RU2575568C2 - Device to define content of glucose in blood - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: claimed device comprises the length of the metallic transfer waveguide line, plane-parallel plate and the second length of the metallic transfer waveguide line. Note here that said first and second lengths of the metallic transfer waveguide line are provided with the flanges fitted at opposite ends of equal magnitude of the inner cross-section. Inner part of the second length of the metallic transfer waveguide line is filled with dielectric. The flange of one end of the first length of the metallic transfer waveguide line, plane-parallel plate and the flange of the second length of the metallic transfer waveguide line are mechanically interconnected. The opposite end of the first length of the metallic transfer waveguide line is meant for connection with the electromagnetic wave source and refection factor meter while the other end of the second length is meant for contact with blood. The second length magnitude is the multiple of half the electromagnetic wavelength in the second length of the metallic transfer waveguide line.

EFFECT: higher accuracy of determination.

2 dwg, 1 tbl, 1 ex

Description

The invention relates to devices designed for non-invasive determination of blood glucose using electromagnetic waves.

Diabetes is one of the common dangerous human diseases. The most important task for the prevention of diabetes and the course of the disease in humans is the constant monitoring of glucose in human blood. In this case, it is necessary to establish in a timely manner when the glucose content approaches critical values and immediately take measures to restore the normal glucose content in the blood.

A device for non-invasively measuring the concentration of glucose in the blood, operating in the optical wavelength range, comprising means for regulating the current in the power supply circuit and for processing data connected in series with a digital-to-analog converter, a semiconductor laser power supply, a temperature controller, a semiconductor laser radiation source and optical tool [1].

The disadvantages of this device:

- a large error (20-30%) in the determination of glucose in the blood,

- the need to use expensive laser and spectral equipment.

A device for determining the glucose content in the blood, containing a segment of a metal waveguide transmission line, equipped with flanges at both ends, with dimensions of the internal cross section, in which an electromagnetic wave of a centimeter or millimeter wavelength range propagates in a segment of a metal waveguide transmission line, a plane-parallel dielectric plate , which is located at one end of a segment of a metal waveguide line perpendicular to the direction of propagation of the electric a magnetic wave in a metal waveguide transmission line, while a plane-parallel dielectric plate located at one end of the said segment of the waveguide transmission line is in contact with the human skin surface — an object with blood, the other end of the metal waveguide transmission line is designed to connect it to an electromagnetic wave source and a meter for the reflection coefficient of the electromagnetic wave [2] - prototype.

This device

- improves the accuracy of measurements due to the coordination of the waveguide transmission line with the skin surface using a matching plane-parallel dielectric plate,

- reduces the cost of medical research through the use of widespread panoramic meters of the reflection coefficient of the electromagnetic wave of the centimeter or millimeter wavelength range.

The disadvantages of this device:

- to improve the matching of the incident electromagnetic wave with the skin of a person - an object with blood, the matching dielectric plate must have a thickness that is a multiple of an odd number of a quarter of the length of the electromagnetic wave in the dielectric material of the plate, while the quality factor is reduced and the reflection coefficient of the electromagnetic wave in power from the skin of a person does not have a clearly defined minimum, which makes it difficult to determine the frequency corresponding to the minimum reflection coefficient of electromagnetic power, and thereby reduces the accuracy of determination of glucose in the blood,

- the dielectric constant of the plate should be chosen so that the optimal matching conditions are met, however, this condition is practically not feasible, since the plate is made of dielectric material with a certain value of dielectric constant, which differs from the optimal value of dielectric constant, which reduces the accuracy of determination of glucose content in blood.

The technical result of the invention is to increase the accuracy of determination of glucose in the blood while maintaining the low cost of the equipment used.

The specified technical result is achieved by the proposed device for determining glucose in the blood, containing

a section of a metal waveguide transmission line equipped with flanges at both ends, with dimensions of the internal cross section, in which an electromagnetic wave of a centimeter or millimeter wavelength range propagates in a section of a metal waveguide transmission line,

a plane-parallel plate located at one end of a segment of a metal waveguide line perpendicular to the direction of propagation of the electromagnetic wave in the metal waveguide transmission line,

while the other end of the segment of the metal waveguide transmission line is designed to connect it to a source of electromagnetic waves and a meter of the reflection coefficient of the electromagnetic wave, in which

additionally introduced a second segment of a metal waveguide transmission line provided with flanges at both ends of the same internal cross section with the first segment of a metal waveguide transmission line,

the inside of the second segment of the metal waveguide transmission line is filled with a dielectric,

a plane-parallel plate is made of metal and is equipped with a resonant window with dimensions smaller than the dimensions of the internal cross section of the first segment of the metal waveguide transmission line,

a flange of one end of the first segment of the metal waveguide transmission line, a plane-parallel plate and a flange of one end of the second segment of the metal waveguide transmission line are mechanically connected,

the other end of the second segment of the metal waveguide transmission line is intended for contact with the object with blood,

the length of the second segment of the metal waveguide transmission line is a multiple of half the length of the electromagnetic wave in the segment of the metal waveguide transmission line with a dielectric.

