Polypyrrole materials for detection and discrimination of volatile organic compounds

A simple method for investigating the sensory properties of free-standing polypyrrole films to be used in an electronic nose is presented. Polypyrrole is electrochemically prepared on stainless steel substrates using three different current densities and two counter-ions (lithium perchlorate and p-toluenesulfonate) at three concentrations to assess the effect of these parameters on the sensing properties of such films. The response to methanol vapour in the range of 1000–20 000 ppm is reported. Signal response showed a slight enhancement of methanol sensitivity across the range of prepared sensors. A seven sensor array constructed in consultation with the original data and forming an electronic nose is subsequently reported. Principal component analysis is used to evaluate the arrayʹs ability to discriminate between methanol, ethanol, acetone, 2-butanone and 2-pentanone.