High-Toughness and Antibacterial Hydrogels via Gelatin and Zr4+ Synergy for Flexible Motion-Monitoring Sensors

Flexible sensors are essential for human–machine interaction and wearable health monitoring in electronics, healthcare, and robotics. However, traditional conductive hydrogels have poor mechanical strength and are susceptibility to microbial infection, limiting their practical application. Herein, a double-network ion-conductive hydrogel (PMAGZr) is fabricated from polyacrylamide (AM), acrylic acid (AA), gelatin, and zirconium oxychloride (ZrOCl2), serving as both a cross-linker and a functional additive. The hydrogel forms a rigid-flexible network, where AM and AA provide rigidity, gelatin enhances toughness and strength via hydrogen bonding, and Zr4+ improves stability through coordination with carboxyl and acylamino groups. The PMAGZr hydrogel exhibits both excellent mechanical properties (with a toughness of 6.11 MJ·m–3 and a fracture elongation of 720.18%) and significant antibacterial activity, showing inhibition zones of 24.70 mm against Escherichia coli and 43.33 mm against Staphylococcus aureus. The hydrogel-based flexible sensor exhibits rapid response (0.6 s), high sensitivity (GF = 4.03), and a wide strain detection range (0%–300%), enabling accurate human motion monitoring, Morse code visualization, and sustained antibacterial function. This research overcomes the big challenge of balancing mechanical toughness and functional versatility in hydrogels. The material enables precise monitoring of human movement and Morse code communication outdoors while ensuring wearer comfort and safety. It overcomes the main defects of conventional hydrogel sensors, providing an alternative solution for next-generation wearables.