KR20070055614A - Non-invasive measuring device of blood sugar level - Google Patents

Abstract

The light source control part 220 which irradiates the irradiation light 11 and 12 of two different near-infrared wavelength ranges is installed in the measurement site of the finger 1, and the irradiation light 11 and 12 is used to measure the measurement site of the finger 1, and the like. The light detectors 51 and 61 which receive the transmitted light 12, 22 and 13, 23 at different distances from each other and detect the amount of transmitted light are provided, and the amount of transmitted light of the same wavelength at the detected two points is provided. Relative permeability, which is the ratio of, is calculated for each wavelength, and blood glucose level is calculated using the relative permeability of each wavelength, and non-invasive measurement of the blood glucose level which is small and easy to carry can be measured non-invasively and without error. Do it.

Description

Non-invasive measuring device of blood sugar level {INSTRUMENT FOR NONINVASIVELY MEASURING BLOOD SUGAR LEVEL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for non-hygroscopically measuring the blood sugar level of a human body, and more particularly, to a non-hygroscopic error of a human's blood sugar level from transmitted light from the human body obtained by irradiating the human body with light of a specific wavelength. It relates to a technique to measure.

In diabetes, the lack of insulin secreted from the liver or the body's cells do not respond to insulin, which leads to no accumulation of sugar in the muscles or liver, resulting in high glucose concentrations in the blood, that is, blood sugar levels. Various complications are caused, including disability and nephropathy. Diabetic patients are more than 6.3 million in Korea, including more than 13 million people, including the reserve army, is a serious national disease. In the present state, there is no complete treatment method for the treatment of diabetes mellitus, and the blood glucose level is maintained at an appropriate level by the administration of insulin or the diet while the blood glucose level is measured.

The current blood glucose level measurement is performed by a measuring device using a glucose sensor method that electrochemically quantifies the reaction of glucose oxidase to blood using the collected blood, and converts it into a blood sugar level. Portable blood glucose meters and the like used for dental management are already commercially available. Such a blood glucose level test has problems such as pain caused by several times of blood collection and infection by acupuncture needles, and requires a non-invasive blood sugar level measuring device capable of measuring the daily fluctuation of the blood sugar level in real time without the need for blood collection.

Therefore, a technique is disclosed in which a human body is irradiated with light having a wavelength in the near infrared region, the diffuse reflected light or transmitted light from the human body is measured by using a spectrometer, and a blood glucose level of the human body is calculated from the spectrum of the diffuse reflected light or transmitted light. (See, eg, Non Patent Literature 1, Non Patent Literature 2, and Patent Literature 1). In Non-Patent Document 1, the light of the wavelength of the near infrared region is alternately irradiated to the forearm skin and the standard reflector, and the spectra of each diffuse reflected light are measured from the diffused reflectance light using a spectrometer or the like, and the diffuse reflected light of the forearm skin and the standard reflector A method for measuring blood glucose levels by multivariate analysis has been proposed from a diffuse reflectance spectrum calculated from the spectral ratio of. Patent Document 1 proposes a method of irradiating light of a wavelength in the near infrared region with a finger or the like, detecting the transmitted light to determine absorbance at specific wavelengths of 944 nm and 964 nm, and measuring blood glucose values from the values.

By the way, according to the method of Non-Patent Document 1, a complex spectrometer composed of a diffraction grating or the like is required in order to irradiate the forearm skin with light having a wavelength in the near infrared region and to measure the continuous spectrum of the diffuse reflected light. This requires reflectance data of continuous wavelengths of light to calculate blood glucose levels, which in turn irradiates the human body with light from a white light source having light of these wavelengths, and requires the spectrometer described above to obtain its reflection spectrum. . In addition, in order to alternately measure the diffuse reflection light from the standard reflector and the human body, variations in the light source cause measurement errors. In the method for measuring blood glucose levels based on such a white light source or a spectrometer, it is difficult to miniaturize and carry a blood glucose level measuring device that is easy to carry in order for a diabetic to manage daily blood sugar levels.

 On the other hand, Patent Document 1 proposes an apparatus that uses light having two specific wavelengths and measures blood glucose levels by the transmitted light. This technique is explained based on FIG. The measuring device shown in FIG. 9 includes a light source 100 for generating near-infrared light, a diffraction grating 340 and a reflecting mirror 360 for irradiating the finger 1 with only a predetermined monochromatic light from the light, and further spectroscopically. A sampling prism 370, an ND filter 390, and a photo detector 380 for detecting a part of the irradiated light 101 which are the monochromatic light are provided. In addition, the signal processing unit 230 for amplifying and digitizing the lens 50 and the light detector 51 for detecting the transmitted light 102 from the human finger 1 and the detection signals from the light detectors 51 and 380. ), And a central control unit 200. The central control unit 200 calculates the transmittance T of the finger 1 by the following equation 1 based on the detection signals from the photodetectors 51 and 380 amplified and digitized by the signal processing unit 230.

