Impedimetric Study of Polypyrrole Coated Zinc Oxide Fibers for Ammonia Detection

This paper reports the impedance spectroscopy of the ZnO-polypyrrole composite as a sensor used for the detection of ammonia. The frequency response of the sensor is studied using Nyquist plot in the frequency range of 100 mHz to 1 MHz. Sensitivity of the sensor is observed using DC measurement method. The impedance spectroscopy is performed for the ammonia vapors with the concentration ranging from 5 ppm to 115 ppm. The equivalent circuit is proposed based on the impedance response of the sensor. Based on the Nyquist plot observed, different elements contributing the changes in the overall impedance of the sensor are discussed.