Mussel-Inspired Conductive Hydrogel with Self-Healing, Adhesive, and Antibacterial Properties for Wearable Monitoring

Hydrogels with multifunctional properties have attracted considerable interest owing to their wide range of applications in soft robotics, wearable device development, and tissue engineering. In this study, an adhesive, self-healing, and antibacterial conductive poly(dopamine methacrylate-co-methacrylatoethyl trimethyl ammonium chloride-co-acrylic acid) (PDDA) hydrogel was prepared by the free-radical copolymerization of dopamine methacrylate (DMA), methacrylatoethyl trimethyl ammonium chloride (DMC), and acrylic acid (AA). The adhesion property of the PDDA hydrogel was explored by regulating the feeding ratios of AA, DMA, and DMC. The hydrogel with a DMA/DMC/AA molar ratio of 1:4:40 exhibited strong adhesion to various materials such as iron, wood, rubber, glass, polytetrafluoroethylene, and plastic. Meanwhile, the hydrogel showed good antibacterial properties, which had a good inhibitory effect against Escherichia coli (37%) and Staphylococcus aureus (44%). In addition, because of its non-covalent bond interactions in the cross-linking network, the hydrogel exhibited excellent self-healing property when damaged. Moreover, the excellent ductility, biocompatibility, and adhesion property of the hydrogel allow better adhesion to the skin surface and conductivity to monitor the physiological activities of the human body by means of the electrical signals recorded using the transformation of strain responses. The self-healing, adhesive, antibacterial, biocompatible, and conductive hydrogel has a wide range of applications in electronic skin and wearable devices.