Chemiresistive sensors of electrically conducting poly(2,5-thienylene vinylene) and copolymers: their responses to nine organic vapours

An apparatus and a method are described to test the sensing capacities, in the context of an electronic nose, of conductimetric sensors for organic vapours. Such a sensor was constructed using iodine doped poly(2,5-thienylene vinylene) (PTV) and tested in detecting nine 'representative' vapours. Responses after I min exposure are high and mostly linear with respect to concentrations. Recoveries, however, using 4 min of clean air, are only partial. Yet, responses and recoveries are reproducible and characteristic for a particular vapour. Partial methanol elimination from the methoxy-precursor polymer of PTV leads to new sensing materials with different selectivities. Also discussed are: (i) influence of the humidity of the carrier gas (air), (ii) possible causes of observed baseline-drift and (iii) possibilities of regeneration of the materials after prolonged use. It is concluded that PTV and derivatives show promise as active materials in sensor arrays. (C) 1998 Elsevier Science S.A. All rights reserved.