Fabrication and Characterization of Thick Film Ammonia Gas Sensor

An ammonia gas sensor with high sensitivity using thick-film technology were fabricated and examined. The material for sensing the ammonia gas was the mixture of oxide semiconductor, . The sensor exhibits resistance increase upon exposure to low concentration of ammonia gas. The resistance of the sensor is decreased, on the other hand, for exposure to reducing gases such as ethyl alcohol, methane, propane and carbon monoxide. A novel method for detecting ammonia gas quite selectively utilizing a sensor array consisting of an ammonia gas sensor and a compensation element were proposed and developed. The compensation element is a Pt-doped gas sensor which shows opposite direction of resistance change in comparison with that of the ammonia gas sensor upon exposure to ammonia gas. Excellent selectivity has been achieved using the sensor array having two sensing elements.