Ultra-stable and self-healing coordinated collagen-based multifunctional double-network organohydrogel e-skin for multimodal sensing monitoring of strain-resistance, bioelectrode, and self-powered triboelectric nanogenerator

Conductive hydrogels are considered as an ideal candidate for next-generation electronic skin due to their excellent softness and conductivity. In particular, the collagen-based conductive hydrogel prepared by using collagen derived from the extracellular matrix as the construction material is the bionic e-skin closest to human soft tissue. However, the current collagen-based conductive hydrogel sensors face three major challenges: the contradiction of mechanical stability and self-healing, lack of environmental adaptability and multifunctionality, single of data acquisition channel, which seriously limit their application as e-skin. Herein, a double network was constructed by forming multiple dynamic covalent cross-linking (e.g., collagen self-assembly, Schiff base, metal coordination, etc.) with collagen, oxidized hyaluronic acid, acrylic acid and Zr4+ ion as raw materials. Meanwhile, by ingeniously introducing ethylene glycol and silver nanoparticles, a collagen-based conductive organohydrogel with synchronous enhancement of mechanical property and self-healing was successfully prepared, which also possessed excellent environmental stability and multifunctional properties such as transparency, antibacterial activity, and biocompatibility. Interestingly, the organohydrogel could simultaneously integrate three monitoring means (including strain-resistance, bioelectrode, and triboelectric nanogenerator self-powered sensing) for multimodal monitoring of human biological signals, thus enhancing the reliability of the testing results. This work not only creates a new platform for the fabrication and design of collagen-based flexible bionic e-skin, but also opens up a novel path for monitoring and sensing of hydrogel, so as to prepare for the commercialization of e-skin.