Interferometric Method and Instrument for Measurement and Monitoring Blood Glucose Through Measurement of Tissue Refractive Index

• US 20070135693A1
• Filed: 12/13/2006
• Published: 06/14/2007
• Est. Priority Date: 12/14/2005
• Status: Active Grant

• Current Assignee: Newton Photonics, Inc.
• Original Assignee: Newton Photonics, Inc.
• Inventors: Cohen, Stephen, Melman, Paul
• Granted Patent: US 8,078,244 B2
• Time in Patent Office: Days
• US Class Current: 600/316
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14558 by polarisation

Abstract

A method of measuring glucose concentration in tissue includes measuring scattering coefficients of the tissue at each of a plurality of temperatures and at a selected tissue depth using optical coherence tomography, and determining the glucose concentration in interstitial fluid of the tissue as a function of the measured scattering coefficients.

Claims

1. A method of measuring glucose concentration in tissue comprising:

measuring scattering coefficients of the tissue at each of a plurality of temperatures and at a selected tissue depth using optical coherence tomography; and

determining the glucose concentration in interstitial fluid of the tissue as a function of the measured scattering coefficients.

2. The method of claim 1, further comprising automatically selecting a tissue depth at which to measure the scattering coefficients.

3. The method of claim 1, further comprising processing the function of the measured scattering coefficients to correct for non-constant intensity of a light beam used to measure the scattering coefficients.

4. The method of claim 1, further comprising processing the function of the measured scattering coefficients to compensate for birefringence of the tissue.

5. The method of claim 1, further comprising correcting for polarization distortion by measuring the scattering coefficients at a number of different polarizations.

6. The method of claim 1, further comprising correcting for polarization effects by measuring the scattering coefficient while rapidly varying the polarization state.

7. The method of claim 1, further comprising improving measurement accuracy of the glucose concentration by reducing speckle noise from the measured scattering coefficients.

8. The method of claim 1, further comprising improving measurement accuracy of the glucose concentration by performing volumetric averaging.

9. The method of claim 1, further comprising automatically performing a calibration of glucose concentration.

10. The method of claim 1, further comprising improving measurement accuracy of the glucose concentration by simultaneously reducing speckle noise and polarization distortion from the measured scattering coefficients and by performing volumetric averaging.

11. The method of claim 1, wherein the function of the measured scattering components includes separating the scattering coefficients into inactive components that do not change with glucose concentration and temperature and active components that do change with glucose concentration and temperature and utilizing the active components to determine the glucose concentration.

12. The method of claim 1, wherein the plurality of temperatures is applied to the tissue using a probe comprising:

a thermoelectric cooler/heater; and

a heat transfer device for rapid and uniform delivery of thermal energy across a surface of the tissue.

13. A system for measuring glucose concentration in tissue comprising:

a probe for applying a plurality of temperatures to the tissue; and

an instrument for measuring a scattering coefficient of light scattered by the tissue at each of the plurality of temperatures at a selected tissue depth using an optical coherence tomography system, and for determining the glucose concentration in interstitial fluid of the tissue as a function of the measured scattering coefficients.

14. The system of claim 13, further comprising a control function for automatically selecting a tissue depth at which to measure the scattering coefficients.

15. The system of claim 13, further comprising a signal processing function for processing the function of the measured scattering coefficients to correct for non-constant intensity of a light beam used to measure the scattering coefficients.

16. The system of claim 13, further comprising a signal processing function for processing the function of the measured scattering coefficients to compensate for birefringence of the tissue.

17. The system of claim 13, further comprising a polarization controller and a control function for correcting polarization distortion by measuring the scattering coefficients at a number of different polarizations of a reference beam used to measure the scattering coefficients.

18. The system of claim 13, further comprising a polarization controller and a control function for correcting for polarization effects by measuring the scattering coefficient while rapidly varying the polarization state in an interferometer arm of the optical coherence tomography system.

19. The system of claim 13, further comprising a signal processing function for improving measurement accuracy of the glucose concentration by reducing speckle noise from the measured scattering coefficients.

20. The system of claim 13, further comprising a signal processing function for improving measurement accuracy of the glucose concentration by performing volumetric averaging.

21. The system of claim 13, further comprising a polarization controller, a control function, and a signal processing function for improving measurement accuracy of the glucose concentration by simultaneously reducing speckle noise and polarization distortion and performing volumetric averaging.

22. The system of claim 13, further comprising a control function for performing an automatic calibration of glucose concentration.

23. The system of claim 13, further comprising a signal processing function for determining the glucose concentration by separating the scattering coefficients into inactive components that do not change with glucose concentration and temperature and active components that do change with glucose concentration and temperature and utilizing the active components to determine the glucose concentration.

24. The system of claim 13, wherein the probe comprises:

a thermoelectric cooler/heater; and

a heat transfer device for rapid and uniform delivery of thermal energy across a surface of the tissue.