An electrocardio electrode and a preparation method thereof

Abstract

This application relates to the field of electrocardiography (ECG), specifically providing an ECG electrode and its preparation method. The electrode includes a substrate layer, a reservoir cavity on one side of the substrate layer, and a gel portion inside the reservoir cavity. A carbon-based fabric electrode layer is fixedly disposed on the side of the substrate layer with the reservoir cavity, and the carbon-based fabric electrode layer is bonded and fixedly connected to the substrate layer at its edge. The carbon-based fabric electrode layer covers the reservoir cavity, and the area of ​​the carbon-based fabric electrode layer is larger than the sum of the areas of the open ends of the reservoir cavity. The size of one open end of the reservoir cavity is larger than the size of one bottom end of the reservoir cavity. The electrode preparation method includes the following steps: Step 1: Prepare the substrate layer; Step 2: Prepare the reservoir cavity on the substrate layer; Step 3: Fill the reservoir cavity with conductive hydrogel; Step 4: Deposit the carbon-based fabric electrode layer. Therefore, the ECG electrode of this invention is suitable for detecting ECG signals, does not cause allergies, has low contact impedance with the skin, low noise, and high detection accuracy.

Description

Technical Field

[0001] This application relates to the field of electrocardiography, and more specifically, to an electrocardiogram electrode and a method for preparing the same. Background Technology

[0002] Electrocardiogram (ECG) signals reflect the occurrence, propagation, and recovery of cardiac excitation; the acquisition of ECG signals is of great significance for clinical testing and health monitoring. ECG electrodes are devices used to collect ECG signals. In general use, the ECG electrodes are in contact with the skin to record the changes in electrical activity generated by the heart during each cardiac cycle from the body surface.

[0003] Commonly used ECG electrodes include metal electrodes, gel electrodes, and fabric electrodes. The latter two offer better flexibility, adhere more closely to the skin, and provide more accurate readings. However, the conductive hydrogel in gel electrodes tends to lose water over time, and this dehydrated hydrogel can easily cause skin allergies upon contact with the skin. Therefore, flexible dry electrode materials without conductive hydrogels have become a research hotspot. See the article titled "Research Progress on Electroactive Fiber Flexible ECG Electrodes" published in the journal "Cotton Textile Technology". Carbon-based fabric electrodes contain carbon materials, such as carbon nanotubes or graphene, and possess good biocompatibility and conductivity. However, carbon-based fabric electrodes do not adhere well to the skin, resulting in higher contact impedance and the potential for noise in the ECG signal, leading to less accurate readings.

[0004] In summary, existing gel electrodes are prone to causing skin allergies with prolonged use, while carbon-based fabric electrodes do not adhere well to the skin, have high contact resistance, and are prone to generating noise, thus reducing the accuracy of detection results; therefore, neither is suitable for detecting electrocardiogram signals. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by providing an electrocardiogram (ECG) electrode and its preparation method. This solves the problems that existing gel electrodes are prone to causing skin allergies after prolonged use, and carbon-based fabric electrodes do not adhere well to the skin, have high contact impedance, and are prone to generating noise, thus reducing the accuracy of detection results. Therefore, they are not suitable for detecting ECG signals.

[0006] The technical concept of this invention is as follows: a conductive hydrogel is disposed in a reservoir cavity on the surface of a substrate layer, and a carbon-based fabric electrode layer is disposed above this surface of the substrate layer, covering all reservoir cavities, so that the conductive hydrogel is surrounded by the substrate layer and the carbon-based fabric electrode layer. In use, pressing one side of the substrate layer causes the conductive hydrogel inside the reservoir cavity to enter the carbon-based fabric electrode layer, allowing the carbon-based fabric electrode layer to make contact with the skin, reducing contact resistance, decreasing noise in the electrocardiogram signal, and improving the accuracy of the detection results. Simultaneously, due to the coverage of the carbon-based fabric electrode layer, on the one hand, the conductive hydrogel does not directly contact the skin, preventing skin allergies; on the other hand, the presence of the carbon-based fabric electrode layer makes it difficult for water molecules in the conductive hydrogel to evaporate, thus preventing the conductive hydrogel from drying out and thus preventing skin allergies in the user.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This application provides an electrocardiogram electrode, which includes a substrate layer, a liquid reservoir on one side of the substrate layer, a gel portion inside the liquid reservoir, a carbon-based fabric electrode layer fixedly disposed on the side of the substrate layer where the liquid reservoir is disposed, the carbon-based fabric electrode layer and the substrate layer are bonded and fixedly connected at the edge, the carbon-based fabric electrode layer covers the liquid reservoir, the area of ​​the carbon-based fabric electrode layer is greater than the sum of the areas of the open portion of the liquid reservoir, and the size of one end of the open portion of the liquid reservoir is greater than the size of one end of the bottom portion of the liquid reservoir.

