Design, Fabrication, and Wearable Medical Application of a High‐Resolution Flexible Capacitive Temperature Sensor Based on the Thermotropic Phase Transition Composites of PEO/PVDF‐HFP/H₃PO₄

Abstract Phase transition materials have the potential to be utilized as high‐resolution temperature‐sensitive materials. However, it is a challenge to develop them into temperature sensors with good stability and repeatability. In this work, inspired by phase transition theory and the electrical double‐layer capacitance principle, a novel high‐resolution flexible capacitive temperature sensor based on Polyethylene oxide(PEO)/Poly(vinylidene fluoride‐co‐hexafluoropropylene)/H 3 PO 4 is proposed for the first time. By blending high and low molecular weight PEO and adding ionic solution, the proposed sensor exhibits high resolution (0.05 °C) and response speed (<12 s) within 35–43 °C. The novel introduction of a mesh structure aids the material in achieving microdomain control of PEO crystallization and improves the repeatability ( E x < 2.2%) of the sensor. The sensor is used for monitoring human body temperature and diabetic foot ulcers, and the results show that the sensor can achieve continuous and comfortable body temperature monitoring and early‐stage diabetic foot ulcer diagnosis, offering broad applications in health monitoring and rehabilitation medicine.