(Equation 1)

T = I ₁ / I ₀

Here, I ₀ is the irradiation light amount of the irradiation light 101, and is calculated by multiplying a detection signal detected by the photo detector 380 by a predetermined number. In addition, I ₁ is calculated by multiplying a detection signal detected by the photodetector 51 with a light quantity of the transmitted light 102 by a predetermined number. Here, two 944 nm and 964 nm are selected as the wavelength of the irradiation light 101, and the blood sugar value C is calculated by the following formula (2) as the transmittances for the respective wavelengths T ₁ and T ₂ , respectively.

(Equation 2)

C = k ₀ + k ₁ * ABS ₁ / ABS ₂

Here, ABS _{1 =} -ln (T ₁ ) and ABS _{2 =} -ln (T ₂ ), respectively. K ₀ and k ₁ represent coefficients determined by the least-squares method using measured blood glucose levels. In addition, although a white light source was used as a light source here, if a 944 nm, 964 nm semiconductor laser etc. can be used for two wavelengths from which the said wavelength differs, non-invasive measurement of the blood glucose level which does not require a complicated spectrometer comprised of a diffraction grating etc. The device can be realized.

However, in this prior art invention, the linear distance r ₁ between the irradiation position P ₀ of the irradiation light 101 and the detection position P ₁ of the transmitted light 102 changes slightly depending on the size of the finger 1. There existed a problem that measurement error which cannot be ignored in calculation of blood sugar value C by the said Formula (2) arises about the said slight change amount. In addition, even if the irradiation position P ₀ is spaced apart by the linear distance r ₁ so as to be not affected by the finger size, for example, even if the irradiation position P ₀ is placed on the same side as the detection position P ₁ , the equation 1 is obtained by the expansion and contraction of the blood vessel that changes in response to the heart rate. There exists a problem that the transmittance | permeability shown changes and the measurement error which cannot be ignored in calculation of the blood glucose level C by said formula (2) arises.

(Non-Patent Document 1)

katsuhiko Maruko, et al., IEEE Journal of Selected Optics in Quantum Electronics, Vol. 9, NO.2, pp.322-330, 2003

(Non-Patent Document 2)

H.M. Heise, et al., Artificial Organs, 18 (6) pp. 439-447, 1994

(Patent Document 1)

Japanese Patent Laid-Open No. 5-176917

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a non-invasive measuring device for blood glucose level, which is compact and portable, which can measure the blood glucose level of a human body without error. .

The structure of this invention which solved such a subject is as follows.

1) An irradiation means for irradiating light having a plurality of different wavelengths is provided at a measurement site of the human body, and the light of the irradiation means receives the transmitted light transmitted through the measurement site of the human body at two points at different distances, and the amount of transmitted light is A transmissive light amount detecting means for detecting a light transmittance and calculating the relative transmittance which is the ratio of the transmissive light quantity of the same wavelength at two points detected by the transmissive light amount detecting means for each wavelength, and using the relative transmittance of the respective wavelengths A non-invasive measuring device of blood sugar level provided with a calculation means for calculating a blood sugar level.

2) irradiating means 2 is to investigate the different wavelengths of light, the computing means for each of the amount of transmitted light transmitted through the short distance side is detected in point 2 as _.λ1 I _1, I _{1 .λ2} and transmission distance is long _2.λ1 the side I, to I _2.λ2 and a relative transmission rate of the two different wavelengths _λ1 R, R _λ2 the formula _{R λ1 = I 2 .λ1 / I} 1 .λ1, R λ2 = I 2 .λ2 / I _{It is 1.λ2} , and the coefficients k ₀ and k ₁ of the following equation are obtained using the previously measured blood glucose level and the relative permeability R _λ1 and R _λ2 , and the blood glucose level C is expressed by the equation C = k ₀ + k ₁ * ln (R _λ1 ) A non-invasive measuring device for the blood glucose level of 1) described above, which is calculated according to / ln (R _{λ 2} ).

3) irradiation means 2 is to investigate the different wavelengths of light, the computing means for each of the amount of transmitted light transmitted through the short distance side is detected in point 2 as _.λ1 I _1, I _{1 .λ2} and transmission distance is long the side _.λ1 I _2, I ₂ to _.λ2 and a relative transmission rate of the two different wavelengths _λ1 R, R _λ2 the formula _{R λ1 = I 2 .λ1 / I} 1 .λ1, R λ2 = I 2 .λ2 / I _{1 .λ2} to, and copper, each relative transmission rate R _{λ1, λ2} by formula R 2 absorbance at different wavelengths a _1, a ₂ a ₁ based on a _{= -1n (R λ1), a} 2 = -1n (R λ2) Using the actual blood glucose values and absorbances A ₁ and A ₂ , obtain the coefficients k ₀ and k ₁ of the following equation, and calculate the blood sugar level C according to the equation C = k ₀ + k ₁ * A ₁ / A ₂ . Non-invasive measurement device for blood sugar level of the above 1).

