| abstract |
A personnel recognition sensor comprises a multiplicity of differentially responding chemo-resistor elements, each element comprising a non-conductive substrate, a plurality of electrodes disposed on the substrate and one or more layers of a conductive polymer overlaying the electrodes, the conductive polymers of at least two of the elements being different; a detector responsive to signals provided by the multiplicity of elements and arranged to provide an output signal characteristic of the multiplicity of signals; the elements being disposed in a housing having an inlet arranged so that a gaseous sample passing into or through the inlet contacts all of the elements in use. |