Study on dielectric properties of humidity sensing nanometer materials

Resistive- (surface-) and capacitive- (sandwich-) types of humidity sensors of nanometer barium titanate were fabricated. The impedance, capacitance and dielectric loss properties of the sensors were tested under different temperatures. In the frequency range of 10–105 Hz, both types of sensors got the dielectric loss nearly in all the relative humidity range, and the peaks of the dielectric loss moved to the high frequency direction as the relative humidity (RH) or temperature increased, respectively. The results indicated that not only the conduction carriers but also the polarizations of the sensing material and/or the adsorbed water existed for both types of the humidity sensors. It is mainly the sensing material rather than the structure or the electrode form that determines the properties of the humidity sensors.