4) A device for non-invasive measurement of blood glucose levels according to 2) or 3) above, wherein the light having two different wavelengths irradiated by the irradiation means is selected from the range of 900 to 1100 nm.

5) irradiating means is to examine the three different wavelengths of light, the computing means and the amount of light transmitted through each of the transmission distance is short edge is detected at two points as _.λ1 I _1, I _{1 .λ2,} I _{1 .λ3} a, p is the transmission distance longer _.λ1 I _2, I _{2 .λ2,} I, and the _{2 .λ3,} relative permeability of the three wavelengths _λ1 R, R _{λ2, λ3} the formula R R I _λ1 = _{2 .λ1} / I _{1 .λ1} , R _λ2 = I _{2 .λ2} / I _{1 .λ2} , R _λ3 = I _{2 .λ3} / I _{1 .λ3} , using the previously measured blood glucose level and relative permeability R _λ1 , R _λ2 , R _λ3 The coefficient k ₀ , k ₁ of the equation is obtained and the blood glucose level C is calculated according to the equation C = k ₀ + k ₁ * ln (R _{λ 1} / R _{λ 3} ) / ln (R _{λ 2} / R _{λ 3} ). Non-invasive measuring apparatus of the blood sugar level of a base material.

6) irradiating means is to examine the three different wavelengths of light, the computing means and the amount of light transmitted through each of the transmission distance is short edge is detected at two points as _.λ1 I _1, I _{1 .λ2,} I _{1 .λ3} a, p is the transmission distance longer _.λ1 I _2, I _{2 .λ2,} I, and the _{2 .λ3,} relative permeability of the three wavelengths _λ1 R, R _{λ2, λ3} the formula R R I _λ1 = _{2 .λ1} / I _{1 .λ1} , R _λ2 = I _{2 .λ2} / I _{1 .λ2} , R _λ3 = I _{2 .λ3} / I _{1 .λ3} and three different wavelengths based on the respective relative transmittances R _λ1 , R _λ2 , R _λ3 Absorbance of A ₁ , A ₂ , A ₃ is the formula A ₁ = -1n (R _λ1 ), A ₂ = -1n (R _λ2 ), A ₃ = -1n (R _λ3 ) Using A ₁ , A ₂ , and A ₃ , the coefficients k ₀ and k ₁ of the following equation are obtained, and the blood glucose level C is expressed by the equation C = k ₀ + k ₁ * (A ₁ -A ₃ ) / (A ₂ -A ₃ ) A non-invasive measurement device for blood sugar levels of the above 1), which is to be calculated according to the above.

7) the light of three different wavelengths irradiated by the irradiation means, two of which are selected from the range of 900 to 1100 nm, and the other is selected from the range of 900 to 930 nm or 1000 to 1030 nm; 6) Non-invasive measuring apparatus of blood sugar level of base material.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the non-invasive measurement apparatus of the blood glucose level of Example 1. FIG.

It is explanatory drawing of the non-invasive measurement apparatus of the blood glucose level using the optical fiber of the other example of Example 1. FIG.

It is explanatory drawing of the non-invasive measurement apparatus of the blood glucose level using the optical fiber of the other example of Example 1. FIG.

4 is an explanatory diagram of a non-invasive measurement device for blood glucose levels of Example 2. FIG.

It is explanatory drawing of the non-invasive measurement apparatus of the blood glucose level of Example 2. FIG.

6 is an explanatory diagram of a non-invasive measurement device for blood glucose levels of Example 3. FIG.

7 is a diagram showing a combined region of an optimum wavelength in a scatterer that mimics a human body.

8 is a diagram illustrating a relationship between a change amount of the detection distance r ₁ and a blood sugar value measurement error.

It is explanatory drawing of the conventional non-invasive measurement apparatus of the blood sugar level.

In the accompanying drawings, each code has the following meaning.

1: finger

10, 20, 30: light source

11, 21, 31, 101: irradiation light

12, 13, 22, 23, 32, 33, 102, 103: transmitted light

41, 50, 60, 120, 310, 320, 410, 420, 430: Lens

40, 330: Prism

51, 61, 380: photo detector

100: white light source

110: power supply for white light source

200: central control unit

210: display unit

220: light source control unit

230: signal processing unit

300, 301: spectrometer

311, 321: Shutter

340: diffraction grating

350: multichannel detector

360 mirror

370: Prism for Sample

390: ND filter

700, 701, 702, 710, 720, 730: optical fiber

(Example)

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail, referring drawings as needed.

(Radiation means) As a best irradiation means, the means which irradiates light which consists of three different wavelengths to substantially the same irradiation position is preferable.

(Wavelength of irradiated light) The wavelength of the best irradiated light is selected from among three different wavelengths, in which two wavelengths are in the range of 900 to 1100 nm, and one wavelength in the range of 900 to 930 nm or 1000 to 1030 nm, respectively. desirable.

