Effect of redox state on the response of poly-N-(2-cyanoethyl)pyrrole coated thickness-shear mode acoustic wave sensors to organic vapours

Different redox states of poly-N-(2-cyanoethyl)pyrrole (PCPY) films were prepared by electropolymerization and subsequent oxidation or reduction on the surface of thickness-shear mode (TSM) acoustic wave sensors. The resulting films were characterized by cyclic voltammetry, impedance spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. The response of the coated sensors to organic vapours consisting of 9-carbon chains with different functionalities was also studied. The observed responses were dependent on both film redox state and organic vapour properties. All films showed high sensitivity to nona-3,6-dien-1-ol, an aroma component characteristic of early degradation of fresh fish. Principal components analysis allowed all five analytes to be distinguished in the discriminant plane using only different redox state PCPY films.