Mechanically Robust, Self-Healable, and Cryotolerant GelMA Hydrogel for Wearable Tactile Sensors with Enhanced Durability, Lifetime, and Environmental Stability.

Gelatin methacryloyl (GelMA) hydrogels are promising for wearable tactile sensors due to their biocompatibility, tissue-mimic softness and conductivity, yet restricted by mechanical property, structure damage, dehydration, and freezing during usage. Herein, a mechanically robust, self-healable, moisturizing, cryotolerant and adhesive GelMA hydrogel is developed by incorporating polyvinyl alcohol, acrylic acid, sodium tetraborate, and glycerol into GelMA matrix via a photoinitiated polymerization process. This unique approach overcomes the chemical-mechanical conflictions among different molecules, and contributes to remarkable stretchability (≥220%, 5.5-fold higher), elasticity (≈91.9% recovery), autonomous self-healing within wide temperature range (from -40°C to 25°C), adhesion (≥23.5 kPa), moisture retention (≥81% after 10 d) and anti-freezing (-55.4°C) properties, significantly outperforming previous GelMA. Based on this, an omni-healable ionotronic pressure sensor is constructed, featuring high sensitivity within broad pressure range (0-25 kPa), rapid recovery time, long-term stability (≈120 h), excellent durability and performance self-repairing (≈100% sensing range recovery) under subzero temperature. Sensitively and consistently monitoring of various physiological signals under harsh conditions, such as multiple structure damages, long period (≥5 d) and subzero temperatures (≤-38.2°C) highlights its prominent durability, lifetime and environmental-stability, demonstrating great promise toward practical application.