SUMMARY OF THE INVENTION

The second segment of the metal waveguide transmission line, filled with a dielectric, on one side of which there is a reflecting wall in the form of a plane-parallel plate made of metal, and on the other hand an absorbing-reflecting wall - an object with blood, is a resonator with reflecting and absorbing-reflecting walls.

Since the length of the second segment of the metal waveguide transmission line L is chosen to be a multiple of half the length of the electromagnetic wave in the segment of the metal waveguide transmission line with a dielectric (L = m × λv / 2, where λv is the length of the electromagnetic wave in a metal waveguide transmission line with a dielectric, m = 1, 2, 3, ...), then standing waves are established in the resonator.

Due to the electromagnetic processes occurring in the resonator, it is a substantially narrow-band device: at frequencies close to the resonant frequency, the reflection coefficient of the electromagnetic wave in power has a sharp minimum.

The value of this minimum of the reflection coefficient of the electromagnetic wave in terms of power and the frequency at which it is achieved is measured on a panoramic meter of the reflection coefficient of electromagnetic waves with high accuracy (less than 1%), which provides a significant increase in the accuracy of determination of glucose in the blood.

In this case, as in the prototype, the minimum value of the reflection coefficient of the electromagnetic wave in power and the frequency at which it is achieved is measured on a panoramic meter of the reflection coefficient of electromagnetic waves of the centimeter or millimeter wavelength range, which ensures the low cost of the equipment used.

Thus, an integrated approach in the proposed device for determining glucose in the blood, namely the implementation

two segments of a metal waveguide transmission line with internal cross-sectional dimensions at which an electromagnetic wave propagates in them in the centimeter or millimeter wavelength range,

with the length of the second segment of the metal waveguide transmission line, a multiple of half the length of the electromagnetic wave,

a plane-parallel plate of metal, equipped with a resonant window with dimensions smaller than the dimensions of the internal cross section of a section of a metal waveguide transmission line,

filling the insulator of the inner part of the second segment of the metal waveguide transmission line,

the mechanical connection of the flange of one end of the first segment of the metal waveguide transmission line, a plane-parallel plate and the flange of one end of the second segment of the metal waveguide transmission line,

compared with the prototype will allow you to use narrow-band resonant phenomena and thereby maximize the accuracy of determination of glucose in the blood.

The invention is illustrated by drawings.

Figure 1 is a drawing of the proposed device for determining glucose in the blood in the context, where

- segments of a metal waveguide transmission line - 1 and 2, respectively,

- flanges of segments of a metal waveguide transmission line - 3, 4, 5 and 6, respectively,

- plane-parallel plate of metal - 7, which is equipped

- resonance window - 8,

- dielectric - 9,

- the investigated object with blood - 10.

In FIG. Figure 2 shows a general view of an experimental setup for measuring blood glucose:

- panoramic meter of reflection coefficient PNA - L N5230C - 1,

- coaxial cable - 2,

- coaxial waveguide transition - 3,

- the proposed device is 4,

- the investigated object with blood - 5.

The claimed device (Fig. 1) contains a second segment of a metal waveguide transmission line 2 with an internal cross section with dimensions of the wide side of the wall equal to a and narrow equal to b, length L, a multiple of half the wavelength in the segment of the metal waveguide line with dielectric 9, and a plane-parallel plate of metal 7, located at one end of the first segment of the metal waveguide line 1. In the plane-parallel plate 7 there is a resonant window 8 of width a1 and height b1. The first segment of the metal waveguide transmission line 1 at one end by means of a flange 3 is connected to the waveguide transmission line from an electromagnetic wave source of a centimeter or millimeter wavelength range. The second segment of the metal waveguide transmission line 2 at one end through the flange 6 is brought into contact with the object with blood. Flanges 4 and 5 of the other ends of the segments of the metal waveguide transmission line and the plate of metal 7 are mechanically interconnected.

The device operates as follows.

When taking measurements on the measuring apparatus shown in FIG. 2, the electromagnetic wave from the panoramic meter of reflection coefficient 1 through the coaxial cable 2 and the coaxial-waveguide transition 3 enters the claimed device 4, where it interacts with the object with blood 5. The electromagnetic wave reflected from the device returns to the panoramic meter, on the screen of which the resonance dependence is displayed power reflection coefficient R of the device from frequency f.

The power reflection coefficient R is defined as the ratio of the power _Pgr reflected from the device to the incident power P _pad

or on a logarithmic scale

where β _St - the coupling coefficient, which is equal to

, $${\beta }_{\mathrm{from}\mathrm{at}}=\frac{{\text{P}}_{\text{sv}}}{{\text{P}}_{\text{res}}}$$

,

P _rez - the power absorbed in the resonator itself,

P _St - power, which returns back from the segment of the transmission line through the resonant window into the supply line.

