Glucose related measurement method and apparatus

• US 6,124,134 A
• Filed: 08/23/1996
• Issued: 09/26/2000
• Est. Priority Date: 06/25/1993
• Status: Expired due to Fees

• Current Assignee: Stark, Edward W.
• Original Assignee: Stark, Edward W.
• Inventors: Stark, Edward W.
• Primary Examiner(s): Soderquist, Arlen
• Application Number:
  US08/697,433
• Time in Patent Office: 1,495 Days
• Field of Search: 250/339.01, 250/339.02, 250/339.05, 250/339.06, 250/339.07, 250/339.09, 250/339.12, 250/341.1, 250/341.5, 356/329, 422/68.1, 422/82.05, 422/82.09, 436/63, 436/67, 436/95, 436/66, 702/85
• US Class Current: 436/63
• 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: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

A method of and apparatus for determining stable and labile glycated compound levels in blood. Electromagnetic energy covering a multiplicity of wavelength bands within a wavelength range from 380 nm to 2500 nm is directed into a sample volume containing blood. Portions of the energy representative of both the source energy and energy after interacting with material within the sample volume are collected. The energy portions carry information relating to the source energy and the levels of labile and stable compounds within the sample volume, respectively. The portions are converted into electrical signals representative of the intensities of the respective portions in each of the multiplicity of wavelength bands. The electrical signals are pretreated in accordance with known information to remove deviations from established reference conditions to form data signals that are a function of the fractional portion of the energy in each of the wavelength bands absorbed and scattered by the material in the measurement volume. Selected groups of the data signals are processed in accordance with chemometric models developed from analysis of such data signals together with known values of the analytes derived from measurements on a calibration set of samples larger in number than the number of wavelength bands included in the set of the selected groups of data signals to develop analyte signals representative of the amounts of glycated compounds for which chemometric models have been developed and utilized. The analyte signals may be stored and displayed in a form suitable for medical use.

Claims

1. In apparatus for determining the response to electromagnetic energy received after passing through material in a measurement volume using a calibrated diode array spectrometer to modify electrical signals developed from said response, the improvement comprising means for calibrating the response of the diode-array spectrometer including:

a) means for measuring the spectral response of each diode-array signal channel over a substantial part of wavelength range covered by said diode-array spectrometer by introducing to said diode-array spectrometer electromagnetic radiation

1) for which the characteristics over said substantial part of wavelength range are known to higher spectral resolution than the spectral width of each diode-array element and

2) for which higher energy amplitude accuracy is known than the desired energy amplitude accuracy of the diode-array spectrometer,

and recording electrical data signal outputs for each diode-array channel as a function of the wavelength of said introduced electromagnetic energy over said substantial part of wavelength range covered by said diode-array spectrometer;

b) means for calculating response factors of each of said diode-array signal channels as the ratio of said electrical data signal output, S, to the output electromagnetic energy for its associated wavelength band (R_jj T_jj) and for each of the other wavelength bands associated with the other diode-array signal channels (R_ij C_ij) where T_jj represents the transmission efficiency for energy in wavelength band j to diode-array element j and C_ij is the coupling of energy in wavelength band I to the diode-array element j, which response factors may be expressed as an n by n response matrix; and

c) means for forming corrected data signals, S'"'"', in accordance with the matrix multiplication [S]×

[R]^-1 where [R]^-1 is the inverse of said measured and calculated matrix [R].

2. The apparatus of claim 1 wherein electromagnetic radiation between the wavelength range of 380 nm and 2500 nm has been introduced into the diode-array spectrometer.

3. The apparatus of claim 1 wherein electromagnetic radiation introduced into the spectrometer is monochromatic.

4. The apparatus of claim 1 wherein electromagnetic radiation introduced into the diode-array spectrometer is produced using a monochromator.

5. The apparatus of claim 1, wherein electromagnetic radiation introduced into the diode-array spectrometer is produced using a tunable laser.

