Flexible IDE-Based ZnO/MWCNT Composite Sensor for Real-Time Nitric Oxide Monitoring

In this paper, synthesis, characterization, and gas sensing application of interdigitated electrode (IDE)-based ZnO/f-MWCNT (Zinc oxide—functionalized Multiwall Carbon Nanotube) composite sensor is reported. Aluminum-based IDE structure is developed on flexible Teflon using a stainless steel mask. IDE developed using thermal evaporation method acts as a bottom contact for the sensor. ZnO/f-MWCNT composite is synthesized via wet chemical method, is further annealed at 400 °C for one hour, and is coated as thin film on the IDE structure using spin coating technique at 3000 rpm for 20 s. The thin film is studied for its microstructure using XRD and FTIR, surface morphology SEM, EDS and AFM, optical property using U-V absorbance. Hollow disk type structure of the composite is further studied for Nitric oxide (NO) gas sensing application. The fabricated flexible ZnO/f-MWCNT sensor showed a good sensitivity of 6.3 and a quick response and recovery time of 23 s and 30 s respectively towards 2.5 ppm of NO at an operating temperature of 150 °C when compared to as prepared ZnO sensor.