RU78325U1 - DEVICE FOR NON-INVASIVE DETERMINATION OF TISSUE TISSUE CHOLESTEROL - Google Patents

Abstract

A device for non-invasive (i.e., without blood sampling) determination of skin tissue cholesterol belongs to the field of medicine and medical technology and can be used to determine the level of skin tissue cholesterol that correlates with cholesterol in the blood.

The device contains a sealed container without a bottom with a device lock on the skin of the palm of the hand, and is characterized in that the sealed container is made in the form of a cylinder with a piston and is connected by a narrow channel in the piston to a photometric cell located at its other end, consisting of an optical cell, two monochromatic light sources with different radiation wavelengths mounted on the carriage for alternately positioning these sources on the optical axis of the optical cell, while the radiation wavelength of one source that lies in the region of the absorption spectrum of the reaction solution, and another - is the absorption spectrum, and a photodetector, whose output is connected to the measurement unit and recording the photocurrent.

The device improves accuracy and expands the range of measurement of cholesterol in tissues, correlating with cholesterol in the blood, in a non-invasive way, automates the measurement process, portability of the device, reduces the complexity and cost of its manufacture, including by eliminating precious metals (for example, platinum used in an electrochemical sensor), which makes it possible to widely use the device for medical examination of the population for the early diagnosis of cardiovascular diseases.

Description

A device for non-invasive (i.e., without blood sampling) determination of skin tissue cholesterol belongs to the field of medicine and medical technology and can be used to determine the level of tissue cholesterol in the skin that correlates with blood cholesterol.

Known devices that allow the photometric method to determine blood cholesterol levels associated with blood sampling from blood vessels (RF Patent No. 2054178, Russian Federation Abstract No. 9301391), which is uncomfortable and there is a risk of infection of the patient and staff through blood contamination of equipment as a result of its previous use by other persons (RF Patent No. 2188424).

A known method of non-invasively determining the level of tissue cholesterol of the skin by measuring the concentration of hydrogen peroxide formed as a result of a biochemical reaction between skin cholesterol and a solution of a special enzyme applied to the skin (RF Patent No. 2130189).

The device for its implementation contains a sealed container (cuvette) without a bottom for an enzyme-containing mixture and a device that fixes the base of the container on the skin of the palm of the hand, which acts as the bottom of the cuvette with an area of ~ 1 cm ² .

The measurement of the level of hydrogen peroxide in the reaction solution is carried out both by the method of "dry chemistry" and in the liquid phase.

In the “dry chemistry” method, a colorimetric indicator on a paper strip (strip) is placed in the solution, and by changing its color

assess using a color scale or using a reflective photometer the level of hydrogen peroxide in the solution.

The method is simple, inexpensive and can be used both in "home" conditions, and in any medical facility.

The disadvantage of this method is the low accuracy and a limited range of measured concentrations of cholesterol in solution.

The determination of the concentration of hydrogen peroxide in the liquid phase is based on measuring the optical density of the solution, which is proportional to the content of hydrogen peroxide in it. The method allows you to determine the concentration of cholesterol with high accuracy and in a wide range of concentrations (the lower limit of detection is ~ 10 ^-6 mol / l), but is possible only in medical facilities equipped with expensive spectrometric equipment and having qualified personnel for its maintenance.

In addition, the measurement process is associated with a number of manual routine operations for extracting the solution from the reaction vessel and transferring it to the spectrophotometer cuvette, which does not fully automate the measurement process.

The technical result to which the claimed utility model is aimed is to increase the accuracy and expand the range of measurement of cholesterol levels in tissues, which correlates with cholesterol levels in the blood, in a non-invasive way, automate the measurement process, portability of the device, reduce the complexity and cost of its manufacture, including including due to the exclusion of precious metals (for example, platinum used in an electrochemical sensor), which makes it possible to widely use the device for medical examination tion of the population for early diagnosis of cardiovascular diseases.

Essential features.

To achieve the specified technical result in the device for non-invasive determination of skin tissue cholesterol containing a sealed container without a bottom with a device lock on the palm skin, the sealed container is made in the form of a cylinder with a piston and is connected by a narrow channel in the piston with a photometric cell located at its other end, consisting of from an optical cuvette, two monochromatic light sources with different radiation wavelengths mounted on the carriage for alternately positioning these sources Ikov on the optical axis of the optical cuvette, and a photodetector, whose output is connected to the measurement unit and recording the photocurrent. Moreover, the radiation wavelength of one monochromatic light source lies in the region of the absorption spectrum of the reaction solution, and the other outside the absorption spectrum.

The list of figures in the drawing.

To clarify the essence of the utility model, figure 1 shows a schematic drawing of the design of a device for non-invasive determination of skin tissue cholesterol, which shows:

1 - cylinder and 2 - piston, forming a sealed container without a bottom;

3 - a narrow channel in the piston;

4 - photometric cell;

5, 6 - monochromatic light sources (LEDs);

7 - carriage for positioning the LEDs;

8 - condenser;

9 - aperture;

10 - photodetector;

11 - optical cuvette;

12 - device lock on the skin of the palm;

13 - unit for measuring and recording the photocurrent;

14 - screw connection;

15 - power supply LEDs.

