Ultra-tough dual-network conductive hydrogel with UV-blocking, antibacterial properties and freeze resistance for wearable strain sensor.

Flexible electronic sensors hold great promise in the fields of wearable health monitoring and human-computer interaction. However, existing hydrogel systems generally suffer from insufficient mechanical strength and limited multifunctional integration. To address these bottlenecks, a self-assembly strategy was employed to fabricate a supramolecular ionic hydrogel based on lignosulfonate (SL) and polyvinyl alcohol (PVA), exploiting the coordination interactions of Zn2+ to construct a PVA/SL/ZnCl2 hydrogel sensor. Owing to the dual network structure of PVA/SL and Zn2+/SL within the supramolecular system, the hydrogel exhibits exceptional mechanical toughness, ensuring reliable and repeatable electrical signal generation across a wide strain range. Specifically, the optimized PVA/SL/ZnCl2 hydrogel exhibits a high tensile strength of 19.8 MPa, a fracture strain of 892%, and excellent toughness of 7.93 MJ/m3, while also demonstrating exceptional freeze resistance down to -38.97 °C, UV-blocking efficiency, broad-spectrum antibacterial activity, and good ionic conductivity (0.83 S/m). As a strain sensor, it demonstrates high sensitivity (Gauge Factor = 0.83), a rapid response time of 252 ms, and excellent long-term durability, enabling precise detection of both large-amplitude joint movements and subtle physiological signals under both ambient and low-temperature conditions. Furthermore, this sensing system was extended to Morse code-encrypted communication and wireless alarm systems for emergency applications in cold outdoor environments. Overall, this work pioneers a new path for the development of next-generation smart sensors. Its outstanding comprehensive performance significantly enhances the application potential of biomass hydrogels in human-machine interaction, smart healthcare, and frigid environment monitoring, offering significant engineering value and socioeconomic benefits.