The following modes of operation of the device are distinguished:

1) when β _st = 1 there is a critical coupling mode, the power dissipated in the resonator P _res is exactly equal to the power radiated from the resonator P _st and dissipated in external transmission lines;

2) when β _sv <1, there is a mode of non-coupling, the power dissipated in the resonator itself exceeds the power dissipated in external transmission lines;

3) _{communication} with β> 1 there reconnection mode, the power transferred from the resonator to the external transmission line exceeds the power dissipated in the resonator.

The maximum sensitivity of the reflection coefficient in the power of the device to a change in the composition of blood in an object with blood will be observed when the coupling coefficient β _sv tends to 1.

Example.

The device was implemented in the centimeter wavelength range. Two segments of the metal waveguide line 1 and 2 are made of copper of the same rectangular inner cross section with a wide side a = 22.86 mm and a narrow side b = 10.16 mm. In a plane-parallel plate made of metal 7, a rectangular resonant window 8 is made with dimensions smaller than the dimensions of the internal cross section of a waveguide line segment, width a ₁ = 9.542 mm, height b ₁ = 10.16 mm and plate thickness 0.28 mm [3]. The dielectric constant of the dielectric 9 - fluoroplastic filling the segment of the waveguide transmission line 2 was 2.04.

The working type of wave in a rectangular waveguide is wave H ₁₀ .

The value of the power loss P _s is determined by the width of the resonance window in the metal plate [3], and the power absorbed in the resonator P _rez is determined by the value of the reflection coefficient at the boundary between the insulator and the object with blood.

To measure small changes in blood glucose, they work in the range of power reflection coefficient modules on a logarithmic scale from minus 30 to minus 40 dB. In this case, the error in measuring the reflection coefficient by the power of the panoramic meter does not exceed 1%.

On the manufactured sample of the device, the power reflection coefficient modules were measured.

Using the claimed device previously shot the so-called "sugar curve". A part of the wrist on the patient’s hand was distinguished, and the resonance curve of the resonator loaded on the selected part on the arm was recorded. The resonant frequency and the minimum of the reflection coefficient at the resonant frequency were recorded. At the same time, the glucose level in the patient's blood was determined using an ONE TOUCH invasive glucometer.

Then, the test patient drank a sweet solution containing 5 teaspoons of sugar dissolved in a glass of water. After that, with an interval of 10 minutes, the resonance dependences were taken, during which the minima of the reflection coefficients and resonance frequencies were determined, and the glucose content in the blood was determined with a glucometer. The measurements were carried out for 90 minutes, the obtained experimental data are presented in the table.

T min 0 10 twenty thirty 40 fifty 60 70 80 90 R _min , dB -34.3 -32.9 -31.8 -30.3 -30.1 -31.8 -33.7 -33.4 -33.5 -36.9 Glucose content, mmol / l 5,6 6.1 6.7 7.4 8.1 8.5 7.4 5.7 5,4 5.1

As can be seen from the table, during the first 50 minutes there was an increase in glucose in human blood from 5.6 to 8.5 mmol / L. At the same time, the modulus of the cavity reflection coefficient increased from minus 34.3 dB to minus 30.1 dB. Then, with a decrease in glucose content, the value of the reflection coefficient also decreased. That is, there is a correlation between changes in the glucose content in the patient’s blood and a change in the reflection coefficient of the device.

Thus, the proposed device will allow you to measure the reflection coefficient by power with high accuracy - 1%, which is about 5 times more than the accuracy of the prototype, and as a result, 5 times will increase the accuracy of determination of glucose in the blood, including human blood.

Information sources

1. US patent. US Patent # 5,243,983. Sept. 14, 1993.

2. US patent. Patent US # 2006/0025664 A1, Published Feb. 2, 2006 - prototype.

3. Gupta K., Garge R., Chadha R. Machine design of microwave devices, M .: Radio and communications. 1987, p. 88.

Claims (1)

A device for determining blood glucose containing
a section of a metal waveguide transmission line equipped with flanges at both ends, with dimensions of the internal cross section, in which an electromagnetic wave of a centimeter or millimeter wavelength range propagates in a section of a metal waveguide transmission line,
a plane-parallel plate located at one end of a segment of a metal waveguide line perpendicular to the direction of propagation of the electromagnetic wave in the metal waveguide transmission line,
while the other end of the segment of the metal waveguide transmission line is designed to connect it to a source of electromagnetic waves and a meter of the reflection coefficient of the electromagnetic wave,
characterized in that
the second segment of the metal waveguide transmission line, equipped with flanges at both ends of the same internal cross section with the first segment of the metal waveguide transmission line, is additionally introduced into the device,
the inside of the second segment of the metal waveguide transmission line is filled with a dielectric,
a plane-parallel plate is made of metal and is equipped with a resonant window with dimensions smaller than the dimensions of the internal cross section of the first segment of the metal waveguide transmission line,
a flange of one end of the first segment of the metal waveguide transmission line, a plane-parallel plate and a flange of one end of the second segment of the metal waveguide transmission line are mechanically connected,
the other end of the second segment of the metal waveguide transmission line is intended for contact with the object with blood,
the length of the second segment of the metal waveguide transmission line is a multiple of half the length of the electromagnetic wave in the second segment of the metal waveguide transmission line with a dielectric.

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