NONINVASIVE MEASUREMENT OF ANALYTE CONCENTRATION USING A FIBERLESS TRANSFLECTANCE PROBE

• US 20130267799A1
• Filed: 04/06/2012
• Published: 10/10/2013
• Est. Priority Date: 04/06/2012
• Status: Abandoned Application

• Current Assignee: Grove Instruments, Inc.
• Original Assignee: Grove Instruments, Inc.
• Inventors: Harjunmaa, Hannu, Kun, Stevan
• Application Number:
  US13/441,467
• Publication Number:
  US 20130267799A1
• Time in Patent Office: Days
• US Class Current: 600/316
• CPC Class Codes: A61B 2560/0431 Portable apparatus, e.g. comprising a handle or case
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/146 for optical coupling
• CPC Class Codes: A61B 5/0051 by applying vibrations
• 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
• CPC Class Codes: A61B 5/6816 Ear lobe
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: F04C 2270/041 Controlled or regulated
• CPC Class Codes: G01N 2021/3148 using three or more wavelengths
• CPC Class Codes: G01N 2021/4709 Backscatter
• CPC Class Codes: G01N 2021/475 Bifurcated bundle
• CPC Class Codes: G01N 21/1717 with a modulation of one or more physical properties of the sample during the optical investigation, e.g. electro-reflectance
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 21/474 Details of optical heads therefor, e.g. using optical fibres
• CPC Class Codes: G01N 21/49 within a body or fluid
• CPC Class Codes: G01N 2201/0221 Portable; cableless; compact; hand-held
• CPC Class Codes: G01N 2201/0631 Homogeneising elements
• CPC Class Codes: G01N 2201/0636 Reflectors
• CPC Class Codes: G01N 33/49 : Blood chemical methods for determining blood cell populations G01N33/5094; chemical analysis of blood groups or blood types G01N33/80

Abstract

A method and apparatus for noninvasively measuring the concentration of a target analyte in a sample matrix using a fiberless transflectance probe is described. It includes directing a beam of electromagnetic radiation, consisting of at least two components of different wavelengths, to the sample matrix and conducting the backscattered radiation to a detector which outputs a signal indicative of the differential absorption of the two wavelengths in the sample matrix. The transflectance probe comprises a tapered tubular housing having an inner reflective surface, an optical rod having an outer reflective surface, and a detection window which serves as an interface between the probe and the surface of the sample matrix. The method and apparatus described are particularly useful in measuring the concentration of glucose in tissue containing blood.

Claims

1. An apparatus for noninvasively interrogating a target region for measuring an amount of a target analyte, comprising:

a source for generating a combined beam of electromagnetic radiation including at least two repetitive periods of radiation having different wavelengths, at least two of the wavelengths having different absorption coefficients for the target analyte;

a detector arranged to detect a portion of the radiation backscattered by the target region, the detector generating an output signal proportional to the detected intensity of the combined beam at each of the two repetitive periods of radiation; and

a fiberless transflectance probe for directing the beam of electromagnetic radiation to the target region and conducting the backscattered radiation to the detector;

wherein the fiberless transflectance probe comprises a tapered tubular housing with an inner reflective surface, a cylindrical optical rod with an outer reflective surface and a detection window through which the beam of electromagnetic radiation is transmitted to the target region.

2. The apparatus of claim 1, wherein the target region comprises a fluid.

3. The apparatus of claim 2, further comprising means for compressing and decompressing the target region to control the amount of fluid within the target region.

4. The apparatus of claim 3, wherein the means for compressing and decompressing the target region is a controllable mechanical device.

5. The apparatus of claim 2, further comprising means for obtaining an estimate of the amount of fluid within the sample matrix during a measurement.

6. The apparatus of claim 5, wherein the means for obtaining an estimate of the amount of fluid comprises a source for directing radiation at the target region, the radiation having a wavelength that is preferentially absorbed by a component of the fluid.

7. The apparatus of claim 6, wherein the radiation is green light.

8. The apparatus of claim 2, further comprising means for measuring a phase of pulsation of the fluid within the target region.

