Conducting polymer gas sensors Part III: Results for four different polymers and five different vapours

The application of four different conducting polymers (polypyrrole, poly-N-methylpyrrole, poly-5-carboxyindole and polyaniline) as sensors for organic vapours has been investigated.

The sensors are formed by the electrochemical polymerization of the appropriate monomers across a 12 μm gap between two gold microband electrodes. Upon exposure to vapours the polymers show conductivity changes that are rapid and in general reversible at room temperature.

Of the four polymers investigated, under the deposition conditions employed and for the vapours used (methanol, ethanol, acetone, ether and toluene), poly-5-caboxyindole is found to give the most stable, reproducible behaviour and to be the most promising material for sensor applications. The use of these materials in intelligent gas sensors is discussed.