Thin-film-type oxide semiconductor sensor for detecting acetone in human expiration aiming at diagnosis of diabetes

Thin-film-type oxide semiconductor gas sensors sensitive to acetone were explored for the diagnosis of diabetes. SnO2 and ZnO were tested as a base sensor material. When fabricated into a thick-film-type sensor, SnO2 was inferior to ZnO in the acetone sensitivity. However, on changing to a thin-film-type sensor, SnO2 proved to be more sensitive to acetone than ZnO. The acetone sensitivity of the SnO2-based thin film sensor could be improved by the addition (0.1wt%) of noble metals, such as Rh and Ru. The resulting sensor using Rh-SnO2 could detect as dilute as 0.2ppm acetone in human expiration at 300°C without being disturbed by changes in O2 and CO2 concentrations.