Carbon fiber microelectrode and its preparation method and application

Abstract

The present invention relates to the field of electrochemistry, and discloses a carbon fiber microelectrode and a preparation method and application thereof. The preparation method comprises: (1) using a conductive adhesive to connect the core of a pretreated insulated wire and one end of a carbon fiber monofilament through a first curing process to form a connecting portion, thereby obtaining an electrode core; (2) inserting the electrode core into a sleeve with a tapered section, and the other end of the carbon fiber monofilament extends through the end opening of the tapered section, and the connecting portion is located in the tapered section; (3) injecting a filler into the tapered section and performing a second curing process to fix the carbon fiber monofilament and the connecting portion in the tapered section, thereby obtaining a carbon fiber microelectrode. The preparation method is simple, and the carbon fiber part of the obtained microelectrode maintains the original morphology and structure. At the same time, the carbon fiber microelectrode provided by the present invention can be used for the study of carbon fiber intrinsic dynamics, and is widely used in the fields of electrochemistry, biology, diagnosis and detection.

Description

Technical Field

[0001] The invention relates to the field of electrochemistry, and in particular to a carbon fiber microelectrode and a preparation method and application thereof. Background Art

[0002] CN2387538Y discloses a method for preparing a low-noise carbon fiber ultramicroelectrode. In this method, the carbon fiber and the electrode lead are connected by conductive glue, and the conductive glue connection part is sealed in a capillary. The tip of the capillary is melted and sealed to fix the carbon fiber, and the tip of the carbon fiber is exposed to obtain an ultramicroelectrode. However, the melting and heating of the glass capillary will change the original morphology, structure and other characteristics of the carbon fiber surface, so that the prepared carbon fiber microelectrode cannot represent the electrochemical catalytic performance of the original carbon fiber.

[0003] CN105203607A discloses a method for preparing a carbon fiber ultramicroelectrode. In the method, carbon fiber and copper wire are bonded together with conductive silver glue, and the electrodes are axially fed into a glass capillary. The exposed end of the carbon fiber is immersed in melted paraffin wax until the paraffin wax fills the glass capillary. The glass capillary with the carbon fiber is drawn into a carbon fiber strip electrode using a drawing instrument. The carbon fiber exposed outside the glass capillary is etched using an electrochemical workstation to obtain a carbon fiber ultramicroelectrode. In the method, the melted paraffin wax is used to wrap the bonding area between the carbon fiber and the copper wire, and heating may change the surface structure of the carbon fiber. In addition, the exposed carbon fiber is etched using the electrochemical workstation, so that the prepared carbon fiber microelectrode cannot represent the electrochemical catalytic performance of the original carbon fiber.

[0004] CN106770574A discloses a method for preparing a multi-walled carbon nanotube fiber microelectrode. In this method, one end of a carbon fiber monofilament is connected to one end of a copper core of an insulated copper wire through a conductive adhesive, and the exposed portion of the connection between the carbon fiber monofilament and the insulated copper wire is wrapped with a conical epoxy resin. The other end of the carbon fiber monofilament is extended and exposed outside the epoxy resin for a certain length to obtain a carbon fiber microelectrode. In this method, the connection between the carbon fiber monofilament and the insulated copper wire is wrapped with epoxy resin to form a cone, which is difficult to operate and has a low success rate.

[0005] CN202662303U discloses a method for preparing an ultrafine carbon fiber electrode, in which resin is poured into a glass tube containing carbon fibers under negative pressure, and the resin is allowed to solidify naturally. During the solidification process, the resin slowly flows downward along the carbon fibers, and it is difficult to control the length of the exposed carbon fibers. The preparation efficiency is low, and after the resin is solidified, the top of the glass tube needs to be polished to be flush with the resin.

[0006] Therefore, there is an urgent need for a simple method for preparing carbon fiber microelectrodes without changing the original surface morphology of the carbon fiber. Summary of the invention

[0007] The purpose of the present invention is to overcome the problems of the prior art that the carbon fiber is damaged during the preparation process, the preparation efficiency is low and the preparation method is complicated, and to provide a carbon fiber microelectrode and its preparation method and application. The preparation method is simple and the carbon fiber part of the obtained microelectrode maintains the original morphology structure.