(Transmitted light amount detecting means) As the best transmitted light amount detecting means, means for detecting the transmitted light at two points at different distances from the irradiation position of the light by the irradiation means is preferable.

(Calculation means) The best calculation means calculates the relative transmittance which is the ratio for each of three different wavelengths from the detected two transmitted lights, and calculates the blood glucose value by the equation (8) from the three relative transmittances.

(Transmitted light) The best transmitted light is preferably the transmitted light detected by the transmitted light amount detecting means at the same side as the irradiation position irradiated to the human body by the irradiating means.

In the present invention, a plurality of light having different wavelengths are generated from a light source, and the light is irradiated to a measurement site (for example, a finger, etc.) of the human body by the irradiation means. The irradiated light is scattered and absorbed in the human body, and is radiated out of the human body to become transmitted light. The transmitted light is detected at two points at different distances from the irradiation position of the light by the transmitted light amount detecting means. The relative transmittance which is the ratio is calculated for each wavelength from the detected two transmitted lights, and the blood glucose level of the human body is calculated from the relative transmittance. The detected transmitted light includes blood sugar level information inside the human body, and the blood sugar level of the human body can be measured by non-invasive.

In addition, by using a light source having two or three wavelengths different from each other, a device that does not require a complex spectrometer for detecting a transmission or reflected light spectrum, such as a conventional blood glucose level measuring device using a white light source, can be realized. In addition, even if the linear distance between the irradiation position of the monochromatic light and the detection position of the transmitted light is changed depending on the size of the finger as the measurement site, a non-invasive measuring device of the blood glucose level with less influence on the measurement error of the blood glucose level can be realized. In addition, even if the amount of transmitted light changes due to the expansion and contraction of blood vessels corresponding to the heart rate, a non-invasive measuring device for blood glucose levels with less influence on the measurement error of blood glucose values can be realized.

In addition, in each symbol of transmitted light quantity I _1.λ1 , I _2.λ1 , and relative transmittance R _λ1 used in the present invention, the numbers of I ₁ and I ₂ represent detection positions, and λ ₁ , λ ₂ , (lambda) ₃ has shown the kind of wavelength.

EMBODIMENT OF THE INVENTION Hereinafter, each Example of this invention is described concretely based on drawing.

Example 1

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the non-invasive measurement apparatus of the blood glucose level of Example 1. FIG.

It is explanatory drawing of the non-invasive measurement apparatus of the blood glucose level using the optical fiber of the other example of Example 1. FIG.

It is explanatory drawing of the non-invasive measurement apparatus of the blood glucose level using the optical fiber of the other example of Example 1. FIG.

1 is finger, 10, 20, 30 is light source, 11, 21, 31 is irradiation light, 12, 13 is transmitted light, 22, 23 is transmitted light, 32, 33 is transmitted light, 41 is lens, 50, 60 is lens, 40 Silver prism, 51 and 61 light detector, 100 white light source, 101 light irradiation, 102 and 103 transmitted light, 110 power for white light source, 120 lens, 200 central control unit, 210 display unit, 220 light source control unit , 230 is a signal processor, 300, 301 is a spectrometer, 310, 320 is a lens, 311, 321 is a shutter, 330 is a prism, 340 is a diffraction grating, 350 is a multichannel detector, 360 is a mirror, 370 is a prism for a sample, 380 Silver light detector, 390 is ND filter, 410, 420, 430 is lens, 700, 701, 702 is optical fiber, 710, 720, 730 is optical fiber.

Example 1 (see FIGS. 1 and 2): The blood glucose level measuring apparatus of Example 1 shown in FIG. 1 includes light sources 10 and 20 for irradiating irradiation light 11 and 21 to fingers 1, and reflections. The prism 40 and the lens 41 are provided. In addition, the amount of transmitted light detection means I composed of a lens 50 and a light detector 51 for detecting the transmitted light 12 and 22 from the finger 1 and a lens for detecting the transmitted light 13 and 23. Transmitted light amount detecting means (II) composed of a 60 and a photo detector 61, and a signal processing unit 230, a central control unit 200, a display unit 210, and a light source control unit 220 is provided. .

 The central control unit 200 calculates and displays the blood glucose value of the human body in the display unit 210 based on the detection signal from the photo detectors 51 and 61 digitized by the signal processing unit 230. The light source control unit 220 includes a power supply unit (not shown) for supplying current to the light sources 10 and 20. A direct current or modulated current is supplied to the light source 10 (light source 20) in accordance with a command from the central control unit 200.

The operation of the non-invasive measurement device for blood glucose levels having the above configuration will be described.

