P A Wallace et al 2001 Meas. Sci. Technol. 12 882 doi:10.1088/0957-0233/12/7/323
P A Wallace, N Elliott, M Uttamlal, A S Holmes-Smith and M Campbell
Show affiliationsA quasi-distributed pH sensing system was developed to utilize information derived from evanescently excited fluorescence signals originating from sensor sites fabricated on an optical fibre. The sensor sites comprise a section of fibre core exposed by polishing upon which is laid down a sensing film. The film comprises a fluorescent indicator dye immobilized covalently within a hydrogel matrix which is then photopolymerized and attached covalently to the exposed fibre core. Position information is determined from the propagation delay of the returning signals. A system comprising eight sensors spaced at 10 m intervals along an optical fibre has been constructed and characterized. The sensors operate in the region pH 6-pH 8 with a response time of 500 s. The properties of the immobilized indicator dye are found to be similar to those of the dye in aqueous solution. Furthermore, the sensing films so created are found to be resistant to dye leaching.
33.50.Dq Fluorescence and phosphorescence spectra
42.81.Bm Fabrication, cladding, and splicing
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
Issue 7 (July 2001)
Received 11 January 2001, accepted for publication 1 May 2001
P A Wallace et al 2001 Meas. Sci. Technol. 12 882
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