A novel process for fabrication of SnO2-based thick film gas sensors

A centrifugal coating technique has been developed for SnO2 thick film gas sensors. The thickness of the films was controlled by changing the concentration of the SnO2 suspension. For thicknesses above 10 μm, the sensitivity was stabilized. A cold isostatic pressing of the films before sintering resulted in a slight reduction of the sensitivity and a considerable reduction in resistivity, showing the applicability of the process. Centrifugally coated samples showed a much higher sensitivity than screen-printed samples. This result was attributed to the stacking of fine powder at the surface which showed a lower resistivity and a higher sensitivity compared to coarse powder.