Long Path Fiber-Optic Sensor for Evanescent Field Absorbance Measurements

Michael D. DeGrandpre, Lloyd W. Burgess

Research output: Contribution to journalArticlepeer-review


A commercially available polymer-clad silica fiber is used as an evanescent field absorbance probe. The slloxane cladding provides a protective and selective layer over the optical Interface. This coating allows long lengths (greater than one meter) of fiber to be colled Into a compact sensor. Coiling the fiber enhances the evanescent field Interaction over that of a straight fiber. Selectivity is obtained because only nonpolar organic solvents penetrate the slloxane cladding and carry the analyte to the evanescent field interaction region. Measurements taken with an organic dye in chloroform indicate the sensor has a dynamic range extending from 0.001 to 1.00 absorbance unit with a precision of ±4%. The response time is from 2 to 3 min. The sensor response as a function of solvent refractive Index, bend radius, and length Is discussed in detail.

Original languageEnglish
Pages (from-to)2582-2586
Number of pages5
JournalAnalytical Chemistry
Issue number23
StatePublished - Dec 1 1988


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