Evaluation of gas concentrations in a mixture using a logarithmitic model for a gas sensor response

Abstract

Changes in electical conductivity are measured for a tin dioxide-based semiconducting sensor, due to reactions occurring between the original adsorbates and the gases present in the surrounding atmosphere. This gas sensor provides a stable and reproducible performance for indoor monitoring of gas leakage and air contamination. However, this type of gas sensors is not selective and the gas concentrations cannot be precisely estimated. Therefore, a model of the gas sensor response using a linear relationship between the gas concentrations in a mixture and the sensor resistance is proposed. Furthermore, using two gas sensors having different characteristic models it is possible to evaluate the concentrations of gases in a mixture. This method has been applied to evaluate the gas concentrations in ammonia-ethanol and CO-ethanol mixtures. The results of this study indicate that the evaluation of the gas ratio and gas concentrations in a mixture is made feasible by using the proposed model for the gas sensor response.