PANI-PVA composite film coated optical fiber probe as a stable and highly sensitive pH sensor

Abstract An intrinsic optical fiber pH sensor coated with polyaniline (PANI)-polyvinyl alcohol (PVA) composite layer is developed and experimentally investigated in this paper. The sensor was fabricated by replacing the polymer cladding of a multimode fiber with pH sensitive PANI-PVA layer whose absorption properties as well as refractive index are pH dependent. PANI was synthesized as stable aqueous dispersion in presence of PVA and the coated film exhibits porous morphology. The experimental results demonstrate high sensitivity of 2.79 μW/pH for 2–9 pH range. The impact of environmental temperature and ionic strength on the sensor performance are studied for the fabricated sensor along with time response and reversibility. Additionally, real sample analysis was done to test for the reliability and chemical stability of the sensor and compared with conventional method. Apart from high sensitivity, wide dynamic range and fast time response, the experimental investigations indicate that the proposed sensor possesses excellent long term stability and durability over multiple measurements.