Self-healing conductive composite hydrogel for human motion and 3D cell culture monitoring

Conductive hydrogels have emerged as versatile materials with promising applications in various fields, as they possess the ability to convert external forces and deformations into electrical signals, enabling them to sense physical and chemical stimuli. However, the development of conductive hydrogels faces a challenge in balancing conductivity and mechanical strength demands. We incorporated lignin-tannic acid (lignin-TA) particles as physical crosslinkers to enhance their mechanical properties. Additionally, the multi-hydroxyl structure of hydroxypropyl cellulose molecules facilitated the formation of a semi-interpenetrating polymer network through hydrogen bond interactions. Furthermore, the bond strength between the lignin-TA-polyacrylamide networks was intensified, resulting in an elevation of their conductivity. This enhancement was achieved by harnessing the electrostatic forces and metal coordination interactions between Fe3+ ions and TA molecules. The resulting hydrogel exhibited outstanding mechanical characteristics due to its unique network structure, combining physical and chemical bonds. Taking advantage of the hydrogel's unique network structure, we successfully utilized its self-adhesion, self-healing capabilities, electromechanical properties, and biocompatibility to monitor human activities and cell proliferation.