IDC gas sensors using organically modified silicate layers as gas-sensing substances

The dielectric properties of organically modified silicates change under the influence of gases such as NO2, NH3 and SO2. Thin layers of these materials are applied as dielectric to thin film interdigital capacitors (IDC). It is possible thereby to detect changes of the dielectric properties of the layers through the change in the capacitance and conductivity of the capacitor. the results obtained with a layer optimized for SO2 detection are presented; The layer is characterized by good linearity in the range of 2 to 10 vpm SO2 and low cross sensitivity to humidity of up to 23000 vpm at 30xC.