Non-invasive blood analyte measuring system and method utilizing optical absorption

• US 20030050541A1
• Filed: 03/21/2002
• Published: 03/13/2003
• Est. Priority Date: 03/21/2001
• Status: Active Grant

• Current Assignee: Minformed LLC
• Original Assignee: Minformed LLC
• Inventors: Wuori, Edward R.
• Granted Patent: US 6,898,451 B2
• Time in Patent Office: Days
• US Class Current: 600/316
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• 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

A device and method for measuring the concentration of analytes in the blood of a portion of tissue. The device includes a sensor module, a monitor, and a processor (separate from or integral with the sensor module). The sensor module includes a radiation source for emitting radiation to the tissue; a collimator and narrow band filter for processing the radiation after it has transmitted through or been reflected by the tissue; and one or more sensors for sensing the transmitted or reflected radiation. The one or more sensors send a signal to the processor which algorithmically converts the radiation using linear regression or orthogonal functions to determine the concentration of one or more blood analytes. The device self-calibrates to eliminate error caused by variables such as skin character. The sensor module is integrated to reduce size and weight such that it is inobtrusive, and the monitor is compact for transport

Claims

1. An apparatus for the non-invasive measurement of the concentration of one or more blood analytes in the blood of a portion of tissue comprising:

a radiation source for generating a spectrum of radiation and transmitting the spectrum of radiation to the portion of tissue;

one or more sensors for detecting radiation from the portion of tissue over a broad spectrum and generating an output regarding the detected radiation; and

a processor for receiving the output from the sensors, the processor being configured for performing an algorithm to determine the concentration of one or more blood analytes in the blood of the portion of tissue.

2. The apparatus of claim 1, wherein the portion of tissue is an ear lobe.

3. The apparatus of claim 1, wherein the portion of tissue is a finger.

4. The apparatus of claim 1, further including a mounting device for positioning the radiation source and the one or more sensors in position for the radiation source to approximately adjacent the portion of tissue.

5. The apparatus of claim 4, wherein the portion of tissue has a first side and a second side, the mounting device positioning the radiation source and the one or more sensors approximately adjacent the first side.

6. The apparatus of claim 4, wherein the portion of tissue has a first side and a second side, the mounting device positioning the radiation source approximately adjacent the first side and the one or more sensors approximately adjacent the second side.

7. The apparatus of claim 1, wherein the one or more sensors are configured for detecting radiation reflected from the portion of tissue.

8. The apparatus of claim 1, wherein the one or more sensors are configured for detecting radiation transmitted through the portion of tissue.

9. The apparatus of claim 1, wherein the radiation source comprises a series of incandescent elements integrated onto a silicon chip.

10. The apparatus of claim 1, wherein the radiation source comprises a thermal radiator.

11. The apparatus of claim 10, wherein the thermal radiator comprises a metal positioned over a reflective heat shield.

12. The apparatus of claim 11, wherein the metal is tungsten.

13. The apparatus of claim 11, wherein the metal is tantalum

14. The apparatus of claim 1, further including a focusing device for focusing the radiation from the radiation source onto a measurement point on the portion of tissue.

15. The apparatus of claim 14, wherein the focusing device is a fresnel lens.

16. The apparatus of claim 1, further including a collimator.

17. The apparatus of claim 16, wherein the collimator is configured for collimation of 5 degrees or less.

18. The apparatus of claim 1, wherein the one or more sensors comprise a spectrometer capable of detecting near infrared radiation.

19. The apparatus of claim 18, wherein the one or more sensors are capable of detecting near infrared regions of wavelengths of about 700 nm to about 2500 nm.

20. The apparatus of claim 1, wherein the apparatus is adapted to detect blood glucose with accuracy within 10% of the actual level of blood glucose.

21. The apparatus of claim 1, wherein the apparatus is adapted to detect blood lactate with accuracy within 10% of the actual level of blood lactate.

