Electrode, electrode clip and preparation method for extracorporeal electrocardiogram monitoring

Abstract

The present invention belongs to the field of medical electrophysiology, and provides an electrode, an electrode clip, and a preparation method for in vitro electrocardiogram monitoring. The present invention uses carbon foam as the substrate of the electrode, adopts an electrochemical deposition method to deposit nanosilver on the carbon foam, and then performs an electrochemical chlorination method to obtain silver chloride. Finally, polyvinyl alcohol hydrogel is poured to prepare a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode. The electrode prepared by the present invention has the advantages of excellent electrical conductivity, long service life, not easy to fall off, good softness, etc. The polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode prepared by the present invention is further improved to prepare a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode clip that can be used for electrocardiogram monitoring, achieving the purpose of in vitro detection with non-invasive, excellent conductivity, high sensitivity, good stability, and long service life. The electrode clip of the present invention will replace traditional acupuncture to detect electrocardiogram changes in mice, and provide a meaningful exploration for in vitro non-invasive electrocardiogram detection.

Description

Technical Field

[0001] The present invention relates to the field of medical electrophysiology, and in particular to electrodes, electrode clips and preparation methods for in vitro electrocardiogram monitoring, in particular to polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrodes, electrode clips made using the electrodes and preparation methods thereof. Background Art

[0002] ECG monitor is a monitoring device for cardiovascular and cerebrovascular diseases. Cardiovascular and cerebrovascular diseases are a general term for cardiovascular and cerebrovascular diseases. Due to hyperlipidemia, poor blood viscosity and fluidity, atherosclerosis and other reasons, ischemic or hemorrhagic diseases of the heart and brain may occur, which seriously threatens human health. The harmful characteristics are high morbidity, high disability rate, high mortality rate, many complications and high recurrence rate. Therefore, it is extremely important to improve the accuracy of detection of related diseases. [1] . Human ECG monitoring experiments often use mice as experimental subjects, because mice and humans have similar gene sequences and there are small differences between individuals. However, ECG detection on mice is often limited by the experimenter's technique and the detection sensitivity of the equipment. For example, when experimenters perform ECG detection on mice, they need to insert electrodes into the mouse's body. The site where the electrodes are inserted will touch some nerves, blood vessels, and meridians. If the technique is not skilled, the electrodes need to be inserted repeatedly, which will cause tissue damage and lead to deviations in the experimental results. Therefore, this field urgently needs an in vitro ECG detection device. The sensitivity and conductivity of the instrument electrodes for detecting ECG changes at the same time are important indicators for measuring the excellence of the instrument. Improving the sensitivity of the instrument electrodes enables it to accurately sense changes in external signals and transmit the signals. Only in this way can the patient's condition be judged based on the measurement results. Therefore, it is very important to improve the sensitivity and conductivity of the instrument electrodes. Therefore, it is crucial to develop an in vitro flexible electrode with high sensitivity, good stability, and excellent conductivity for use in in vitro ECG detectors.

[0003] There are a lot of studies on silver / silver chloride electrodes, but the preparation methods, experimental materials and application fields are very different. [2] The preparation of silver / silver chloride electrodes using PDMS as a substrate is applied in the field of biosensors. The production process is to peel off the cured PDMS from ITO-Ag to obtain PDMS-Ag as a substrate, and then chemically chlorinate to obtain silver / silver chloride electrodes. Sun Jing et al. [3] PDMS was used as a substrate to prepare silver / silver chloride electrodes, and chemical chlorination was used to obtain the electrodes during the preparation process. Zhang Guojun et al. [4] A flexible silver / silver chloride electrode for electrocardiography (ECG) detection has been fabricated by screen-printing a silver-silver chloride paste onto polyimide and heat-curing it. This electrode can be used to detect weak fetal ECG signals. However, some of these electrodes still suffer from complex preparation processes, poor stability and reproducibility, short service life, and uncertain chloride content. Summary of the Invention

[0004] To overcome the shortcomings of the existing technology, the present invention provides a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode, an electrode clip, and a preparation method that are non-invasive in vitro, highly sensitive, stable, and excellently conductive. The inventive concept of the present invention is: first, using carbon foam as the electrode substrate, silver / silver chloride, and hydrogel as working layers, a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode is prepared, and then the electrode clip is further designed.

