Monopolar complex microelectrode system for cardiac activation mapping and method of making the same

Abstract

The application discloses a single-pole composite microelectrode system for cardiac activity mapping and a preparation method thereof, and belongs to the technical field of bioelectric physiological detection. The single-pole composite microelectrode system is prepared by connecting an inner core of a detection electrode and a tail end of the electrode to form an electrode body, then connecting the electrode body with an electrode coupler, a signal amplifier and a digital-to-analog converter in sequence, and arranging an outer shielding layer outside the electrode body; the inner core of the detection electrode is composed of a tungsten inner core and a gold plating layer, and a glass tube capable of reducing noise interference is arranged outside; the tail end of the electrode is composed of a copper wire and an inner insulation layer; the signal sensitivity of the single-pole composite microelectrode system prepared by using the preparation method meets the highest resolution of 50 um 2 , the minimum recognizable signal voltage amplitude is 50 uV, and the single-pole composite microelectrode system has certain anti-electromagnetic interference capability and can be used in a conventional shielding net environment; in addition, the electrode structure has strong operability and can realize repeated mapping use.

Description

Technical Field

[0001] This invention relates to the field of bioelectrophysiological detection technology, and in particular to a monopolar composite microelectrode system for cardiac activity mapping and its preparation method. Background Technology

[0002] Bioelectrical signals are a crucial component in maintaining biological activities and intercellular information exchange. The bioelectrical activity of cardiac tissue also plays a vital role in maintaining cardiac electrical conduction and mechanical coupling; abnormal changes can lead to cardiac rhythm disturbances or the development of arrhythmias. Identifying changes in electrical activity among cardiac tissues is a key means of understanding the mechanisms by which the heart maintains its physiological state and its pathological processes. Research on cardiac electrical signals has a history of over a century, from the earliest electrocardiograms recording the overall electrical activity of the heart, to patch technology recording cellular action potentials, and more recently, the application of high-density three-dimensional electrical mapping technology for the entire heart. The accuracy and throughput of bioelectrical signal detection have significantly improved. A deeper understanding and analysis of bioelectrical activity has further promoted the development of related drugs and improved the success rate of surgical treatment for clinical arrhythmias.

[0003] Currently applied bioelectric mapping techniques are mainly divided into intracellular mapping and extracellular mapping, depending on the research objective. Intracellular mapping is mainly achieved using patch-clamp techniques, which can record changes in cellular action potentials and the electrical activity of individual ion channels. It offers high precision but low throughput, often recording only the activity within a single cell, making it difficult to analyze the effects of electrical signals at the tissue level. Its main applications are in intracellular signal transduction analysis and drug toxicity to cellular ion channels. Extracellular mapping primarily targets tissue levels or whole organs, recording changes in extracellular potentials across different ranges depending on the electrode cross-section, enabling high-throughput recording. However, its current precision is lower, generally consisting of mixed potential signals from a swarm of cells (three-dimensional signals typically contain over a hundred cells). It is mainly used for intraoperative mapping in clinical electrophysiological surgery, integrating information from tens of thousands of points to study the overall electrical activity of tissues or organs. This technology has achieved a surgical intervention success rate of nearly 90% for clinical premature ventricular contractions, supraventricular tachycardia, and typical atrial tachycardia. However, progress in understanding the mechanisms of complex arrhythmias, such as scar atrial tachycardia, atrial fibrillation, and ventricular tachycardia, is difficult, mainly because the spatial resolution of extracellular electrical mapping is generally greater than 1 mm. This causes the recorded electrical signals to overlap due to the synchronous excitation of cellular electrical activity in time, making it impossible to distinguish the timing and direction of excitation in local space, thus limiting the analysis of conduction mechanisms.

