Optical detection of toluene in water by using IGI fibers

The use of a sensor employing a short, straight segment of a silica fiber with an inverted parabolic refractive index profile in the core for the detection of aqueous solutions of toluene was investigated. The sensing layer of the fiber was prepared by depositing a thin polydimethylsiloxane layer on the bare fiber core by the dip-coating technique. The performance of the fiber was examined in relatively long static and dynamic exposures of the fiber to toluene solutions, during which saturated values of the output sensor signal were reached. Detection sensitivities of several milligrams per liter were achieved for both types of exposures.