[0005] The primary purpose of the present invention is to protect an electrode for extracorporeal electrocardiogram monitoring. The electrode uses modified carbon foam as a substrate, deposits nanosilver on the modified carbon foam by an electrochemical deposition method to obtain a carbon foam-silver electrode, and prepares a carbon foam-silver / silver chloride electrode by an electrochemical chlorination method; then, a polyvinyl alcohol hydrogel mixture is poured on the surface of the carbon foam-silver / silver chloride electrode to form a polyvinyl alcohol hydrogel encapsulation film on the surface of the carbon foam-silver / silver chloride electrode to obtain a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode.

[0006] Another object of the present invention is to protect the method for preparing the above-mentioned electrode.

[0007] First, in the step of preparing the foam carbon-silver electrode, the electrolyte solution used for electrochemical deposition is a mixed solution of 0.2-0.8 mol / L AgNO3 and NaNO3, the deposition potential is -0.2V--0.4V, and the deposition time is 500-1500s.

[0008] As a preferred embodiment, the electrolyte solution used for electrochemical deposition is a 0.5 mol / L mixed solution of AgNO 3 and NaNO 3 , the deposition potential is -0.2 V, and the deposition time is 1000 s.

[0009] Secondly, in the step of preparing the foam carbon-silver / silver chloride electrode, the foam carbon-silver electrode is placed in a 0.1-1M hydrochloric acid solution and an electrochemical chlorination method is used to prepare the foam carbon-silver / silver chloride electrode; wherein the chlorination time is 1000-2000s and the chlorination potential is 230-300mV.

[0010] As a preferred embodiment, a foam carbon-silver electrode is placed in a 0.1 M hydrochloric acid solution and an electrochemical chlorination method is used to prepare a foam carbon-silver / silver chloride electrode; wherein the chlorination time is 1500 s and the chlorination potential is 300 mV.

[0011] In order to further realize the preparation of polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride electrodes, the technical solution adopted in the present invention is: using the freeze-thaw cycle method, polyvinyl alcohol (PVA), phytic acid (PA) and amino-polysilsesquioxane (NH2-POSS, NP) are prepared into a mixed solution and evenly poured on the electrode surface to form a polyvinyl alcohol hydrogel encapsulation film, thereby obtaining a polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride electrode that is not easy to fall off, has strong affinity and high softness.

[0012] As a preferred embodiment, a polyvinyl alcohol hydrogel film carbon foam-silver / silver chloride electrode is immersed in a 0.5M to 0.9M KCl solution for 12 to 24 hours, and then the electrode is transferred to a vacuum oven and dried at 20°C to 50°C for 1.5 hours to 4 hours to obtain a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode.

[0013] As a preferred embodiment, the freeze-thaw cycle method is specifically as follows: polyvinyl alcohol is used as raw material, phytic acid and amino-polysilsesquioxane are used as cross-linking agents, the above materials are prepared into a mixed solution and evenly poured on the surface of the dried foam carbon-silver / silver chloride electrode, frozen at -20°C for 16 hours, thawed at room temperature for about 3 hours, and the freeze-thaw cycle is repeated 3 times to obtain a foam carbon-silver / silver chloride electrode with a polyvinyl alcohol hydrogel film.

[0014] In addition to the above steps, the present invention further performs a modification treatment on the carbon foam. Specifically, the carbon foam is sequentially cleaned with deionized water, acetone, and ethanol, and then modified with nitric acid. The carbon foam is a foam-like porous carbon material with low density and high strength, composed of interconnected pores and pore walls. The modification treatment increases the number of oxygen-containing functional groups on the surface, which is more conducive to the deposition of substances. Nanosilver is then deposited on the modified carbon foam by electrochemical deposition. The carbon foam-silver electrode is further placed in a hydrochloric acid solution and electrochemical chlorination is used to prepare a carbon foam-silver / silver chloride electrode. The electrode obtained by the present invention has the characteristics of large specific surface area, multiple active sites, and excellent conductive properties.

[0015] As a preferred embodiment of the present invention, the carbon foam was sequentially placed in deionized water with ultrasonic treatment at 15°C for 30 minutes, in an acetone solution with ultrasonic treatment at 15°C for 30 minutes, and in ethanol with ultrasonic treatment at 15°C for 30 minutes to remove impurities from the carbon foam surface. After cleaning, the carbon foam was immersed in 10 mM nitric acid at 80°C for 10 hours and then allowed to air dry at room temperature for later use.

