<title>Thin film technology of conductive polymer for optical fiber sensor application</title>

Abstract

With the aim to apply vacuum deposited polyaniline (PAN) films as sensing elements of fiber -optic sensors (FOS), the technology of polymer deposition that gives a possibility to obtain conductive emeraldine PAN form by standard protonation methods has been developed. The influence of deposition temperature on refractive index and spectral characteristics of films is specified. On the base of the results change in PAN films optical properties with the change in pH value of the medium, pH level (as well as ammonia, CO) FOS are elaborated. The distinctive feature of sensor optical response is its high sensitivity to pH value, such as, due to increase in pH changes of optical adsorption are observed that is especially high at 500-550nm and 800-900nm of spectral range. For a FOS processing analysis, we carried out measurements of sensor optical response to pH value in two wavelengths (540 nm and 900 nm). Obtained results give us a possibility to suggest an application vacuum deposited PAN films as FOS sensitive element for a pH value determination. It was estimated that FOS has high reversibility of optical response due to redox reaction, that take place on modified fiber part. The inertial FOS parameters are within a minute range.