Fiber optic sensors fluorescence based

Optical transduction modes applied in combination with enzyme based fiber-optic sensors include absorbance, reflectance, fluorescence,... 

R. B. Thompson, Fluorescence-based fiber-optic sensors, in Topics in Fluorescence Spectroscopy, Volume 2 (J. R. Lakowicz, ed.), pp. 345-365, Plenum Press, New York (1991). 

Perhaps the first detailed discussion of such a technique in fluorescent thermometry (shown in Figure 11.10) was given by Zhang et al. in their work(36) based on both mathematical analysis and experimental simulation. Examples of the electronic design of the corresponding system and the application of the technique in a ruby fluorescence-based fiber-optic sensor system are also listed. This shows that there is no difference in the measurement sensitivity between a system using square-wave modulation and one using sinusoidal modulation. However, the former performs a little better in terms of the measurement resolution. 

W. A. Wyatt, F. V. Bright and G. M. Hieftje, Characterization and comparison of three fiber-optic sensors for iodide determination based on dynamic fluorescence quenching ofrhodamine 6G, Anal. Chem. 59, 2272-2276 (1987). 

Fiber-optic sensors based on controlled-release polymers provide sustained release of indicating reagents over long periods. This technique allows irreversible chemistries to be used in the design of sensors for continuous measurements. The sensor reported in this paper is based on a fluorescence energy transfer immunoassay. The sensor was cycled through different concentrations of antigen continuously for 30 hours. 

A useful specialized type of analytical iastmmentation is the fiber-optic sensor or optrode (253 54), in which an optical transducer monitors some chemically selective change. These are often based on the fluorescence of a reagent immobilized at the distal end of the fiber (255). 

Hale Z M and Payne F P 1994 Fluorescent sensors based on tapered single-mode optical fibres Sensors Actuators 17 233 0 Luo S and Walt D R 1989 Avidin-biotin coupling as a general method for preparing enzyme-based fiber-optic sensors Anal. Chem. 61 1069-72 Li L and Walt D R 1995 Dual-analyte fiber-optic sensor for the simultaneous and continuous measurement of glucose and oxygen Anal. Chem. 67 3746-52 Tan W, Shi Z-Y, Smith S, Bimbaum D and Kopelman R 1992 Submicrometer intracellular chemical optical fiber sensors Science 258 778-81 Tan W, Shi Z-Y and Kopelman R 1992 Development of submicron chemical fiber optic sensors Anal. Chem. 64 2985-90... 

Fiber-optic sensors, particularly fluorescent sensors, have become the object of considerable interest among researchers. The action of most fluorescent sensors is based on the change in the fluorescence properties of organic reagents immobilized on a solid matrix upon contact with solutions of metals in a continuous system. Zelters et al. [187] studied the immobilization and complex formation of immobilized Morin with zirconium and tin in order to develop a procedure for sorption fluorimetric determination of these elements. The selection of polyoxiflavones for immobilization was determined as a valuable analytical procedure. 

These criteria limit the applicahility of fluorescent dye-based sensors to only a handful of analytes. If a fluorescence-based method does not exist or is Incompatible with an optical sensor, an absorption sensor is the only alternative. There exist a large number of different absorbing dyes that are sensitive, selective and absorb in convenient regions of the spectrum. Several absorbance-based fiber-optic sensors have been described (8,25.26). Unfortunately, a major drawback with absorption spectroscopy is its inherent insensitivity. We decided to explore the possibility of using other optical techniques that can be used with indirect methods. A successful example has been presented which combines the sensitivity of the fluorescence measurement with the specificity of an absorbing dye and is based on an energy transfer mechanism (15). 

MacCraith, B.D., Mcdonagh, C.M., Okeefe, G., Keyes, T.E., Vos, J.G., Okelly, B., and Megilp, J.F. (1993) Fiber optic sensor based on fluorescence quenching of evanescent-wave excited ruthenium complexes in sol-gel derived porous coatings. Analyst, 118, 385-388. 

Describe in detail the fabrication and operation of one example for each of the following a) A conductometric sensor for the detection of organic vapors, b) An amperometric sensor for the same, c) A sensor interfaceable to a PC and usable as a detector in chromatography, d) A conductometric sensor for glucose, e) An amperometric sensor for the same, e) A potentiometric sensor for the same, f) A sensor whose sensitivity can be controlled electrically, g) A sensor incorporating an enzyme into the CP film wherein the enzyme concentration is precisely controllable, h) A sensor using an optical fiber probe and fluorescence-based detection. 

As the potential of optical fiber probes for pH measurements was rapidly recognized, several other articles appeared within a few years75 83. Most were reflectance-based, and Seitz reported the first fluorescent pH sensors84, 78. The article by Janata85 on whether pH optical sensors can really measure pH is another "must" in the early literature since it points to aspects hardly addressed in pH sensor work. 

Other medical products based on optical sensor technology include those of Cardiomed (System 4000), Puritan-Bennett, and one of Radiometer (Copenhagen) which has been withdrawn meanwhile. Optical (but non-fiber) sensors for oxygen and for C02 also are widely used for the determination of bacteria in blood. In 1986, Gehrich et al.36 described an optical fluorescence... 

Fuh M.R.S., Burgess L.W., Christian G.D., Single fiber-optic fluorescence enzyme-based sensor, Anal. Chem. 1988 60 433-435. 

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