[0016] The three-electrode system for preparing the foam carbon-silver electrode in the present invention is: the foam carbon is used as a working electrode, a saturated calomel electrode is used as a reference electrode, and a platinum wire is used as a counter electrode.

[0017] The three-electrode system for preparing the foam carbon-silver / silver chloride electrode in the present invention is as follows: the foam carbon-silver electrode is a working electrode, the silver / silver chloride electrode is a reference electrode, and the platinum wire is a counter electrode.

[0018] Another object of the present invention is to request protection for an electrode clamp for in vitro electrocardiogram monitoring composed of the above-mentioned electrodes, the electrode clamp mainly consisting of a clamp shaft, an upper clamp, a lower clamp, a conductive tape and a 0.8 cm × 0.3 cm polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride electrode, the upper and lower clamps are connected by the clamp shaft, and the polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride electrodes are fixed to the inner walls of the upper and lower clamps with grooves by conductive tape to obtain a polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride electrode clamp.

[0019] The electrodes and electrode clips claimed in the present invention can be applied to an in vitro electrocardiogram monitoring device, in particular to an electrocardiogram monitoring device for mice.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The advantages of using foam carbon as the substrate of the electrode in the present invention are: foam carbon is a lightweight porous foam-like carbon material with a three-dimensional network structure, which has the advantages of low density, high strength, good pore structure, smooth ligaments, no cracks, good conductivity, etc. It can be combined with other metal materials to easily obtain high-performance composite materials, and is often used in chemical industry, aerospace, medicine and other fields.

[0022] The advantages of depositing nanosilver on carbon foam are: nanosilver exhibits nanoscale size effects, a high specific surface area, good electrical conductivity, low resistivity, and high electrical conductivity, making it a widely used material in various fields. Using the modified carbon foam as a substrate facilitates the deposition of the silver layer, and combining the carbon foam with nanosilver to form an electrode yields a multifunctional composite material with excellent electrical conductivity.

[0023] The electrode preparation process of the present invention first uses carbon foam as a substrate, and silver and conductive polyvinyl alcohol hydrogel as auxiliary conductive materials to improve the electrode's conductivity and enhance signal collection capabilities. Secondly, nanosilver is prepared by electrochemical deposition. Nanosilver has the characteristics of high purity and uniform particle size compared to silver, thereby improving the electrode's conductivity. Finally, the present invention uses electrochemical chlorination to prepare silver chloride. Compared with chemical chlorination, electrochemical chlorination is easier to control the degree of silver chlorination and ensure stability between samples. Furthermore, electrochemical chlorination is easy to operate, the chlorination process is simple, and the prepared silver / silver chloride is more stable than silver and less susceptible to oxidation.

[0024] The electrodes prepared by the present invention have the advantages of excellent conductivity, long service life, resistance to shedding, and good flexibility. The polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode prepared by the present invention is further improved to prepare a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode clip that can be used for electrocardiogram monitoring.

[0025] The present invention prepares a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode clip. Compared with traditional devices for monitoring mouse electrocardiograms (ECGs), this device achieves the goal of non-invasive, highly conductive, highly sensitive, and stable in vitro testing. Traditional mouse ECG monitoring involves inserting a needle into the mouse and then connecting it to an ECG monitoring instrument. The electrode clip provided by the present invention clamps the mouse's limb and connects to a BL-420 biosignal acquisition system to detect ECG changes in the mouse. The advantages of this electrode are: on the one hand, it can achieve non-invasive in vitro testing of mice. The electrode is placed in a groove in the clip, increasing the contact area with the mouse's limb and reducing the pain caused by the electrode insertion into the mouse's body. It also reduces signal interference caused by repeated insertion of the electrode into the mouse's tissue due to poor technique, which can damage the mouse's arteries and nerves. The polyvinyl alcohol hydrogel on the electrode clip surface not only improves the electrode clip's conductivity but also increases the mouse's comfort. On the other hand, the electrode clip provided by the present invention has a long service life and can be used for long-term ECG monitoring. Therefore, the hydrogel carbon foam-silver / silver chloride electrode clip prepared by the present invention achieves the goal of non-invasive and accurate in vitro monitoring of ECG signals in mice, providing a meaningful exploration of in vitro non-invasive ECG testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 :Flowchart for the preparation of polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode clips;

