A logarithmic multi-parameter model using gas sensor main and cross sensitivities to estimate gas concentrations in a gas mixture for SnO2 gas sensors

In a metal-oxide semiconductor gas sensor, the sensitivity of the metal-oxide resistance to concentrations of reducing gases in the surrounding atmosphere is known to be related to adsorption and desorption of gas on the redox reactions between the gas and oxygen. Changes in the electric conductance due to these reactions were measured for tin dioxide semiconductor gas sensors. In this study, we propose a model of gas sensor responding behaviour using a relationship between sensor conductance and gas concentrations in a mixture. A least-squares method fit of measured data was applied to determining the values of coefficients. The proposed method uses main and cross sensitivities the describing the response of a gas sensor. Applying two-gas sensors which show different characteristics, the gas concentrations in a gas mixture can be evaluated. The proposed method has been applied to the estimation of gas concentrations in a mixture of hydrogen–methane, carbon monoxide–methane, propane–methane, ethanol–ammonia and propane–ammonia. The concentrations determined from the response curves were accurate within a 5% error. The results indicate that the proposed model is feasible for recognition of calculated estimations in a gas mixture. This paper shows a significant result through utilization of the proposed model of gas sensor response.