[0004] Extracellular mapping is categorized into unipolar and bipolar mapping based on the content of the acquired signals. Unipolar mapping typically uses a 2-4mm high-conductivity metal probe tip, connected to a single-strand conductive wire encased in insulating, interference-resistant plastic, which then connects to a signal amplifier. It generally records the entire electrical activity throughout the cell cycle. In two-dimensional mapping, the depth of the signal source can be indirectly determined by identifying the positive or negative sign of the recorded waveform. However, unipolar signals often incorporate more signals from the surrounding electrodes, resulting in lower accuracy for analyzing local signals. Bipolar mapping requires a dual-channel probe tip. The recorded electrical signal is related to the distance between the two probe tips, recording only the electrical signal between the electrodes. This shields signals outside the two probe tips, offering advantages in local signal analysis. However, some information may be lost due to algorithmic limitations.

[0005] Therefore, further improving the accuracy of extracellular mapping electrodes is of great significance for understanding the overall performance of electrical signals under physiological conditions and for the diagnosis and treatment of complex clinical arrhythmias. By further reducing the probe tip of the monopolar electrode, the influence of ambient field potential on the target potential can be reduced without affecting signal integrity. However, this requires simultaneously improving the signal's anti-interference capability, because a smaller probe electrode will obtain a more precise target signal source, but its amplitude will be significantly reduced, potentially making it more susceptible to the influence of ambient electromagnetic fields. Simultaneously, the interaction between the microelectrode and the mapped tissue needs to be feasible; smaller probe tips are more prone to damage due to low operational tolerance. Generally, microelectrode recording is achieved using high-conductivity metal wires and glass electrodes filled with electrolyte. Metal-based microelectrodes are currently mostly used for tissue field potential mapping, with mapping accuracy ranges generally greater than 200 μm. Metal electrodes have better toughness and hardness, are highly maneuverable, and are suitable for high-throughput, large-scale, repetitive mapping, but their sensitivity is relatively low, making it difficult to identify signals from single cells or small cell populations. Meanwhile, metal electrodes have a larger exposed volume in contact with the environment, making them more susceptible to electromagnetic interference and resulting in higher background noise during calibration. Glass electrodes can be thermally drawn to achieve probe tips as small as μm, but they are more brittle and have lower maneuverability. They are generally only used for single calibration and cannot be reused. Furthermore, they typically require a dedicated patch-clamp amplifier for connection, resulting in poor versatility. Summary of the Invention

[0006] To address the aforementioned problems, this invention aims to provide a monopolar composite microelectrode system for cardiac activity mapping and its fabrication method. This monopolar composite microelectrode system achieves a signal sensitivity that meets a maximum resolution of 50 μm. 2 It can identify a minimum signal voltage amplitude of 50uV and has a certain anti-electromagnetic interference capability. It can be used in conventional shielded mesh environments. Moreover, the electrode structure is highly operable and can be used for repeated calibration.

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

[0008] A method for fabricating a monopolar composite microelectrode system for cardiac activity mapping, characterized by comprising the following steps:

[0009] S1: Fabrication of the probe electrode core for cardiac activity mapping;

[0010] S2: Prepare the electrode tail end;

[0011] S3: Connect the inner core of the detection electrode in step S1 to the tail end of the electrode in step S2 to form the electrode body;

[0012] S4: Connect the rear end of the electrode body to the electrode coupler, signal amplifier and digital-to-analog converter in sequence;

[0013] S5: An outer shielding layer is set outside the electrode body to form a monopolar composite microelectrode system.

[0014] Furthermore, the detection electrode core mentioned in step S1 includes a tungsten wire core, with a gold-plated layer on the outer front end of the tungsten wire core. The tungsten wire core and the gold-plated layer form a composite metal control electrode. A glass tube is provided outside the composite metal control electrode. The rear end of the glass tube is fixedly connected to the tungsten wire core through a sealing block, and the rear end of the tungsten wire core passes through the sealing block. The front end of the composite metal control electrode passes through the glass tube.

[0015] Furthermore, the length of the front end of the composite metal control electrode penetrating the glass tube is <30µm.

[0016] Furthermore, the electrode tail end mentioned in step S2 includes a copper wire, the copper wire is covered with an inner insulating layer, and both the front end and the rear end of the copper wire penetrate the inner insulating layer.

