A Highly Stable and Durable Capacitive Strain Sensor Based on Dynamically Super-Tough Hydro/Organo-Gels

Abstract

Capacitive-type strain sensors based on hydrogel ionic conductors have undergone rapid development benefited from their robust structure, drift-free sensing, higher sensitivity, and precision. However, the unsatisfactory electro-mechanical stability of the conventional hydrogel conductors, which are normally vulnerable to large deformation and severe mechanical impacts, remains a challenge. In addition, there is not enough research regarding the adhesiveness and mechanical properties of the dielectric layer, which is also critical for the mechanical adaptability of the whole device. Here, a dynamically super-tough capacitive-type strain sensor based on energy-dissipative dual-crosslinked hydrogel conductors and an organogel dielectric with high adhesive strength is developed. Combining with the mechanical advantages of the hydro/organo-gels, the capacitive strain sensor exhibits high stretchability and superior linear dependence of sensitivity with a gauge factor of ≈0.8% at 100% strain. Moreover, the sensor displayed ultrastability against various severe mechanical stimuli that can even survive unprecedentedly from extremely catastrophic car run-over by 20 times. With these synergistic mechanical advantages, the capacitive strain sensor is successfully applied as a highly-reliable wearable sensing system to monitor diverse faint physiological signals and large-range human motions.