Discrimination of carbon dioxide and fluorocarbon using semiconductor gas sensors

In this paper, we present the discrimination of two antagonist gases, using an array composed of five commercial gas sensors (two TGS 832, two TGS 813 , one TGS 800). From the characterisation of the sensor array under forane R134a, carbon dioxide and mixtures of these two gases in dry synthetic air, we have extracted two main parameters, transient and steady-state conducta nce values. In general, only the steady-state conductance value is taken. H owever, we have characterised the sensor transient behaviour by using the m easurement of the slope of the conductance when there is a step change in t he gas concentration. Thus, discriminant factorial analysis (DFA) is carrie d out to show qualitatively that the selectivity is improving when taking i nto account simultaneously the two parameters. This makes possible the dete rmination of the nature of several gases present in the studied atmosphere. (C) 2000 Elsevier Science S.A. All rights reserved.