[0027] Figure 2 : Schematic diagram of the polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode clip structure;

[0028] Figure 3 : XRD of foam carbon-silver electrode;

[0029] Figure 4 : SEM of carbon foam-silver electrode;

[0030] Figure 5 : XRD of carbon foam-silver / silver chloride electrode;

[0031] Figure 6 : SEM of carbon foam-silver / silver chloride electrode;

[0032] Figure 7 : Reference diagram of the polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode clamp in use;

[0033] Figure 8:Polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode clamp was used to detect the electrocardiogram curve of mice for the first time;

[0034] Figure 9 : The polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode clamp detected the electrocardiogram curve of mice for the 100th time;

[0035] Figure 10 : Traditional method to detect mouse electrocardiogram;

[0036] Figure 11 :Traditional methods were used to detect the ECG curve of mice. DETAILED DESCRIPTION

[0037] The present invention is described in detail below by specific examples, but the scope of protection of the present invention is not limited. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0038] Example 1 Preparation of polyvinyl alcohol conductive hydrogel-carbon foam-silver / silver chloride electrode

[0039] Step S1: Modification of carbon foam

[0040] like Figure 1 As shown, a 0.8 x 0.3 cm carbon foam was cleaned by ultrasonicating it in deionized water at 15°C for 30 minutes, in acetone at 15°C for 30 minutes, and in ethanol at 15°C for 30 minutes to remove surface impurities. After cleaning, the carbon foam was immersed in 10 mM nitric acid at 80°C for 10 hours, then allowed to air dry at room temperature before use. Because carbon foam is a porous, low-density, high-strength carbon material composed of interconnected pores and pore walls, the numerous pores lead to the presence of impurities that can affect the experimental process. Therefore, the carbon foam was treated with deionized water, acetone, and ethanol. Next, a high-temperature acid treatment with nitric acid was performed to increase the surface oxygen content, making the carbon foam more susceptible to silver deposition.

[0041] Step S2 Preparation of Carbon Foam-Silver / Silver Chloride

[0042] A three-electrode system was used, with the cleaned and modified carbon foam as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum wire as the counter electrode. A 0.5 mol / L mixed solution of AgNO3 and NaNO3 was placed in the electrolyte solution for electrochemical deposition of silver. The deposition potential was -0.2 V and the deposition time was 1000 s. After electrochemical deposition, nanosilver was deposited on the surface of the carbon foam, which improved the conductivity of the electrode. Figure 3 The X-ray diffraction pattern shown shows that the deposition of nanosilver is complete. Figure 4 SEM diagram of carbon-silver foam.

[0043] A three-electrode system consisting of a carbon foam-silver electrode as a working electrode, a silver / silver chloride electrode as a reference electrode, and a platinum wire as a counter electrode was placed in a 0.1 mol / L hydrochloric acid solution and chlorinated by electrochemical chlorination. The chlorination time was 1500 s and the chlorination potential was 300 mV. The carbon foam-silver / silver chloride electrode was prepared. The preparation process is as follows: Figure 1 shown. Figure 5 This is the X-ray diffraction pattern of the carbon foam-silver / silver chloride electrode. It can be seen that there is chlorine on the nanosilver, indicating that the chlorination is complete. Figure 6 This is the SEM image of the foam carbon-silver / silver chloride electrode. It was observed that the electrode structure changed from the original smooth rod shape to a rough rod shape, indicating that the nanosilver on the electrode surface was indeed chlorinated to form silver chloride.

[0044] Step S3 Preparation of polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode

[0045] 1g PVA and 0.25g NH2-POSS were dissolved in 6mL deionized water and stirred in a 95°C oil bath for 0.5h until homogeneous. 4mL phytic acid was then added to the solution, and stirring continued for 1.5h until the solution became colorless and transparent. The mixed solution was ultrasonically shaken for 0.5h until bubbles disappeared. The dried carbon foam-silver / silver chloride electrode was placed in a Petri dish, and the mixed solution was evenly poured onto the electrode surface. The electrode was frozen at -20°C for 16h and then thawed at room temperature for approximately 3h. This freeze-thaw cycle was repeated three times to obtain a carbon foam-silver / silver chloride electrode with a polyvinyl alcohol hydrogel film. The electrode was then immersed in 0.7M KCl solution for 10h and then dried in a vacuum oven at 30°C for 2-3h to obtain a polyvinyl alcohol conductive hydrogel-carbon foam-silver / silver chloride electrode.

