Modelling the response of a tungsten oxide semiconductor as a gas sensor for the measurement of ozone

• Published in: Measurement science & technology Vol. 13; no. 6; pp. 923 - 931
• Main Authors: Williams, David E, Aliwell, Simon R, Pratt, Keith F E, Caruana, Daren J, Jones, Roderic L, Cox, R Anthony, Hansford, Graeme M, Halsall, John
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.06.2002
• ISSN: 0957-0233; 1361-6501
• DOI: 10.1088/0957-0233/13/6/314

The behaviour of gas-sensitive resistors based on WO(sub3) towards small concentrations of ozone in air can be understood with a simple model involving the reaction of ozone with surface oxygen vacancies. This model has been validated by comparison with experimental results for the effects of varying oxygen partial pressure on the ozone response. A complete description of the behaviour of devices constructed by printing WO(sub3) as porous layers onto an impermeable substrate requires consideration of the effects of the microstructure of such a device upon its response. A very simple series-parallel equivalent circuit model captures the effects and allows a simple interpretation of the sensor behaviour, including the quadratic limiting steady state resistance response to ozone and the effects of variation of device thickness. (Original abstract - amended)