RU220817U1 - COMBINED ELECTRODE ECG-METABOLYTES - Google Patents

Abstract

The technical solution relates to microelectronics and can be used in medical instrumentation in the technology of manufacturing sensors for simultaneous recording of an electrocardiogram and human sweat metabolites. A combined ECG-metabolite electrode having a dielectric base, a reference electrode, an auxiliary electrode, two working electrodes, both coated with a layer of Prussian blue, characterized in that the dielectric base is made of a flexible material - polyimide, all electrodes are made of copper foil coated with silver Ag, the reference electrode is additionally coated with a layer of silver chloride AgCl, the first working electrode is additionally coated with the enzyme lactate oxidase, the second working electrode is additionally coated with the enzyme glucose oxidase, while the reference electrode is located on the side of the electrode adjacent to the human body, and is at the same time an electrode for recording ECG, an auxiliary electrode and the working electrodes are located on the opposite side of the electrode and are covered with a pad of sweat-absorbing material, and the dielectric base has a series of holes for the penetration of sweat. Using the proposed combined electrode ECG-metabolites, it is possible to register any electrical signals from human skin (ECG, electroencephalogram, myogram) simultaneously with recording the concentration of any metabolites (lactates, glucose, urine). The proposed combined ECG-metabolite electrode has an increased wearing time due to the absorption of sweat formed on the human skin under the electrode. The design of the combined ECG-metabolite electrode can be manufactured using standard technologies for serial production of printed circuit boards, thereby achieving high manufacturability and feasibility of use in disposable electrodes. The combined ECG-metabolite electrode has increased functionality and manufacturability for the purpose of accurately measuring a person’s condition. 3 ill.

Description

The proposed technical solution relates to microelectronics and can be used in medical instrumentation in the technology of manufacturing sensors for simultaneous recording of the electrocardiosignal and the concentration of human sweat metabolites.

It is known that to determine the condition of the human body and identify certain pathologies, a number of medical studies are carried out, which include recording an electrocardiogram (ECG) and measuring the concentration of such important metabolites of the human body as glucose and lactates.

An ECG is taken by recording electrical potentials from the human body by installing special electrodes at certain points of the human body (ECG leads).

Metabolite concentrations can be measured in human body fluids such as blood, saliva and sweat.

The concentration of metabolites can be measured by planar electrodes, which are miniature electrochemical cells modified with specific chemical reagents to determine the concentration of a particular chemical.

In medical systems for 24-hour ECG recording - monitoring systems, disposable self-adhesive ECG electrodes are used due to their ease of installation and low cost due to their production in the amount of billions of pieces per year. From 5 to 12 such electrodes are installed on the human body, depending on the number of recorded ECG leads.

To measure the concentration of sweat metabolites in monitoring systems, a separate sensor is used, placed on the human body in the right place and connected to the monitoring system with a separate cable.

To accurately record both the ECG and the concentration of sweat metabolites, it is necessary that the electrode is flexible and follows the curves of the body surface, otherwise air cavities may develop between the skin and the electrode, impairing the accuracy of the measurement.

One of the problems of long-term ECG monitoring is the spontaneous separation of disposable self-adhesive electrodes from the human body due to the formation of a significant amount of sweat under the electrode.

The proposed technical solution is aimed at creating a high-tech combined long-term wear electrode that combines the functions of ECG recording and the concentration of human sweat metabolites.

The technical solution is known [patent US 3805769, Sessions R.W., IPC A61B 5/04, 04/23/1974], which underlies all manufactured disposable self-adhesive ECG electrodes.

To record ECG in such electrodes, a contact metal pad with a diameter of 5...10 mm is used, coated with a layer of Ag/AgCl, which reduces the polarizability of the electrode upon contact with human skin.

The advantages of the known electrode are ease of connection with one electrical contact, as well as high manufacturability.

The disadvantage of the known electrode is its use only for ECG recording, as well as limited wearing time due to separation from the human body when a layer of sweat forms under the electrode.

There is a known method for manufacturing modified electrodes for determining analytes in biological fluids [patent RU 2442130 C2, RICCI Francesco et al., IPC G01N 3/00, G01N 33/543, 02/10/2012]. The known electrode is produced by screen printing on the insulating base of an electrochemical cell formed by two electrodes - a working electrode and a reference electrode, wherein the working electrode is modified with Prussian blue, and the reference electrode is made of silver paste. To determine glucose in biological fluids, the enzyme glucose oxidase is additionally immobilized on the working electrode.

