Modeling The Influence Of H2O On Metal Oxide Sensor Responses To CO

It is well know that the relative humidity largely affects the response of MOX gas sensors to the target gases. The influence of water vapor on MOX sensor operation has been deeply studied and many results can be found in the literature. Nevertheless the effect of water was not incorporated in the sensor models presented up to now. In this work the authors propose, on the basis of experimental evidence, a simplified model for SnO2 sensors, able to account for the water contribution, when the target gas is CO. The authors start from a model already presented and tested for dry gases (CO and O2), and add the water contribution, assuming that the direct reaction between CO and water can be neglected.