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

• US 9,814,415 B2
• Filed: 09/11/2012
• Issued: 11/14/2017
• 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): DOUGHERTY, SEAN PATRICK
• Application Number:
  US13/610,387
• Publication Number:
  US 20130006073A1
• Time in Patent Office: 1,890 Days
• Field of Search: 600309, 600310, 600316, 600322, 600323, 600335, 600336
• 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 at least one light source configured to strike a target area of a sample, at least one light detector, which includes a preamplifier having a feedback resistor, positioned to receive light from the at least one light source and to generate an output signal, having a time dependent current, which is indicative of the power of light detected, and a processor configured to receive the output signal from the at least one light detector and based on the received output signal, calculate the attenuance attributable to blood in a sample present in the target area and eliminate effect of uncertainty caused by temperature dependent detector response of the at least one light detector, and based on the calculated attenuance, determine a blood glucose level associated with a sample.

Claims

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

at least one light beam generating structure generating one or more light beams having a wavelength in a range between 800 nm and 1600 nm to strike a target area of a biological sample;

at least one photocurrent signal generating light detector, which includes a preamplifier having a feedback resistor, 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;

wherein the preamplifier having a feedback resistor is configured to convert the time dependent current into a time dependent voltage signal; 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 the biological sample present in the target area, eliminate effect of uncertainty caused by temperature dependent detector response of the at least one photocurrent signal generating light detector by calculating the standard deviation of a logarithm of the time dependent voltage signal, and based on the calculated attenuance, determine a blood glucose level associated with the biological sample present in the target area.

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 a normalization factor Q_i(C,T) based on the output voltage V_i (t) of the ith preamplifier as a function of time and standard deviation σ

according to the equation;

3. 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 a ratio factor Y_ij(C,T) based on the output voltage V_i(t) of the ith preamplifier and V_j(t) of the jth preamplifier as a function of time and standard deviation σ

according to the equation;

4. The system for detecting glucose in a biological sample according to claim 1, further comprising an analog-to-digital convertor having a digitized voltage output.

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 calculate a normalization factor Q_i(C,T) based on the voltage output Δ

(ADC)_i of the ith analog-to-digital converter, where a is standard deviation according to the equation;

6. 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 calculate a ratio factor Y_ij(C,T) based on the voltage output Δ

(ADC)_i of the ith analog-to-digital convertor and the voltage output Δ

(ADC)_j of the jth analog-to-digital convertor, where σ

is standard deviation according to the equation;

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

utilizing at least one light beam generating structure generates one or more light beams having a wavelength in a range between 800 nm and 1600 nm to strike a target area of a biological sample;

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

converting the time dependent current into a time dependent voltage signal with the preamplifier having a feedback resistor;

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 based on the received output photocurrent signal,

calculating attenuance attributable to blood in the biological sample present in the target area with the light absorbance change determining algorithm implemented processor;

eliminating effect of uncertainty caused by temperature dependent detector response of the at least one photocurrent signal generating light detector with the light absorbance change determining algorithm implemented processor by calculating the standard deviation of a logarithm of the time dependent voltage signal; 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.

8. The method for detecting glucose in a biological sample according to claim 7, further comprising calculating a normalization factor Q_i(C,T) based on the voltage output V_i(t) of the ith preamplifier as a function of time and standard deviation σ

according to the equation;

9. The method for detecting glucose in a biological sample according to claim 7, further comprising calculating a ratio factor Y_ij(C,T) based on the output voltage V_i(t) of the ith preamplifier and V_j(t) of the jth preamplifier as a function of time and standard deviation σ

according to the equation;

10. The method for detecting glucose in a biological sample according to claim 7, further comprising utilizing an analog-to-digital convertor having a digitized voltage output.

11. The method for detecting glucose in a biological sample according to claim 10, further comprising calculating a normalization factor Q_i(C,T) based on the voltage output Δ

(ADC)_i of the ith analog-to-digital convertor, where a is standard deviation according to the equation;

12. The method for detecting glucose in a biological sample according to claim 10, further comprising calculating a ratio factor Y_ij(C,T) based on the voltage output Δ

(ADC)_i of the ith analog-to-digital convertor and the voltage output Δ

(ADC)_i of the jth analog-to-digital convertor, where a is standard deviation according to the equation;