Highly sensitive and wearable self-powered sensors based on a stretchable hydrogel comprising dynamic hydrogen bond and dual coordination bonds

Abstract Most of the reported hydrogel-based strain sensors need an external power supply to translate mechanical deformations into detectable electrical signals. Herein, we prepare a gelatin-graphene oxide-ferric ion cross-linked poly(acrylic acid) (Gel-GO-PAA-Fe3+) hydrogel for constructing a self-powered strain sensor. The hydrogel exhibit favorable self-healing, stretchable and resilient properties due to the formation of dynamic hydrogen bond and dual coordination bond within the gel matrix. With a constant elongation of 400% and high conductivity of 0.50 S/m, the hydrogel-based sensor can monitor various human movements. Interestingly, the hydrogel electrolyte integrating zinc anode and MnO2/graphite air cathode are developed into a flexible zinc-air battery, and then connected to a fixed resistor to achieve the self-powered strain sensor. By transforming the resistance variations caused by applied strain into voltage output signals, the integrated system could monitor human activities in a wide range without external power, demonstrating its huge practical application in wearable electronics for sensing.