[0009] Furthermore, the depth of the liquid storage cavity is one-third to two-thirds of the thickness of the substrate layer.

[0010] Furthermore, there are multiple liquid storage chambers, and each of the multiple liquid storage chambers is equipped with a gel section.

[0011] Furthermore, the nth row of the liquid storage cavity is aligned with the (n+2)th row, and the (n+1)th row of the liquid storage cavity is not aligned with the nth row, and they are arranged alternately, where n represents the nth row of the liquid storage cavity.

[0012] Furthermore, the liquid storage cavity is cone-shaped, with the bottom of the cone located on the surface of the substrate layer and the apex of the cone located inside the substrate layer, forming the bottom of the liquid storage cavity.

[0013] Furthermore, the liquid storage chamber is shaped as a closed ring with its ends connected.

[0014] Furthermore, the material of the carbon-based fabric electrode layer is a carbon-based fabric electrode, wherein the carbon material is carbon nanotubes or graphene, and the thickness of the carbon-based fabric electrode layer is 0.5-3.0 mm.

[0015] Furthermore, the gel portion is a conductive hydrogel, the substrate layer is made of an elastic material, and the thickness of the substrate layer is 0.5mm-5.0mm.

[0016] A method for preparing the above-mentioned electrocardiogram electrode, the method comprising the following steps:

[0017] Step 1: Prepare the substrate layer;

[0018] Step 2: Prepare a liquid reservoir on the substrate layer;

[0019] Step 3: Fill the reservoir with conductive hydrogel;

[0020] Step 4: Set up the carbon-based fabric electrode layer.

[0021] Furthermore, in step four, the carbon-based fabric electrode layer is disposed on the side of the substrate layer where the conductive hydrogel is disposed, and the time interval between step four and step three is less than 30 minutes.

[0022] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides an electrocardiogram (ECG) electrode structure and its preparation method. In this invention, a conductive hydrogel is disposed within a reservoir cavity. The conductive hydrogel does not directly contact the air, water molecules do not easily evaporate, and the conductive hydrogel does not easily dry out, thus preventing allergic reactions. The presence of a carbon-based fabric electrode layer further reduces the occurrence of allergies by preventing direct skin contact with the conductive hydrogel. During use, the conductive hydrogel is compressed into the carbon-based fabric electrode layer, resulting in a more consistent contact between the carbon-based fabric electrode layer and the skin. Therefore, this invention's ECG electrode is suitable for detecting ECG signals with high accuracy and does not cause allergies.

[0023] Furthermore, the ECG electrode of this invention effectively reduces ECG noise and improves the accuracy of detection results by applying external force to the substrate layer, thereby reducing the impact of external force on the substrate layer and making it easy to operate. Different degrees of pressure, i.e., different magnitudes of external force, cause different degrees of deformation, thus adjusting the amount of conductive hydrogel overflow, preventing unnecessary waste and extending the lifespan of the entire device. Attached Figure Description

[0024] Figure 1 A schematic diagram of an electrocardiogram electrode provided by the present invention;

[0025] Figure 2 A cross-sectional schematic diagram of the reservoir cavity of another electrocardiogram electrode provided by the present invention;

[0026] Figure 3 A top view of the substrate layer and conductive hydrogel of another electrocardiogram electrode provided by the present invention.

[0027] Icons: 1-Substrate layer; 2-Gel layer; 3-Carbon-based fabric electrode layer. Detailed Implementation

[0028] To make the implementation process of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings.