[0008] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a carbon fiber microelectrode, which comprises: a sleeve with a tapered section, and a carbon fiber monofilament and an insulated wire with a core passing through the sleeve; wherein one end of the carbon fiber monofilament is connected to the core by a conductive adhesive to form a connecting portion, and the connecting portion is located in the tapered section; only the tapered section is filled with filler to fix the carbon fiber monofilament and the connecting portion in the tapered section; the other end of the carbon fiber monofilament extends through the end opening of the tapered section and is exposed outside the sleeve.

[0009] Preferably, the diameter of the carbon fiber monofilament is 3-30 μm.

[0010] A second aspect of the present invention provides a method for preparing a carbon fiber microelectrode, the method comprising:

[0011] (1) using a conductive adhesive to connect one end of the pretreated insulated wire core and one end of the carbon fiber monofilament through a first curing process to form a connection portion to obtain an electrode core;

[0012] (2) inserting the electrode core into a sleeve with a tapered section, with the other end of the carbon fiber monofilament extending out of the end opening of the tapered section, and the connecting portion being located within the tapered section;

[0013] (3) Injecting a filler into the conical section and performing a second curing to fix the carbon fiber monofilaments and the connecting parts in the conical section to obtain a carbon fiber microelectrode.

[0014] Preferably, the pretreatment includes: stripping off the insulation layer at both ends of the insulated wire, and the numbers of core wires at the two ends of the insulated wire are different.

[0015] The third aspect of the present invention provides a carbon fiber microelectrode prepared by the above method.

[0016] A fourth aspect of the present invention provides an application of the above-mentioned carbon fiber microelectrode in the fields of electrochemistry, biology, diagnosis and detection.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The preparation method of the carbon fiber microelectrode provided by the present invention does not require heating, does not pollute the surface structure of the carbon fiber, and is simple to operate and highly repeatable;

[0019] (2) The carbon fiber microelectrode provided by the present invention can be used for carbon fiber intrinsic dynamics research and can be quickly used to evaluate and compare the performance of different carbon fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the carbon fiber microelectrode S1 prepared in Example 1;

[0021] Figure 2 is a SEM image of the carbon fiber microelectrode S1 prepared in Example 1;

[0022] Figure 3 is a SEM image of the carbon fiber microelectrode S2 prepared in Example 2;

[0023] Figure 4 is a schematic diagram of the carbon fiber microelectrode S4 prepared in Example 4;

[0024] Figure 5 is a cyclic voltammetry curve of the carbon fiber microelectrode S1 prepared in Example 1;

[0025] Figure 6 is a cyclic voltammetry curve of the carbon fiber microelectrode S2 prepared in Example 2;

[0026] Figure 7 This is the cyclic voltammetry curve of the carbon fiber microelectrode S4 prepared in Example 4.

[0027] Description of Reference Numerals

[0028] 1. Carbon fiber monofilament 2. Filler 3. Conductive adhesive

[0029] 4. Sleeve with tapered section 5. Insulation layer of insulated wire 6. Core of insulated wire DETAILED DESCRIPTION

[0030] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0031] The first aspect of the present invention provides a carbon fiber microelectrode, which comprises: a sleeve with a tapered section, and a carbon fiber monofilament and an insulated wire having a core passing through the sleeve; wherein one end of the carbon fiber monofilament is connected to the core by a conductive adhesive to form a connecting portion, and the connecting portion is located in the tapered section; only the tapered section is filled with filler to fix the carbon fiber monofilament and the connecting portion in the tapered section; the other end of the carbon fiber monofilament extends through the end opening of the tapered section and is exposed outside the sleeve.

[0032] According to the present invention, preferably, compared with passing through the sleeve, the carbon fiber monofilament passes through the tapered portion of the sleeve, which is more conducive to reducing production costs and avoiding damage to the original morphology of the carbon fiber.

[0033] According to the present invention, the schematic diagram of the carbon fiber microelectrode is as follows Figure 1 As shown by Figure 1 It can be seen that the carbon fiber electrode includes: a sleeve 4 with a tapered section, a carbon fiber monofilament 1, one end of the carbon fiber monofilament 1 is connected to one end of the core 6 of the insulated wire through a conductive adhesive 3 to form a connecting portion, the connecting portion is in the tapered portion, and the connecting portion is wrapped with a filler 2, the other end of the carbon fiber monofilament 1 extends through the end opening of the tapered section, and the other end of the insulated wire extends through the end opening of the cylindrical section of the sleeve, wherein the insulated wire also includes an insulating layer 5.

