THE SENSING OF HUMIDITY BY SURFACE-TYPE Ag/FORMYL-TIPPCu(II)/Ag SENSOR FOR ENVIRONMENTAL MONITORING

Abstract

In this paper, we have studied the effects of changing relative humidity on the electrical parameters and their multi frequency response of the surface type Ag /formyl- TIPPCu ( II )/ Ag humidity sensors. The silver electrodes of thickness 100 nm were primarily deposited on cleaned glass substrates by thermal evaporator. A gap of 40 μm was created between the electrodes of each device by using mask during the evaporation process. Thin films of formyl- TIPPCu ( II ) of 140 nm thickness were grown on silver electrodes by thermal sublimation technique. The values of capacitance and resistance of the sensors were found at different humidity levels at frequency of 1, 10 and 100 kHz of AC input signal. A remarkable increase in capacitance and decrease in resistance were observed during the rise of relative humidity from 45% to 95% RH. The hysteresis response of these humidity sensors was also studied at 1 kHz AC signal.