Polypyrrole thin films gas sensors

Thin films of polypyrrole doped with different counter-ions, prepared by in situ polymerization on conducting glass electrodes, are used for the development of gas sensors with fast response time. On exposure to a given vapor, each individual film exhibits a fast change in the fractional difference of its electrical resistivity and with the adopted arrays of 7 sensors it was possible to detect and identify simple organic solvents. The morphology and structure of the films, and therefore the level of response to the volatile compounds, is determined by the structure of the counter-ion used.