Polyaniline film-based interdigitated capacitive sensor for ammonia gas detection

Abstract

In this work, an ammonia gas sensor based on Polyaniline(PANI) was fabricated using a custom made Interdigitated capacitive sensor(IDC-S). PANI films were successfully deposited on the IDC-S using the solution casting method. The sensor responded to a low ammonia concentration of 50 ppm with a capacitance change of 10% with respect to capacitance in air in room temperature. And the response increased to 44% as the concentration increased to 300 ppm. This showed a good linear relationship between sensor response and ammonia concentration. Furthermore, the effect of relative humidity on the sensor was also studied and it showed that there is a significant change in capacitance of the sensor as the relative humidity levels changed. Moreover, the sensor response to a fixed ammonia concentration of 200 ppm at different humidity levels was studied and it diminished from 26% to 4% as the humidity level increased from 20% to 90%.