Hypersensitive and Selective Interferometric Nose for Ultratrace Ammonia Detection with Fast Response Utilizing PANI@SnO₂ Nanocomposite

Abstract

Ammonia is one of the most toxic gases present in our environment, and its presence in the atmosphere is very unpleasant since its higher concentration in blood causes the coma and convulsion. Hence, in light of advance photonics technology, we report a contemporary approach to design and develop hypersensitive ammonia gas sensor realizing Mach–Zehnder interferometer (MZI) by a single mode fiber (SMF)-photonic crystal fiber (PCF)-SMF fiber optic substrate for realizing the interference by immobilizing PANI@SnO2 nanocomposite to achieve sensing. In this case, excitation of core and cladding modes of PCF is achieved using collapse region that is formed at the junction of SMF and PCF specialty fiber. The method claimed to have very fast response and recovery times of 7 and 2 s, respectively, which can detect as low as 8.09 ppt (47.59 fM). The reusable probe shows the potential for rapid detection of ultratrace ammonia with high selectivity and reproducible features, thereby opening a new window for environmental monitoring and online measurements.