and sodium chloride (NaCl). Bet remarkably enhances the compressive strength and mechanical properties, while dissociated NaCl provides abundant free ions, significantly boosting ionic conductivity. The resulting hydrogel demonstrates outstanding overall performance: a toughness of 6.99 MJ/m³ an ionic conductivity of 5.56 S/m, a compressive stress of 6.68 MPa at 90% strain, and a high self-healing efficiency of 96.6% within 16 h. Based on this hydrogel, the fabricated strain and pressure sensors exhibit high sensitivity (gauge factor GF = 3.18 within 250%-500%; pressure sensitivity S₁ = 0.642 kPa^-1 within 0-50 kPa), enabling effective monitoring of diverse human motions. Furthermore, this work successfully extends the application of the hydrogel sensor to information transmission and handwritten character recognition, offering a novel strategy for designing high-performance flexible sensors.