In-situ calibration of humidity with simultaneous effect of resistance and capacitance at different frequencies

The measurement and control of humidity is one of the most crucial issues in several fields of applications such as automated systems, instrumentation, agriculture, climatology and GIS. Various kinds of materials are being examined for their humidity sensing properties. Here we investigate humidity sensing characteristics of organic-inorganic composite based sensor fabricated on a glass substrate. Carbon nanotubes-zinc oxide (CNTs-ZnO) blend prepared in ethanol is used as organic-inorganic composite layer. The resistance and capacitance of the device are measured as function of relative humidity (RH) at different frequencies. The decrease in resistance and increase in capacitance of the device manifests humidity sensitivity of CNTs-ZnO composite. The capacitive and resistive response of the hygrometer was analyzed at frequencies of 0.1 kHz, 1 kHz and 10 kHz. The sensor shows higher sensitivity at lower frequency as compared with the higher ones