[0029] This invention provides an electrocardiogram electrode, such as... Figure 1 As shown, the ECG electrode includes a substrate layer 1, a gel portion 2, and a carbon-based fabric electrode layer 3. Multiple fluid reservoirs are provided on the upper side of the substrate layer 1. The gel portion 2 is disposed inside the fluid reservoirs, and its material is conductive hydrogel, with a volume equal to the volume of the fluid reservoirs. The carbon-based fabric electrode layer 3 is fixedly disposed on the upper side of the substrate layer 1, completely covering the gel portion 2 and separating it from the human skin. The area of ​​the carbon-based fabric electrode layer 3 is larger than the sum of the opening areas of the fluid reservoirs on the upper side of the substrate layer 1. The material of the substrate layer 1 can be one of rubber, silicone, or polyethylene terephthalate; preferably, it is an elastic material. Specifically, the top view shape of the substrate layer 1 can be any shape, such as circular or rectangular. The thickness of the substrate layer 1 is 0.5mm-5.0mm, which facilitates the placement of the fluid reservoirs. The depth of the fluid reservoirs on the surface of the substrate layer 1 is one-third to two-thirds of the thickness of the substrate layer 1. The carbon-based fabric electrode layer 3 is a carbon-based fabric, which means that carbon materials, such as carbon nanotubes and graphene, are woven together with polyester and cotton fabrics; specifically, the thickness of the carbon-based fabric electrode layer 3 is 0.5-3.0 mm.

[0030] During use, the substrate layer 1 is compressed, and the cavity wall of the reservoir exerts a force on the conductive hydrogel, causing some of the conductive hydrogel at the opening of the reservoir to enter the carbon-based fabric electrode layer 3. The gap between the carbon material and the fabric is filled with conductive hydrogel. The carbon-based fabric electrode layer 3 easily adheres to the skin, reducing the impedance between the carbon-based fabric electrode layer 3 and the skin, thereby reducing noise and improving detection accuracy. The carbon material and fabric interweave to form the carbon-based fabric electrode layer 3. The carbon material is a conductor, and the fabric is an insulator. The conductive hydrogel, acting as a conductor, fills the gap between the carbon material and the fabric. This increases the contact area between the conductor and the skin, while connecting adjacent carbon materials together. In this way, on the one hand, the distance between the carbon material and the skin is reduced, reducing drilling, noise, and improving detection accuracy; on the other hand, the free electrons in the conductive hydrogel connect the carbon materials together, changing the "line contact" between the carbon material and the skin into a "surface contact," effectively reducing motion artifacts. Slight relative movement will not have a significant impact on the detection results, improving the accuracy of ECG signal detection. The improved conductivity of the carbon-based fabric electrode layer 3 allows for faster electron transfer between carbon materials, thereby enhancing detection sensitivity. The carbon-based fabric electrode layer 3 isolates the conductive hydrogel from the air, preventing water molecules from evaporating and the hydrogel from drying out, thus reducing the likelihood of allergies. Furthermore, the presence of the carbon-based fabric electrode layer 3 prevents direct contact between the conductive hydrogel and the skin, ensuring that even if a small amount of the conductive hydrogel dries out, it will not cause skin allergies.

