Nanoelectrode preparation method and preparation device

Abstract

The present invention relates to the field of nanoelectrode device manufacturing, and more particularly to a method and apparatus for preparing nanoelectrodes. These methods and apparatus achieve the encapsulation and drawing of metal wires into capillary glass tubes through the selection of a heat source and the design of a stretching structure, resolving the difficulties of wire drawing and forming. Nanoelectrode devices, including dual-aperture homogeneous metal tunneling nanoelectrode devices, single-aperture metal nanoelectrode devices, and dual-aperture heterogeneous metal tunneling nanoelectrode devices, can be stably manufactured for research in the fields of electrochemistry, tunneling sensing, single-molecule detection, and nanothermocouples.

Description

Technical Field

[0001] The present invention relates to the field of nano-electrode device manufacturing, and in particular to a method and device for preparing a nano-electrode. Background Art

[0002] Nanoelectrode fabrication is a research hotspot in nanotechnology and related fields, attracting widespread attention and attention from both the scientific community and high-tech instrument companies in industry. As a novel electrochemical sensor material, nanoelectrodes possess extremely high mass transfer rates and sensing sensitivity, making them widely used in cutting-edge fields such as electrochemistry, single-molecule chemical reactions, single-molecule detection, single-cell research, and high-resolution imaging. Furthermore, two or more independent nanoelectrodes can form nanoelectrode pairs at the tunneling scale, playing a crucial role in quantum tunneling, plasmon nano-optics, and DNA and protein sequencing.

[0003] Numerous methods exist for fabricating nanoelectrode devices, including photolithography, electrochemical etching, electromigration, fracture junction technology, and capillary glass tube drawing. Among these, the method of forming nanoelectrode devices by drawing capillary glass tubes using a taper puller offers advantages such as low cost, convenience, and high yield. However, conventional laser heating methods suffer from long drawing times, difficulty forming the metal wire, and the risk of damage to the laser heating module, which can harm the device.

[0004] It can be seen that the current capillary glass tube drawing method has low preparation efficiency, high equipment consumption and difficult maintenance. Therefore, based on the capillary glass tube drawing method, how to make the preparation of nanoelectrodes more efficient and economical is the problem to be solved by the present invention. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention discloses a method and device for preparing a nanoelectrode.

[0006] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0007] A method for preparing a nanoelectrode, comprising:

[0008] Providing a capillary glass tube with a built-in metal wire;

[0009] The capillary glass tube is first heated at a temperature higher than the softening point of the capillary glass tube and lower than the melting point of the metal wire, and the capillary glass tube is first stretched to pre-thin the capillary glass tube;

[0010] Fixing the metal wire, evacuating the capillary glass tube, and performing a second heating on the to-be-processed region of the capillary glass tube at a temperature higher than the softening point of the capillary glass tube and lower than the melting point of the metal wire, so that the capillary glass tube pre-thinned in the to-be-processed region is bonded to the metal wire to achieve a packaging operation;

[0011] The capillary glass tube-metal wire assembly in the area to be processed is subjected to a third heating operation at a heating temperature higher than the softening point of the capillary glass tube and higher than the melting point of the metal wire, and the capillary glass tube-metal wire assembly is subjected to a second stretching operation, so that the area to be processed of the capillary glass tube is stretched and broken, forming a nanoelectrode with a nanotip.

[0012] Optionally, the speed of the first stretching operation is lower than the speed of the second stretching operation.

[0013] Optionally, by controlling the stretching distance of the first stretching operation, thinning of the capillary glass tube to different thicknesses can be achieved.

[0014] Optionally, at the beginning of the third heating operation, the heating temperature is higher than the softening point of the capillary glass tube but has not risen to the melting point of the metal wire. At this time, a slow horizontal displacement is performed, and the capillary glass tube with the embedded metal wire is only subjected to a uniform first tension; when the heating temperature rises to the melting point of the metal wire, the capillary glass tube with the embedded metal wire receives a second tension, which is greater than the first tension, and the acceleration of the tensile motion increases, so that the softened capillary glass tube and the molten metal wire are rapidly stretched under the action of the tension until they break, forming a nanoelectrode with a nanotip.

[0015] Optionally, it also includes: while the hole of the capillary glass tube at the nano tip remains open and closed, electrochemical deposition is performed to fill the hole position of the electrode tip with deposited metal, so that the nano-deposited metal is exposed from the tip, and further electrochemical deposition is performed until a nanoelectrode is formed.

