Humidity Sensor Based on Orange Dye and Graphene Solid Electrolyte Cells

The fabrication and characterization of thin film humidity sensors based on orange dye (OD) and OD–graphene solid electrolytes cells were done in this paper. The 200 nm thick silver (Ag) and copper (Cu) electrodes were deposited on glass substrate by thermal evaporation. There was gap of 20 µm between the electrodes, where the 8 to 12 µm thick film of solid electrolyte was deposited. The pure OD and the OD–graphene composites with 40 and 60% (by weight) graphene were used as solid electrolytes. The dependences of the open-circuit voltage of the cells on humidity were measured in the humidity interval from 34 to 90% relative humidity (RH). It was found that with increase in humidity the open-circuit voltage of the cells increased. In the OD–graphene composite cells on increasing the concentration of graphene the open-circuit voltage increased accordingly.