Irradiation light 11 generated from the light source 10 passes through the prism 40 and is irradiated onto the finger 1 by the lens 41, and the irradiation light 11 emits scattering and absorption inside the finger 1. The light is radiated in all directions other than the finger 1 to be transmitted light. Thereafter, the transmitted light 12 from the position P ₁ on the finger ₁ separated by the linear distance r ₁ from the irradiation position P ₀ of the irradiation light 11 is collected by the lens 50 on the light receiving surface of the photo detector 51. Further, the transmitted light 13 from the position P ₂ on the finger 1 separated by the linear distance r ₂ from the irradiation position P ₀ of the irradiation light 11 is collected by the lens 60 on the light receiving surface of the photodetector 61. 1, r ₁ <r ₂ , and a photodiode is used for the photo detectors 51 and 61.

From the photo detectors 51 and 61, detection signals proportional to the light intensities of the transmitted light 12 and 13 are output and digitized by the signal processing unit 230, and a central control unit using a computer based on the detection signals ( Relative transmittance R _{lambda 1} is calculated by the following equation.

Subsequently, similar to the calculation procedure of the relative transmittance R _{lambda 1} by the irradiation light 11 described above, the calculation of the relative transmittance R _{lambda 2} by the irradiation light 21 is performed. When the calculation calculation of the relative transmittance R _{lambda 2} by the irradiation light 21 is finished, both the light sources 10 and 20 are turned off (lighted off), and the blood glucose level measurement operation of the finger 1 is completed. The central control unit 200 calculates the blood glucose value of the finger 1 from the calculated relative transmittances R _{λ 1} and R _{λ 2} by the following equation, and displays the result on the display unit 210.

Next, the software of the calculation methods of the relative transmittances R _{lambda 1} and R _{lambda 2} performed by the central control unit 200 will be described. The amount of light of the irradiation light 11 and the transmitted light 12 and 13 for each wavelength is set to I _{0.0 lambda 1} , I _{1.1 lambda 1} and I _{2. lambda 1} , respectively. The relative transmittance R _lambda 1 of the finger 1 with respect to the irradiation light 11 is represented by the following expression (3).

(Equation 3)

R _λ1 = I _{2 .λ1} / I _{1 .λ1}

When the light quantity-to-voltage conversion coefficients in the photo detectors 51 and 61 are β ₅₁ and β ₆₁ , the detection signals (voltages) V ₅₁ and V ₆₁ detected by the photo detectors 51 and 61 are represented by the following mathematical expressions. It is represented by Formula 4.

(Equation 4)

V ₅₁ = β ₅₁ * I _{1 .λ1}

(Equation 5)

V ₆₁ = β ₆₁ * I _{2 .λ1}

From the above equations (3) to (5), the relative transmittance R _lambda 1 of the finger ₁ is calculated by the following equation (6) and is represented in a form that does not depend on the light amount I _{0 .λ 1} of the irradiation light 11.

(Equation 6)

R _λ1 = (β ₅₁ / β ₆₁ ) * V ₆₁ / V ₅₁

Here, the value in () is a constant unique to the blood glucose level measuring device, and can be easily corrected by using a light source capable of knowing the amount of light. The relative transmittance R _{λ 2} of the finger 1 with respect to the irradiation light 21 can also be calculated in the same manner as the relative transmittance R _λ 1 of the finger 1 with respect to the irradiation light 11. The blood glucose level C of the finger 1 is calculated by the following equation (7) using the calculated relative transmittances R _{lambda 1} and R _{lambda 2} .

(Equation 7)

C = k ₀ + k ₁ * ln (R _λ1 ) / ln (R _λ2 )

Where k ₀ and k ₁ represent the coefficients determined by the least-squares method using the measured blood glucose level. In addition, in Example 1, as another two wavelengths for blood sugar value estimation, it is set as the wavelength each chosen from the range of 900-1100 nm.

Further, a laser can be used as the light sources 10 and 20 for generating the irradiation light 11 and 21 in the above wavelength range. If a semiconductor laser is used for this laser, a compact blood glucose level measuring device can be realized. It is also possible to use a light emitting element such as a light emitting diode for the light sources 10 and 20. In addition, when using the white light source 10 and 20 which generate | occur | produces the light of the wavelength of a near-infrared region continuously for the light sources 10 and 20, even if it implement | achieves by using the optical filter which transmits the light from the light source 10 and 20 only the above-mentioned wavelength. good. As shown in FIG. 2, the irradiation light 11 and 21 from the light sources 10 and 20 are irradiated to the finger 1 using the optical fiber 700, and the detection point P ₁ on the finger 1 is irradiated. , The transmitted light 12, 13 (22, 23) from P ₂ may be guided to the transmitted light amount detecting means I, II using the optical fibers 701, 702. The optical fiber 700 shown in FIG. 2 may be disposed on the detection side and measured as shown in FIG. 3.

Example 2

4 is an explanatory diagram of a non-invasive measurement device for blood glucose levels of Example 2. FIG.

It is explanatory drawing of the non-invasive measurement apparatus of the blood glucose level of Example 2. FIG.

