A fiber-shaped temperature sensor composed of chitosan/rGO with high sensitivity and ultra-fast response and recovery for real-time temperature monitoring

Wearable sensors are the development trend in the future iteration of medical devices, in which, flexible tem-perature sensors with high resolution, fast response speed, and good reliability under deformations, are one of the much important devices. In this study, a nano multilayer sensing structured fiber temperature sensor is fabricated via in situ coating reduced graphene oxide (rGO) and chitosan (CS) on the surface of stretchable polyurethane fiber (PF) by a layer-by-layer self-assembly method. The introduction of CS not only enhances the temperature sensitivity (with a temperature coefficient of -1.379 %.degrees C-1 in the range of 30-60 degrees C) of the rGO-based fiber sensors but also greatly increases the mechanical stability of the nanofibrous membrane. Most importantly, the fiber-shaped temperature sensor shows a fast response time (2.4 s) and recovery time (3.9 s) to temperature. Moreover, the sensor achieves a high temperature resolution of 0.1 degrees C. Made from a simple and low-cost process, the fiber-like devices can be easily integrated into items such as gloves or face masks to monitor the real-time temperature changes. The results demonstrate the great potential of rGO-based fiber sensors for applications in human healthcare monitoring.