[0046] Comparative Example 1 Comparison of polyvinyl alcohol conductive hydrogel-foam carbon-silver / silver chloride reference electrode with prior art electrodes

[0047] Table 1 Comparison of electrodes of the present invention and prior art

[0048]

[0049]

[0050] There are currently a large number of studies on silver / silver chloride electrodes, but the preparation methods, experimental materials and application fields are very different. This paper will compare them from multiple angles such as materials, preparation methods, and applications.

[0051] Sun Jing et al. [2]The preparation of silver / silver chloride electrodes using PDMS as a substrate is used in the field of biosensors. The production process involves peeling the cured PDMS from ITO-Ag to obtain PDMS-Ag as a substrate, and then chemically chlorinating the resulting silver / silver chloride electrode. The present invention, however, uses a significantly different carbon foam as a substrate and an electrochemical chlorination method to prepare the silver / silver chloride electrode. A hydroconductive gel is also used to fix the surface, improving electrode stability. The chemical chlorination method involves directly immersing the object in a solution, resulting in a more difficult and intense reaction process. In contrast, the electrochemical chlorination method involves placing the object in a relatively low-concentration solution, applying an electric current, and allowing the reaction to proceed slowly. In electrochemical chlorination, the current and time can be controlled, indirectly controlling the degree of chlorination. Furthermore, during the experimental process, the results or values ​​obtained from each experiment are relatively similar, resulting in better stability.

[0052] Sun Jing et al. [3] Silver / silver chloride electrodes are prepared using PDMS as a substrate. During the preparation process, chemical chlorination is used to obtain the electrodes. However, the present invention adopts an electrochemical chlorination method, which can more accurately control the degree and time of chlorination and does not require a complicated preparation process to obtain a preliminary foam carbon-silver / silver chloride electrode. To solve the problem of poor repeatability during the use of the foam carbon-silver / silver chloride electrode, the present invention uses hydrogel cast on the electrode surface, which not only prevents the silver nanostructure on the electrode surface from falling off, but also increases the service life of the electrode.

[0053] Zhang Guojun et al [4] A flexible silver / silver chloride electrode for electrocardiographic detection was prepared by thermally curing silver-silver chloride paste on polyimide using a screen printing process. The electrode can be used to detect weak fetal electrocardiographic signals. The present invention uses completely different materials and preparation methods, using foam carbon as a substrate and an electrochemical chlorination method to prepare the silver / silver chloride electrode, which is further made into an electrode clip. The electrochemical method is used to control the content of deposited silver, reducing material waste. The chlorination time can also be controlled to ensure the chlorination content of chloride ions, thereby improving electrode stability.

[0054] Example 2 Preparation of electrode clip

[0055] In this embodiment, the electrode clamp is mainly composed of a clamp shaft, an upper clamp, a lower clamp, a conductive tape, and a 0.8 cm × 0.3 cm polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode. The polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode is fixed to the inner wall of the upper and lower clamps with grooves by conductive tape. The upper and lower clamps are connected by the clamp shaft to obtain a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode clamp. The specific electrode clamp structure is as follows: Figure 2 shown.

[0056] Example 3 ECG testing using polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrodes

[0057] The polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride electrode clip prepared by the present invention was used to perform electrocardiogram test on mice. Figure 7 The ECG detection process is to first anesthetize the mouse and place it on the operating table, then fix the prepared electrode clips to the mouse's limbs, connect it to the BL-420 biological signal acquisition system, and monitor the mouse's ECG in real time. The experimental results are shown in Figure 8-11 As shown, it can be seen that by using the electrode clip provided by the present invention, mice can undergo accurate ECG detection without puncturing their skin, and the electrode clip has good stability, high accuracy, and a long service life, and can be used for long-term ECG monitoring.

[0058] The above description is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the protection scope of the present invention.

[0059] References

[0060] [1] Ma Wenge. Analysis of cardiovascular and cerebrovascular diseases in the elderly[J]. China Health Industry, 2011, 8(04):113.

