Highly Stretchable, Self‐Healable, and Conductive Gelatin Methacryloyl Hydrogel for Long‐Lasting Wearable Tactile Sensors

Abstract Constructing hydrogels with both remarkable mechanical and self‐healing properties is highly desirable for soft electronics, yet remains challenging due to conflicting demands on chemical bonds and polymer chain mobility. Herein, a highly stretchable, self‐healing, and conductive gelatin methacryloyl (GelMA) hydrogel is developed by incorporating polyvinyl alcohol, N‐(2‐amino‐2‐oxoethyl)‐2‐propenamide, sodium tetraborate, and sodium chloride into GelMA, followed by a two‐step polymerization process. The introduced novel interpenetrating networks, hierarchical hydrogen bonds (weak and strong H‐bonds), and borate ester bonds (BEBs) synergistically improve the mechanical strength, and concurrently function as sacrificial bonds for energy dissipation under deformation. Moreover, the constructed reversible BEBs and weak H‐bonds enable autonomous self‐healing at room temperature. The resulting hydrogel achieves remarkable stretchability (≈160%), tensile strength (≈130 kPa), and self‐healing efficiency (86%), surpassing previously reported GelMA hydrogels. Importantly, a self‐healing GelMA hydrogel strain sensor is demonstrated, featuring a high gauge factor (≈3.28), ultra‐low detection limit (0.1%), and excellent recovery of sensitivity (≈100%) and detection range (≈75%) after damage. Successful monitoring of subtle and large‐scale human motions with both original and healed sensors highlights the device's durability and longevity. This study provides a promising approach for the rational design and practical application of GelMA hydrogels in wearable bioelectronics.