Fluorescent fluid determination method and apparatus
First Claim
1. A fluorescence-based optical sensor comprisinga fluorophor having an acid form and a base form, the relative amounts of said acid and base forms being pH dependent,means for exposing said fluorophor to a sample to be analyzed,means for exciting said fluorophor at first and second wavelengths, said first wavelength exciting said acid form of said fluorophor and said second wavelength exciting said base form of said fluorophor,detector means for sensing at a single wavelength the intensities of fluorescence of said fluorophor when said fluorophor is excited at said first wavelength and at said second wavelength, andmeans for taking the ratio of the intensities of fluorescence at said single wavelength as sensed by said detector means as a measure of a characteristic of the sample being analyzed.
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Abstract
A fluorescence-based optical sensor includes a membrane immobilized fluorophor secured to one end of a bifurcated fiber optic channel for exposure to the sample to be analyzed. The fiber optic channel also has an input end coupled to a radiation source arranged to supply radiation at two different wavelengths and an output end coupled to a bandwidth limited photosensor. The radiation source alternately excites the fluorophor at a first wavelength that excites an acid form of the fluorophor and at a second wavelength that excites a base form of the fluorophor, and a ratio of the resulting fluorescence intensities is taken as a measure of a characteristic of the sample being analyzed.
90 Citations
18 Claims
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1. A fluorescence-based optical sensor comprising
a fluorophor having an acid form and a base form, the relative amounts of said acid and base forms being pH dependent, means for exposing said fluorophor to a sample to be analyzed, means for exciting said fluorophor at first and second wavelengths, said first wavelength exciting said acid form of said fluorophor and said second wavelength exciting said base form of said fluorophor, detector means for sensing at a single wavelength the intensities of fluorescence of said fluorophor when said fluorophor is excited at said first wavelength and at said second wavelength, and means for taking the ratio of the intensities of fluorescence at said single wavelength as sensed by said detector means as a measure of a characteristic of the sample being analyzed.
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15. A method of measuring a characteristic of a sample using an optical pH sensor,
said sensor comprising a multi-wavelength light source, a limited bandwidth light detector, and a pH-sensitive fluorphor, said fluorophor having a first dissociation constant associated with the ground-state dissociation of said fluorophor into a hydrogen ion and the corresponding anion and a second dissociation constant associated with the excited-state dissociation, said second dissociation constant being several orders of magnitude larger than said first dissociation constant, said method comprising exposing said fluorophor to said sample, measuring the fluoroescence intensity IFa at an emission wavelength λ -
e using the excitation wavelength λ
a of the acid form of the fluorophor, measuring the fluorescence intensity IFb at said λ
e using the excitation wavelength λ
b of the base form of the fluorophor, and taking the ratio of IFb /IFa as a measure of a characteristic of the sample. - View Dependent Claims (16, 17, 18)
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e using the excitation wavelength λ
Specification