Example 2 shown in FIG. 4 is an example of the non-invasive measurement apparatus of blood glucose levels using three wavelengths. The blood glucose level measuring apparatus of Example 2 shown in FIG. 4 includes light sources 10, 20, 30, lenses 410, 420, 430 for irradiating the irradiation light 11, 21, 31 to the finger 1. And an optical fiber 700 which irradiates the irradiation light 11, 21, and 31 to the finger 1 by integrating the optical fibers 710, 720, and 730 and the optical fibers 710, 720, and 730. In addition, the transmitted light amount detecting means I composed of the optical fiber 701, the lens 50, and the photo detector 51 for detecting the transmitted light 12, 22, and 32 from the finger 1, and the transmitted light 13 And a transmission light amount detecting means (II) composed of an optical fiber 702, a lens 60, and a photo detector 61 for detecting the signals 23, 33, and a signal processor 230 and a central controller 200. ), A display unit 210, and a light source control unit 220.

The central control unit 200 calculates the blood glucose value of the human body by an equation described below based on the detection signals from the photo detectors 51 and 61 digitized by the signal processing unit 230, and displays the blood glucose value of the human body in the display unit 210. The light source controller 220 has a power supply unit (not shown) for supplying current to the light sources 10, 20, and 30. A direct current or a modulated current is supplied to the light source 10 (light source 20, light source 30) in response to a command from the central control unit 200. Fingers corresponding to the respective irradiation lights 11, 21, and 31 The relative permeabilities R _λ1 , R _λ2 , and R _λ3 of (1) can be calculated in the same order as in Example 1. The blood glucose value C of the finger 1 is calculated using the calculated relative permeabilities R _λ1 , R _λ2 , R _λ3 . It calculates by the following formula (8).

(Equation 8)

C = k ₀ + k ₁ * ln (R _λ1 / R _λ3 ) / ln (R _λ2 / R _λ3 )

Here, k ₀ and k ₁ represent coefficients determined by the least-squares method using the measured blood glucose level. As three different wavelengths for measuring blood glucose levels using Equation 8, in Example 2, the irradiation lights 11 and 21 are each selected from the range of 900 to 1100 nm, and the remaining irradiation light 31 is also used. The wavelength is selected from the range of 900 to 930 nm or 1000 to 1030 nm. Although the optical fiber 700 is arrange | positioned in the opposite side to the detection side of the finger 1 in FIG. 3, you may arrange | position it to a detection side as shown in FIG.

Example 3

6 is an explanatory diagram of a non-invasive measurement device for blood glucose levels of Example 3. FIG.

7 is a diagram showing a combined region of an optimum wavelength in a scatterer that mimics a human body.

8 is a diagram showing a relationship between the amount of change in the detection distance r1 and a blood sugar level measurement error.

In Examples 1 and 2, the light emitted to the human body was limited to two or three lights having different wavelengths. As a result, a device that does not require a complex spectrometer for detecting the transmitted or reflected light spectrum, such as a conventional blood glucose level measurement device using a white light source, can be realized. Further, even if the linear distance between the irradiation position of the irradiation light and the detection position of the transmitted light changes depending on the size of the measurement site such as a finger, a non-invasive measuring device of the blood glucose level with less influence on the measurement error of the blood glucose level can be realized. In addition, even if the amount of transmitted light changes due to the expansion and contraction of blood vessels corresponding to the heart rate, a non-invasive measuring device for blood glucose levels with less influence on the measurement error of blood glucose levels is produced.

On the other hand, even in the conventional non-invasive measurement device for blood glucose levels using a white light source and a spectrometer, even if the linear distance between the irradiation position of the light and the detection position of the transmitted light varies depending on the size of the measurement site such as a finger, You can make less impact. In addition, even if the amount of transmitted light changes due to the expansion and contraction of blood vessels corresponding to the heart rate, the influence on the measurement error of the blood glucose level can be reduced. In addition, there is no need to use a standard reflector as described in Non-Patent Document 1.

The example applied to the non-invasive measurement apparatus of the blood glucose level using the conventional white light source and a spectrometer is demonstrated based on FIG.

In the non-invasive measurement device for blood glucose levels shown in FIG. 6, a white light source 100 such as a halogen lamp including light having a wavelength in the near infrared region and a power source 110 for the white light source are provided, and the irradiation from the light source 100 is performed. The light 101 is irradiated to the finger 1 through the lens 120 and the optical fiber 700. The irradiation light 101 irradiated to the finger 1 receives scattering and absorption in the finger 1 and is radiated in all directions other than the finger 1 to be transmitted light. Transmitted light 102, 103 from positions P ₁ , P ₂ on fingers _{1 at} linear distances r ₁ , r ₂ from the irradiation position P ₀ on the finger 1 of the irradiation light 101 by the optical fiber 700. To the spectrometer 300 by optical fibers 701 and 702.

