Headspace analysis using conducting polymer sensor arrays

Research efforts have been under way for over twenty years aimed at investigating and understanding the use of conducting polymers to monitor volatile chemicals. In some cases, this work has led to commercial exploitation. The mechanisms by which interaction between the polymer surface and the volatile chemicals give rise to electrical changes in the polymer are not fully understood and this paper will briefly review this fundamental topic. It will go on to show that major advantages accrue from interrogating conducting polymers using high frequency techniques rather than the de methods used by most researchers. These advantages will be quantified by reference to simple lumped circuit models that have been built for a sensor configuration in use by the present authors. In addition, comparisons between the dielectric properties of the sensors predicted by the model and from a number of measurements will be used to justify the model structure. The paper will also discuss conducting polymer array technology, methods of interrogating such sensor arrays and their deployment as part of new sampling strategies aimed at eventually achieving ppt levels of detection of contamination in water using headspace analysis.