System for determining the concentration of an analyte

• US 8,160,666 B2
• Filed: 10/12/2007
• Issued: 04/17/2012
• Est. Priority Date: 02/11/2002
• Status: Active Grant

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC (Bayer AG)
• Inventors: Rebec, Mihailo V., Smous, James E., Brown, Steven D., Tan, Hu-Wei
• Primary Examiner(s): Winakur, Eric
• Application Number:
  US11/974,477
• Publication Number:
  US 20080045821A1
• Time in Patent Office: 1,649 Days
• Field of Search: 600/310, 600/316, 600/322, 600/473, 250/338.1, 250/341.3
• 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
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 2201/067 Electro-optic, magneto-optic, acousto-optic elements

Abstract

A system for determining the concentration of an analyte in at least one body fluid in body tissue comprises an infrared light source, a body tissue interface, a detector, and a central processing unit. The body tissue interface is adapted to contact body tissue and to deliver light from the infrared light source to the contacted body tissue. The detector is adapted to receive spectral information corresponding to infrared light transmitted through the portion of body tissue being analyzed and to convert the received spectral information into an electrical signal indicative of the received spectral information. The central processing unit is adapted to compare the electrical signal to an algorithm built upon correlation with the analyte in body fluid, the algorithm adapted to convert the received spectral information into the concentration of the analyte in at least one body fluid.

Claims

1. A system for determining the concentration of an analyte in at least one body fluid in body tissue, the system comprising:

an infrared light source;

a body tissue interface to deliver light from the infrared light source to the body tissue;

a load cell for measuring an amount of pressure applied to the body tissue;

a detector adapted to receive spectral information corresponding to the infrared light reflected from the at least one body fluid and to convert the received spectral information into a signal indicative of the spectral information; and

a central processing unit adapted to use the signal indicative of the spectral information and the measured pressure from the load cell in an algorithm built upon correlation with the analyte in body fluid, the algorithm adapted to convert the received spectral information into the concentration of the analyte in at least one body fluid.

2. The system of claim 1 further including an index matching medium disposed between the body tissue interface and the received body tissue, wherein the infrared light delivered to the body tissue and reflected by the body tissue passes through the index matching medium.

3. The system of claim 1 wherein the body tissue interface further includes a clamping device having two plates for contacting the body tissue, at least one of the two plates including a temperature control element for controlling the temperature of the body tissue contacted by the clamping device.

4. The system of claim 3 wherein the temperature control element is a thermal electric device.

5. The system of claim 3 wherein the temperature control element is adapted to control the temperature of the body tissue to a temperature ranging between about 50 °

F. and 105 °

F.

6. The system of claim 5 wherein the temperature control element is adapted to control the temperature of the body tissue to a temperature ranging between about 99 °

F. and 101 °

F.

7. The system of claim 1 wherein the wavelength ranges between approximately 1400 nanometers and 2500 nanometers.

8. The system of claim 1 further comprising an acoustic optical tunable filter for receiving the reflected infrared light and outputting predetermined wavelength bands of the reflected light to the detector.

9. A method for determining the concentration of an analyte in at least one body fluid in body tissue, the method comprising the acts of:

contacting body tissue to be analyzed;

compressing the contacted body tissue;

measuring an amount of pressure applied to the body tissue being analyzed;

controlling the temperature of the body tissue such that the body tissue is maintained at a substantially uniform temperature;

directing infrared light into the body tissue;

detecting infrared light reflected from the body tissue;

analyzing the detected spectral information corresponding to the infrared light using an algorithm built upon correlation with the analyte in the at least one body fluid, the algorithm being adapted to use the detected spectral information corresponding to the infrared light to convert into the concentration of the analyte in at least one body fluid; and

determining the concentration of the analyte in at least one body fluid using the measured pressure to correct for spectral information.

10. The method of claim 9 further including disposing an index matching medium on a surface of body tissue.

11. The method of claim 9 wherein the controlling the temperature further comprises controlling the body tissue to a temperature ranging between about 99 °

F. and about 101 °

F.

12. The method of claim 11 wherein directing infrared light further comprises directing monochromatic light onto the body tissue.

13. The method of claim 12 wherein directing infrared light further comprises:

directing the infrared light to an acoustic optical tunable filter; and

outputting a monochromatic beam of light from the acoustic optical tunable filter onto the contacted body tissue.

14. The method of claim 9 wherein the directing of monochromatic light further comprises directing a beam of monochromatic light having a wavelength ranging between approximately 750 nanometers and approximately 11,000 nanometers.

15. The method of claim 14 wherein the wavelength ranges between approximately 1400 nanometers and 2500 nanometers.

16. The method of claim 9 wherein the at least one body fluid is plasma.

17. The method of claim 9 wherein the at least one body fluid is interstitial fluid.

18. The method of claim 9 wherein the analyte is glucose.

19. A method for determining the concentration of an analyte in at least one body fluid in body tissue, the method comprising the acts of:

contacting body tissue to be analyzed;

compressing the contacted body tissue;

directing infrared light into the body tissue;

detecting infrared light reflected from the body tissue;

measuring pressure applied to the body tissue;

measuring temperature of the body tissue;

analyzing the detected spectral information corresponding to the infrared light using an algorithm built upon correlation with the analyte in the at least one body fluid, the algorithm being adapted to use the detected spectral information corresponding to the infrared light into the concentration of the analyte in at least one body fluid; and

determining the concentration of the analyte in at least one body fluid using the measured pressure and temperature to correct for spectral information.

20. The method of claim 19 further including disposing an index matching medium on a surface of body tissue.

21. The method of claim 19 wherein directing infrared light further comprises selectively directing monochromatic light onto the body having a wavelength ranging between approximately 750 nanometers and approximately 11,000 nanometers.

22. The method of claim 19 wherein the wavelength ranges between approximately 1400 nanometers and 2500 nanometers.

23. The method of claim 19 wherein the analyte is glucose.

24. The method of claim 19 wherein the pressure and temperature are controlled so as to obtain desirable spectral information.

25. A method for determining the concentration of an analyte in at least one body fluid in body tissue, the method comprising the acts of:

disposing an index matching medium on a surface of body tissue;

contacting body tissue to be analyzed;

compressing the contacted body tissue;

directing infrared light into the body tissue;

detecting infrared light reflected from the body tissue after passing through the index matching medium;

measuring pressure applied to the body tissue being analyzed;

analyzing the detected reflected light using an algorithm built upon correlation with the analyte in the body fluid, the algorithm being adapted to convert the detected reflected light into the concentration of the analyte in at least one body fluid; and

determining the concentration of the analyte in at least one body fluid using the measured pressure to correct for spectral information.