Some Considerations on Stability of Electrical Resistance of the TiO2/SnO2Ceramic Moisture Sensor

Studies on the stability of the electrical resistance of the ceramic moisture sensor related to the water adsorption properties of the ceramics by using a solid disk device made of Ti0
2
/SnO
2
ceramics are reported. The relationships between the resistance increase of the device due to chemisorption of water to form hydroxyl groups and the microstructure of the ceramics by analyzing the'data of scanning electron micrograph (SEM), powder X-ray diffraction, and by the resistance variation tests of the device in vacuum with water injection were studied. Also the life-tests of the device over 3000 h were performed under the excitation of AC 100 Hz in the atmosphere. Finally the possibility of the practical use of the device without heating the moisture-sensitive element by introducing the simplified equivalent circuit of the ceramic moisture sensor was discussed.