[0016] Optionally, the method further includes: grinding the nanotip of the nanoelectrode by using a needle grinder or focused ion beam etching to expose the metal wire in the capillary glass tube from the tip to form a nanoelectrode.

[0017] Optionally, the capillary glass tube is a single-hole capillary glass tube or a double-hole capillary glass tube, wherein the metal wires built into the double-hole capillary glass tube are metal wires made of the same material or metal wires made of different materials.

[0018] Optionally, the nanoelectrode is used to prepare a double-pore homogeneous metal tunneling nanoelectrode device, a single-pore metal nanoelectrode device, or a double-pore heterogeneous metal tunneling nanoelectrode device.

[0019] The present invention also provides a device for preparing a nanoelectrode using the above-mentioned method for preparing a nanoelectrode, comprising:

[0020] A fixing structure, comprising a first fixing member and a second fixing member located in the same straight line and arranged separately, wherein the first fixing member and the second fixing member are used to fix the capillary glass tube and the metal wire;

[0021] a heating structure, the heating structure being located between the first fixing member and the second fixing member and corresponding to the region of the capillary glass tube to be processed, and utilizing the heating structure to heat the region of the capillary glass tube to be processed;

[0022] a stretching structure connected to the first fixing member and the second fixing member, and performing a stretching operation on the first fixing member and the second fixing member to move away from each other;

[0023] An air extraction structure is used to be connected to the capillary glass tube to keep the capillary glass tube in a vacuum state.

[0024] Optionally, the stretching structure includes a traction rope, a magnetic traction block, a traction shaft, and a magnetic base;

[0025] The first fixing member, the second fixing member and the magnetic traction block are connected to each other through a traction rope. The magnetic traction block is connected to the traction shaft by magnetism. The magnetic traction block applies a pulling force to the capillary glass tube under the magnetic force of the magnetic base below.

[0026] The present invention has significant technical effects due to the adoption of the above technical solutions:

[0027] The present invention provides a method and device for preparing a nanoelectrode. By selecting a heat source and designing a stretching structure, the metal wire is encapsulated and drawn into shape in a capillary glass tube, thereby solving the problems of difficulty in drawing and forming the metal wire. Nanoelectrode devices can be stably manufactured, including double-hole homogeneous metal tunneling nanoelectrode devices, single-hole metal nanoelectrode devices and double-hole heterogeneous metal tunneling nanoelectrode devices, which are used for research in the fields of electrochemistry, tunneling sensing, single-molecule detection and nanothermocouples. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A simplified structural diagram of a nanoelectrode preparation device provided in an embodiment of the present invention;

[0029] Figure 2 A schematic structural diagram of a nanoelectrode preparation device provided in an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of the stretching structure of a nanoelectrode preparation device provided in an embodiment of the present invention;

[0031] Figure 4A schematic flow chart of a method for preparing a nanoelectrode provided in an embodiment of the present invention;

[0032] Figure 5 This is an image of the drawn nanoelectrode provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0034] The present application provides a nanoelectrode preparation device, such as Figure 1 As shown, the preparation device includes:

[0035] A heating structure 1, located between the first fixing member and the second fixing member and corresponding to the area of the capillary glass tube to be processed, and utilizing the heating structure to heat the area of the capillary glass tube to be processed;

[0036] A fixing structure 2, comprising a first fixing member and a second fixing member located in the same straight line and arranged separately, the first fixing member and the second fixing member being used to fix the capillary glass tube and the metal wire;

[0037] a stretching structure 3, the stretching structure being connected to the first fixing member and the second fixing member, and performing a stretching operation on the first fixing member and the second fixing member to move away from each other;

[0038] an air extraction structure 4, the air extraction structure being used to be connected to the capillary glass tube to keep the capillary glass tube in a vacuum state;

[0039] The capillary glass tube 5 with embedded metal wire is used to prepare nanoelectrodes.

[0040] Furthermore, the heating structure 1 uses a hydrogen-oxygen flame as a heat source and utilizes an AYH-500 hydrogen generator to generate hydrogen and oxygen. The initial setting of the hydrogen to oxygen gas flow ratio is 2:1, the hydrogen purity is 99.999%, and the output flow range is 0 ~ 500 mL / min; the heating temperature is controlled by modifying the hydrogen and oxygen gas flow rates, and the temperature of the hydrogen-oxygen flame is the highest during equivalent combustion.