[0034] In the present invention, unless otherwise specified, the sleeve has a tapered portion and a cylindrical portion, and the insulated wire has an insulating layer and a core portion.

[0035] In the present invention, in order to more accurately study the intrinsic dynamics of carbon fiber, preferably, the diameter of the carbon fiber monofilament is 3-30 μm, more preferably 5-20 μm, and more preferably 5-8 μm.

[0036] In the present invention, the insulated wire has a wide range of choices. Preferably, the insulated wire is a multi-core wire, more preferably at least one of a copper multi-core wire, a silver multi-core wire, a platinum multi-core wire, a titanium multi-core wire, an iron multi-core wire and an aluminum multi-core wire, more preferably a copper multi-core wire. In the embodiments, a copper multi-core wire is used for exemplary description, but the present invention is not limited thereto.

[0037] In the present invention, the material of the sleeve is not specifically limited, as long as the sleeve has a conical portion and a cylindrical portion. Preferably, the sleeve is selected from at least one of a glass tube, a ceramic tube and a plastic tube, and more preferably a glass tube. The glass tube is used to facilitate direct observation of the internal structure of the microelectrode.

[0038] In the present invention, the filler has a wide range of choices, as long as the filler can be cured under certain conditions. Preferably, the filler is selected from resin and / or inorganic sealant, more preferably resin, more preferably, the resin is selected from at least one of natural curing resin, heat curing resin and light curing resin, preferably natural curing resin.

[0039] In some embodiments of the present invention, preferably, the resin can be purchased from at least one of EpoFix cold mounting resin, Spon812 epoxy resin, EpoxyBond110 adhesive and UV crystal glue, and the inorganic sealant can be purchased from Changde high temperature resistant inorganic glue and water glass. In the embodiments, EpoFix cold mounting resin and EpoxyBond 110 adhesive are used for exemplary description, but the present invention is not limited thereto.

[0040] According to the present invention, conductive glue can be used to connect one end of the carbon fiber monofilament and the core of the insulated wire. Preferably, the conductive glue is selected from at least one of conductive silver glue, conductive carbon glue and conductive silver paste, preferably conductive silver glue.

[0041] The present invention, in a second aspect, provides a method for preparing a carbon fiber microelectrode, the method comprising:

[0042] (1) using a conductive adhesive to connect one end of the pretreated insulated wire core and one end of the carbon fiber monofilament through a first curing process to form a connection portion to obtain an electrode core;

[0043] (2) inserting the electrode core into a sleeve with a tapered section, with the other end of the carbon fiber monofilament extending out of the end opening of the tapered section, and the connecting portion being located within the tapered section;

[0044] (3) Injecting a filler into the conical section and performing a second curing to fix the carbon fiber monofilaments and the connecting parts in the conical section to obtain a carbon fiber microelectrode.

[0045] According to the present invention, preferably, in step (1), the insulated wire is pretreated to facilitate the operation of connecting with the carbon fiber monofilament.

[0046] Preferably, the pretreatment includes: stripping off the insulation layer at both ends of the insulated wire to form an A end and a B end of the insulated wire with different numbers of core wires;

[0047] Further preferably, in the insulated wire, the number of core filaments included in the core portion of the A end is smaller than the number of core filaments included in the core portion of the B end, and the A end is connected to the carbon fiber monofilament.

[0048] Preferably, the B end extends through the end opening of the cylindrical section of the sleeve. The preferred conditions are used to facilitate the connection of the insulated wire to the chemical workstation and the testing of the carbon fiber properties.

[0049] According to the present invention, preferably, the first curing and the second curing are independently dry curing and / or heat curing. Compared with heat curing, dry curing can avoid heating affecting the surface structure of the carbon fibers.

[0050] Further preferably, the drying and curing conditions are: temperature of 15-40°C, preferably 20-30°C, time of 10-36h, preferably 15-30h; the heating and curing conditions are: temperature of 80-200°C, preferably 100-150°C, time of 10-60min, preferably 15-30min.

