JP2004113434A - Blood sugar measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blood sugar measuring instrument enabling the so-called non-invasive measurement for measuring the concentration of glucose in blood from the outside of a human body and having high precision and excellent reproducibility. <P>SOLUTION: The light emitted from a semiconductor laser diode 20 is incident on the sample 21 of a subject through a rotary deflecting plate 25 and subsequently detected by a photodetector 23 through a fixed deflecting plate 22. The reference light emitted from a reflection type sensor 24 passes through the fixed deflecting plate 22 and the rotary deflecting plate 25 to be incident on a rotary reflecting mirror 26 and the reflected light again passes through the rotary deflecting plate 25 and the fixed deflecting plate 22 to be incident on the reflection type sensor 24. The rotary deflecting plate 25 and the rotary reflecting mirror 26 are rotated by a motor driver 28 and a motor 27. The semiconductor laser diode 20 is controlled by a semiconductor laser diode control unit 29. The light signals detected by the photodetector 23 and the reflection type sensor 24 are sent to a measuring personal computer 30. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a blood glucose measuring device, and more particularly, to a non-invasive blood glucose measuring device by means of a biological polarized pulse wave measurement capable of non-invasively measuring blood glucose from the outside of a human body without requiring blood collection.
[0002]
[Prior art]
With the remarkable increase in the number of diabetic patients in recent years, a simple, quick and accurate blood glucose measuring device is required to obtain blood glucose data necessary for the management. Further, if a blood glucose meter that can be used safely and easily by the patient himself is provided, it can be said that the contribution to blood glucose control is extremely large.
[0003]
At present, blood glucose measurement uses a method of collecting blood with a syringe or piercing the skin with a needle to collect and measure blood. In diabetes, neonatal medicine, and the like, blood glucose measurement is repeatedly performed by blood sampling for complications and improvement of prevention. Because of problems such as pain associated with needles, subcutaneous bleeding, and blood-borne infections, there is a great demand for painless, non-invasive, noninvasive blood glucose measurement.
[0004]
Blood glucose can be grasped by measuring the concentration of glucose contained in the blood.However, a conventional non-invasive blood glucose measurement method uses absorption of light having a wavelength in the near infrared to infrared region, which is a specific absorption wavelength of glucose. Several methods have been reported, such as a measuring method, a method for measuring the angle of rotation of polarized light by glucose, and a Raman light measurement. (For example, see Patent Document 1)
[0005]
[Patent Document 1]
JP-A-2002-202258
[0006]
However, the measurement of the specific absorption wavelength of glucose has large absorption by subcutaneous tissue and water, and the temperature and the effect of the probe contact condition are serious obstacles, and there is no practical use yet.
[0007]
In the measurement of the angle of polarization of the polarized light, measurement in the anterior aqueous humor of the eye has been reported. However, the optical path length cannot be specified and birefringence due to the cornea is a problem. Others are still exploring possibilities.
[0008]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a device capable of so-called non-invasive measurement for measuring glucose concentration in blood from the outside of the human body in view of the above-described circumstances, and which has high accuracy and excellent reproducibility. Is to provide.
[0009]
[Means for Solving the Problems]
The inventors irradiate the blood of the body with light having a wavelength of 600 to 1700 nm from the blood sample or the outside of the body, for example, from the finger of the hand, receive the light transmitted through the human body tissue, and analyze the angle of rotation of the obtained transmitted light, By calculating and calculating the glucose concentration in the blood, it has been found that blood glucose measurement with high measurement accuracy and high reproducibility can be realized.
[0010]
That is, the present invention provides a light source means for generating irradiation light, a light receiving means for receiving light transmitted through a living body, a rotating polarizer positioned between the light source means and the living body, In a blood glucose measuring device comprising a living body and a polarizing plate located between the light receiving means, a blood glucose is measured by measuring and analyzing a change in light intensity and a change in an optical rotation angle due to pulsation of the living body. The present invention relates to a blood glucose measurement device.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail. Glucose has left-handed optical properties that rotate the polarization of light counterclockwise. This angle of rotation is related to optical thickness and glucose concentration.
[0012]
FIG. 3 is a schematic diagram illustrating the measurement of the relationship between the glucose concentration and the optical rotation angle. The light emitted from the semiconductor laser diode 1 having an oscillation wavelength of 787 nm passes through the polarizing plate 2 and is incident on the specimen 3 having a constant optical thickness, and is rotated counterclockwise by an angle of rotation 5 by glucose contained in the specimen. Rotated.
