Non-invasive system and method for measuring an analyte in the body

• US 8,180,422 B2
• Filed: 04/13/2006
• Issued: 05/15/2012
• Est. Priority Date: 04/15/2005
• Status: Active Grant

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC (Bayer AG)
• Inventors: Rebec, Mihailo V.
• Primary Examiner(s): Winakur, Eric
• Assistant Examiner(s): Liu, Chu Chuan (JJ)
• Application Number:
  US11/918,537
• Publication Number:
  US 20090062632A1
• Time in Patent Office: 2,224 Days
• Field of Search: 600/310, 600/316, 600/322, 600/331, 600/335
• 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: G01J 2003/2866 Markers; Calibrating of scan
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0262 Constructional arrangements for removing stray light
• CPC Class Codes: G01J 3/0272 Handheld
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/1256 using acousto-optic tunable filter; acousto-optic elements or systems G02F1/11, G02F1/33
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/433 Modulation spectrometry; Derivative spectrometry
• CPC Class Codes: G01N 2021/3144 for oxymetry
• CPC Class Codes: G01N 2021/3185 typically monochromatic or band-limited
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence

Abstract

A system for determining an analyte concentration in a fluid sample (e.g., glucose) comprises a light source, a detector, and a central processing unit. The detector is adapted to receive spectral information corresponding to light returned from the fluid sample 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 is adapted to convert the received spectral information into the analyte concentration in body fluid. Spectral information is delivered from the central processing unit to the light source and used to vary the intensity and timing of the light to improve the accuracy of conversion into analyte concentration.

Claims

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

an infrared light source delivering substantially monochromatic light sequentially across a predetermined wavelength range;

a body tissue interface adapted to contact body tissue and to deliver light from said infrared light source to the contacted body tissue;

a detector adapted to receive spectral information corresponding to infrared light transmitted through the contacted body tissue and to convert the received spectral information into an electrical signal indicative of the received spectral information; and

a central processing unit adapted to compare the electrical signal to an algorithm built upon correlation with the analyte in the body fluid, the algorithm adapted to convert the received spectral information into the concentration of the analyte in the body fluid, said central processing unit controlling said infrared light source and varying the intensity and timing of the delivery of said monochromatic light within the predetermined wavelength range to improve the accuracy of conversion of the received spectral information into concentration of said analyte in said body fluid.

2. The system of claim 1, wherein said infrared light source is an acoustic optical tunable filter (AOTF) spectrometer.

3. The system of claim 1, wherein said wavelength range is from about 1400 nanometers to about 2500 nanometers.

4. The system of claim 1, wherein said body fluid is extracellular fluid and said analyte is glucose.

5. The system of claim 1, wherein said varying the intensity and timing of the delivery of said monochromatic light comprises modulating said infrared light source to correspond to a spaectrum obtained by interaction of the infrared light with a glucose sample.

6. The system of claim 1, wherein the intensity of said monochromatic light is uniform over said predetermined wavelength range.

7. The system of claim 1, wherein the intensity of said monochromatic light is varied across said predetermined wavelength range to provide spectral information received from said sample having uniform intensity across said predetermined wavelength range.

8. The system of claim 1, wherein said monochromatic light is delivered to said sample for predetermined periods of time at predetermined wavelengths.

9. The system of claim 8, wherein said monochromatic light is delivered to said sample at predetermined wavelengths where the signal-to-noise ratio is the greatest.

10. The system of claim 1 wherein the body tissue interface comprises a clamping device having two plates for contacting the body tissue.

11. The system of claim 10 wherein at least one of the two plates includes a temperature control element for controlling the temperature of the body tissue contacted by the clamping device.

12. The system of claim 1 wherein the wavelength ranges between 750 nanometers and 2500 nanometers.

13. A method for determining the concentration of an analyte in body fluid, the method comprising the acts of:

delivering substantially monochromatic light from an infrared light source sequentially across a predetermined wavelength range;

contacting body tissue with a body tissue interface;

delivering light from said infrared light source to the contacted body tissue;

receiving spectral information corresponding to infrared light transmitted through the contacted body tissue;

converting the received spectral information into an electrical signal indicative of the received spectral information;

comparing the electrical signal to an algorithm built upon correlation with the analyte in the body fluid using a central processing unit; and

converting the received spectral information into the concentration of the analyte in the body fluid using the algorithm, the central processing unit controlling said infrared light source and varying the intensity and timing of the delivery of said monochromatic light within the predetermined wavelength range to improve the accuracy of conversion of the received spectral information into concentration of said analyte in said body fluid.

14. The method of claim 13, wherein said analyte is glucose.

15. The method of claim 13 further including measuring pressure applied to the body tissue being analyzed;

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

16. The method of claim 13 further including measuring temperature of the body tissue and wherein determining the concentration of the analyte in at least one body fluid comprises using the measured temperature to correct for spectral information.

17. The method of claim 13 further including measuring pressure applied to the body tissue being analyzed;

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

18. The method of claim 13, wherein said wavelength range is from about 1400 nanometers to about 2500 nanometers.

19. The method of claim 13 further including compressing the body tissue.