Capacitive Properties of Ceramic Humidity Sensors Made from Porous Perovskite Films

In this research, ceramic-based capacitive humidity sensors based on the barium strontium titanate perovskite nanocomposite and doped with the various concentrations of magnesia nanoparticles were fabricated and investigated. The particle size of the sensing elements is varied from 56 nm to 35 nm per dopant surcharges. The interaction between bulk perovskites (pellet) and water vapor was studied by impedance spectroscopy. Presence of the ionic transport even at low RH values is observed from the bulk frequency-capacitance spectra. The EIS results of the bulk sample confirm that the proton transfer operates only by charge transfer kinetics and not diffusion process to metals (up to 90% RH). Among all the proposed sensors, the device contains of 3 mol% magnesia exhibits the most capacitance change (21 pF – 25200 pF) with the sensitivity of 335 pF/RH% in the range of 20–95% RH, and a maximum hysteresis of 5.2% RH at 60% RH. The impact of rest of dopant values on the main perovskite is negative.