PEDOT:PSS modified Screen Printed Graphene-Carbon Ink based Flexible Humidity Sensor

In this work, we present a screen-printed humidity sensor fabricated on a flexible polyvinyl chloride (PVC) substrate. A comparative analysis has been carried out for printed graphene-carbon electrode with and without Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) modification in the humidity sensing range of 25 - 90 %RH. The sensor modified with PEDOT:PSS demonstrated enhanced performance ( ~ 1 %/%RH versus ~ 0.8 %/%RH of unmodified sensor). Further, the enhancement in the performance of the modified sensor was found to be prominent in the low to moderate humidity range (≤60 %RH). The repeatability, response and recovery time were also analysed for both types of sensors and their applicability has been demonstrated for neonatal care by monitoring the humidity level of a wet baby diapers. This demonstration shows the potential application of presented humidity sensors in areas such as environmental monitoring, healthcare, industrial, and agriculture.