[0031] The substrate layer 1 has multiple liquid storage cavities arranged in an alternating pattern. That is, the nth row aligns with the (n+2)th row, while the (n+1)th row's liquid storage cavities are not aligned with the nth row's cavities, creating a staggered arrangement. This reduces the distance between adjacent liquid storage cavities and increases their effective coverage area. The smaller cavity spacing makes the corresponding areas of adjacent liquid storage cavities on the carbon-based fabric electrode layer 3 more easily influenced by the corresponding areas of the liquid storage cavities, maximizing the area on the carbon-based fabric electrode layer 3 that can absorb conductive hydrogel. Specifically, the staggered arrangement makes the areas on the carbon-based fabric electrode layer 3 that do not correspond to liquid storage cavities appear as small, localized regions rather than strip-shaped areas. These irregularly shaped localized regions are more likely to absorb conductive hydrogel from surrounding liquid storage cavities. This allows the conductive hydrogel to fully penetrate the carbon-based fabric electrode layer 3, further reducing its impedance, noise, and detection accuracy; it also reduces motion artifacts, improving the accuracy of ECG signal detection; simultaneously, it enhances the conductivity of the carbon-based fabric electrode layer 3, enabling faster electron transfer between carbon materials and increasing detection sensitivity. The reservoir cavity can be any shape, such as hemispherical, cuboid, semi-ellipsoidal, or wedge-shaped. The spacing between the reservoir cavities is less than 0.5 cm; this ensures that the conductive hydrogel can fully diffuse into the corresponding carbon-based fabric electrode layer 3 between the two reservoir cavities. The reservoir cavity at the upper edge of the substrate layer 1 is more than 0.8 cm away from the edge of the substrate layer 1, forming an isolation area that prevents the conductive hydrogel from reaching the edge of the substrate layer 1, ensuring that no conductive hydrogel overflows around the ECG electrodes.

[0032] The force exerted on the substrate layer 1 is not necessarily perpendicular to the plane in which the substrate layer 1 is located; it can also be parallel to the plane. Since the substrate layer 1 is an elastic material, any deformation of the substrate layer 1 will cause deformation of the reservoir cavity, resulting in the overflow of the conductive hydrogel. The pressure on the substrate layer 1 can come from any external pressure, such as pressure from bandages, finger pressure, or the pulling force of clothing when it is fixed to clothing. During operation, the side of the carbon-based fabric electrode layer 3 away from the substrate layer 1 contacts the skin. Under external pressure, the substrate layer 1 deforms, causing deformation of the reservoir cavity wall. Under the squeezing action, the conductive hydrogel inside the reservoir cavity is squeezed out and seeps into the carbon-based fabric electrode layer 3. The arrangement of the reservoir cavities allows the carbon-based fabric electrode layer 3 to absorb the conductive hydrogel evenly and sufficiently. Under the action of the conductive hydrogel and the carbon material in the carbon-based fabric electrode layer 3, the electrical signals caused by heart activity are transmitted. Specifically, changes in cardiac activity cause alterations in the charge carrier states within the conductive hydrogel and carbon material. The movement of these charge carriers can be detected by an external circuit, and changes in voltage or current within this circuit reflect the state of cardiac activity. In this invention, the conductive hydrogel permeates the carbon-based fabric electrode layer 3, enhancing the adaptive contact between the carbon-based fabric electrode layer 3 and the skin, reducing impedance, noise, and improving detection accuracy. Simultaneously, it transforms the "line contact" between the carbon material and the skin into "surface contact," effectively reducing motion artifacts and improving the accuracy of ECG signal detection. It also enhances the conductivity of the carbon-based fabric electrode layer 3. The presence of the carbon-based fabric electrode layer 3 prevents direct contact between the conductive hydrogel and the skin, avoiding allergic reactions. Furthermore, the carbon-based fabric electrode layer 3 blocks air from the conductive hydrogel, making it difficult for water molecules inside the hydrogel to evaporate, thus preventing the hydrogel from drying out and further reducing the risk of user allergies.

[0033] The present invention also provides a method for preparing the above-mentioned electrocardiogram electrode, the steps of which are as follows:

[0034] Step 1: Prepare the substrate layer;

[0035] The substrate layer 1 is made of elastic materials such as rubber or silicone. The rubber or silicone is cut into cylinders with a thickness of 0.5mm-5.0mm and a circular or rectangular cross-section. The dimensions of the circle or rectangle are 1.0cm-5.0cm; specifically, the diameter of the circle is 1.0cm-5.0cm, and the length and width of the rectangle are both between 1.0cm-5.0cm. The length and width can be the same or different. The elastic substrate layer 1 can deform under force, ultimately extruding the conductive hydrogel.

