Self-powered integrated system of a strain sensor and flexible all-solid-state supercapacitor by using a high performance ionic organohydrogel

Abstract

The rapid development of human–machine interface technologies is dependent on flexible and wearable soft devices such as sensors and energy storage systems. One of the key factors for these devices is the hydrogel electrolyte. In this work, firstly we constructed an anti-freezing, self-healing, adhesive and tough conductive double network ionic organohydrogel by simultaneously introducing NaCl and glycerol (Gly) into poly(vinyl alcohol)/poly(acrylic amide-acrylic acid) (PVA/PAMAA). Then, based on this organohydrogel, a strain sensor and a flexible all-solid-state supercapacitor were assembled separately and their properties were measured. The fabricated strain sensor showed a highly sensitive response (gauge factor = 8.303) in a broad strain range (from 500 to 1000%), enabling the accurate and reliable detection of various mechanical deformations. Meanwhile, the flexible all-solid-state supercapacitor demonstrated a specific capacitance of 75.75 mF cm⁻², high cycling stability (90.2% retention rate after 5000 cycles) and excellent mechanical stability. Lastly, a self-powered integrated system composed of the strain sensor and flexible all-solid-state supercapacitor was fabricated. The sensor can be driven by the supercapacitor and operate stably in a wide strain range sensing test with low power consumption. More importantly, the self-powered integrated system could be directly attached to the human body to detect human motions, showing its great potential application in wearable devices. This work would enlarge the research and application of high-performance ionic hydrogel electrolytes.