Pt-doped SnO2 thin film based micro gas sensors with high selectivity to toluene and HCHO

Thin film-based micro gas sensors using undoped and Pt-doped SnO2 thin films with thicknesses of 50 and 120 nm are deposited using RF sputtering on MEMS structures and their sensing characteristics to 25 ppm CO, 25 ppm toluene, and 1 ppm HCHO gases were investigated at 300-440 degrees C. The Pt-doped SnO2 gas sensors with the thickness of 120 nm showed the selectivity to 1 ppm HCHO gas at 31.5 mW power consumption and to 25 ppm toluene gas at 45 mW. The control of gas selectivity by tuning thickness of sensing film and Pt catalyst loading was discussed. The results of this study suggest the possibility of employing thin film-based micro gas sensors for real applications with mass productivity and cost effectiveness. (C) 2017 Elsevier B.V. All rights reserved.