22. The apparatus of claim 1, wherein the sensors comprise direct silicon sensors sensitive to radiation of a wavelength range from about 0.4 to 1.1 microns and infrared sensors sensitive to radiation of a wavelength range from 1 to 10 microns.

23. The apparatus of claim 22, wherein the sensors further comprise an array of approximately 1024 elements.

24. The apparatus of claim 22, wherein the direct silicon sensors comprise photodiodes.

25. The apparatus of claim 22, wherein the direct silicon sensors comprise charge coupled device arrays.

26. The apparatus of claim 25, wherein the charge coupled device arrays further comprise a plurality of elements sensitive to differing portions of a wavelength range of about 0.4 to 1.1 microns.

27. The apparatus of claim 22, wherein the infrared sensors are selected from the group consisting of extrinsic silicon, pyroelectric, photoconductor, and thermocouple sensors.

28. The apparatus of claim 22, wherein the infrared sensors are thermocouples comprising two layers of metal and a layer of gold black.

29. The apparatus of claim 28, wherein one of the metal layers is a nickel-chromium alloy.

30. The apparatus of claim 28, wherein one of the metal layers is a nickel-copper alloy.

31. The apparatus of claim 1, further including a filter for separating radiation from the portion of tissue into various wavelengths, the filter being positioned such that the radiation from the tissue passes through the filter prior to detection by the one or more sensors.

32. The apparatus of claim 31, wherein the filter is an optical narrow-band filter having a passband of about 0.22 percent of its center wavelength or frequency.

33. The apparatus of claim 31, wherein the filter is a Fabry-Perot narrow band interference filter comprising a dielectric film between two metal films.

34. The apparatus of claim 31, wherein the dielectric film has a graded thickness.

35. The apparatus of claim 34, wherein the dielectric film has a short wavelength end with a thickness of about 100 nm and a long wavelength end with a thickness of about 2.5 microns.

36. The apparatus of claim 35 further comprising a planarizing layer positioned between the narrow band interference filter and the one or more sensors.

37. The apparatus of claim 1, wherein the processor is configured for wirelessly receiving the output from the sensors

38. The apparatus of claim 37, further including an RF transmitter for communicating the output from the sensors to the processor.

39. The apparatus of claim 1, wherein the processor is a CMOS microprocessor.

40. The apparatus of claim 39, wherein the CMOS microprocessor uses a Boolean algorithm for processing the output.

41. The apparatus of claim 1, further including a display for displaying the concentration of the one or more blood analytes.

42. The apparatus of claim 41, wherein the display is a liquid crystal display.

43. The apparatus of claim 1, wherein the blood analytes are selected from the group consisting of lactate, glucose, insulin, ethanol, triglycerides, albumin, proteins, hemoglobin, immunoglobulins, cholesterol, and urea.

44. A system for the continuous, non-invasive measurement of the concentration of one or more blood analytes in a perambulatory human, comprising:

a sensor module including a radiation source and one or more sensors, the radiation source being configured for generating radiation to the portion of tissue, and the one or more sensors being adapted for sensing radiation from the tissue as analyte spectra, and a transmitter for transmitting the analyte spectra to a processor, the sensor module being compact;

a processor for receiving the analyte spectra from the sensor module, the processor being adapted for processing the analyte spectra to determine the concentration of one or more blood analytes; and

a lightweight monitor for displaying the concentration of the one or more blood analytes.

45. The system of claim 44, wherein the processor is integral with the sensor module.

46. The system of claim 44, wherein the sensor module comprises two chips, the radiation source being positioned on one of the chips and the one ore more sensors being positioned on the other chip.

47. The system of claim 44, wherein the portion of tissue has a first side and a second side, one chip being configured for positioning approximately adjacent the first side, the other chip being configured for positioning approximately adjacent the second side.

48. The system of claim 44, wherein the one or more sensors are adapted for sensing radiation transmitted through the portion of tissue.

49. The system of claim 44, wherein the sensor module comprises one chip, the radiation source and the one or more sensors being positioned on the chip.

