PEDOT:PSS-Coated Screen-Printed Graphene–Carbon Ink-Based Humidity and Temperature Sensor

Abstract

This work presents a multifunctional humidity and temperature sensor, fabricated on a flexible polyvinyl chloride (PVC) substrate using a facile screen-printing and drop casting. The sensor comprises of screen-printed graphene-carbon (G-C) layer coated with Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The sensor displays good sensing performance (~1%/%RH) towards wide humidity range (25 %RH - 90 %RH) at room temperature (RT; 27 °C ± 2 °C). The influence of operating temperature on humidity sensing performance is examined in the temperature range of 15 - 55 °C and a nearly linear relation (with Adj. R 2 of value 0.959) is observed towards change in temperature (35 to 55 °C). Further, temperature sensing performance of the sensor is analysed in 15 - 35 °C temperature range. The sensor displays good performance with temperature coefficient of resistance as -3.18 % °C -1 and -1.3 % °C -1 for 15-25 °C and 25-35 °C, respectively. Other important sensing characteristics like repeatability, hysteresis, response, and recovery times are also analysed and presented here.