Verification of a logarithmic model for estimation of gas concentrations in a mixture for a tin oxide gas sensor response

Changes in electrical conductivity due to a reaction occurring between the original adsorbents and the gases present in the surrounding atmosphere were measured for a tin dioxide-based gas sensor. In this study, a model of the gas sensor response using a relationship between the gas concentration in a mixture and the sensor resistance is proposed. The values of coefficients are determined by a least-squares fit of measured data. Using two gas sensors having different characteristics, the concentrations of gases in a mixture can be evaluated. The proposed method has been applied to the evaluation of the gas concentrations in ammonia–ethanol and CO–ethanol mixtures. Furthermore, we verified our model for a gas mixture of carbon monoxide, propane and methane gases, namely for a three-gas system. The results of the present study indicated that the evaluation of gas concentrations in a mixture is feasible using the proposed model of gas sensor response, which can be used as an inexpensive monitor for air pollution.