The spectrometer 300 is composed of lenses 310 and 320, shutters 311 and 321, a prism 330, a diffraction grating 340, and a multichannel detector 350. A linear array sensor such as a CCD is used for the multichannel detector 350. In the case of measuring the transmission spectrum of the transmitted light 102 emitted from the position P ₁ , the shutter 311 is opened, and the transmission spectrum S ₁ of the transmitted light 102 can be obtained on the multichannel detector 350. In this case, the shutter 321 is closed. Similarly, when measuring the transmission spectrum S ₂ of the transmitted light 103 emitted from the position P ₂ , the shutter 321 is opened to obtain the transmission spectrum S ₂ of the transmitted light 103 on the multi-channel detector 350. Can be. In this case, the shutter 311 is closed. The relative transmittance spectrum T = S ₂ / S ₁ is calculated from the transmission spectra S ₁ and S ₂ measured as described above. From the obtained relative transmittance spectrum, the absorbance or the first (or second) derivative value of the absorbance can be calculated, and the blood glucose level C can be calculated by the multivariate analysis described in the above equations or Non-Patent Document 1.

The result of having examined the non-invasive blood sugar level measuring method of each Example is shown in FIG. 7 and FIG. FIG. 7 is a graph illustrating the correlation between the glucose and the glucose concentration expressed by Equation 9 below using a relative transmittance R (λ _{i = 1, 2, 3} ) for a scatterer that mimics a human body. The theoretical analysis of the case measured by the non-invasive measuring device is performed, and the square value of the correlation coefficient R ² The combined area | region of the wavelength used as> 0.995 is shown by the oblique line. The theoretical analysis was performed with reference to A. Ishimaru: Wave Propagation and Scattering in Random Media, Academic Press, New York (1978). In the theoretical calculation here, in FIG. 7, the linear distances r ₁ and r ₂ were set to 10 mm and 20 mm, respectively. In addition, the equivalent scattering coefficient is constant regardless of the glucose concentration and wavelength, and here the general value of the human body is 1.0 mm ⁻¹ [Reference: Giron, 59, 561B (1993), PP. 338-340].

In addition, the absorption coefficient depending on the wavelength and glucose concentration was measured using the aqueous glucose solution. Moreover, wavelength (lambda) ₃ = 900 nm was set.

(Equation 9)

γ = ln [R ( _λ1 ) / R ( _λ3 )] / ln [R ( _λ2 ) / R ( _λ3 )]

It can be seen from FIG. 7 that there is a combination of optimal wavelengths λ ₁ and λ ₂ for estimating glucose concentration with the above index γ in the wavelength range of 900 to 1100 nm.

Next, in the blood glucose value measuring apparatus described in Examples 1 and 2, the results of analyzing the measurement error of the blood sugar value when the distances r ₁ and r ₂ are changed in FIG. 3 and FIG. 5 are shown in FIG. 8. . In this case was a constant distance between the transmitted light detection position P _1, P ₂ to 10 mm. Also in the case of the prior art, it was expected that the irradiation position P ₀ was on the same side as the detection position P ₁ . When the irradiation position and the detection position are on the same side, the influence of the finger thickness can be almost ignored, but the amount of transmitted light changes due to the expansion and contraction of the blood vessel that changes in response to the heart rate. This change in the amount of transmitted light can be considered to be due to a change in the distances r ₁ and r ₂ in appearance. In Example 1, it can be seen that the measurement error of the blood sugar level is about 1/2 compared to the conventional technique, and in Example 2, the measurement error of the blood glucose level is reduced to about 1/40, respectively, compared with the conventional technique. In other words, the expansion and contraction of blood vessels corresponding to the heart rate changes the amount of transmitted light in the same way as the change in the finger thickness, but the measurement error of blood glucose values can be reduced in comparison with the prior art according to Examples 1 and 2, respectively.

As described above, according to the present invention, a plurality of different wavelengths of light are irradiated to the human body, and the transmitted light is detected at two points each having a different distance from the irradiation position of the light. The detected transmitted light includes blood sugar level information inside the human body, and the blood sugar level of the human body can be measured. In addition, a device that does not require a complex spectrometer for detecting the transmitted or reflected light spectrum, such as a conventional blood glucose level measuring device using a white light source, can be realized, and since a small semiconductor laser or the like can be used as the light source, A blood sugar level measuring device can be realized. Further, even if the amount of transmitted light changes depending on the change in the size of a measurement site such as a finger or the expansion / contraction of blood vessels, a non-invasive measuring device for blood glucose levels with less influence on the measurement error of blood glucose levels can be realized.