The advantage of the known electrode is a high level of reproducibility at the stage of applying solutions and manufacturability, which allows it to be used as a disposable metabolite sensor.

The disadvantage of the known electrode is the determination of only one type of metabolite. In addition, the use of only two electrodes in the analysis can lead to a deterioration in the accuracy of measurements when a current flowing in the electrochemical cell of more than 1 μA.

Based on a well-known technical solution, modified electrodes have been developed and mass-produced - sensors of various substances, made by screen printing (Screen-Printed Electrodes, SPE) and having an electrochemical cell that includes 3 electrodes - a working electrode, a reference electrode and an auxiliary electrode. The reference electrode is always made of silver coated with silver chloride - Ag/AgCl, or silver Ag, and the working and auxiliary electrodes are made of various materials with good electrical conductivity - from graphite to gold. To measure the concentration of metabolites, the working electrode is successively coated with layers of Prussian blue and the oxidase enzyme of the desired substance.

A known electrode for measuring glucose concentration manufactured by DropSense - Ref. GLU10 [https://dropsens.com/en/pdfs_productos/new_brochures/glu10.pdf], having dimensions 33×10×0.5 mm, in which the insulating base is made of ceramic, the working and auxiliary electrodes are made of graphite, the working electrode is coated with Berlin azure and the enzyme glucose oxidase.

A known electrode of similar design for measuring lactate concentrations from the same company is Ref. LACT10 [https://dropsens.com/en/pdfs_productos/new_brochures/lact10.pdf], in which the working electrode is coated with Prussian blue and lactate oxidase enzyme.

The disadvantages of the known electrodes are:

a design intended for the analysis of significant volumes of solution that completely covers the area of the electrochemical cell, which does not allow its use for the analysis of small volumes of sweat;

fragility and rigidity of the ceramic base;

analysis of the concentration of only one type of chemical substance.

The closest in technical essence is the planar electrode produced by DropSense - Ref. C1110CNF [https://dropsens.com/pdfs_productos/new_brochures/110cnf-c1110cnf.pdf]. The known electrode contains two working electrodes made of graphite for the analysis of two different chemical substances. A variation of the well-known electrode is also produced - DRP-X7710, in which both working electrodes are additionally coated with Prussian blue. This electrode is adopted as a prototype.

The advantages of the known electrode are its ability to simultaneously analyze two different chemical substances and its miniature size.

The disadvantages of the known electrode are:

a design intended for the analysis of significant volumes of solution that completely covers the area of the electrochemical cell, which does not allow its use for the analysis of small volumes of sweat;

fragility and rigidity of the ceramic base.

The objective of creating a new technical solution is to obtain a combined ECG-metabolite electrode by modifying a known electrode with two working electrodes, as well as increasing the functionality and manufacturability of the resulting combined ECG-metabolite electrode by manufacturing it in the form of a flexible dielectric base with thin-film metal electrodes.

The objective is achieved by the fact that a combined ECG-metabolite electrode having a dielectric base, a reference electrode, an auxiliary electrode, two working electrodes, both coated with a layer of Prussian blue, according to the claimed technical solution, the dielectric base is made of a flexible material - polyimide, all electrodes are made of copper foil, the reference electrode is additionally coated with silver Ag and a layer of silver chloride AgCl, the first working electrode is additionally coated with the enzyme lactate oxidase, the second working electrode is additionally coated with the enzyme glucose oxidase, while the reference electrode is located on the side of the electrode adjacent to the human body and is also an electrode for For ECG recording, the auxiliary electrode coated with Ag silver and the working electrodes are located on the opposite side of the electrode and covered with a pad of sweat-absorbing material, and the dielectric base has a series of holes for the penetration of sweat.

The essence of the technical solution is illustrated by the drawings of Fig. 1, Fig. 2 and Fig. 3.

Figure 1 shows a view of the combined ECG-metabolite electrode from the side in contact with the human body.

Figure 2 shows a view of the combined ECG-metabolite electrode from the opposite side (without a sweat-absorbing pad).

Figure 3 shows an example of a multilayer design of a combined ECG-metabolite electrode (auxiliary electrode not shown).

