Dielectric gas sensors for SO2 (ranges 1-200 vpm and 10-6000 vpm) with low cross-sensitivity to other gases and humidity have been developed. The sensors consist of planar interdigital capacitors (IDCs) with a heteropolysiloxane (HPS) coating containing tertiary amino groups as a sensitive layer. For the first time, the dependence of the geometrical properties of the interdigital capacitors and the sensitivity have been investigated. The sensitivity of the gas sensors can be improved by alterations in their geometrical properties. In the electrical adsorption saturation of SO2, depending on the sensitive film, a capacitance change of up to 40% can be obtained at a frequency of 10 kHz with an electrode distance of 26-mu-m.
