Multi-physics coupling reinforced polyvinyl alcohol/cellulose nanofibrils based multifunctional hydrogel sensor for human motion monitoring

Ionic conductive hydrogels have been widely used for sensor, energy storage and human-machine interface. To address the problems of the traditional ionic conductive hydrogels fabricated with the soaking method, such as the lack of frost resistance, poor mechanical properties, time-consuming and chemical-wasting, herein, a multi-physics crosslinking reinforced strong, anti-freezing and ionic conductive hydrogel sensor is fabricated utilizing the tannin acid-Fe2(SO4)3 through the simple one-pot freezing-thawing process at low electrolyte concentration. The results show that the P10C0.4T8-Fe2(SO4)3 (PVA10%CNF0.4%TA8%-Fe2(SO4)3) displayed better mechanical property and ionic conductivity due to hydrogen bonding and coordination interaction. The tensile stress reaches up to 0.980 MPa (570 % strain). Moreover, the hydrogel presents excellent ionic conductivity (0.220 S⋅m−1 at room temperature), anti-freezing performance (0.183 S⋅m−1 at −18 °C), large gauge factor (1.75), excellent sensing stability, repeatability, durability and reliability. This work paves a way for preparing mechanical strong and anti-freezing hydrogel based on multi-physics crosslinking with one-pot freezing-thawing process.