Performance Evaluations of Ammonia ‎Sensors Using Cladding Modified Single-‎Mode Optical Fiber Coated with ‎Polyaniline Nanofibers

In this paper, we developed a cladding modified optical fiber to detect low concentrations of ammonia (NH_3). The Modification is coating with polyaniline (PANI) nanofibers. By using single mode optical fiber (SMF), two sensors are fabricated. The first one is etched with the chemical agent which is hydrofluoric acid (HF), and the other is tapered with a glass processing workstation so that the waist diameters of 15 µm for both modified sensors. Modified fibers are spray coated. The modification done on SMFs considerably enhances the interaction between them. The proposed modification is considerably enhancing how the evanescent field and the (PANI) sensing layer interact with each other. The modified SMF sensors are subjected to NH_3 with different concentrations within the visible wavelength range. The modified SMF and the nanostructured PANI films pattern results in a highly sensitive ammonia sensor at room temperature. The tapered SMF coated with PANI works better compared with the etched SMF. The results show that the response equals 89s, the recovery times equal 433s, and the sensitivity equals 139.1%. The modified fiber sensors have a limit of detection (LOD) of 0.0034% (34 ppm).