The fiber-optic evanescent wave fluorescence sensor with a novel sensing architecture for determining penicillin G

In this paper, we describe a specific fiber-optic evanescent wave (EW) fluorescence sensor with a naturally built-in high signal to noise ratio, including a novel sensing architecture. It includes two identical, low hydroxyl content, large core, multimode plastic-clad silica fibers that are positioned side to side, with a fiber for delivering incident exciting light and the other for receiving fluorescent light. By optimizing inclination of the incident fiber end-face, incident light illuminates perpendicularly receiving fiber after end-face reflection to excite fluorescent molecular in surrounding aqueous solution, and excited fluorescence couples into receiving fiber as the form of EW. Through increasing receiving fiber end-face´s roughness, the total internal reflection of massive low-loss tunneling modes occurs on the end-face, providing a high signal to noise ratio without some filters in existence. Finally, by means of the fluorescence quenching analysis, we investigated the content determination of penicillin G on the fiber-optic evanescent wave sensing platform, and obtained corresponding standard working curve.