Claims (7)

Irradiation means for irradiating light having a plurality of different wavelengths to a measurement site of the human body; Transmitted light quantity detecting means for receiving the transmitted light transmitted by the light of the irradiation means through the measurement site of the human body at two points at different distances and detecting the amount of transmitted light; Calculation means for calculating the relative transmittance which is the ratio of the amount of transmitted light of the same wavelength at two points detected by the said transmitted light quantity detection means for each wavelength, and calculating the blood glucose level of a human body using the relative transmittance of each same wavelength Non-invasive measurement device of the blood sugar level comprising a. The method according to claim 1, wherein the irradiating means irradiates light of two different wavelengths, The calculation means is the amount of transmitted light transmitted through each of the shorter of the distance is detected in point 2 as _.λ1 I _1, I ₁ and _.λ2, and the transmitting side is a long distance to _.λ1 I _2, I _{2 .λ2,} 2 relative permeability of the different wavelengths _λ1 R, R _λ2 the formula _{R λ1 = I 2 .λ1 / I} 1 .λ1, R λ2 = I 2 , and in _.λ2 / I _{1 .λ2,} a pre-measured blood glucose level and the relative transmission rate R _λ1 , R _λ2 to obtain the coefficients k ₀ , k ₁ of the following equation, and the blood glucose value C is calculated according to the formula C = k ₀ + k ₁ * ln (R _{λ 1} ) / ln (R _{λ 2} ) Non-invasive measuring device. The method according to claim 1, wherein the irradiating means irradiates light of two different wavelengths, The calculation means is the amount of transmitted light transmitted through each of the shorter of the distance is detected in point 2 as _.λ1 I _1, I ₁ and _.λ2, and the transmitting side is a long distance to _.λ1 I _2, I _{2 .λ2,} 2 relative permeability of the different wavelengths _λ1 R, R _λ2 the formula _{R λ1 = I 2 .λ1 / I} 1 .λ1, R λ2 = I 2 , and in _.λ2 / I _{1 .λ2,} the same respective relative transmission rate R _{λ1, λ2} R Absorbances A ₁ and A ₂ of two different wavelengths are given by the formulas A ₁ = _-1 n (R λ ₁ ) and A ₂ = _-1 n (R λ ₂ ), and the previously measured blood glucose levels and absorbances A ₁ and A ₂ are given. A device for measuring non-invasive blood glucose levels, wherein the coefficient k ₀ , k ₁ of the following equation is obtained, and the blood sugar level C is calculated according to the equation C = k ₀ + k ₁ * A ₁ / A ₂ . The non-invasive measuring device for blood glucose level according to claim 2 or 3, wherein the light having two different wavelengths irradiated by the irradiation means is selected from the range of 900 to 1100 nm. The method according to claim 1, wherein the irradiating means irradiates light of three different wavelengths, The calculation means is the amount of light transmitted through each of the transmission distance is shorter in the detected two points _.λ1 I _1, I _{1 .λ2,} the I side and a _{1 .λ3,} a long transmission distance _.λ1 I _2, I _{2. λ2,} and the said I _{2 .λ3,} relative permeability of the three wavelengths _λ1 R, R _{λ2, λ3} the formula R _{R λ1 = I 2 .λ1 / I} 1 .λ1, R λ2 = I 2 .λ2 / I 1. _{λ2, λ3} = I R _2, and the _.λ3 / I _{1 .λ3,} to obtain a pre-measured blood glucose level and a relative transmission rate R _{λ1, λ2} R, coefficient from the following formula using the R _λ3 k _0, k _1, the blood glucose level C A device for measuring non-invasive blood glucose levels, which is calculated according to the formula C = k ₀ + k ₁ * ln (R _{λ 1} / R _{λ 3} ) / ln (R _{λ 2} / R _{λ 3} ). The method according to claim 1, wherein the irradiating means irradiates light of three different wavelengths, The calculation means is the amount of light transmitted through each of the transmission distance is short edge is detected at the two points I _1.λ1, I _{1 .λ2,} the I side and a _{1 .λ3,} a long transmission distance _.λ1 I _2, I _{2. λ2,} the I _{2 .λ3,} and relative permeability of the three wavelengths _λ1 R, R _{λ2, λ3} the formula R _{R λ1 = I 2 .λ1 / I} 1 .λ1, R λ2 = I 2 .λ2 / I 1 .λ2 , R I ₂ = _λ3 and by _.λ3 / I _{1 .λ3,} the same respective relative transmission rate R _{λ1, λ2} R, the absorption of three different wavelengths on the basis of the _{R λ3 a 1, a 2,} a 3 of formula a ₁ = -1n (R _λ1 ), A ₂ = -1n (R _λ2 ), A ₃ = -1n (R _λ3 ), and the coefficient of the following equation using the previously measured blood glucose level and absorbance A ₁ , A ₂ , A ₃ A device for measuring non-invasive blood glucose levels, wherein k ₀ and k ₁ are obtained and blood glucose levels C are calculated according to the formula C = k ₀ + k ₁ * (A ₁ -A ₃ ) / (A ₂ -A ₃ ). 7. The light according to claim 5 or 6, wherein the three different wavelengths of light irradiated by the irradiation means are two selected from the range of 900 to 1100 nm, and the other is 900 to 930 nm or 1000 to 1030 nm. Non-invasive measuring device of the blood sugar level is selected from the range.

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