The device contains a latch 12, a sealed container without a bottom, made in the form of a cylinder 1 with a piston 2 and connected by a narrow channel 3 in the piston 2 with a photometric cuvette 4 located at its other end. The cuvette 4 contains an optical cuvette 11, two monochromatic light sources (LEDs) 5, 6 mounted on the carriage 7 for alternately positioning the LEDs on the optical axis of the condenser 8, and a photodetector 10, which is connected to the unit for measuring and recording the photocurrent 13.

The device operates as follows:

Using the lock 12, the end face of the cylinder 1 is pressed against the surface of the skin of the palm (in the tenar region) with constant force. The piston 2 moves in the cylinder 1 when it is rotated due to the screw connection 14 .. In this case, for the convenience of operation, the thread pitch is preferably chosen 2-3 times the range of movement of the piston. At the beginning of operation, the piston 2 is in its highest position.

The volume formed between the palm and the piston is filled with a metered amount of an enzyme-containing mixture (about 0.1 ml) using, for example, a low-volume medical syringe, through the side walls of the optical cell 9 with through holes, coaxial with a narrow channel 3 in the piston 2, with a diameter of commensurate with the diameter of the channel 3 in the piston (~ 1 mm).

The exposure of the solution on the skin of the palm is carried out within a few minutes. During the exposure of the solution, a biochemical reaction of skin cholesterol with an enzyme occurs, resulting in the formation of hydrogen peroxide, the concentration of which is directly proportional to the cholesterol content. After exposure of the solution, the piston lowers to the lower position and squeezes the reaction solution into the optical cuvette 11.

A voltage (6-10 V) of direct current is supplied to the LEDs 5, 6 from the power supply 15. The light from the LED 5 with a radiation wavelength λ _{1 of a} capacitor 8 with a diaphragm 9 is directed into an optical cuvette 11 and is focused on the photodetector 10. The signal from the photodetector 10 U _0λ1 from LED 5 is fed to the unit for measuring and recording the photocurrent.

The carriage for positioning the LEDs 7 moves the LED 6 with the radiation wavelength λ ₂ to the optical axis of the cell 11, and the signal value from the photodetector 10 U _{0λ2 is measured} . By adjusting the current through the LEDs at the output of the power supply, equality of values U _0λ1 = U _{0λ2 is achieved} .

Then a dye is added to the reaction solution (for example, the enzyme peroxidase with a substrate), and the values of the signals from the photodetector 10 U _λ1 and U _λ2 are measured similarly.

The LEDs are chosen so that the radiation of one of them is in the region of the absorption spectrum of the reaction solution after adding a dye, and the other is outside the absorption spectrum.

The optical density of the solution at a wavelength of λ ₁ : D _λ1 = log (U _0λ1 / U _λ1 ), and at a wavelength of λ ₂ : D _λ2 = log (U _0λ2 / U _λ2 ).

Since the LED radiation at the wavelength λ _{2 is} not absorbed by the colored solution, theoretically, U _λ2 = U _0λ2 and D _λ2 = log (U _0λ2 / U _λ2 ) = 0. In practice, U _λ2 may differ from U _0λ2 for reasons not related to the selectivity of the absorption spectrum of the solution, and in general the level

hydrogen peroxide in solution (C _nv ), proportional to the concentration of cholesterol in the skin, is determined by the expression:

where R _λ1 - coefficient taking into account the geometry of the optical cell, the molar absorption coefficient of the solution at a wavelength of λ ₁ , the spectral sensitivity of the photodetector 10.

Considering that the cholesterol content in the skin correlates with the blood cholesterol content (C _k ), it is possible to directly correlate the blood cholesterol level with the optical density of the reaction solution, the amount of which is responsible for hydrogen peroxide as the final product of the biochemical reaction in the solution:

Here N (mol / l) is represented as the product K · R _λ1 , where K is a coefficient that in turn takes into account the relationship between the level of cholesterol in the skin and the concentration of hydrogen peroxide in the solution, as well as the correlation between the level of tissue cholesterol of the skin and its concentration in blood.

The value of N can be experimentally determined for each specific device when it measures the optical density of the reaction solution in patients whose blood cholesterol is known (determined, for example, in a medical facility using the “classical” invasive method).

Claims (1)

A device for the non-invasive determination of tissue cholesterol of the skin, containing a sealed container without a bottom with a device lock on the palm skin, characterized in that the sealed container is made in the form of a cylinder with a piston and is connected by a narrow channel in the piston with a photometric cell located at its other end, consisting of an optical cuvettes, two monochromatic light sources with different radiation wavelengths mounted on a carriage for alternately positioning these sources on the optical axis of the optical th cell, wherein the length of one light emission wavelength lies in the region of the absorption spectrum of the reaction solution, and another - is the absorption spectrum, and a photodetector, whose output is connected to the measurement unit and recording the photocurrent.