Optofluidic integrated in-fiber fluorescence online optical fiber sensor

An in-fiber integrated fluorescence online optofluidic sensor is realized in a hollow optical fiber with a suspended core. A micro-region for fluorescence quenching reaction is built in the hollow optical fiber. By etching microholes on the surface of the fiber, the fluorescence reagents can be injected into the optical fiber and form microflows in the region. Simultaneously, indicator molecules can be excitated through the evanescent field of the suspended core and the fluorescence is efficiently coupled into the core and can be detected. In this report, the concentration of nitrite can be determined by quenching the fluorescence of rhodamine 6G during optofluidic reaction in the optical fiber. Furthermore, the results demonstrate the feasibility of the integrated in-fiber optofluidic method for trace fluorescence detection.