6. In a method for determining the response to electromagnetic energy received after passing through material in a measurement volume using a calibrated diode array spectrometer to modify electrical signals developed from said response, the improvement comprising:

calibrating the response of the diode-array spectrometer by;

a) measuring the spectral response of each diode-array signal channel over a substantial part of wavelength range covered by said diode-array spectrometer by introducing to said diode-array spectrometer electromagnetic radiation

1) for which the characteristics over said substantial part of wavelength range are known to higher spectral resolution than the spectral width of each diode-array element and

2) for which higher energy amplitude accuracy is known than the desired energy amplitude accuracy of the diode-array spectrometer,

and recording electrical data signal outputs for each diode-array channel as a function of the wavelength of said introduced electromagnetic energy over said substantial part of wavelength range covered by said diode-array spectrometer;

b) calculating response factors of each of said diode-array signal channels as the ratio of said electrical data signal output, S, to the output electromagnetic energy for its associated wavelength band (R_jj T_jj) and for each of the other wavelength bands associated with the other diode-array signal channels (R_ij C_ij) where T_jj represents the transmission efficiency for energy in wavelength band j to diode-array element j and C_ij is the coupling of energy in wavelength band I to the diode-array element j, which response factors may be expressed as an n by n response matrix; and

c) forming corrected data signals, S'"'"', in accordance with the matrix multiplication [S]×

[R]^-1 where [R]^-1 is the inverse of said measured and calculated matrix [R].

7. The method of claim 6, including the additional step of using said method for correction of optical stray energy and electrical crosstalk.

8. Apparatus for determining the response to electromagnetic energy received after passing through material in a measurement volume using a calibrated diode array spectrometer, the apparatus comprising means for calibrating the response of the diode-array spectrometer including:

a) means for measuring the spectral response of each diode-array signal channel over a substantial part of wavelength range covered by said diode-array spectrometer by introducing to said diode-array spectrometer electromagnetic radiation

1) for which the characteristics over said substantial part of wavelength range are known to higher spectral resolution than the spectral width of each diode-array element and

2) for which higher energy amplitude accuracy is known than the desired energy amplitude accuracy of the diode-array spectrometer,

and recording electrical data signal outputs for each diode-array channel as a function of the wavelength of said introduced electromagnetic energy over said substantial part of wavelength range covered by said diode-array spectrometer;

b) means for calculating response factors of each of said diode-array signal channels as the ratio of said electrical data signal output, S_j, to the input electromagnetic energy for its associated wavelength band (R_jj T_jj) and for each of the other wavelength bands associated with the other diode-array signal channels (R_ij C_ij) where T_jj represents the transmission efficiency for energy in wavelength band j to diode-array element j and C_ij is the coupling of energy in wavelength band I to the diode-array element j, which response factors may be expressed as an n by n response matrix; and

c) means for forming corrected data signals, S'"'"', in accordance with the matrix multiplication [S]×

[R]^-1 where [R]^-1 is the inverse of said measured and calculated matrix [R] and vector [S] expresses a measured data signal.

9. A method for determining the response to electromagnetic energy received after passing through material in a measurement volume using a calibrated diode array spectrometer, the method comprising:

calibrating and correcting the response of the diode-array spectrometer by;

a) measuring the spectral response of each diode-array signal channel over a substantial part of wavelength range covered by said diode-array spectrometer by introducing to said diode-array spectrometer electromagnetic radiation

1) for which the characteristics over said substantial part of wavelength range are known to higher spectral resolution than the spectral width of each diode-array element and

2) for which higher energy amplitude accuracy is known than the desired energy amplitude accuracy of the diode-array spectrometer,

and recording electrical data signal outputs, S_j, for each diode-array channel as a function of the wavelength of said introduced electromagnetic energy over said substantial part of wavelength range covered by said diode-array spectrometer;

b) calculating response factors of each of said diode-array signal channels as the ratio of said electrical data signal output, S_j, to the input electromagnetic energy for its associated wavelength band (R_jj T_jj) and for each of the other wavelength bands associated with the other diode-array signal channels (R_ij C_ij) where T_jj represents the transmission efficiency for energy in wavelength band j to diode-array element j and C_ij is the coupling of energy in wavelength band I to the diode-array element j, which response factors may be expressed as an n by n response matrix; and

c) forming corrected data signals, S'"'"', in accordance with the matrix multiplication [S]×

[R]^-1 where [R]^-1 is the inverse of said measured and calculated matrix [R] and vector [S] expresses measured data signals.

10. The method of claim 9 wherein electromagnetic radiation between the wavelength range of 380 nm and 2500 nm has been introduced into the diode-array spectrometer.

11. The method of claim 9 wherein electromagnetic radiation introduced into the spectrometer is monochromatic.

12. The method of claim 9 wherein electromagnetic radiation introduced into the diode-array spectrometer is produced using a monochromator.

13. The method of claim 9 wherein electromagnetic radiation introduced into the diode-array spectrometer is produced using a tunable laser.