Abstract
Humidity and temperature sensors were fabricated from a nanocomposite consisting of CeO2-Co3O4 hybrid nanoparticle-silicone adhesive and CeO2-Co3O4 hybrid nanoparticle-polymer adhesive, respectively, to fix the material on a glass supported copper electrode. The impedance of the sensor decreases by a factor of 960 at a working frequency of 100 Hz, and by a factor of 800 at 1 kHz, on increasing relative humidity (RH) from 30 to 90 %. In parallel, the capacitances increase by factors of 567 and 355, respectively, under the same experimental conditions. The effect of temperature in the range from 25 to 70 A degrees C on impedance (again at 100 Hz and 1 kHz) was also studied and found to decrease with increasing temperature. On going from 25 to 70 A degrees C, the impedance measured at 100 Hz and 1 kHz decreases 2.22 and 1.58 times, respectively, in surface type sensors, while in sandwich type sensors this decrease is 3.0 and 2.08 times. The calculated average sensitivity to temperature is -1.02 and -0.8 % A degrees C-1 for the surface type and -1.5 and -1.2 % A degrees C-1 for the sandwich type sensors at frequencies of 100 Hz and 1 kHz, respectively.