[0017] Furthermore, the specific operation of step S3 includes: fixing the rear end of the tungsten wire core in the inner core of the detection electrode to the front end of the copper wire in the tail end of the electrode by welding with a tin transition section.

[0018] Furthermore, the specific operation of step S4 includes: connecting the end of the copper wire in the electrode tail end to the electrode coupler, the signal amplifier and the digital-to-analog converter in sequence.

[0019] Furthermore, the outer shielding layer mentioned in step S5 includes, from the inside out, a copper mesh layer, an aluminum foil layer, and an outer insulating layer, and the front end of the inner core of the detection electrode and the rear end of the electrode both penetrate the outer shielding layer.

[0020] Furthermore, a monopolar composite microelectrode system was prepared using the above-described method for preparing a monopolar composite microelectrode system for cardiac activity mapping.

[0021] The beneficial effects of this invention are: compared with the prior art, the improvement of this invention lies in that...

[0022] 1. This invention discloses a method for fabricating a monopolar composite microelectrode system for cardiac activity mapping. The probe electrode core is formed by a tungsten wire core and a gold-plated layer to create a composite metal control electrode. A silicate-drawn glass tube is placed outside the composite metal control electrode to reduce noise. The length of the front end of the composite metal control electrode penetrating the glass tube is <30µm, the diameter of the tungsten wire core is 10µm, and the thickness of the gold plating layer is 0.3µm. Under the premise of reducing the contact cross-section with the mapped tissue, the high conductivity material is used without increasing signal loss. The minimum amplitude of the signal voltage can be identified as 50µV, which can realize the extracellular potential mapping at the fine level of a single myocardium.

[0023] 2. Compared with existing metal monopolar micro-gauges, the monopolar composite microelectrode system in this invention has higher signal sensitivity and a maximum resolution of 50 μm. 2 It produces voltage signals at approximately 10 times the level of a typical cell. This allows for a better reduction of the influence of surrounding tissue field potential on the target potential.

[0024] 3. In this invention, the rear end of the tungsten wire core in the inner core of the detection electrode is welded and fixedly connected to the front end of the copper wire in the tail end of the electrode through a tin transition section, which can achieve a stable connection between the 10um diameter tungsten wire and the 0.5mm diameter copper wire; the outer shielding layer outside the electrode body can not only bear the electrode body, but also achieve continuous calibration controllability and good anti-electromagnetic interference capability, and the background noise of the recorded signal can be less than 50uV; moreover, the electrode body is small in size, has high electrode operability, can be repeatedly used and realize high-throughput calibration.

[0025] 4. The monopolar composite microelectrode system prepared using the method described in this invention can be used to detect high-resolution cardiac tissue electrical signals, achieving stable monopolar recording and programmed stimulation recording. The high-resolution characteristics of the electrodes allow for further in-depth exploration of physiological myocardial conduction characteristics, particularly in the atrioventricular junction, an anatomically complex region with multiple tissue junctions, where high-resolution signals are even more crucial. In complex arrhythmias, it can be used to distinguish differences in myocardial cell conduction under various states in scar-related atrial flutter and ventricular tachycardia, which is of significant value in revealing the mechanisms of arrhythmias and improving electrophysiological surgical treatment protocols. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the unipolar composite microelectrode system for cardiac activity mapping in this invention.

[0027] Figure 2This is a schematic diagram of the electrode body and outer shielding layer structure in this invention.

[0028] Figure 3 For the present invention Figure 2 Enlarged view of a portion of the structure in section A.

[0029] Figure 4 This is a schematic diagram of the electrode body structure in this invention.

[0030] Figure 5 This is a schematic diagram of the core structure of the probe electrode in this invention.

[0031] Figure 6 For the present invention Figure 5 Enlarged view of a portion of the structure in section B.

[0032] Figure 7 A schematic diagram of the application mode of the monopolar composite microelectrode system for cardiac activity mapping in this invention.