[0051] In the present invention, the first curing and the second curing depend on the types of the conductive glue and the filler, respectively. When the conductive glue is conductive silver glue and / or conductive carbon glue, the first curing is natural curing or heating curing. When the filler is a naturally curing resin, such as EpoFix cold mounting resin, the second curing is natural curing; when the filler is a heat curing resin, such as Epoxybond 110 adhesive, the second curing is heating curing.

[0052] According to a preferred embodiment of the present invention, in order to facilitate the study of carbon fibers with original morphological structures, the length of the portion of the carbon fiber monofilament passing through the conical section is 20 μm to 5 mm, and more preferably 50 μm to 1 mm.

[0053] According to the present invention, preferably, in step (2), the electrode core is axially inserted into the sleeve.

[0054] Preferably, step (3) further comprises: raising the conical section upward and injecting the filler from the end opening of the conical section. In the present invention, the filler is injected from the end opening of the conical portion to fill the gap of the conical portion, so that the filler includes carbon fiber and seals the end of the conical portion of the sleeve. Compared with injecting the filler from the cylindrical portion of the sleeve, since the filler needs a period of time for the second curing, the filler is accumulated at the end opening of the conical portion, and the filler contaminates the carbon fiber monofilament.

[0055] According to the present invention, the method further comprises: when the filler fills the gap of the conical portion, adding another drop of filler to form a hemispherical droplet at the end of the conical portion. The preferred method is more conducive to sealing the end of the conical portion of the sleeve.

[0056] In the present invention, the diameter of the carbon fiber monofilament, the insulating wire, the sleeve, the filler, and the conductive adhesive are all based on the above-mentioned definitions, and the present invention will not elaborate on them here.

[0057] According to a preferred embodiment of the present invention, the method for preparing the carbon fiber comprises:

[0058] (1) Strip off a section of insulation layer at each end of a multi-core insulated wire, and cut off several core wires at one end until only two core wires remain, forming the A end of the insulated wire;

[0059] (2) using a conductive adhesive to connect the carbon fiber monofilament to the A end of the insulated wire through a first curing process to form a connection portion, thereby obtaining an electrode core;

[0060] (3) inserting the electrode core axially into a sleeve with a tapered portion, so that the other end of the carbon fiber monofilament passes through the end opening of the tapered section and the connecting portion is located in the tapered section;

[0061] (4) The conical part is stood up, and the filler is carefully injected into the gap of the conical part from the end opening of the conical part until it is full, and a second curing is performed to obtain a carbon fiber microelectrode.

[0062] According to the present invention, preferably, the method also includes: carefully injecting the filler into the gap of the conical portion from the end opening of the conical portion until it is full, then adding one drop to form a hemispherical droplet at the end of the conical portion, and then performing a second curing to obtain a carbon fiber microelectrode.

[0063] Preferably, the method further comprises: after step (4), adding a drop of filler to the top of the carbon fiber monofilament to obtain a carbon fiber microelectrode. In the carbon fiber microelectrode obtained by this method, only the surface of the carbon fiber monofilament participates in the electrochemical reaction, while the top section does not participate in the electrochemical reaction.

[0064] The third aspect of the present invention provides a carbon fiber microelectrode prepared by the above method.

[0065] The preparation method provided by the present invention is simple and does not require grinding, while retaining the original morphology and structure of the carbon fiber to a great extent.

[0066] A fourth aspect of the present invention provides an application of the above-mentioned carbon fiber microelectrode in the fields of electrochemistry, microbiology, diagnosis and detection.

[0067] The present invention will be described in detail below through examples.

[0068] Epofix cold mounting resin is a commercial product of Struers (Shanghai) International Trading Co., Ltd.;

[0069] EpoxyBond 110 adhesive is a commercial product of Allied High Tech Products, Inc.

