PVA-Based Organohydrogel Strain Sensors with Balanced Comprehensive Properties Coreinforced by Polyzwitterions and Tannic Acid

Conductive hydrogels have attracted much attention because of their flexibility and electrical performance, showing great potential in fabricating high-performance strain sensors. However, conventional hydrogel-based sensors frequently exhibit freezing-induced brittleness and lose electrical conductivity at subzero temperatures, both of which restrict their practical applications. To address these limitations, this study fabricates a polyzwitterion–tannic acid (TA) coreinforced poly(vinyl alcohol) (PVA) organohydrogel via a novel photoinitiated polymerization–freezing/thawing–drying–rehydration strategy in a binary solvent of glycerol–water containing CaCl₂. The innovation lies in three synergistic mechanisms: the polyzwitterion–glycerol–CaCl₂ ternary antifreezing system depresses the freezing point by disrupting ice crystallization; TA contributes to coordination with Ca²⁺ and multihydrogen bonds for the effective energy dissipation network; PVA crystalline regions function as physical cross-linking points to enhance mechanical properties. The optimized PVA-6Ca-2G-3W organohydrogel achieves eminent electrical conductivity (12.1 mS/cm at 25 °C vs 8.63 mS/cm at −18 °C) and strain sensitivity (gauge factor, GF = 2.29) with exceptional linearity (R² = 0.997). Crucially, it exhibits favorable mechanical properties (a toughness of 3.08 MJ/m³, a tensile strength of 2.44 MPa, and an elongation at break of 269%) and a desirable antifreezing property with a freezing point at −41.3 °C. It shows great potential in the field of monitoring human motions and human–machine interaction.