[0041] Furthermore, the fixing structure 2, such as Figure 2 As shown, it includes a slide rail, a guide pulley, a fastening block, and a fastener; wherein the first fixing member includes a first slide rail, a first fastening block and a first fastener, and the second fixing member includes a second slide rail, a second fastening block and a second fastener.

[0042] The front ends of the first slide rail 201 and the second slide rail 202 are each provided with a V-shaped groove containing a silicone pad, which is respectively connected to the first fastening block 211 and the second fastening block 212 for fixing the capillary glass tube 5; the ends of the two slide rails are respectively connected to the first fastener 209 and the second fastener 210 for fixing the metal wire embedded in the capillary glass tube; the guide pulleys 203, 204, and 205 slide through the first slide rail 201, and the guide pulleys 206, 207, and 208 slide through the second slide rail 202.

[0043] Furthermore, the tensile structure, such as Figure 2 、 Figure 3 As shown, it includes a rigid traction rope, a magnetic traction block composed of weights, a traction shaft and a magnetic base;

[0044] One end of the first rigid traction rope 301 is connected to the first slide rail 201, and the other end of the first rigid traction rope 301 is connected to the weight 307 in the vertical direction through the steering pulley 303 and the steering pulley 304; one end of the second rigid traction rope 302 is connected to the second slide rail 202, and the other end of the second rigid traction rope 302 is connected to the weight 307 in the vertical direction through the steering pulley 305 and the steering pulley 306; a programmable controllable displacement guide rail is installed on the vertical plane where the weight 307 is located as a traction shaft 308, and the weight 307 is magnetically adsorbed on the traction shaft; a magnetic base 309 is placed under the weight 307.

[0045] Furthermore, the traction axis is composed of a programmable displacement guide rail, which, in conjunction with the magnetic base, causes the first and second fixing members to move at variable acceleration during the stretching process. At the beginning of the third heating operation, the heating temperature is above the softening point of the capillary glass tube but not yet at the melting point of the metal wire. At this time, slow horizontal displacement is performed, and the capillary glass tube with the embedded metal wire is only subjected to a uniform first tension. After the heating temperature rises to the melting point of the metal wire, the capillary glass tube with the embedded metal wire is subjected to a second tension that is greater than the first tension. The acceleration of the stretching motion increases, causing the softened capillary glass tube and the molten metal wire to be rapidly stretched under the action of the tension until they break, forming a nanoelectrode with a nano-tip.

[0046] Specifically, when the third heating operation and the second stretching operation are carried out simultaneously, when the heating temperature has not risen to the melting point of the metal wire in the capillary glass tube, only the traction shaft applies a small pulling force to the capillary glass tube with the embedded metal wire through the stretching structure, causing the first fixing member and the second fixing member to move slowly; when the heating temperature rises to the melting point of the metal wire in the capillary glass tube, the current intensity passing through the magnetic base is increased, so that the magnetic traction block is subjected to a larger magnetic force in the vertical direction, causing the first fixing member and the second fixing member to move rapidly, forming a variable acceleration motion during the entire stretching process, improving the uniformity of heating of the capillary glass tube and the metal wire in the tube, and improving the success rate of preparing metal nanoelectrodes embedded in the capillary glass tube.

[0047] Furthermore, the air extraction structure adopts a circulating water multi-purpose vacuum pump, uses rubber hoses to cover the two ends of the capillary glass tube, and connects the rubber hoses at both ends to the interfaces of the vacuum pump through a Y-shaped splitter to extract the air in the capillary glass tube; when the interior of the capillary glass tube is in a vacuum state, the middle area is heated by a heat source, and due to the effect of atmospheric pressure, it will shrink in the heated area, thereby tightly wrapping the metal wire in the tube, thereby achieving the encapsulation of the metal wire in the glass capillary tube.

