Viologen polymer-coated impedance sensors for midrange humidity levels and other volatile organic compounds

We have demonstrated a sensor based on an interdigitated electrode platform coated with a conductive viologen polymer that has excellent moisture sensitivity, response time, and low power consumption. Work has been done to explain the limits of sensitivity and characterize the response of the sensor in low-humidity environments and also characterize the response of the device to various organic interferents such as alcohols and organophosphonates. Using lumped-circuit models, the nature of the response is explained and design parameters are isolated that will allow future performance improvements. In addition, the temperature dependence of moisture sensitivity is presented.