Semiconducting metal oxide sensor array for the selective detection of combustion gases

A sensor array consisting of discrete thick-film sensors based on various semiconductor metal oxides (SMO) has been designed and fabricated for flue gas analysis purposes. The selection of the sensitive materials for the array has been accomplished as a result of extensive studies of gas-sensitive properties of SMO. The thick-film sensors, prototypes and the array's components, were fabricated on the basis of commercial sensor platforms. A drop-coating technique was used for metal oxide paste deposition followed by in situ drying and annealing of the deposited films in air by platinum heaters integrated into the platforms. We show the results obtained with a variety of thick-film metal oxide species and examine their sensitivities at different fixed operating temperatures (200-400 degreesC). The feasibility of the electronic system consisted of SnO2, ZnO, WO3, CuO, and In2O3 sensors to discriminate and recognize various gaseous constituents of a combustion gas is demonstrated. Principal component analysis along with several classification schemes were used to identify nitrogen oxides, ammonia, sulfur dioxide, and other gaseous pollutants. (C) 2003 Elsevier Science B.V. All rights reserved.