The ECG-metabolite combination electrode includes:

dielectric base 1, made of flexible material, with holes for penetration of sweat 2;

reference electrode 3, which is also an electrode for recording ECG, consisting of three layers - a layer of conductive material 3.1 is covered with a layer of silver 3.2 and silver chloride 3.3;

working electrode 4, consisting of three layers - a layer of conductive material 4.1 is covered with a layer of Prussian blue 4.2 and lactate oxidase enzyme 4.3;

working electrode 5, consisting of three layers - a layer of conductive material 5.1 is covered with a layer of Prussian blue 5.2 and a glucose oxidase enzyme 5.3;

an auxiliary electrode 6 made of a conductive material coated with a layer of silver;

pad 7 made of sweat-absorbing material.

The proposed technical solution can be implemented using well-known technologies for the serial production of flexible printed circuit boards (for example, https://www.rezonit.ru/pcb/gibkie/serial/).

In the embodiment shown in Fig. 3, the combined ECG-metabolite electrode can be made of the following materials:

dielectric base 1 - polyimide, foiled with copper foil on both sides, with a total thickness of 61 µm;

layers 3.1, 4.1, 5.1 and the auxiliary electrode 6 are made of copper foil in a known manner (for example, by photolithography followed by etching);

layer 3.2 - immersion silver Ag with a thickness of 0.1...0.4 µm;

layer 3.3 - silver chloride AgCl is formed on silver Ag using known methods (for example, electrolysis in a bath with a NaCl solution);

layers 4.2, 4.3, 5.2, 5.3 are applied to copper foil by known methods;

pad 7 - a layer of sweat-absorbing material (for example, microfiber) 0.5...1 mm thick.

The total thickness of the combined ECG-metabolite electrode (without spacer 7) will be no more than 100 µm.

The combined ECG-metabolite electrode with a thickness of 0.1 mm made from the proposed materials has good flexibility for bending along any of the coordinate axes, as well as for giving a round convex shape.

The proposed combined ECG-metabolite electrode can be built into the known design of a disposable ECG electrode instead of a standard contact pad.

The ECG-metabolite combination electrode works as follows:

when installed on human skin, the combined ECG-metabolite electrode touches the skin and records the ECG with a reference electrode (aka ECG electrode) 3;

sweat, which begins to accumulate under the reference electrode 3, penetrates through the holes 2 and wets the gasket 7 covering the working electrodes 4 and 5 and the auxiliary electrode 6;

working electrode 4, reference electrode 3 and auxiliary electrode 6 form an electrochemical cell for measuring lactate concentration;

working electrode 5, reference electrode 3 and auxiliary electrode 6 form an electrochemical cell for measuring glucose concentration;

both electrochemical cells begin to work when a certain amount of sweat accumulates in pad 7;

The positive effect of the proposed technical solution is based on a set of design solutions and consists of the following:

1. Using the proposed combined electrode ECG-metabolites, it is possible to register any electrical biosignals from human skin (ECG, electroencephalogram, myogram) simultaneously with recording the concentration of any metabolites (lactates, glucose, urine).

2. The proposed combined ECG-metabolite electrode has an increased wearing time due to the absorption of sweat formed on the human skin under the electrode.

3. The proposed combined ECG-metabolite electrode, due to its flexibility, ensures high-quality contact with human skin and accurate measurement of electrical biosignals.

4. The proposed combined ECG-metabolite electrode has stable characteristics due to the use of materials that are stable to external influences and temperature.

5. The proposed combined ECG-metabolite electrode has biological compatibility with human skin due to the use of biologically neutral materials that directly touch human skin (polyimide and Ag/AgCl layers).

6. The proposed design of a combined ECG-metabolite electrode can be manufactured using standard technologies for serial production of printed circuit boards, thereby achieving high manufacturability and feasibility of use in disposable electrodes.

Claims (1)

A combined ECG-metabolite electrode containing a dielectric base, a reference electrode, an auxiliary electrode, two working electrodes, both coated with a layer of Prussian blue, characterized in that the dielectric base is made of a flexible material - polyimide, all electrodes are made of copper foil, the reference electrode is additionally coated silver Ag and a layer of silver chloride AgCl, the first working electrode is additionally coated with the enzyme lactate oxidase, the second working electrode is additionally coated with the enzyme glucose oxidase, while the reference electrode is located on the side of the electrode adjacent to the human body and is also an electrode for recording ECG, an auxiliary electrode coated Ag silver, and the working electrodes are located on the opposite side of the electrode and covered with a pad of sweat-absorbing material, and the dielectric base has a series of holes for sweat to penetrate.