Highly sensitive flexible thermoplastic polyurethane/graphene composite temperature sensor with linear PTC effect

Conductive polymer composites (CPC) usually have a non-monotonic dependence on temperature. Therefore, the preparation of CPC flexible temperature sensors with linear temperature coefficient remains a challenge. A thermoplastic polyurethane/graphene (TPU/GNs) temperature sensing composite temperature sensor was successfully prepared using solution blending combined with microelectronic printing technology. The sensor is characterized by high sensitivity (Temperature coefficient of resistance (TCR)=2.20%/℃), fast time response (5 s), high linearity (Fit degree (R²)=0.99) over the temperature sensing range of 25—55℃, and good flexibility, bending resistance (the performance is almost unchanged after 500 times of bending), and resistance to perspiration interference (the resistance remains stable after 30 min of immersion). In addition, a temperature readout circuit is designed in anticipation of its wireless transmission of temperature data via Bluetooth and WiFi, which enables real-time temperature monitoring and display on the cell phone to be provided to the user, healthcare professionals, etc. Thus, the TPU/GNs flexible temperature sensor with high sensitivity, comfort, real-time performance and durability will significantly improve the practical application of wearable temperature sensors in smart healthcare.