A microfabricated array of multiple thin film metal oxide sensors for multicomponent gas and vapor quantification

The authors report on an integrated array consisting of eight thin film metal oxide sensors for analyzing mixtures of gases and vapors. The sensors were fabricated into a 3.1 mm*2.9 mm silicon chip in an eleven-mask process sequence. The sensing elements were constituted using single layers and bilayers of reactively sputtered thin films of SnO/sub 2/, ZnO, TiO/sub 2/ and WO/sub 3/ with and without Pd catalyst. Elevated sensor temperature was achieved through on-chip boron-diffused heating elements. The array was characterized with mixtures of methanol and acetone. The sensor response spectra were processed by an artificial neural network for calibration of the sensor array and prediction of the vapor concentrations. The results show that the concentrations of acetone and methanol corresponding to the sensor responses can be quantitatively discriminated at a low cost of precision.<>