The FGC/CNTs-Based High-Sensitivity Temperature Sensor With Fast Response Time and Negative Temperature Coefficient

Abstract

Temperature sensors play an essential and important role in the vigorous development of biomedical, smart home, and e-skin fields. It is meaningful to investigate a low-cost flexible temperature sensor that exhibits excellent performance. The introduction of flexible 3-D cloths can better fit home devices and bring the possibility of more application scenarios for temperature sensors. In this work, a sandwich structured sensor consisting of a polyimide (PI) film as a flexible substrate and encapsulation layer, and a fiberglass cloth modified with carbon nanotubes (FGC/CNTs) as a temperature sensitive layer exhibiting a negative temperature coefficient (NTC) is proposed. Results show that the flexible temperature sensor based on FGC/CNTs obtained a high sensitivity of −0.8122% ${}^{\circ }\text {C}^{-{1}}$ with excellent stability, fast response time (1.17 s), and a wide temperature sensing range ( $16~^{\circ }$ C– $95~^{\circ }$ C), due to the porosity, high temperature resistance, and corrosion resistance of fiberglass cloth. As a flexible device, it can be installed on a variety of daily necessities such as water cups, masks, and garbage bins for temperature monitoring. For example, the integration of temperature sensors into masks allows real-time and accurate detection of the experimenter’s breathing for identifying health conditions, demonstrating high potential applications in health monitoring. It can also be integrated into the bottom of the garbage bin and combined with a circuit board application to sense real-time temperature changes inside the garbage bin. When an abnormal temperature is detected, a fire alarm can be issued in a timely manner, providing a promising avenue for the subsequent development of wearable flexible temperature sensors for applications in human health.