50. The system of claim 49, wherein the portion of tissue has a first side and a second side, the chip being configured for positioning approximately adjacent either side.

51. The system of claim 49, wherein the one or more sensors are configured for sensing radiation reflected from the portion of tissue.

52. An apparatus capable of attachment to an ear lobe for the non-invasive measurement of the concentration of one or more blood analytes comprising:

a radiation source for generating a spectrum of radiation and transmitting the spectrum of radiation to the portion of tissue;

a focusing device for focusing the radiation from the radiation source onto a measurement point on the portion of tissue;

a collimator for refocusing the radiation from the measurement point;

a filter for separating the radiation into separate wavelengths;

one or more sensors for detecting radiation from the measurement point and generating an output regarding the detected radiation;

a processor for receiving the output from the sensors, the processor being configured for performing an algorithm to determine the concentration of one or more blood analytes in the blood of the portion of tissue; and

a monitor for displaying the concentration of the one or more blood analytes.

53. The apparatus of claim 52, further including a radio antenna coil for transmitting a signal corresponding to the concentration of one or more blood analytes.

54. A method of measuring the concentration of one or more blood analytes in a portion of tissue with a non-invasive measuring apparatus comprising the steps of:

positioning a portion of tissue approximately adjacent one or more sensors and a radiation source;

exposing the tissue to radiation from the radiation source;

detecting radiation from the tissue with the one or more sensors;

generating a signal from the one or more sensors in response to the detected radiation and communicating that signal to a processor, the signal including spectra of the one or more blood analytes; and

using an algorithm to interpret the signal communicated to the processor to determine the concentration of one or more blood analytes.

55. The method of claim 54, further including the step of displaying the concentration of one or more blood analytes.

56. The method of claim 54, wherein the step of exposing the tissue to radiation from the radiation source includes focusing the radiation from the radiation source onto a spot on the tissue.

57. The method of claim 54, further including the step of filtering the radiation from the tissue into a plurality of wavelengths.

58. The method of claim 54, wherein the step of detecting radiation from the tissue with the one or more sensors comprises detecting radiation that has transmitted through the tissue.

59. The method of claim 54, wherein the step of detecting radiation from the tissue with the one or more sensors comprises detecting radiation that has been reflected from the tissue.

60. The method of claim 54, wherein the portion of tissue is an earlobe.

61. The method of claim 54, wherein the portion of tissue is a finger.

62. The method of claim 54, wherein the blood analytes are selected from the group consisting of lactate, glucose, insulin, ethanol, triglycerides, albumin, proteins, hemoglobin, immunoglobulins, cholesterol, and urea.

63. The method of claim 54, wherein the algorithm used to interpret the signal is a form of linear regression.

64. The method of claim 54, wherein the algorithm used to interpret the signal uses an orthogonal function technique.

65. The method of claim 64, wherein the algorithm further applies orthogonal function to Beer'"'"'s law wherein the spectra of the blood analytes is modified by at least one weighting function to make the spectra orthogonal.

66. The method of claim 64, wherein the first derivative of the spectra are taken for use in the orthogonal function.

67. The method of claim 64, wherein the second derivative of the spectra are taken for use in the orthogonal function.

68. The method of claim 64, wherein a matrix of about 1000×

1000 or more is inverted to determine the weighted function in the orthogonal function technique.

69. The method of claim 54, further including the step of self-calibrating the signal.

70. The method of claim 69, wherein the step of self-calibrating the signal is done using a ratio of analyte measurement against a reference material.

71. The method of claim 70, wherein the reference material is water.

72. The method of claim 70, wherein the reference material is hemoglobin.

73. The method of claim 69, wherein the step of self-calibrating the signal is done using a ratio of pulsatile hemoglobin to total hemoglobin.

74. The method of claim 54, wherein the step of positioning the portion of tissue is carried out such that the one or more sensors and the radiation source have minimal or no contact with the portion of tissue.

75. The method of claim 54 wherein the concentration of blood analytes is determined in less than 5 seconds.