REFLECTANCE CALIBRATION OF FLUORESCENCE-BASED GLUCOSE MEASUREMENTS

• US 20140330098A1
• Filed: 07/14/2014
• Published: 11/06/2014
• Est. Priority Date: 07/29/2009
• Status: Abandoned Application

• Current Assignee: Cercacor Laboratories
• Original Assignee: Cercacor Laboratories
• Inventors: MERRITT, SEAN, LAMEGO, MARCELO
• Application Number:
  US14/330,273
• Publication Number:
  US 20140330098A1
• Time in Patent Office: Days
• US Class Current: 600/316
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters

Abstract

A noninvasive or minimally invasive procedure and system for measuring blood glucose levels is disclosed. A set of photodiodes detects the fluorescence and reflectance of light energy emitted from one or more emitters, such as LEDs, into a patient'"'"'s skin. In an embodiment, small molecule metabolite reporters (SMMRs) that bind to glucose are introduced to the measurement area to provide more easily detected fluorescence.

Claims

1. A method of measuring a glucose level, comprising:

directing a first excitation wavelength at a first skin location within a stratum corneum skin layer;

measuring a first fluorescence intensity from the first skin location;

measuring a first reflectance intensity from the first skin location; and

calibrating the first fluorescence intensity using the first reflectance intensity to determine a first glucose level.

2. The method of claim 1, further comprising delivering to the first skin location a quantity of small molecule metabolite reporters (SMMRs) configured to bind to glucose.

3. The method of claim 2, wherein delivering to the first skin location the quantity of SMMRs comprises at least one of brushing and wiping the SMMRs to the first skin location.

4. The method of claim 1, wherein calibrating the first fluorescence intensity comprises calculating a first ratio, wherein a numerator of the first ratio is the first fluorescence intensity and a denominator of the first ratio is the first reflectance intensity.

5. The method of claim 1, further comprising:

directing a second excitation wavelength at a second skin location within the stratum corneum skin layer;

measuring a second fluorescence intensity from the second skin location; and

measuring a second reflectance intensity from the second skin location.

6. The method of claim 5, wherein no small molecule metabolite reporters (SMMRs) are delivered the second skin location.

7. The method of claim 5, further comprising calibrating the first glucose level with the second fluorescence intensity and the second reflectance intensity.

8. The method of claim 7, wherein calibrating the first glucose level comprises:

calculating a second ratio comprising the second fluorescence intensity and the second reflectance intensity; and

calculating a third ratio comprising the first ratio as a numerator of the third ratio and the second ratio as a denominator of the third ratio.

9. The method of claim 1, wherein directing the first excitation wavelength at the first skin location comprises directing a wavelength from 320 nanometers (nm) to 390 nm.

10. A system for measuring a glucose level, comprising:

an excitation module configured to direct a first excitation signal at a first skin location within a stratum corneum skin layer for probing a fluorophore at the first skin location;

a fluorescence measurement module configured to measure a first fluorescence intensity emitted from the first skin location;

a reflectance measurement module configured to measure a first reflectance intensity emitted from the first skin location; and

a glucose calculation module configured to determine a first measured glucose level using the first fluorescence intensity and the first reflectance intensity.

11. The system of claim 10, wherein the first skin location comprises small molecule metabolite reporters (SMMRs), and wherein the first excitation signal is configured to probe the SMMRs.

12. The system of claim 10, wherein the excitation module is configured to emit the first excitation signal at a wavelength of 320 nanometers (nm) to 390 nm.

13. The system of claim 12, wherein the excitation module further comprises two light emitting diodes (LEDs) each configured to emit the first excitation signal at the wavelength of 320 nanometers (nm) to 390 nm.

14. The system of claim 10, wherein the glucose calculation module is further configured to calibrate the first fluorescence intensity using the first reflectance intensity by calculating a first ratio, wherein a numerator of the first ratio is the first fluorescence intensity and a denominator of the first ratio is the first reflectance intensity.

15. The system of claim 10, wherein the excitation module is further configured to direct a second excitation signal at a second skin location within the stratum corneum skin layer, wherein the fluorescence measurement module is further configured to measure a second fluorescence intensity from the second skin location;

and wherein the reflectance measurement module is further configured to measure a second reflectance intensity from the second skin location.

16. The system of claim 15, wherein the second excitation signal has a same wavelength as the first excitation signal.

17. The system of claim 15, wherein the glucose calculation module is further configured to calibrate the first measured glucose level using the second fluorescence intensity and the second reflectance intensity by calculating a second ratio using the second fluorescence intensity and the second reflectance intensity.

18. The system of claim 15, wherein the second skin location is a background skin location lacking small molecule metabolite reporters (SMMRs).

19. The system of claim 10, wherein the calculation module is further configured to compare the calibrated first measured glucose level with a calibration curve for determining a glucose reading for the body.

20. The system of claim 10, wherein the fluorescence measurement module is configured to measure emitted wavelengths at 430 nanometers (nm) and 440 nm.