[0036] Step 2: Prepare a liquid reservoir on the substrate layer;

[0037] Multiple staggered liquid storage cavities are prepared on the upper surface of the substrate layer, i.e., the top surface of the column. The depth of each liquid storage cavity is one-third to two-thirds of the thickness of the substrate layer 1. The liquid storage cavities are narrower at the bottom and wider at the top, with the upper side being wider, which increases the contact area between the conductive hydrogel and the carbon-based fabric electrode layer 3. This allows the conductive hydrogel to penetrate the carbon-based fabric electrode layer 3 more fully, thereby reducing the impedance between the carbon-based fabric electrode layer 3 and the skin and improving the conductivity of the carbon-based fabric electrode layer 3. The staggered arrangement of the liquid storage cavities means that the nth row is aligned with the (n+2)th row, while the liquid storage cavities in the (n+1)th row are not aligned with the liquid storage cavities in the nth row, and they are staggered. The liquid storage cavities can be prepared by etching. Specifically, the shape and size of the liquid storage cavities can be controlled by controlling the amount of etchant and the etching time. The etchant can be a strong acid or a strong base, such as hydrofluoric acid, sodium hydroxide, concentrated sulfuric acid, etc. They can also be prepared by mechanical cutting or by electron beam bombardment.

[0038] Step 3: Fill the reservoir with conductive hydrogel;

[0039] Conductive hydrogel is filled into multiple reservoirs, each completely filled. To ensure complete filling, a portion can be added beyond the reservoir level, allowing the conductive hydrogel to overflow. The excess conductive hydrogel is then scraped off. Specifically, the reservoirs can be filled sequentially or simultaneously. Preferably, multiple reservoirs are filled simultaneously to prevent the initially filled conductive hydrogel from being exposed to air for too long, causing some water molecules to evaporate. Filling can be done using syringes, which can be arranged in a row to fill all reservoirs sequentially. More specifically, the syringe nozzle initially touches the bottom of the reservoir, and as more conductive hydrogel is added, the syringe height gradually increases, always remaining below the liquid surface. This prevents the inclusion of micro-air bubbles in the filled conductive hydrogel, thereby enhancing the localized electron capacity of the conductive hydrogel. Finally, any excess conductive hydrogel at the opening of the reservoir is scraped off.

[0040] Step 4: Set up the carbon-based fabric electrode layer.

[0041] A carbon-based fabric electrode layer 3 is deposited on the conductive hydrogel within 30 minutes of filling. An adhesive is applied around the perimeter of the substrate layer 1 to fix the carbon-based fabric electrode layer 3. Preferably, no adhesive is applied in the central region, as this would prevent the conductive hydrogel from fully penetrating the carbon-based fabric electrode layer 3. Specifically, the carbon-based fabric electrode layer 3 can be prepared by first depositing graphene oxide onto polyester, then preparing graphene using a reduction reaction, with the deposition process completed using vacuum filtration; alternatively, graphene can be obtained by screen printing onto cotton fabric; or graphene can be impregnated onto fabric. The graphene used in the above preparation processes can also be carbon nanotubes. The prepared carbon-based fabric electrode layer 3 is dried at 40-50°C for at least 0.5 hours in an inert gas atmosphere. The dried carbon-based fabric electrode layer 3 covers the liquid storage cavity, and the perimeter of the carbon-based fabric electrode layer 3 is bonded and fixed to the edge of the substrate layer 1 using adhesive.

[0042] Furthermore, this invention also proposes two structures for the liquid storage cavity. The liquid storage cavity is cone-shaped, narrow at the bottom and wide at the top, with the apex of the cone located at the bottommost point, as shown below. Figure 2 The diagram shows a cross-sectional view of the reservoir. The sidewall of the reservoir forms a conical surface. When the substrate layer 1 is subjected to external force, the sidewall of the conical surface generates two directional components. One component points towards the central axis of the reservoir, meaning that under the action of this component, the conductive hydrogel is compressed, increasing its density. The other component points perpendicularly towards the opening of the reservoir, that is, perpendicularly towards the carbon-based fabric electrode layer 3. Under the action of this component, the conductive hydrogel inside the reservoir overflows from the reservoir and penetrates into the carbon-based fabric electrode layer 3. In this way, under the action of these two components, the conductive hydrogel fully enters the carbon-based fabric electrode layer 3, resulting in improved conductivity, greater impedance reduction, and better contact with the skin. Preferably, the radius of the conical cavity opening is greater than the height of the cone. This means the component pointing towards the opening is greater than the component pointing towards the central axis. The lower extrusion force prevents the conductive hydrogel from suddenly overflowing, causing waste, and avoids excessively high localized conductive hydrogel concentration, which would reduce the conductivity of the carbon-based fabric electrode layer 3 and increase contact resistance. The larger force pointing towards the carbon-based fabric electrode layer 3 allows the conductive hydrogel to fully penetrate it, ensuring thorough mixing. Furthermore, the larger opening of the reservoir cavity provides a larger contact area between the conductive hydrogel and the carbon-based fabric electrode layer 3. After diffusion within the plane of the carbon-based fabric electrode layer 3, the conductive hydrogel distribution is more uniform, thus enhancing the aforementioned beneficial effects of increased conductivity and reduced impedance.