[0070] Example 1

[0071] (1) Strip 3 mm of insulation from each end of a section of multi-core copper wire (8 cm long, 1.5 mm in diameter), and cut off several copper wires at one end to leave only two copper wires, forming end A;

[0072] (2) connecting the carbon fiber monofilament (7 μm in diameter) to the A end of the multi-core copper wire with a conductive silver glue to form a connecting portion to obtain an electrode core, and curing the conductive silver glue at room temperature for 24 hours;

[0073] (3) inserting the electrode core axially into the tapered glass tube so that the other end of the carbon fiber monofilament passes through the end opening of the tapered section and the connecting portion is located inside the tapered section;

[0074] (4) The conical part is stood upright, and the Epofix cold embedding resin is carefully injected into the gap of the conical part from the end opening of the conical part until it is full. Then, one more drop is added. A hemispherical droplet is formed at the end of the conical part due to the action of surface tension. The resin is naturally cured at room temperature for 24 hours to obtain a carbon fiber microelectrode S1.

[0075] The schematic diagram of the carbon fiber microelectrode S1 is as follows: Figure 1 As shown, the SEM of the carbon fiber microelectrode S1 is Figure 2 shown.

[0076] Example 2

[0077] (1) Strip 5 mm of insulation from each end of a section of multi-core aluminum wire (8 cm long, 1.5 mm in diameter), and cut off several aluminum wires at one end, leaving only two aluminum wires to form end A;

[0078] (2) connecting a carbon fiber monofilament (7 μm in diameter) to the A end of a multi-core aluminum wire using a conductive silver paste to form a connecting portion to obtain an electrode core, and heating at 150° C. for 30 minutes to solidify the conductive silver paste;

[0079] (3) inserting the electrode core axially into the tapered glass tube so that the other end of the carbon fiber monofilament passes through the end opening of the tapered section and the connecting portion is located inside the tapered section;

[0080] (4) The conical part is stood upright, and EpoxyBond 110 adhesive is carefully injected into the gap of the conical part from the end opening of the conical part until it is full. Then, one more drop is added. A hemispherical droplet is formed at the end of the conical part due to the action of surface tension. The filler is cured by heating at 150°C for 30 minutes to obtain a carbon fiber microelectrode S2.

[0081] The schematic diagram of the carbon fiber microelectrode S2 is as follows: Figure 1 Similarly, the SEM image of the carbon fiber microelectrode S2 is as follows: Figure 3 Compared with the SEM image of the carbon fiber microelectrode S1 prepared in Example 1 ( Figure 2 ), the surface of the carbon fiber microelectrode S2 made by heating and curing is rougher.

[0082] Example 3

[0083] (1) Strip 5 mm of insulation from each end of a section of multi-core iron wire (8 cm long, 1.5 mm in diameter), and cut off several wires at one end, leaving only one wire, to form end A;

[0084] (2) connecting the carbon fiber monofilament (diameter 7 μm) to the A end of the multi-core iron wire with a conductive silver glue to form a connecting portion to obtain an electrode core, and drying at 45° C. for 20 h to solidify the conductive silver glue;

[0085] (3) inserting the electrode core axially into the tapered glass tube so that the other end of the carbon fiber monofilament passes through the end opening of the tapered section and the connecting portion is located inside the tapered section;

[0086] (4) The conical part is stood upright, and water glass is carefully injected into the gap of the conical part from the end opening of the conical part until it is full. Then, one more drop is added. A hemispherical droplet is formed at the end of the conical part due to the action of surface tension. The resin is cured by drying at 45°C for 20 hours to obtain a carbon fiber microelectrode S3.

[0087] The schematic diagram of the carbon fiber microelectrode S3 is as follows: Figure 1 similar.

[0088] Example 4

[0089] The method of Example 1 is followed, except that a drop of Epofix cold mounting resin is placed on the top of the carbon fiber monofilament to obtain a carbon fiber microelectrode S4.

[0090] The schematic diagram of the carbon fiber microelectrode S4 is as follows: Figure 4 shown.

[0091] Test Case

[0092] The carbon fiber microelectrodes prepared in Examples 1-4 were characterized for their activity.

[0093] The carbon fiber microelectrodes S1-S4 were used as working electrodes, the graphite rod was used as the counter electrode, the Ag / AgCl electrode was used as the reference electrode, and the electrolyte was 5mmol / L K4Fe(SCN)6 and 1mol / L Na2SO4 to construct a three-electrode system. The activity of the carbon fiber microelectrodes was characterized using a CHI1000C electrochemical workstation. The test conditions were: potential window -0.1 to 0.6V, scan rate 10mV / s, and the test results are shown in Table 1. The cyclic voltammetry curves of the carbon fiber microelectrodes prepared in Example 1, Example 2 and Example 4 are shown in Table 1. Figure 5 , Figure 6 , Figure 7 shown.

