Wearable Supercapacitive Temperature Sensors with High Accuracy Based on Ionically Conductive Organogel and Macro-Kirigami Electrode

Abstract

Wearable temperature sensors with high accuracy are critical for human health monitoring. Ideally, they should show accuracy matching that of medical-grade thermometers (i.e., ± ≈0.1–0.2 °C). Achieving this goal has proven challenging for sensors that must also meet key wearable requirements, such as flexibility, stretchability, and breathability. Herein, a new stretchable supercapacitive temperature sensor with a resolution of ±0.2 °C, is presented, which was achieved by. Two new strategies to increase temperature sensitivity and minimize the interferences of mechanical stretching and pressure: a) synthesizing an ion-conductive NaCl-organogel to serve as the redox-active separator to increase sensitivity and suppress interference of compression; and b) using a kirigami design to decrease the interference of stretch and improve breathability. These two novel strategies endow the supercapacitive temperature sensors with a temperature accuracy of ±0.2 °C and exceptionally high sensitivity of 0.095 °C−1, which is more than 13 times higher than traditional dielectric-capacitive sensors. The potential of the supercapacitive sensor in measuring body temperature is demonstrated by continuously monitoring skin temperatures under a medical compression garment that exerts pressure on the skin and the unsteady wrist flexion. The findings confirm that the organogel-based supercapacitive sensors offer an extraordinary temperature accuracy significantly better than wearable sensors reported in the literature. The combined characteristics of high resolution, linearity, breathability, and stretchability make this sensor a promising candidate for skin-interfaced health monitoring devices.