Electrospray printing of graphene layers for chemiresistive gas sensors

In this work we investigate the electrospray technique for the preparation of graphene layers for use in chemiresistive gas sensors. A dispersion of reduced graphene oxide (rGO) in isopropanol (0.1 mg/mL) is electrosprayed and the rGO flakes are deposited onto a polymeric substrate with printed interdigitated electrodes. The surface area of the substrate covered with rGO is mainly determined by the distance between the needle and the substrate, while the rGO deposition pattern strongly depends on the flowrate and the applied voltage. Homogeneous layers of rGO are obtained in stable cone-jet regime, and the room temperature detection behavior of the sensors towards NO₂, O₃ and CO is assessed. The sensors were not capable of detecting CO (up to 5 ppm), but they detected 0.2 ppm NO2 and 0.05 ppm O₃. The results are encouraging regarding the use of electrospray for production of low-cost and low-power consumption gas sensors based on graphene for air quality applications.