[0013]
FIG. 7 shows a measurement system for measuring the optical rotation angle. The light emitted from the semiconductor laser diode 20 passes through the rotating polarizer 25 and enters the sample 21. The semiconductor laser diode 20 has a quarter-wave plate, and the emitted light is circularly polarized. Light transmitted through the sample 21 passes through the fixed polarizing plate 22 and is received by the photodetector 23.
[0014]
On the other hand, the reference light emitted from the reflection type sensor 24 passes through the fixed polarizing plate 22 and the rotating polarizing plate 25 and is reflected by the rotating reflecting mirror 26. The reflected light passes through the rotating polarizer 25 and the fixed polarizer 22 again, and is incident on the reflective sensor 24. The rotating polarizing plate 25 and the rotating reflecting mirror 26 are rotated by a motor driver 28 and a motor 27. The semiconductor laser diode 20 is controlled by a semiconductor laser diode control device 29. Optical signals received by the photodetector 23 and the reflection type sensor 24 are sent to a personal computer 30 for measurement.
[0015]
FIG. 8 shows a temporal change (phase difference) of the light intensity of the signal light 40 and the reference light 41 measured in FIG. The optical rotation angle is represented by the phase difference between the reference light and the signal light.
[0016]
FIG. 4 shows the relationship between the glucose concentration and the optical rotation angle measured using the measurement system of FIG. The glucose solution used as the specimen did not contain human body tissue (scatterers) and had a constant optical thickness 4 of 9 mm in FIG.
This figure shows that the glucose concentration and the optical rotation angle have a negative correlation. Thus, the glucose concentration is determined from the optical rotation angle with the optical thickness as a variable.
[0017]
Next, a measurement result when a sample containing a scatterer is used as a specimen will be described. The sample used was a scatterer containing 0.02% of a fat emulsion. FIG. 9 shows the relationship between the glucose concentration and the optical rotation angle. As can be seen from this figure, even when a sample having a scatterer is used, the relationship between the glucose concentration and the optical rotation angle has a negative correlation.
[0018]
On the other hand, when a finger of the human body is used as the specimen, the optical thickness of the specimen changes due to the pulsation of the artery, and the optical rotation angle of the received light has a pulsation. In order to measure an accurate glucose concentration, it is necessary to consider the pulsation of the living body.
[0019]
Generally, in a medium containing an optically active substance such as glucose, the optical rotation angle A is proportional to the optical path length L and the concentration C of the optically active substance. That is,
A = αCL (1)
It is expressed as α is the specific rotation, which is determined by the type of material, temperature, and wavelength. The specific rotation of glucose is 4.562 (degree cm ² / g) at an oscillation wavelength of 633 nm. C is the concentration of the optically active substance, in this case the glucose concentration.
[0020]
In this blood glucose measurement method, in order to exclude influences other than blood as much as possible, attention is paid only to a fluctuation component due to arterial pulsation. That is, equation (1) is
ΔA = α × ΔL × C (2)
From this, C = ΔA / α / ΔL (3)
It becomes.
Here, α is a constant which is a specific rotation, ΔA is a fluctuation of the optical rotation angle, and ΔL is a fluctuation of an optical thickness estimated from a fluctuation of a transmitted light intensity.
[0021]
Therefore, it can be seen that the blood sugar level (glucose concentration) C correlates with the ratio of ΔA to ΔL. Thus, the glucose concentration can be calculated by measuring the polarized pulse wave.
[0022]
In the present invention, the glucose concentration is measured by measuring a biologically polarized pulse wave whose optical rotation angle pulsates by a living body, using a high-speed ellipsometry that measures the optical rotation angle with high speed and high accuracy.
High-speed ellipsometry requires 20 data samplings per second to measure pulsation, and requires a polarizing plate that can rotate at high speed.
[0023]
FIG. 1 is a schematic diagram of a measurement system for measuring the glucose concentration of a living body (such as a finger). Light emitted from the semiconductor laser diode 10 having an oscillation wavelength of 805 nm passes through a rotating polarizer 11 having a servo hollow motor with an encoder and is incident on a finger 12 which is a specimen sample. 13 and is received by the high-sensitivity photodiode 14. The semiconductor laser diode 10 has a quarter-wave plate, and the emitted light is circularly polarized. As the rotating polarizing plate 11, an electric rotating polarizing plate using a Faraday element or the like may be used.
[0024]
FIG. 2 shows a transmitted light waveform of a living body (finger) which is a specimen sample measured using the measurement system of FIG. The encoder signal 42 of the servo hollow motor was 1 pulse / 1 cycle, and the measurement data 43 was 2 waves / 1 cycle (28 to 30 Hz in frequency). The envelope of the measurement data 43 of the signal light indicates a periodic change due to the pulse. This frequency was 1-2 Hz.
