Highly stretchable and rehealable wearable strain sensor based on dynamic covalent thermoset and liquid metal

Abstract Cutting-edge technologies of wearable electronics have recently attracted tremendous attention. One of the key issues lies in the choice of compliant and environmental-friendly materials and cost-effective fabrication methods. We here report a rehealable and highly stretchable wearable strain sensing system enabled by advanced materials. By embedding patterned liquid metal (LM) line traces into dynamic covalent thermoset polyimine through a low-cost fabrication method, a mechanically flexible and electrically sensitive strain sensor is obtained. We proposed an analytical model based on length fractions of the strain sensor to describe the resistance change under applied strain. The results show good agreement with finite element simulation and experiment. Because of the bond exchange reactions in polyimine and the flowability of LM, the sensing system has excellent rehealability when it is damaged. These superior properties make the strain sensor quantitatively precise, economically friendly and environmentally sustainable, and thus can find wide applications in various areas.