Dynamic network hydrogel with cryogenic mechanical reinforcement, self-healing for motion sensing

This study reports a frost-resilient nanocomposite hydrogel engineered for flexible electronics operating under cryogenic conditions. The hydrogel integrates a polyvinyl alcohol–guar gum (PVA-GG) dual-network matrix with cellulose nanocrystals (CNCs) grafted with glycosylated borate ammonium phytate (GBAP) and L-proline (L-Pro), forming hierarchical hybrid reinforcements through molecular interface engineering. Phytic acid (PA) enables multivalent coordination crosslinking, while L-Pro provides cryoprotection and maintains ductility at low temperatures. The resulting hydrogel exhibits excellent stability at −20 °C, including a tensile modulus of 2.11 MPa and 92.94 % self-healing efficiency. As a flexible sensor, it delivers a gauge factor of 2.72 and a rapid response time of 270 ms at −20 °C, enabling reliable monitoring of human motion. This work presents a scalable strategy for designing hydrogels with synergistic mechanical, self-healing, and anti-freezing capabilities, advancing flexible electronics for extreme-environment, wearable, and biomedical applications.