9. The apparatus of claim 8, wherein the means for measuring a phase of pulsation of the fluid within the target region comprises a source for directing radiation at the target region, the radiation having a wavelength that is preferentially absorbed by a component of the fluid.

10. The apparatus of claim 1, wherein the apparatus is a handheld unit comprising an on-board processor for calculating the concentration of the target analyte.

11. The apparatus of claim 10, further comprising a graphic display screen.

12. The apparatus of claim 10, further comprising a rechargeable battery.

13. The apparatus of claim 10, further comprising a memory for storing user instructions and measurement results.

14. The apparatus of claim 13, wherein the memory comprises a reference database.

15. The apparatus of claim 10, wherein the handheld unit can communicate with an external device using a wireless communication link.

16. The apparatus of claim 1, wherein the inner surface of the tubular housing is faceted to spread the radiation beam evenly on the target region.

17. The apparatus of claim 1, wherein the cylindrical optical rod is positioned perpendicularly in the center of the detection window.

18. The apparatus of claim 1, wherein the tubular housing is positioned around the cylindrical optical rod.

19. The apparatus of claim 2, wherein the fluid is blood and the target analyte measured is glucose.

20. A transflectance probe for measuring a property of a sample, comprising:

a detection window through which the sample is irradiated;

an optical rod with an outer reflective surface positioned perpendicular to the detection window;

a tapered tubular housing with an inner reflective surface positioned around the optical rod;

at least one light source for irradiating the sample; and

a detector positioned at the proximal end of the optical rod for detecting the light backscattered by the sample.

21. The transflectance probe of claim 20, wherein the cylindrical optical rod, the tubular housing and the detection window are comprised of quartz.

22. The transflectance probe of claim 20, wherein the tubular housing and the detection window are comprised of a thermoplastic polymer.

23. The transflectance probe of claim 22, wherein the tubular housing and the detection window are injection molded.

24. The transflectance probe of claim 20, wherein the outer surface of the optical rod is coated with a reflective coating.

25. The transflectance probe of claim 20, wherein the inner surface of the tubular housing is coated with a reflective coating.

26. The transflectance probe of claim 20, wherein the inner surface of the tubular housing is faceted.

27. The transflectance probe of claim 26, wherein the facets are in the form of convex cylinders.

28. The transflectance probe of claim 27, wherein the number of facets correspond to the number of light sources.

29. The transflectance probe of claim 20, wherein light from the at least one light source is transmitted to the sample by reflecting on the outer surface of the optical rod and the inner surface of the tubular housing.

30. The transflectance probe of claim 29, wherein the light backscattered by the sample is conducted to the detector through the optical rod.

31. The transflectance probe of claim 20, wherein the at least one light source comprises a laser diode.

32. The transflectance probe of claim 31, wherein the laser diode is mounted on a heat sink at the proximal end of the tubular housing.

33. A method of noninvasively interrogating a target region for measuring an amount of a target analyte, comprising the steps of:

providing a fiberless transflectance probe comprising a tapered tubular housing with an inner reflective surface, a detection window and an optical rod with an outer reflective surface positioned perpendicular to the detection window;

providing at least two light sources operating at two different wavelengths for generating a radiation beam consisting of at least two time multiplexed components;

transmitting the radiation beam to the target region by reflecting on the inner surface of the tubular housing and the outer surface of the optical rod;

conducting a backscattered beam from the target region to the detector by reflecting on the inner surface of the optical rod; and

providing a detector that detects the backscattered beam and produces an output signal indicative of the differential absorption of the two wavelengths by the target region.

34. The method of claim 33, wherein the tapered tubular housing is faceted to spread the radiation beam uniformly on the target region.

35. The method of claim 33, wherein the differential absorption signal is used to calculate the concentration of the target analyte.

36. The method of claim 33, wherein the analyte measured is glucose.

37. The method of claim 36, wherein the two wavelengths are about 1380 nm and about 1620 nm.

38. The method of claim 37, wherein the two wavelengths are 1385+/−

20 nm and 1630+/−

20 nm.