Self-repairable and recyclable self-powered human motion sensor with NIR/pH-responsive amplified Stretchable, Conductive, and Self-Healable hydrogel

A self-repairable and reusable self-powered electronic skin sensor is developed from NIR/pH-responsive polymer dot (PD) embedded hydrogel with amplified mechanical and electrochemical properties after self-healing. The pH/NIR-controlled mechanical, electrochemical and self-healing performance of the designed hydrogel is achieved by manipulating the hydrogen bond formation with tunable mobility from the PD components. The hydrogel formed at pH 7.4, after treatment with pH 10 and NIR-driven healing, the mechanical stretchability (585%), conductivity (6.8 mS cm−1), capacitance (184.2 mF cm−2), and gauge factor (1.09) was increased by 125%, 4.9 times, 37%, and 72%, respectively. Further, the hydrogel system was explored as a reusable physiological strain sensor which showed excellent strain sensitivity of 0.36 kPa−1 with remarkable repeatability of 12,000 stretching-bending operations over two cutting-healing cycles. The real-time pH/NIR-dependent amplified sensing performance is effectively monitored remotely by using a wireless connection via a smartphone. Additionally, the hydrogel-based supercapacitor was attached with a solar cell for a self-powered body sensor that works seamlessly under sunlight. The integrated system obtains enhanced energy storage upon healing, reaching an overall power conversion efficiency of 2.32%. The NIR/pH-driven durability, the reproducible amplified mechanical and electrical performance of the self-powered electronic skin can be efficiently used for detecting movements ranging from a subtle human wrist pulse to rough finger motions presenting their potential application in wearable human-health monitoring systems.