A novel single chip thin film metal oxide array
Two silicon-based sensor arrays are described and tested, one based on films deposited onto bulk silicon wafers and the second, on a novel micromachined device in which the heated membranes are suspended from glass posts to insure low power dissipation. The sensing elements examined in the arrays included p-type Cr1 .8Ti0.2O3+z, n-type ZnO, n-type SnO2, n-type WO3 and n-type V2O5. The sensor arrays were investigated under trace gas exposure (H2, CO, NO2 and NH3) and, in all cases, at least one of the semiconducting metal oxide films reacted with sufficient sensitivity to the investigated gases. The measured response provided different patterns for each of the metal oxides and is thus appropriate for evaluation by pattern recognition techniques. A technological concept for an integrated device comprising the gas sensor array and circuitry for sensor control and data readout is discussed.