Quartz crystal microbalance coated with PEDOT–PSS/PVA nanofiber for a high-performance humidity sensor

Quartz crystal microbalance (QCM) coated with poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate mixed with polyvinyl alcohol (PEDOT–PSS/PVA) nanofiber has been fabricated as a humidity sensor using the electrospinning method. Three types of PEDOT–PSS/PVA nanofiber sensors are fabricated with different needle-to-collector electrospinning distances. The scanning electron microscope images confirm the presence of beads in the nanofiber structure. The results show that the sensor mass deposition increased with the decrease in needle-to-collector distance. The best sensor performance is exhibited by the sample with medium needle-to-collector distance (QCM NF 2). The QCM NF 2 nanofiber sensor shows excellent sensitivity of up to 33.56 Hz per percentage point of relative humidity, with rapid response (5.6 s) and recovery (3.5 s) times, good linearity, excellent repeatability, low hysteresis, and long-term stability and response. The QCM PEDOT–PSS/PVA nanofiber sensor provides a simple method to fabricate high-performance humidity sensors.