[0033] Figure 8 This is a size comparison diagram of the monopolar composite microelectrode and the pathological slide in Embodiment 3 of the present invention.

[0034] Figure 9 The cardiac electrical signal obtained by mapping the atrioventricular junction using a monopolar composite microelectrode system in Embodiment 3 of the present invention.

[0035] Figure 10 The intracardiac electrical signal is recorded using a monopolar composite microelectrode system under electrophysiological programming in Embodiment 4 of the present invention.

[0036] Wherein: 1-Tungsten wire core, 2-Gold plating layer, 3-Glass tube, 4-Sealing block, 5-Copper wire, 6-Inner insulation layer, 7-Tin transition section, 8-Copper mesh layer, 9-Aluminum foil layer, 10-Outer insulation layer, 11-Electrode coupler, 12-Signal amplifier, 13-Digital-to-analog converter. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0038] Example 1:

[0039] As attached Figure 1-6 As shown, the fabrication method of a monopolar composite microelectrode system for cardiac activity mapping includes the following steps:

[0040] S1: Fabrication of the probe electrode core for cardiac activity mapping;

[0041] Specifically, the inner core of the detection electrode includes a tungsten wire core 1, with a gold-plated layer 2 on the outer front end of the tungsten wire core 1. The tungsten wire core 1 and the gold-plated layer 2 form a composite metal control electrode. A glass tube 3 is provided outside the composite metal control electrode. The front end of the glass tube 3 has an open structure. The rear end of the glass tube 3 is fixedly connected to the tungsten wire core 1 through a sealing block 4, and the rear end of the tungsten wire core 1 passes through the sealing block 4. The front end of the composite metal control electrode passes through the glass tube 3.

[0042] Preferably, the diameter of the tungsten wire core 1 is 10 μm, the thickness of the gold plating layer 2 is 0.3 μm, the glass tube 3 is made of silicate drawn glass tube, which can reduce noise, its front end outer diameter is 15 μm, the inner diameter is larger than the outer diameter of the gold plating layer 2, the rear end outer diameter of the glass tube 3 is larger than the front end outer diameter, and the rear end of the glass tube 3 is provided with a cylindrical sealing block 4 made of ethyl cyanoacrylate, the rear end of the gold plating layer 2 passes through the sealing block 4 and is fixedly connected to the sealing block 4.

[0043] The length of the front end of the composite metal control electrode formed by the tungsten wire core 1 and the gold plating layer 2 penetrating the glass tube 3 is <30um, that is, the exposed height of the measuring head end of the composite metal control electrode is <30um.

[0044] S2: Prepare the electrode tail end;

[0045] Specifically, the electrode tail end includes a copper wire 5, which is covered with an inner insulating layer 6. Both the front and rear ends of the copper wire 5 penetrate the inner insulating layer 6. The copper wire 5 is a low-resistance, malleable copper wire with a diameter of 0.5 mm.

[0046] S3: Connect the inner core of the detection electrode in step S1 to the tail end of the electrode in step S2 to form the electrode body;

[0047] Specifically, by welding the rear end of the tungsten wire core 1 in the inner core of the detection electrode to the front end of the copper wire 5 in the tail end of the electrode through a tin transition section 7, a stable connection between the tungsten wire with a diameter of 10 μm and the copper wire with a diameter of 0.5 mm can be achieved.

[0048] S4: Connect the rear end of the electrode body to the electrode coupler 11, the signal amplifier 12 and the digital-to-analog converter 13 in sequence;

[0049] Specifically, the copper wire 5 at the tail end of the electrode is connected in sequence to the electrode coupler 11, the signal amplifier 12, and the digital-to-analog converter 13.

[0050] S5: An outer shielding layer is set outside the electrode body to form a monopolar composite microelectrode system;

[0051] Specifically, the outer shielding layer comprises, from the inside out, a copper mesh layer 8, an aluminum foil layer 9, and an outer insulating layer 10. The front end of the inner core of the detection electrode and the rear end of the electrode both penetrate the outer shielding layer.

