Highly robust, self-adhesive, self-healing, pH-responsive, cytocompatible and degradable collagen/PVA/tannin-based conductive hydrogel sensor for motion-monitoring

It is the era of technological progress, contributing to the booming development in personalized smart wearable devices. As a representative of smart devices, flexible sensor devices are popular in many fields including electronic skin, tissue engineering, and soft robotics. Among them, hydrogel with high water-containing and stable structures is one of the most promising candidates for flexible sensor devices, attracting the attention of researchers. However, the topics of environmental protection and energy conservation are also currently unavoidable, so friendly materials and preparation strategies for the hydrogel are required for relieving the pressure on energy and the environment. In this work, the collagen-based multi-functional conductive hydrogel (PBTC) based on natural biomass materials, eco-friendly polyvinyl alcohol (PVA), and "one pot" strategy had been prepared rationally for balancing the issues in the environment, energy, and multi-functional sensing hydrogel. The mechanical property, adhesive property, self-healing property, conductive property, degradability, and cytocompatibility of PBTC were tested in detail and confirmed. In particular, the excellent extensibility (strain over 1500 %), rapid self-healing efficiency (over 90 % within 90 s), stable and repeatable conductivity (fatigue testing for 1000 s and GF (gauge factor) of 2.66), and high cell viability (over 95 %) of PBTC are further proved, which is favorable for its applications of human motion monitoring. Overall, this work provides further inspiration and understanding of the natural biomass materials for applications, as well as new ideas and methods for developing more efficient, reliable, multi-functional, and sustainable flexible sensing devices.