Transient Flexible Multimodal Sensors Based on Degradable Fibrous Nanocomposite Mats for Monitoring Strain, Temperature, and Humidity

Flexible sensors have been extensively investigated because of their potential applications in various wearable devices, but the fabrication of transient multifunctional flexible sensors with high performances and low environmental impact remains a challenge. In this work, transient flexible multimodal sensors are fabricated utilizing degradable silver nanowires (AgNWs)-decorated fibrous mats as the signal-converting materials. The fibrous mats are prepared by an electrospinning process from citrate-based polyester elastomer (POC-PEG) and poly(butylene terephthalate) (PBT). Because of the elasticity of fibrous PBT/POC-PEG mats and conductive network composed of AgNWs, AgNWs/PBT/POC-PEG mats are promising materials for multimodal flexible sensors. A high gauge factor (GF) of 155.3, a low response time of 142 ms, and high stability (>1500 cycles) have been achieved when strains are applied to such flexible sensors. More interestingly, such flexible sensors also efficiently respond to variations in temperature in the temperature range of 20–100 °C with a TCR of 0.2% °C–1 and humidity in the relative humidity range of 15–90% with a GF of 0.12. Due to their high performances and multiple response ability, such flexible sensors have the potential to monitor a variety of human motions and physiological activities, such as bending of joints, breathing, and others. Due to the intrinsic chemical structure, AgNWs/PBT/POC-PEG mats exhibit excellent degradability and can be used in transient flexible sensors with low environmental impact. Overall, this work has developed promising green materials for transient multimodal sensors and future electronic devices.