A metallic oxide gas sensor array for a selective detection of the CO and NH3 gases

An analysis of single gases using non-selective sensor elements is presented. It contains two steps: the identification of an unknown substance and the estimation of its concentration. To prepare the identification step, a calibration procedure is done to associate a class with each definite gas. In order to do this classification, the signals of the sensor array are transformed into quantities independent of the gas concentration but characteristic for its chemical compound. Then, the analysis parameters of an unknown substance allow to identify it with one of the calibration classes. After the identification of the gas, its concentration can be estimated with the model which is specific for each class of a single gas. The accuracy of this estimation is discussed. (C) 1999 Elsevier Science S.A. All rights reserved.