Improved chemical sensing characteristics of conducting polymers interrogated at high frequencies

Research efforts have been under way for almost twenty years aimed at 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 cause electrical changes in the polymer are not fully understood and this paper will begin by briefly reviewing this important area. It will go on to show that major advantages accrue from interrogating conducting polymers using high frequency techniques rather than the dc methods used by most researchers. These advantages will be quantified by reference to simple 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 measurements will be compared. The paper will conclude with a few examples of measurements made using a device for conducting polymer gas sensors operating at less than 1 MHz.