[0094] Table 1

[0095] Carbon fiber microelectrode Cyclic voltammetry curve / shape Example 1 S1 S Example 2 S2 S Example 3 S3 S Example 4 S4 S

[0096] It can be seen from the results in Table 1 that the cyclic voltammetry curve of the carbon fiber microelectrode prepared by the method provided by the present invention presents an "S" shape unique to the microelectrode, indicating that the carbon fiber microelectrode provided by the present invention has good electrochemical activity.

[0097] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a carbon fiber microelectrode, the method comprising: (1) using a conductive adhesive to connect one end of the pretreated insulated wire core and one end of the carbon fiber monofilament by first curing to form a connection portion to obtain an electrode core; (2) The electrode core is axially inserted into a sleeve with a tapered section, the other end of the carbon fiber monofilament extends through the end opening of the tapered section, and the connecting portion is located inside the tapered section; the length of the portion of the carbon fiber monofilament that passes through the tapered section is 20 μm to 5 mm; (3) standing the conical section upright, injecting filler from the end opening of the conical section, and performing a second curing to fix the carbon fiber monofilaments and the connecting part in the conical section to obtain a carbon fiber microelectrode; The pretreatment includes: stripping the insulation layer of both ends of the insulated wire to form an A end and a B end of the insulated wire with different numbers of core wires; the number of core wires contained in the core of the A end is less than the number of core wires contained in the core of the B end, and the A end is connected to the carbon fiber monofilament; the B end extends through the end opening of the cylindrical section of the sleeve; The method further comprises: when the filler fills up the gap in the conical section, adding another drop of the filler to form a hemispherical droplet at the end opening of the conical section.

2. The method according to claim 1, wherein: The first curing and the second curing are each independently drying curing and / or heating curing; The drying and curing conditions are as follows: temperature of 15-40°C and time of 10-36h; The heating and curing conditions are as follows: temperature of 80-200° C. and time of 10-60 min.

3. The method according to claim 2, wherein: The drying and curing conditions are: temperature of 20-30°C and time of 15-30h; The conditions for the heating and curing are as follows: a temperature of 100-150° C. and a time of 15-30 min.

4. The method according to claim 1, wherein: The length of the portion of the carbon fiber monofilament passing through the tapered section is 50 μm to 1 mm.

5. The method according to claim 1, wherein: The diameter of the carbon fiber monofilament is 3-30 μm; The insulated wire is a multi-core wire; The sleeve is selected from at least one of a glass tube, a ceramic tube and a plastic tube; The filler is selected from at least one of a resin and / or an inorganic sealant; The resin is selected from at least one of a naturally curing resin, a heat curing resin and a light curing resin; The conductive glue is selected from at least one of conductive silver glue, conductive carbon glue and conductive silver paste.

6. The method according to claim 5, wherein: The insulated wire is selected from at least one of a copper multi-core wire, a silver multi-core wire, a platinum multi-core wire, a titanium multi-core wire, an iron multi-core wire and an aluminum multi-core wire; The sleeve is selected from a glass tube; The filler is selected from resin; The resin is selected from naturally curing resins; The conductive glue is selected from conductive silver glue.

7. The method according to claim 6, wherein: The insulated wire is selected from copper multi-core wire.

8. A carbon fiber microelectrode prepared by the method according to any one of claims 1 to 7; wherein The carbon fiber microelectrode comprises: a sleeve with a tapered section, and a carbon fiber monofilament passing through the sleeve and an insulated wire with a core; wherein one end of the carbon fiber monofilament is connected to the core by a conductive adhesive to form a connecting portion, and the connecting portion is located in the tapered section; only the tapered section is filled with a filler to fix the carbon fiber monofilament in the tapered section and the connecting portion; the other end of the carbon fiber monofilament extends through the end opening of the tapered section and is exposed outside the sleeve.

9. Application of the carbon fiber microelectrode according to claim 8 in the fields of electrochemistry, biology, diagnosis and detection.

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