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United States Patent  [ii] Patent Number: 5,462,879
Bentsen  Date of Patent: Oct. 31,1995
 References Cited
U.S. PATENT DOCUMENTS
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(List continued on next page.)
Primary Examiner—Jeffrey R. Snay
Attorney, Agent, or Firm—Gary L. Griswold; Walter N.
Kirn; F. Andrew Ubel
The present invention relates to a sensing instrument and method for measuring the concentration of an analyte. The sensing instrument includes: a sensing element including at least a first emissive indicator characterized by a bimolecular quenching rate constant k9, one or more fluorescence lifetimes x0 above a lowest lifetime xoL, and capable of emitting analyte concentration dependent signals when exposed to an excitation signal in the presence of quencher; an excitation system which provides an amplitude modulated excitation signal at one or more radial modulation frequencies co; a detector; and a processor. The processor univariantly processes the detected signals and provides output signals representative of analyte concentration. The sensing element and/or excitation system are configured to enable the instrument to operate sufficiently within the condition [(k9[Q])2+to2]T„2 »l+2k9TD[Q] such that a slope of the relationship between the concentration dependent parameter and analyte concentration is independent of t„ variability and/or heterogeneity for all analyte concentrations within the operating range and for all lifetimes xa greater than ioL.
32 Claims, 22 Drawing Sheets
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