Non-Invasive System and Method for Measuring an Analyte in the Body

• US 20090062632A1
• Filed: 04/13/2006
• Published: 03/05/2009
• 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.
• Granted Patent: US 8,180,422 B2
• Time in Patent Office: Days
• 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 a fluid sample, the system comprising:

a light source delivering light within a predetermined wavelength range;

a detector adapted to receive spectral information corresponding to light returned from said fluid sample 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 said analyte in said fluid sample, the central processing unit controlling the light source and varying the intensity and timing of the delivery of said light within said predetermined wavelength range to improve the accuracy of conversion of the received spectral information into concentration of said analyte in said fluid sample.

2. The system of claim 1, wherein said light source is a series of beams of monochromatic light that scan across the predetermined wavelength range.

3. The system of claim 2, further comprising a reference detector adapted to receive a portion of said series of beams of monochromatic light and to convert the received light into a reference electrical signal.

13. The system of claim 1, wherein said light source delivers to said sample predetermined wavelengths of light at predetermined intensities and said spectral information returned from said sample is processed to provide spectral information at wavelengths where said analyte is more readily distinguished from interfering substances.

14. The system of claim 1, wherein said light source contains information that is used to correct for the effect on the light spectra of the sample, light delivery and collection systems, and detector.

15. The system of claim 1, wherein said light source contains information that corrects for changes in the analyte-related spectrum by the sample, light delivery and collection methods, and detector distortions.

16. The system of claim 1, wherein said light source contains concentration-related spectra that correct for non-linear responses of the analyte.

4-12. -12. (canceled)

17. A method for determining the concentration of an analyte in a fluid sample, the method comprising the acts of:

delivering light within a predetermined wavelength range from a light source;

receiving spectral information corresponding to light returned from said fluid sample;

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 fluid sample; and

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

18. 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.

19. The system of claim 18, wherein said infrared light source is an acoustic optical tunable filter (AOTF).

20. The system of claim 19, wherein said wavelength range is from about 1400 nanometers to about 2500 nanometers.

21. The system of claim 18, wherein said body fluid is extracellular fluid and said analyte is glucose.

22-33. -33. (canceled)

34. 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.

35-50. -50. (canceled)

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

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

contacting body tissue using a body tissue interface;

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

receiving light reflected from the body fluid;

converting the received reflected light into an electrical signal indicative of the received reflected light;

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

converting the received spectral information into the concentration of the analyte in said body fluid,

wherein the central processing unit controls said infrared light source and varies the intensity and timing of the delivery of said monochromatic light with the predetermined wavelength range to improve the accuracy of conversion of the received spectral information into concentration of said analyte in said fluid.

52. The method of claim 51 further including disposing 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.

53. The method of claim 51, wherein the infrared light has a wavelength ranging between approximately 1400 nanometers and approximately 2500 nanometers.

54. The method of claim 51, wherein the intensity of said monochromatic light is uniform over said predetermined wavelength range.

55. The method of claim 51, 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.

56. The method of claim 51, wherein said monochromatic light contains information that is used to correct for the effect on the light spectra of the sample, light delivery and collections systems and detector distortions.

57. The method of claim 51, wherein said light source contains concentration-related spectra that correct for non-linear responses of the analyte.