[0048] The present application provides a method for preparing a nanoelectrode, such as Figure 4 As shown, including:

[0049] Step S10, providing a capillary glass tube with a built-in metal wire;

[0050] Step S20, performing a pre-thinning operation on the to-be-processed region of the capillary glass tube; first heating the to-be-processed region of the capillary glass tube using a heating temperature higher than the softening point of the capillary glass tube and lower than the melting point of the metal wire, and performing a first stretching operation on the capillary glass tube;

[0051] Step S30, performing a packaging operation on the to-be-processed region of the capillary glass tube; fixing the metal wire, evacuating the capillary glass tube, and performing a second heating on the to-be-processed region of the capillary glass tube at a temperature higher than the softening point of the capillary glass tube and lower than the melting point of the metal wire, so that the pre-thinned capillary glass tube in the to-be-processed region is bonded to the metal wire to achieve packaging;

[0052] Step S40, performing a stretching operation on the capillary glass tube with the embedded metal wire; performing a third heating on the capillary glass tube-metal wire assembly in the area to be processed using a heating temperature that is higher than the softening point of the capillary glass tube and higher than the melting point of the metal wire, and performing a second stretching operation on the capillary glass tube-metal wire assembly, so that the area to be processed of the capillary glass tube is stretched and broken, forming a nanoelectrode with a nanotip.

[0053] Specifically, step S10 is performed to provide a capillary glass tube with a built-in metal wire. The capillary glass tube with a built-in metal wire includes a single-hole capillary glass tube with a built-in metal wire, a double-hole capillary glass tube with a built-in metal wire of the same type, and a double-hole capillary glass tube with a built-in metal wire of different types. Specific parameters of the metal wire and capillary glass tube included in the embodiment of the present application are shown in Table 1:

[0054] Table 1

[0055]

[0056] In other embodiments, metal wires and capillary glass tubes made of other materials may also be used.

[0057] Specifically, step S20 is executed to perform a pre-thinning operation on the to-be-processed region of the capillary glass tube, perform a first heating on the to-be-processed region of the capillary glass tube using a heating temperature higher than the softening point of the capillary glass tube and lower than the melting point of the metal wire, and perform a first stretching operation on the capillary glass tube.

[0058] The pre-thinning operation is performed by setting the gas flow rate of the gas generated by the hydrogen generator so that the heating temperature is higher than the softening point of the capillary glass tube and lower than the melting point of the metal wire, so that the tension of the tensile structure only stretches the capillary glass tube, while the state of the metal wire remains unchanged. The pre-thinning operation further reduces the inner diameter of the capillary glass tube before the metal wire is encapsulated in the capillary glass tube, thereby limiting the position of the metal wire in the capillary glass tube, improving the problem of random position distribution of the metal wire when encapsulated in the capillary glass tube, and ensuring that the metal wire remains symmetrically distributed in the glass tube after encapsulation, effectively reducing the distance between the metal wire and the tube wall after drawing.

[0059] Specifically, step S30 is executed to pre-thin the area to be processed of the capillary glass tube, and then a second heating operation is performed. The interior of the capillary glass tube is placed in a vacuum state through the air extraction structure, and the heating temperature is controlled to be higher than the softening temperature of the capillary glass tube and lower than the melting point of the metal wire. The stretching structure remains unchanged and is not further stretched. Under the combined action of the heat source heating and the atmospheric pressure, the area to be processed of the capillary glass tube begins to shrink, tightly wrapping the metal wire in the tube, thereby achieving the encapsulation of the metal wire in the glass capillary tube.

[0060] Specifically, step S40 is executed to perform a second stretching operation on the capillary glass tube with the metal wire embedded therein. The capillary glass tube with the metal wire embedded therein is in a variable acceleration motion throughout the stretching process. The variable acceleration motion is caused by the change in tension applied to the capillary glass tube with the metal wire embedded therein during the second stretching operation. At the beginning of the third heating operation, the heating temperature is higher than the softening point of the capillary glass tube but has not risen to the melting point of the metal wire. At this time, the magnetic traction block is driven by the programmed traction shaft to perform slow horizontal displacement, and the capillary glass tube with the metal wire embedded therein is only subjected to the tension provided by the traction shaft. After the heating temperature rises to the melting point of the metal wire, While the traction shaft continues to work, the current is controlled to pass through the magnetic base, so that the magnetic traction block is subjected to the magnetic force from the magnetic base in the vertical direction. The magnetic force is much greater than the pulling force provided by the traction shaft. At this time, the movement acceleration of the first fastener and the second fastener increases, and the capillary glass tube with embedded metal wire is subjected to increased pulling force under the simultaneous action of the traction shaft and the magnetic base, so that the softened capillary glass tube and the molten metal wire are rapidly stretched under the action of the pulling force until they break, forming a nano-sized tip; the variable acceleration motion improves the uniformity of heating of the capillary glass tube and the metal wire in the tube, thereby increasing the success rate of preparing metal nanoelectrodes embedded in the capillary glass tube.