[0052] Example 2:

[0053] Example 2 discloses a monopolar composite microelectrode system prepared using the preparation method in Example 1.

[0054] Specifically, the structure of this unipolar composite microelectrode system is shown in the attached figure. Figure 1-6 As shown, it specifically includes an electrode body and an outer shielding layer disposed outside the electrode body, and the rear end of the electrode body is sequentially connected to an electrode coupler 11, a signal amplifier 12 and a digital-to-analog converter 13.

[0055] More specifically, the electrode body includes a detection electrode core and an electrode tail end. The detection electrode core includes a tungsten wire core 1. A gold-plated layer 2 is provided on the outer front end of the tungsten wire core 1. The tungsten wire core 1 and the gold-plated layer 2 form a composite metal control electrode. A glass tube 3 is provided outside the composite metal control electrode. The rear end of the glass tube 3 is fixedly connected to the tungsten wire core 1 through a sealing block 4, and the rear end of the tungsten wire core 1 passes through the sealing block 4. The front end of the composite metal control electrode passes through the glass tube 3.

[0056] Preferably, the diameter of the tungsten wire core 1 is 10 μm, the thickness of the gold plating layer 2 is 0.3 μm, the glass tube 3 is made of silicate drawn glass tube, which can reduce noise, its front end outer diameter is 15 μm, the inner diameter is larger than the outer diameter of the gold plating layer 2, the rear end outer diameter of the glass tube 3 is larger than the front end outer diameter, and the rear end of the glass tube 3 is provided with a cylindrical sealing block 4 made of ethyl cyanoacrylate, the rear end of the gold plating layer 2 passes through the sealing block 4 and is fixedly connected to the sealing block 4.

[0057] The length of the front end of the composite metal control electrode formed by the tungsten wire core 1 and the gold plating layer 2 penetrating the glass tube 3 is <30um, that is, the exposed height of the measuring head end of the composite metal control electrode is <30um.

[0058] The electrode tail end includes a copper wire 5, which is covered with an inner insulating layer 6. Both the front and rear ends of the copper wire 5 penetrate the inner insulating layer 6. The copper wire 5 is a low-resistance, malleable copper wire with a diameter of 0.5 mm.

[0059] The rear end of the tungsten wire core 1 in the inner core of the detection electrode is fixedly connected to the front end of the copper wire 5 in the electrode tail end by welding through a tin transition section 7, which can achieve a stable connection between the 10um diameter tungsten wire and the 0.5mm diameter copper wire. After the inner core of the detection electrode, the electrode tail end and the tin transition section 7 are fixedly connected, they form the electrode body structure.

[0060] The outer shielding layer comprises, from the inside out, a copper mesh layer 8, an aluminum foil layer 9, and an outer insulating layer 10. The front end of the inner core of the detection electrode and the rear end of the electrode both penetrate the outer shielding layer.

[0061] Example 3:

[0062] Example 3 applies the monopolar composite microelectrode system from Example 2 to record electrical activity in the chamber-compartment junction area. A schematic diagram of the specific application of this monopolar composite microelectrode system is attached. Figure 7 As shown.

[0063] The specific application implementation process is as follows:

[0064] 1. Materials

[0065] 1.1 Animals

[0066] Adult New Zealand White Rabbit

[0067] 1.2 Reagents

[0068] Heparin (3125 U / kg), an anticoagulant for intraperitoneal injection.

