Conductivity switching in polypyrrole-coated textile fabrics as gas sensors

Polypyrrole (PPy)-coated textile fabrics were prepared with varying surface resistivities and were studied for their gas sensing capabilities by monitoring conductivity changes. Approximately an order of magnitude reversible change in conductivity was observed when these fabrics were sequentially exposed to NH3 and HCl gases. While the change in conductivity is reversible, the magnitude of the change decreases with time. In order to probe the sensitivity of the PPy-coated textiles to less reactive gases, the HCl was replaced with CO2 and a two-fold change in conductivity was observed. In this case although the magnitude of the conductivity change was smaller, it was more highly reversible and did not decrease with time.