Method and system for non-invasive optical blood glucose detection utilizing spectral data analysis

• US 9,566,024 B2
• Filed: 09/11/2012
• Issued: 02/14/2017
• Est. Priority Date: 05/22/2008
• Status: Active Grant

• Current Assignee: St. Louis Medical Devices, Inc.
• Original Assignee: St. Louis Medical Devices, Inc.
• Inventors: Xu, Zhi
• Primary Examiner(s): Stout, Michael C
• Application Number:
  US13/610,256
• Publication Number:
  US 20130006071A1
• Time in Patent Office: 1,617 Days
• Field of Search: 600/309, 600/310, 600/316, 600/322, 600/323, 600/335, 600/336
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0238 Optical sensor arrangements for performing transmission measurements on body tissue
• CPC Class Codes: A61B 2576/00 Medical imaging apparatus involving image processing or analysis A61B1/00009, A61B6/52 and A61B8/52 take precedence; image processing per se G06T; details of algorithms for analysing medical images G06T7/0012
• 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 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

Systems and methods are disclosed for non-invasively measuring blood glucose levels in a biological sample based on spectral data. This includes utilizing at least one light source configured to strike a target area of a sample, utilizing at least one light filter positioned to receive light transmitted through the target area of the sample from the at least one light source, utilizing at least one light detector positioned to receive light from the at least one light source and filtered by the at least one light filter, and to generate an output signal, having a time dependent current, which is indicative of the power of light detected, receiving the output signal from the at least one light detector with a processor, calculating the attenuance attributable to blood with a ratio factor based on the received output signal, and determining a blood glucose level based on the calculated attenuance.

Claims

1. A system for detecting glucose in a biological sample, comprising:

at least one light source configured to generate one or more light beams having a wavelength in a range between 800 nm and 1600 nm and to strike a target area of a sample;

at least one photocurrent signal generating light detector positioned to receive light from the at least one light source and to generate an output photocurrent signal, having a time dependent current, which is indicative of the power of light detected; and

a light absorbance change determining algorithm implemented processor programmed to calculate a change in a light absorption caused by blood in the biological sample and configured to receive the output photocurrent signal from the at least one photocurrent signal generating light detector and based on the received output photocurrent signal, calculate the attenuance attributable to blood in a sample present in the target area with a ratio factor, and based on the calculated attenuance, determine a blood glucose level associated with a sample present in the target area;

wherein the light absorbance change determining algorithm implemented processor is configured to calculate the ratio factor using a standard deviation of a logarithm of the time dependent output photocurrent current generated by the light power from the same target area of the biological sample, wherein the light absorbance change determining algorithm implemented processor is configured to calculate the ratio factor Y_ij(C,T) at a plurality of wavelengths, the i^th wavelength being represented by λ

_i, the j^th wavelength being represented by λ

_j, C is a blood glucose concentration, T is temperature of the biological sample, I_D (λ

_i, t) is the time dependent output current, σ

[log I_D(λ

_i,t)] is standard deviation of the logarithm of the time dependent output current, and t is time, according to the equation;

2. The system for detecting glucose in a biological sample according to claim 1, wherein the light absorbance change determining algorithm implemented processor is configured to calculate the blood glucose level C_optical based on the optical measurement, Y_ij(C,T) and f_i(T), which is a temperature dependent regression coefficient corresponding to wavelength λ

_i according to the equation;

3. The system for detecting glucose in a biological sample according to claim 2, wherein the light absorbance change determining algorithm implemented processor is configured to extract the values of the temperature dependent regression coefficient corresponding to wavelength λ

_i, which is f_i(T), using partial least squares regression.

4. The system for detecting glucose in a biological sample according to claim 1, wherein the light absorbance change determining algorithm implemented processor is configured to calculate the blood glucose level C_optical based on a temperature independent regression coefficient h_i, a regression coefficient β

for the temperature of the biological sample T, the ratio factor Y_ij(C,T) for a number of wavelengths N according to the equation;

5. The system for detecting glucose in a biological sample according to claim 4, wherein the light absorbance change determining algorithm implemented processor is configured to extract the values of the temperature independent regression coefficient h_i and the regression coefficient β

for the temperature of the biological sample T using partial least squares regression.

6. A method for detecting glucose in a biological sample, comprising:

utilizing at least one light source configured to generate one or more light beams having a wavelength in a range between 800 nm and 1600 nm and to strike a target area of a biological sample;

utilizing at least one photocurrent signal generating light detector positioned to receive light from the at least one light source and to generate an output photocurrent signal, having a time dependent current, which is indicative of the power of light detected;

receiving the output photocurrent signal from the at least one photocurrent signal generating light detector with a light absorbance change determining algorithm implemented processor programmed to calculate a change in a light absorption caused by blood in the biological sample and;

calculating a ratio factor using a standard deviation of a logarithm of the time dependent output photocurrent current generated by the light power from the same target area of the biological sample;

calculating the attenuance attributable to blood in the biological sample present in the target area with the ratio factor based on the received output photocurrent signal with the light absorbance change determining algorithm implemented processor; and

determining a blood glucose level associated with the biological sample present in the target area based on the calculated attenuance with the light absorbance change determining algorithm implemented processor; and

calculating the ratio factor Y_ij(C,T) at a plurality of wavelengths with the light absorbance change determining algorithm implemented processor, where the i^th wavelength being represented by λ

_i, the i^th wavelength being represented by λ

_j, C is a blood glucose concentration, T is temperature of the biological sample, I_D(λ

_i,t) is the time dependent output current σ

[log I_D (λ

_i,t)] is standard deviation of the logarithm of the time dependent output current, and t is time, according to the equation;

7. The method for detecting glucose in a biological sample according to claim 6, further comprising calculating the blood glucose level C_optical with the light absorbance change determining algorithm implemented processor based on the optical measurement, Y_ij(C, T) and f_i(T), which is the temperature dependent regression coefficient corresponding to wavelength λ

_i according to the equation;

8. The method for detecting glucose in a biological sample according to claim 7, further comprising extracting the values f_i(T) of the temperature dependent regression coefficient corresponding to wavelength λ

_i utilizing partial least squares regression with the light absorbance change determining algorithm implemented processor.

9. The method for detecting glucose in a biological sample according to claim 6, further comprising calculating blood glucose level C_optical with the light absorbance change determining algorithm implemented processor based on a temperature-independent regression coefficient h_i, a regression coefficient β

for the temperature of the biological sample T, and the ratio factor Y_ij(C,T) for a number of wavelengths N according to the equation;

10. The method for detecting glucose in a biological sample according to claim 9, further comprising extracting values of the temperature-independent regression coefficient h_i and the regression coefficient β

for the temperature of the biological sample T utilizing partial least squares regression with the light absorbance change determining algorithm implemented processor.