[0069] 10% Chloral Hydrate for Anesthesia of Laboratory Animals

[0070] Continuous infusion with saturated gas (95% O2 + 5% CO2)

[0071] Modified perfusion solution for benchtop use (119mM NaCl, 25mM NaHCO3, 1.2mM NaH2PO4, 1.0mM MgSO4·6H2O, 4.0mM KCl, 1.8mM CaCl2, 10mM D-GlucoseH2O)

[0072] 1.3 Equipment

[0073] PC-100 glass electrode drawing instrument; 2 AM 1800 amplifiers; Digidata 1440B digital-to-analog converter;

[0074] 2. Methods

[0075] 2.1 Modified Langendorff isolated heart perfusion

[0076] Rabbits were intraperitoneally injected with heparin for anticoagulation (3125 U / kg). Fifteen minutes later, the animals were anesthetized with 10% chloral hydrate. After thoracotomy, the heart was removed and placed in a modified Tyrode buffer solution (119 mM NaCl, 25 mM NaHCO3, 1.2 mM NaH2PO4, 1.0 mM MgSO4·6H2O, 4.0 mM KCl, 1.8 mM CaCl2, 10 mM D-GlucoseH2O) saturated with gas (95% O2 + 5% CO2). Connective tissue and lung tissue were rapidly removed, leaving 3-5 mm of aorta. The aorta was cannulated and connected to a Langendorff perfusion system, and Tyrode's solution was pumped retrogradely through the aorta at a rate of 8-10 mL / min. The perfusion solution was kept at a constant temperature of 35 ± 1 °C and continuously oxygenated (95% O2 + 5% CO2) throughout the process.

[0077] 2.2 Fabrication of a Monopolar Composite Microelectrode System

[0078] The unipolar composite microelectrode system was fabricated using the preparation method described in Example 1.

[0079] 2.3 Electrophysiological mapping in the atrioventricular junction

[0080] After the ex vivo heart was fixed to the Langendorff perfusion apparatus, the right atrium was cut open to expose the atrioventricular junction, and reference electrodes (HIS electrode, high right atrial electrode, and lateral Tudaro tendon electrode) and stimulation electrodes (atrial stimulation electrode and ventricular stimulation electrode) were placed. A dual-channel Axopatch 200B patch-clamp amplifier or an AM1800 multi-channel amplifier was connected, and a Digidata 1440B digital-to-analog converter was used for analog signal output. Micro-manipulation control was used to map the microelectrodes, and continuous mapping of the target was performed. Up to three microelectrodes can be placed on the region of interest. Clampex 10 sampling software was used to monitor the field potential of all channels in real time.

[0081] 3. Results

[0082] (1) Appendix Figure 8 The comparison between the pathological sections of the atrioventricular junction and the mapping electrode size shows that the distance between the tips of the unipolar electrodes is approximately 3-5 cells in size.

[0083] (2) Appendix Figure 9 The application of ultra-microelectrodes to map the boundary area between the chamber and the display room.

[0084] Recording was performed using Clampex software. Under sinus rhythm, the electrodes clearly recorded atrial potentials, His potentials, and ventricular potentials. Baseline noise was less than 50 µV.

[0085] Example 4:

[0086] Example 4 describes the use of the monopolar composite microelectrode system from Example 2 to record intracardiac electrical signals under electrophysiological programming. The specific implementation process is as follows:

[0087] 1. Materials

[0088] 1.1 Animals

[0089] Adult New Zealand White Rabbit

[0090] 1.2 Reagents

[0091] Heparin (3125 U / kg), an anticoagulant for intraperitoneal injection.

[0092] 10% Chloral Hydrate for Anesthesia of Laboratory Animals

[0093] Continuous infusion with saturated gas (95% O2 + 5% CO2)

[0094] Modified perfusion solution for benchtop use (119mM NaCl, 25mM NaHCO3, 1.2mM NaH2PO4, 1.0mM MgSO4·6H2O, 4.0mM KCl, 1.8mM CaCl2, 10mM D-GlucoseH2O)

[0095] 1.3 Equipment

[0096] PC-100 glass electrode drawing instrument; 2 AM 1800 amplifiers; Digidata 1440B digital-to-analog converter;

