Facile Fabrication of Graphene Oxide-based Flexible Temperature Sensor and Improving its Humidity Stability

Abstract

Graphene derivatives and their composites have attracted significant research interest for the development of novel sensors. Optimizing the formulation of graphene-based composites plays a significant role in developing sensors with improved features, such as high sensitivity and humidity stability. In this work, graphene oxide (GO)-based temperature sensors with high sensitivity were developed on a flexible substrate, using a facile fabrication method, and the humidity stability of the sensors was improved by ~58% while maintaining a high sensitivity towards the temperature. GO ink was used as the sensing layer of one temperature sensor (TS1), and a composite of GO and poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) was used as the sensing layer of another temperature sensor (TS2). The resistive responses of sensors towards varying temperatures ranging from 10 °C to 80 °C were investigated. The temperature sensors showed linear responses, with slopes of -0.98 and -0.69, and correlation coefficients of 0.9994 and 0.998 for TS1 and TS2 temperature sensors, respectively. The temperature coefficient of resistance (TCR) of temperature sensors were calculated as -1.00 and -0.68 %/°C for TS1 and TS2 sensors, respectively. The sensitivity of temperature sensors towards humidity was calculated as 0.107 and 0.045 %/%RH for TS1 and TS2 temperature sensors, respectively. It was observed that adding PEDOT:PSS to GO improves the humidity stability of the temperature sensors by ~58% while maintaining a high TCR.