Ammonia gas sensor based on the frequency-dependent impedancecharacteristics of ultrathin polyaniline films.

Abstract

This paper describes a variety of experiments that reveal the potential application of impedance spec-troscopy (IS) measurements to enhance performance of ultrathin polyaniline (PANI)-based films onflexible substrate to control ammonia gas exposure in the 0–20 ppm range. Further, the device is mechan-ically robust for making electrical contact without lithography. We have employed the IS technique toproper adjust the optimal operation frequency of an easy-to-process, inexpensive and user-friendly PANI-based resistometric detectors in which drift current and delay problems related to electrode effects anddielectric absorption of PANI are insignificant. These requirements place emphasis upon the material anddevice configuration, and the range of frequencies from 10 to 100 Hz corresponds to the ideal workingregion to operate the device to unify sensibility inside 5%, reproducibility, linearity, stability and lowresponse time (<1 min). These results are as efficient as those obtained using a more expensive commer-cial apparatus and can rival the affordability of traditional sensors. Linear Discriminant Analysis (LDA)and K-Means clustering confirmed that the device has the capacity to recognize ammonia concentrationaround 20 ppm with total accuracy of 95%. Our study provides evidence of a new way to improve theperformance of PANI-based sensors that can potentially be employed to monitor the environment oflivestock buildings, for example.