Non-invasive blood glucose measurement techniques

• US 6,477,393 B1
• Filed: 07/19/2000
• Issued: 11/05/2002
• Est. Priority Date: 07/19/2000
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Chou, Mau-Song
• Primary Examiner(s): Hindenburg, Max
• Assistant Examiner(s): KREMER, MATTHEW J
• Application Number:
  US09/619,588
• Time in Patent Office: 839 Days
• Field of Search: 600/309-310, 600/316, 600/319, 600/322, 600/326, 600/365, 356/39-42
• US Class Current: 600/316
• 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

Non-invasive measurement of blood glucose is achieved by transmitting a ring of electromagnetic radiation to the surface of a subject (S) by a ring illuminator (22). The radiation diffuses into the subject illuminated and emits a portion of the radiation in area (E2) displaced from the illuminated area. A CCD camera (40) collects at least a portion of the emitted radiation and generates detection signals which are processed by a processor (100) in order to measure blood glucose concentration. The processing may be synchronized with the heart beat of the subject by an electrocardiogram (74).

Claims

1. Apparatus for noninvasive measurement of glucose concentration in a biological matrix of a subject comprising in combination:

a source of electromagnetic radiation generating an illuminated first portion of surface of the subject, said first portion comprising a geometric element defined by moving a point in a path, said illuminated first portion resulting in a part of said radiation being emitted from said surface in a second portion of the surface displaced from the first portion, said first portion comprising one of a straight line and a closed curve defining a center point;

a detector or detectors defining a field of view and responsive to said radiation emitted from at least a part of the second portion within the field of view to generate detection signals, said field of view defining one of a rectangle perpendicular to said straight line and a portion of the area within the inside of said closed curve passing through the center point; and

a processor analyzing said detection signals to measure blood glucose of the subject.

2. Apparatus, as claimed in claim 1, wherein the source comprises radiation having wavelengths in the range of 400 to 1600 nanometers.

3. Apparatus, as claimed in claim 1, wherein the detector comprises a camera, a CCD camera, a CMOS or near-infrared imager, or photodiode detectors.

4. Apparatus, as claimed in claim 3, wherein the subject comprises a heart and further comprising a trigger for said detector responsive to signals generated by said heart.

5. Apparatus, as claimed in claim 3, wherein the detector further comprises a graded neutral density filter.

6. Apparatus, as claimed in claim 1, wherein the processor compares said detection signals to a reflectance profile based on calibration measurements from conventional blood glucose measurements of said subject.

7. Apparatus, as claimed in claim 1, wherein the geometric element defines a straight line, with the width of the line less than 0.3 mm.

8. Apparatus, as claimed in claim 1, wherein the processor compares said detection signals to one or more reflectance profiles.

9. Apparatus, as claimed in claim 1, wherein the rectangle passes through the middle half of the straight line.

10. Apparatus, as claimed in claim 1, wherein the processor analyzes the detection signals resulting from the portions of the field of view receiving radiation displaced 0 to 30 mm, from said straight line.

11. Apparatus, as claimed in claim 1, wherein the processor analyzes the detection signals resulting from the portions of the field of view receiving radiation from the portion of the area inside said curve.

12. A noninvasive method of measuring blood glucose of a subject comprising in combination:

illuminating with electromagnetic radiation a first portion of a surface of the subject comprising a geometric element defined by moving a point in a path, said illuminated first portion resulting in a part of said radiation being emitted from a second portion of said surface displaced from the first portion, said first portion comprising one of a straight line and a closed curve defining a center point;

generating detection signals responsive to said radiation emitted from at least a part of the second portion within a field of view, said field of view defining one of a rectangle perpendicular to said straight line and a portion of the area within the inside of said closed curve passing through the center point; and

analyzing said detection signals to measure the blood glucose of the subject.

13. A method, as claimed in claim 12, wherein said illuminating comprises illuminating with radiation having wavelengths in the range of 400 to 1600 nanometers.

14. A method, as claimed in claim 12, wherein said generating comprises digital imaging.

15. A method, as claimed in claim 14, and further comprising triggering said generating responsive to signals generated by a heart beat oF said subject.

16. A method, as claimed in claim 15, wherein said generating further comprises graded neutral density filtering.

17. A method, as claimed in claim 12, wherein said straight line has a width of less than 1 mm.

18. A method, as claimed in claim 12, wherein the rectangle passes through the middle half of said straight line.

19. A method, as claimed in claim 12, wherein said analyzing comprises analyzing the detection signals resulting from the portions of the field of view receiving radiation displaced 0 to 15 mm from the straight line.

20. A method, as claimed in claim 12, wherein the analyzing comprises comparing said detection signals to one or more reflectance profiles.

21. A method, as claimed in claim 12, wherein the analyzing comprises comparing said detection signals to a reflectance profile based on calibration measurements from conventional blood glucose measurements of said subject.