[0025]
FIG. 6 shows the envelope of the periodic change in the optical rotation angle and the phase relationship between the signal light 40 and the reference light 41 in the maximum region and the minimum region of the envelope. The maximum area of the envelope is low in blood volume and has a low optical thickness. On the other hand, the minimum area of the envelope has a large blood volume and a large optical thickness. When the optical thickness is small (the maximum region of the envelope), the optical rotation angle is small, and when the optical thickness is large (the minimum region of the envelope), the optical rotation angle is large.
By analyzing these measurement data (biologically polarized pulse wave measurement data), a periodic change in the optical rotation angle is calculated.
[0026]
Further, it can be seen from the biological polarization pulse wave measurement data that the change due to the pulse is 1-2 Hz. By analyzing these data, a periodic change in the optical thickness is calculated.
[0027]
By analyzing the periodic changes in the optical thickness and the polarization angle, the glucose concentration can be calculated.
[0028]
FIG. 5 shows a method of calculating the glucose concentration. Deriving y = f (L, A) and y = f (ΔL, ΔA) which are functions of the glucose concentration y using the optical thickness L and the optical rotation angle A as parameters.
[0029]
Next, transmitted light measurement (envelope, frequency analysis, etc.) and biological polarization pulse wave measurement are performed using the measurement apparatus of FIG. By analyzing these data, the fluctuation component ΔL of the optical thickness L and the fluctuation component ΔA of the optical rotation angle A are analyzed, and ΔL and ΔA are extracted.
[0030]
Next, the correlation between ΔL and ΔA is analyzed. Finally, the glucose concentration y is derived. In this way, a highly accurate glucose concentration can be measured with good reproducibility without a measurement error due to a change in optical thickness due to pulsation of a living body or the like.
[0031]
In addition, by increasing the number of rotations of the rotating polarizer, a more accurate glucose concentration can be measured with good reproducibility.
[0032]
【The invention's effect】
According to the present invention, it is possible to provide a blood glucose measuring device which measures glucose concentration in blood from the outside of a human body, and is capable of so-called non-invasive measurement, and has high accuracy and excellent reproducibility.
[Brief description of the drawings]
FIG. 1 shows a schematic diagram of a blood glucose measurement according to an embodiment of the present invention.
FIG. 2 shows transmitted light data measured by the blood glucose measuring device of the present invention.
FIG. 3 shows a measurement schematic diagram using a specimen sample having a constant optical thickness.
FIG. 4 shows a relationship between a glucose concentration and an optical rotation angle when no scatterer is used, using the measuring apparatus of FIG. 7;
FIG. 5 shows a flowchart for deriving a periodic change in glucose concentration.
FIG. 6 shows the envelope of the periodic change in the optical rotation angle and the phase relationship between the signal light 40 and the reference light 41 in the maximum region and the minimum region of the envelope.
FIG. 7 shows a measurement system for measuring an optical rotation angle.
8 shows a phase difference between the light intensities of the signal light 40 and the reference light 41. FIG.
FIG. 9 shows the relationship between the glucose concentration and the optical rotation angle in the presence of a scatterer using the measurement device of FIG.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 semiconductor laser diode 2 polarizing plate 3 sample sample 4 optical thickness 5 optical rotation angle 10 semiconductor laser diode 11 rotating polarizing plate 12 finger 13 polarizing plate 14 photodiode 20 semiconductor laser diode 21 sample sample 22 fixed polarizing plate 23 photodetector 24 reflection Type sensor 25 Rotating polarizing plate 26 Rotating reflector 27 Motor 28 Motor driver 29 Semiconductor laser diode controller 30 Measurement personal computer 40 Signal light 41 Reference light 42 Encoder signal 43 Measurement data

Claims (5)

Light source means for generating irradiation light, light receiving means for receiving light transmitted through the living body, a rotating polarizer positioned between the light source means and the living body, and the living body and the light receiving means What is claimed is: 1. A blood glucose measuring device comprising a polarizing plate interposed therebetween, wherein the blood glucose is measured by measuring and analyzing a change in light intensity and a change in an optical rotation angle due to pulsation of a living body. The blood glucose measuring device according to claim 1, wherein an electric rotating polarizing plate is used as the rotating polarizing plate. The blood glucose measuring device according to claim 1, wherein the light source has an oscillation wavelength of 600 to 1700 nm. The blood glucose measuring device according to claim 1, wherein the light source is a semiconductor laser diode. The blood glucose measuring device according to claim 1, wherein the semiconductor laser diode is circularly polarized.

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