System and method for diagnosing sensor performance using analyte-independent ratiometric signals
First Claim
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1. A system for performing a diagnostic test on an analyte sensor, comprising:
- a sensing element comprising a polyethylene glycol matrix suspended analyte binding protein element introduced to an analyte environment, said binding protein labeled with a dye fluorescing with an intensity spectrum related to a concentration of said analyte concentration in said environment;
the sensing element disposed at a distal end of an optical conduit;
an excitation source at a proximal end of the optical conduit for supplying excitation energy to the optical conduit and a fluorescence intensity measuring device comprising first and second detectors for measuring fluorescence intensity at first and second respective frequencies, the first frequency being higher than an isosbestic frequency of the dye, and the second frequency being lower than the isosbestic frequency of the dye;
a microprocessor that stores and executes program instructions to determine a GIIC value based on the first and second measured fluorescence intensities, and to determine a performance of the analyte sensor based on the determined GIIC value; and
an output device electrically connected to the microprocessor that receives the GIIC value from the microprocessor and provides an output indicative of the determined performance;
wherein said microprocessor executes program instructions to calculate a glucose independent intensity according to the following equation;
GII=(KDg/KDb−
1)*Fb*Fg+Fb*(Fginf−
(KDg/KDb)*Fg0)+Fg(Fb0−
(KDg/KDb)*Fbinf)whereGII is the glucose independent intensity;
Fb is the measured intensity of the first frequency component;
Fg is the measured intensity of the second frequency component;
KDg is the apparent dissociation constant determined when using only the second frequency component;
KDb is the apparent dissociation constant determined when using only the first frequency component;
Fginf is the intensity of the second frequency component at saturated concentration;
Fg0 is the intensity of the second frequency component at zero concentration;
Fbinf is the intensity of the first frequency component at saturated concentration; and
Fb0 is the intensity of the first frequency component at zero concentration.
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Abstract
A system and method are provided for utilizing radiometric fluorescence detection to determine a glucose independent concentration value when measuring frequency bands that do not contain the system isosbestic point. Preferably two bands are chosen such that a first band is below the system isosbestic point, and a second band is above the system isosbestic point, and both points are sufficiently far from the frequency endpoints to maximize the signal to noise ratio.
57 Citations
9 Claims
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1. A system for performing a diagnostic test on an analyte sensor, comprising:
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a sensing element comprising a polyethylene glycol matrix suspended analyte binding protein element introduced to an analyte environment, said binding protein labeled with a dye fluorescing with an intensity spectrum related to a concentration of said analyte concentration in said environment;
the sensing element disposed at a distal end of an optical conduit;an excitation source at a proximal end of the optical conduit for supplying excitation energy to the optical conduit and a fluorescence intensity measuring device comprising first and second detectors for measuring fluorescence intensity at first and second respective frequencies, the first frequency being higher than an isosbestic frequency of the dye, and the second frequency being lower than the isosbestic frequency of the dye; a microprocessor that stores and executes program instructions to determine a GIIC value based on the first and second measured fluorescence intensities, and to determine a performance of the analyte sensor based on the determined GIIC value; and an output device electrically connected to the microprocessor that receives the GIIC value from the microprocessor and provides an output indicative of the determined performance; wherein said microprocessor executes program instructions to calculate a glucose independent intensity according to the following equation;
GII=(KDg/KDb−
1)*Fb*Fg+Fb*(Fginf−
(KDg/KDb)*Fg0)+Fg(Fb0−
(KDg/KDb)*Fbinf)where GII is the glucose independent intensity; Fb is the measured intensity of the first frequency component; Fg is the measured intensity of the second frequency component; KDg is the apparent dissociation constant determined when using only the second frequency component; KDb is the apparent dissociation constant determined when using only the first frequency component; Fginf is the intensity of the second frequency component at saturated concentration; Fg0 is the intensity of the second frequency component at zero concentration; Fbinf is the intensity of the first frequency component at saturated concentration; and Fb0 is the intensity of the first frequency component at zero concentration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for performing a diagnostic test on a glucose sensor, comprising:
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a sensing element comprising a polyethylene glycol suspended glucose binding protein element suspended within a matrix for introduction to a glucose environment, said binding protein labeled with a dye fluorescing with an intensity spectrum related to a concentration of said analyte concentration in said environment;
the sensing element disposed at a distal end of an optical conduit;an excitation source at a proximal end of the optical conduit for supplying excitation energy to the optical conduit and a fluorescence intensity measuring device comprising first and second detectors for measuring fluorescence intensity at first and second respective frequencies, the first frequency being higher than an isosbestic frequency of the dye, and the second frequency being lower than the isosbestic frequency of the dye; a microprocessor that stores and executes program instructions to determine a GIIC value based on the first and second measured fluorescence intensities, and for determining a performance of the glucose sensor based on the determined GIIC value; and an output device device electrically connected to the microprocessor that receives the GIIC value from the processor and to provide an output indicative of the determined performance; wherein said microprocessor executes program instructions to calculate a glucose independent intensity according to the following equation;
GII=(KDg/KDb−
1)*Fb*Fg+Fb*(Fginf−
(KDg/KDb)*Fg0)+Fg(Fb0−
(KDg/KDb)*Fbinf)where GII is the glucose independent intensity; Fb is the measured intensity of the first frequency component; Fg is the measured intensity of the second frequency component; KDg is the apparent dissociation constant determined when using only the second frequency component; KDb is the apparent dissociation constant determined when using only the first frequency component; Fginf is the intensity of the second frequency component at saturated concentration; Fg0 is the intensity of the second frequency component at zero concentration; Fbinf is the intensity of the first frequency component at saturated concentration; and Fb0 is the intensity of the first frequency component at zero concentration.
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Specification