Body fluid constituent measurement utilizing an interference pattern

• US 5,146,091 A
• Filed: 12/04/1990
• Issued: 09/08/1992
• Est. Priority Date: 04/19/1990
• Status: Expired due to Fees

• Current Assignee: Integ Incorporated (Johnson & Johnson)
• Original Assignee: Inomet, Inc.
• Inventors: Knudson, Mark B.
• Primary Examiner(s): Fields, Carolyn E.
• Assistant Examiner(s): BEYER, JAMES
• Application Number:
  US07/621,771
• Time in Patent Office: 644 Days
• Field of Search: 356/41, 356/39, 250/341, 128/633, 128/664
• US Class Current: 250/341.6
• 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 5/6817 Ear canal

Abstract

An apparatus is disclosed for measuring a body fluid constituent. In a preferred embodiment, the apparatus directs light against a tissue containing the constituent and detects an amount of light absorption in a reflected light from said tissue. The amount of absorption is analyzed to determine the amount of constituent in the blood within the tissue.

Claims

1. An apparatus for determining a level of a constituent in a body fluid contained within a body tissue, said apparatus comprising:

light generating means for generating a beam of a source light including at least one wavelength absorbable by said constituents;

light detecting means for receiving light and measuring an intensity of said light;

beam splitting and directing means for splitting said source beam into at least a reference beam and a test beam with said reference beam directed toward said light detecting means and with said test beam directed toward said tissue for said test beam to be modified by at least partial absorption of said at least one wavelength by said constituent within said tissue and with said modified light reflected off said tissue toward said light detecting means, said modified light and said reference light at said light detecting means cooperating to generate an interference pattern corresponding at least in part to a level of said constituent within said tissue;

processing means for receiving an output of said light detecting means and calculating said level of said constituent in response to said output.

2. An apparatus according to claim 1 comprising means for moving said tissue to vary an angle between said tissue and said light source.

3. An apparatus according to claim 1 comprising means for measuring a distance from said apparatus to said tissue.

4. An apparatus according to claim 1 comprising means for controlling a temperature of said tissue.

5. An apparatus according to claim 1 wherein said constituent is glucose.

6. An apparatus according to claim 1 wherein said light generating means, said light detecting means said beam splitting and directing means and said processing means are elements of a Fourier transform infrared spectrometry apparatus having said tissue as a moving mirror for said apparatus.

7. An apparatus for determining a level of a constituent in a body fluid contained within a tympanic membrane, said apparatus comprising:

light generating means for generating a beam of a source light including at least one wavelength absorbable by said constituents;

light detecting means for receiving light and measuring an intensity of said light;

beam splitting and directing means for splitting said source beam into at least a reference beam and a test beam with said reference beam directed toward said light detecting means and with said test beam directed toward said membrane for said test beam to be modified by at least partial absorption of said at least one wavelength by said constituent with said membrane and with said modified light reflected off said membrane toward said light detecting means, said modified light and said reference light at said light detecting means cooperating to generate an interference pattern corresponding at least in part to a level of said constituent within said membrane;

processing means for receiving an output of said light detecting means and calculating said level of said constituent in response to said output.

8. An apparatus according to claim 7 comprising means for moving said membrane to vary an angle between said membrane and said light source.

9. An apparatus according to claim 7 comprising means for measuring a distance from said apparatus to said membrane.

10. An apparatus according to claim 7 comprising means for controlling a temperature of said membrane.

11. An apparatus according to claim 7 wherein said constituent is glucose.

12. An apparatus to claim 7 wherein said light generating means, said light detecting means, said beam splitting and directing means and said processing means are elements of a Fourier transform infrared spectrometry apparatus having said membrane as a moving mirror for said apparatus.