[0097] 2. Methods

[0098] 2.1 Modified Langendorff isolated heart perfusion

[0099] Rabbits were intraperitoneally injected with heparin for anticoagulation (3125 U / kg). Fifteen minutes later, the animals were anesthetized with 10% chloral hydrate. After thoracotomy, the heart was removed and placed in a modified Tyrode buffer solution (119 mM NaCl, 25 mM NaHCO3, 1.2 mM NaH2PO4, 1.0 mM MgSO4·6H2O, 4.0 mM KCl, 1.8 mM CaCl2, 10 mM D-GlucoseH2O) saturated with gas (95% O2 + 5% CO2). Connective tissue and lung tissue were rapidly removed, leaving 3-5 mm of aorta. The aorta was cannulated and connected to a Langendorff perfusion system, and Tyrode's solution was pumped retrogradely through the aorta at a rate of 8-10 mL / min. The perfusion solution was kept at a constant temperature of 35 ± 1 °C and continuously oxygenated (95% O2 + 5% CO2) throughout the process.

[0100] 2.2 Electrophysiological Program Stimulation Scale Measurement

[0101] After the isolated heart was fixed into the Langendorff perfusion apparatus, reference electrodes, mapping electrodes, and stimulation electrodes (atrial and ventricular stimulation electrodes) were placed. A dual-channel Axopatch 200B patch-clamp amplifier or an AM1800 multi-channel amplifier was connected, and a Digidata 1440B digital-to-analog converter was used for analog signal output. Micromanipulation control was applied to the mapping microelectrodes for continuous mapping of the target. Clampex 10 sampling software was used to monitor the field potential of all channels in real time.

[0102] 3 Results

[0103] Appendix Figure 10 This demonstrates the use of microelectrodes for cardiac electrical activity mapping under programmed stimulation.

[0104] Recording was performed using Clampex software. The top image shows that under atrial stimulation, the electrodes clearly recorded atrial potentials, His potentials, and ventricular potentials. Baseline noise was less than 50 µV. The bottom image shows that under ventricular stimulation, the electrodes clearly recorded retrograde atrial potentials. Baseline noise was less than 50 µV.

[0105] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a monopolar composite microelectrode system for cardiac activity mapping, characterized in that, Includes the following steps, S1: Fabrication of the probe electrode core for cardiac activity mapping; S2: Prepare the electrode tail end; S3: Connect the inner core of the detection electrode in step S1 to the tail end of the electrode in step S2 to form the electrode body; S4: Connect the rear end of the electrode body to the electrode coupler, signal amplifier and digital-to-analog converter in sequence; S5: An outer shielding layer is set outside the electrode body to form a monopolar composite microelectrode system; In step S1, the inner core of the detection electrode includes a tungsten wire core. A gold-plated layer is provided on the outer front end of the tungsten wire core. The tungsten wire core and the gold-plated layer form a composite metal control electrode. A glass tube is provided outside the composite metal control electrode. The rear end of the glass tube is fixedly connected to the tungsten wire core through a sealing block. The rear end of the tungsten wire core passes through the sealing block, and the front end of the composite metal control electrode passes through the glass tube. The length of the front end of the composite metal control electrode penetrating the glass tube is <30 μm; The electrode tail end includes a copper wire, which is covered with an inner insulating layer, and both the front and rear ends of the copper wire penetrate the inner insulating layer; the rear end of the tungsten wire core is fixedly connected to the front end of the copper wire in the electrode tail end by a tin transition section.

2. The method for preparing a monopolar composite microelectrode system for cardiac activity mapping according to claim 1, characterized in that, The specific operation of step S4 includes: connecting the end of the copper wire in the electrode tail to the electrode coupler, signal amplifier and digital-to-analog converter in sequence.

3. The method for preparing a monopolar composite microelectrode system for cardiac activity mapping according to claim 2, characterized in that, The outer shielding layer mentioned in step S5 includes, from the inside out, a copper mesh layer, an aluminum foil layer, and an outer insulating layer. The front end of the inner core of the detection electrode and the rear end of the electrode both penetrate the outer shielding layer.

4. A monopolar composite microelectrode system prepared by the preparation method of any one of claims 1-3 for mapping cardiac activity.

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