Selectivity enhancement of SnO2 gas sensors: simultaneous monitoring of resistances and temperatures

We present results obtained with microstructured tin dioxide-based gas sens ors. Thick films with controlled nanocrystallite sizes were deposited on mi cromachined substrates. Discrimination between CO, CH4, and C2H5OH, and bet ween CO, CH4 and H-2 in changing humidity conditions was achieved by simult aneously measuring temperature and resistance changes upon gas exposure. Th ese results make it possible to fulfil the American and European safety sta ndards for CO and CH4 detection with tin dioxide based gas sensors. The phy sico-chemical origin of temperature and resistance changes are discussed. ( C) 1999 Elsevier Science S.A. All rights reserved.