Ways to Improve the Sensitivity and Selectivity of Gas Sensors Based on Polyaniline

The possibility of increasing the sensitivity and selectivity of gas sensors on the basis of polyaniline (PANI) has been investigated. Basing on the analysis of PANI optical absorption spectra the possibility of significant increase in sensitivity and selectivity of gas sensors is shown with help of additional measurement of optical absorption at wavelengths 800 nm (to increase sensitivity) and 720 nm (to increase selectivity), without complicating synthesis of sensory elements. We establish, that sensitivity to ammonia of the PANI thin films increases almost twice due to optical measurements absorption simultaneously in the visible and near-infrared spectral region and summation the absolute values of their changes. It is shown that the isobestic point of absence gas-stimulated changes in optical absorption spectra of PANI in the vicinity of wavelength 720 nm can be a reference point for the presence of ammonia in gas sensors, which improves their selectivity.