Mid-IR fiber optic chemical sensors using Teflon and other polymer coatings

Brian D. MacCraith; James Edward Walsh; Kieran O'Dwyer; F. Regan; M. Meaney; Johannes G. Vos

doi:10.1117/12.260607

10 December 1996 Mid-IR fiber optic chemical sensors using Teflon and other polymer coatings

Brian D. MacCraith, James Edward Walsh, Kieran O'Dwyer, F. Regan, M. Meaney, Johannes G. Vos

Proceedings Volume 2836, Chemical, Biochemical, and Environmental Fiber Sensors VIII; (1996) https://doi.org/10.1117/12.260607
Event: SPIE's 1996 International Symposium on Optical Science, Engineering, and Instrumentation, 1996, Denver, CO, United States

Abstract

The development of a novel Teflon-coated optical fiber sensor for chlorinated organic determination and a PVC- coated sensor for pesticide determination is described. Current analytical techniques for these compounds in water are not suited to in-situ or on-site measurements. As a result, straight-forward techniques that feature a short analysis time, sufficient selectivity and adequate sensitivity are in high demand. An infrared fiber optic sensor which operates in the 4 to 16 micrometer wavelength region has been developed for the in-situ monitoring of chlorinated hydrocarbons and pesticides in water. The sensing element consists of a silver halide (AgCl_xBr_{1- x}) optical fiber, coated with Teflon or poly (vinyl chloride) (PVC) which enriches the analyte in the evanescent wave region of the fiber. Enrichment of the analytes occurs in the minute range and is reversible. Using trichloroethylene (TCE) and alachlor as representative pollutants, evanescent wave spectrometry in the mid-infrared (MIR) region is shown to provide good performance down to single ppm levels. Absorbance data were recorded at 938 cm^-1 and 1104 cm^-1 for TCE and alachlor respectively. Furthermore, it is shown that the technique can be applied to multi-analyte samples.

Citation Download Citation

Brian D. MacCraith, James Edward Walsh, Kieran O'Dwyer, F. Regan, M. Meaney, and Johannes G. Vos "Mid-IR fiber optic chemical sensors using Teflon and other polymer coatings", Proc. SPIE 2836, Chemical, Biochemical, and Environmental Fiber Sensors VIII, (10 December 1996); https://doi.org/10.1117/12.260607

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