Crossed-Optical-Fiber Oxygen Sensors with Intensity and Temperature Referencing for Use in High-Spatial-Resolution Sensor Arrays

Abstract

We investigated the fabrication of an optical-fiber oxygen sensor based on luminescence quenching of a ruthenium (II) complex for our optical-fiber-sensor arrays. Sensor regions are located between two optical fibers forming orthogonal fiber-fiber junctions. Ruthenium molecules are embedded in a photo-polymerized hydrogel matrix, which is covalently attached to the surface-modified fiber-core. For the optical evaluation of these sensors, the fiber sensor junctions are placed in a flow cell. When gaseous oxygen diffuses into the hydrogel, it quenches the luminescence, with the degree of quenching correlating with oxygen partial pressure; this behavior was indeed observed in the crossed-fiber configuration with a sensor response time of 1 s. To account for intensity fluctuations, an oxygen-insensitive dye in an adjacent fiber-fiber junction was used for intensity referencing, which markedly improved the response curves. The oxygen sensor was also corrected for the temperature-dependence of the ruthenium complex using the dye Kiton Red