Chemoresistive conducting polymer-based odour sensors: influence of thickness changes on their sensing properties

Abstract

Conducting polymer films are widely used in the detection of odours. The change of resistance in the presence of odorants depends on the polymer thickness, and affects the sensitivity properties of the device. Using the vapour phase polymerization technique it is possible to fabricate polymer layers of controllable, uniform thickness. Aiming at the characterization of polymeric sensors as a function of their thickness, we implemented sensors of different thicknesses and carried out sensitivity measurements using toluene as an analyte. Sensitivity in terms of percentage variation of resistance per unitary odour concentration change was found to decrease with increasing thickness. Data on sensitivity as a function of thickness is presented and a possible explanation is proposed to account for the experimentally observed behaviour.