[0061] [2] Sun Jing, Wang Qingxiang, Shen Guijun, Lang Mingfei. Preparation method and application of reusable PDMS-based Ag / AgCl microelectrode[P]. CN108195911B, 2020-05-19.

[0062] [3] Sun Jing, Wang Qingxiang, Shen Guijun, Lang Mingfei. A method for preparing and applying a reusable PDMS-based Ag / AgCl microelectrode[P]. CN108195911A, 2018-06-22.

[0063] [4] Zhang Guojun, Zhang Shiyu, Fan Zhequan, Gao Linming. Silver-silver chloride paste for flexible electrocardiogram detection electrodes and its application [P]. CN114334218A, 2022-04-12.

Claims

1. A method for preparing an electrode for extracorporeal electrocardiogram monitoring, characterized in that: include: S1. Preparation of carbon foam-silver electrode: The modified carbon foam is used as a substrate, and nanosilver is deposited on the modified carbon foam by electrochemical deposition to obtain a carbon foam-silver electrode. The electrolyte solution used for the electrochemical deposition is a mixed solution of 0.2-0.8 mol / L AgNO3 and NaNO3, the deposition potential is -0.2V--0.4V, and the deposition time is 500-1500s. S2. Preparation of carbon foam-silver / silver chloride electrode: The foamed carbon-silver electrode is placed in a 0.1-1 M hydrochloric acid solution to prepare a foamed carbon-silver / silver chloride electrode by an electrochemical chlorination method; wherein the chlorination time is 1000-2000 s and the chlorination potential is 230-300 mV; S3. Preparation of polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode: Using the freeze-thaw cycle method, a mixed solution of polyvinyl alcohol, phytic acid and amino-polysilsesquioxane was evenly poured on the electrode surface to form a polyvinyl alcohol hydrogel encapsulation film, thereby obtaining a polyvinyl alcohol hydrogel-foam carbon-silver / silver chloride electrode.

2. The preparation method according to claim 1, characterized in that In step S1, the electrolyte solution used for electrochemical deposition is a 0.5 mol / L mixed solution of AgNO3 and NaNO3, the deposition potential is -0.2 V, and the deposition time is 1000 s.

3. The preparation method according to claim 1, characterized in that In step S2, a foamed carbon-silver electrode is placed in a 0.1 M hydrochloric acid solution and an electrochemical chlorination method is used to prepare a foamed carbon-silver / silver chloride electrode; wherein the chlorination time is 1500 s and the chlorination potential is 300 mV.

4. The preparation method according to claim 1, characterized in that The method for foam carbon modification treatment is as follows: the foam carbon is placed in deionized water at 15°C for 30 minutes, in acetone solution at 15°C for 30 minutes, and in ethanol at 15°C for 30 minutes to remove impurities on the surface of the foam carbon. After cleaning, the foam carbon is placed in 10mM nitric acid at a constant temperature of 80°C for 10 hours, and then placed at room temperature to dry naturally for use.

5. The preparation method according to claim 1, wherein Step S3 also includes immersing the polyvinyl alcohol hydrogel film carbon foam-silver / silver chloride electrode in a 0.5M to 0.9M KCl solution for 12 to 24 hours, then transferring the electrode to a vacuum oven and drying it at 20°C to 50°C for 1.5 hours to 4 hours to obtain a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride reference electrode.

6. An electrode holder composed of electrodes prepared by the preparation method according to claim 1, characterized in that: The invention consists of a clamp shaft, an upper clamp, a lower clamp, a conductive tape and a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode. The upper and lower clamps are connected by the clamp shaft, and the polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrodes are fixed to the inner walls of the upper and lower clamps with grooves by conductive tape to obtain a polyvinyl alcohol hydrogel-carbon foam-silver / silver chloride electrode clamp.

7. Application of an electrode or electrode clip as an external ECG monitoring device, characterized in that: The electrode is prepared using the preparation method as claimed in claim 1, and the electrode clip is the electrode clip as claimed in claim 6.

8. Application of an electrode or an electrode clip as a device for monitoring the electrocardiogram of a mouse, characterized in that: The electrode is prepared using the preparation method as claimed in claim 1, and the electrode clip is the electrode clip as claimed in claim 6.

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