Freeze-resistant and conductive self-healing carbonized lignin-based hydrogels for human motion monitoring

Conductive self-healing hydrogels have dual properties of self-healing and conductivity, and have become a research hotspot in recent years as a new member of the smart material family. However, it is still a great challenge to prepare hydrogels with excellent performance through simple synthesis steps and low-cost raw materials. Most current hydrogels have problems such as low mechanical strength and poor tensile properties, making it difficult to meet the needs of practical applications in wearable devices. Here, a conductive self-healing hydrogel PVA-B(OH)₃-CL-Gly₂ was prepared simply and quickly based on the dynamic borate ester bond formed by the reaction of boric acid and polyvinyl alcohol. PVA-B(OH)₃-CL-Gly₂ has various properties such as self-healing capabilities, excellent physical and mechanical properties (maximum breaking strain of 310 %, maximum tensile strength of 251 kPa), conductivity (conductivity of 0.37 S/m), and anti-freeze properties. As a sensor, PVA-B(OH)₃-CL-Gly₂ can be utilized for motion monitoring and exhibits good specificity in recognizing both large and subtle movements of the human body. In summary, the prepared PVA-B(OH)₃-CL-Gly₂ hydrogel effectively addresses the limitations of traditional conductive hydrogels, which are often confined to a single application environment and have few application scenarios. This hydrogel demonstrates significant potential for multifunctional applications in fields such as artificial intelligence, sports management, soft robotics, and human-machine interfaces.