[0043] Furthermore, the liquid storage cavity is annular in shape, with a semi-circular or triangular cross-section along the central axis of the annulus. In the top view, it is a circular ring, i.e., a closed loop formed by connecting the two ends. The conductive hydrogel is disposed within the ring, such as... Figure 3The diagram shows a top view of the reservoir. A ring is formed within the substrate layer, and conductive hydrogel is disposed inside the ring. This results in a longer edge length for the reservoir, including the circumference of both the inner and outer rings. In other words, there are more diffusion sources for the conductive hydrogel within the carbon-based fabric electrode layer 3. The inner and outer edges of the ring are the main diffusion sources for the conductive hydrogel to diffuse into the carbon-based fabric electrode layer 3. The longer the edge length, the more diffusion sources there are, and the more uniform the distribution of the conductive hydrogel in the carbon-based fabric electrode layer 3. This leads to better conductivity of the carbon-based fabric electrode layer 3, better skin contact, lower contact impedance, and more accurate detection results.

[0044] Simultaneously, the interconnected rings form a closed loop. Freely moving charge carriers exist within the conductive hydrogel, and changes in the external electromagnetic field induce a potential within the ring, leading to an induced current. This induced current is localized within the conductive hydrogel inside the reservoir, thus avoiding the influence of external electromagnetic interference on the ECG signal detection process, reducing ECG signal noise, and improving the accuracy of the detection results. In the absence of external electromagnetic interference...

[0045] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An electrocardiogram (ECG) electrode, the ECG electrode comprising a substrate layer, characterized in that, A liquid storage cavity is provided on one side of the substrate layer, and a gel portion, which is a conductive hydrogel, is disposed inside the liquid storage cavity. A carbon-based fabric electrode layer is fixedly disposed on the side of the substrate layer where the liquid storage cavity is located. The periphery of the carbon-based fabric electrode layer is bonded to the edge of the substrate layer using an adhesive. The carbon-based fabric electrode layer covers the liquid storage cavity, and the area of ​​the carbon-based fabric electrode layer is larger than the sum of the open areas of the liquid storage cavity. The depth of the liquid storage cavity is one-third to two-thirds of the thickness of the substrate layer. Multiple liquid storage cavities are provided, and each of the multiple liquid storage cavities contains the conductive hydrogel. The nth row of the reservoir is aligned with the (n+2)th row, and the (n+1)th row of the reservoir is not aligned with the nth row, arranged alternately, where n represents the number of rows in the reservoir. The reservoir is shaped as a ring with its ends connected. The conductive hydrogel disposed in the ring forms a closed loop. Freely moving charge carriers exist in the conductive hydrogel. Changes in the external electromagnetic field will generate an induced potential in the ring, thereby generating an induced current. The induced current is localized in the conductive hydrogel inside the reservoir, thus avoiding the influence of external electromagnetic interference on the ECG electrode's detection of ECG signals.

2. The electrocardiogram electrode according to claim 1, characterized in that, The carbon material of the carbon-based fabric electrode layer is carbon nanotubes or graphene, and the thickness of the carbon-based fabric electrode layer is 0.5-3.0 mm.

3. The electrocardiogram electrode according to claim 1, characterized in that, The substrate layer is made of an elastic material, and the thickness of the substrate layer is 0.5mm-5.0mm.

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