CONDUCTIVITY SWITCHING IN POLYPYRROLE-COATED TEXTILE FABRICS AS GAS SENSORS

Polypyrrole (PPy)-coated textile fabrics were prepared with varying su rface resistivities and were studied for their gas sensing capabilitie s by monitoring conductivity changes. Approximately an order of magnit ude reversible change in conductivity was observed when these fabrics were sequentially exposed to NH3 and HCl gases. While the change in co nductivity is reversible, the magnitude of the change decreases with t ime. In order to probe the sensitivity of the PPy-coated textiles to l ess reactive gases, the HCl was replaced with CO2 and a two-fold chang e in conductivity was observed. In this case although the magnitude of the conductivity change was smaller, it was more highly reversible an d did not decrease with time. (C) 1998 Elsevier Science S.A.