[0061] The specific steps of the method for preparing a nanoelectrode provided by the present application are described in detail below through specific examples.

[0062] Example 1

[0063] A method for preparing a double-pore borosilicate glass capillary / double-pore quartz glass capillary embedded with gold wire / platinum wire nanoelectrode comprises the following steps:

[0064] Use conductive silver glue to connect the two ends of a 3 cm long gold wire (30 μm diameter) to a copper wire (0.5 mm diameter), and insert it into a double-bore borosilicate glass capillary so that the metal wire is located in the middle of the double-bore borosilicate glass capillary.

[0065] Alternatively, use conductive silver glue to connect the two ends of a 3 cm long platinum wire (30 μm diameter) to a copper wire (0.5 mm diameter), and then insert the connected metal wire into a double-hole quartz glass capillary so that the metal wire is located in the middle of the capillary glass tube.

[0066] like Figure 1 and Figure 2 As shown, the capillary glass 5 with the metal wire is installed in the slots of the first slide rail 201 and the second slide rail 202, and is fixed and pressed with the first fastening block 211 and the second fastening block 212. Then, the rubber hose is connected to the interface of the vacuum pump and the capillary glass tube respectively through the Y-type splitter;

[0067] After the capillary glass tube is fixed, a pre-thinning operation is started, and the area to be processed of the capillary glass tube is prepared for the first heating. The gas flow rates of hydrogen and oxygen generated by the hydrogen generator are monitored in real time. For the combination of the double-pore borosilicate glass capillary tube and the gold wire, the gas flow rates of hydrogen and oxygen are set to 60 SCCM and 10 SCCM, respectively. The double-pore borosilicate glass capillary tube is heated, and it can be observed that the middle part of the double-pore borosilicate glass capillary tube softens. At the same time, a first stretching operation is performed on the capillary glass tube. A programmable traction shaft applies tension to the double-pore borosilicate glass capillary tube through a stretching structure. The softened part in the middle of the double-pore borosilicate glass capillary tube is stretched under the action of the tension. The stretching distance is determined by the programmable traction shaft. The stretching process of the processing area of the double-pore borosilicate glass capillary tube is observed by a monitoring device. When the stretching reaches the specified distance, the heating and stretching are stopped.

[0068] In other embodiments, for the combination of a double-hole quartz glass capillary and a platinum wire, the gas flow rates of hydrogen and oxygen are set to 150 SCCM and 75 SCCM, respectively.

[0069] After stopping the first heating and stretching operations, the vacuum pump is turned on to evacuate the air from the double-pore borosilicate glass capillary. A second heating operation is performed on the area to be processed of the double-pore borosilicate glass capillary. It is observed that the middle portion softens and collapses toward the middle under the action of atmospheric pressure, thereby encapsulating the gold wire in the double-pore borosilicate glass capillary. After encapsulation, the second heating operation is stopped. The encapsulation time is 8s to 20s.

[0070] In other embodiments, for the combination of a double-hole quartz glass capillary and a platinum wire, the gas flow rates of hydrogen and oxygen are set to 150 SCCM and 75 SCCM, respectively, and the packaging time is 120 s to 180 s.

[0071] After packaging, use a vacuum pump to check the airtightness of the package. Remove the rubber tube at one end of the glass tube and pinch the rubber tube with your hand. If the vacuum pump shows a vacuum state, it means that the capillary glass tube with embedded metal wire is packaged successfully, indicating that the metal wire is not broken or melted in the packaging area, and the packaging effect is good.

[0072] After testing the airtightness of the capillary glass tube, the metal wires at both ends are fixed with a first fastener 209 and a second fastener 210, so that the metal wires are subjected to the tension of the tensile structure simultaneously with the capillary glass tube during the stretching process; a third heating operation is performed on the to-be-processed area of the capillary glass tube with the embedded metal wire; at the same time, the tensile structure performs a second tensile operation on the capillary glass tube, so that the capillary glass tube is in a state of variable acceleration during the stretching process; the monitoring equipment observes that after the double-hole borosilicate glass capillary tube with the embedded metal wire is heated, it rapidly contracts in the middle under the action of the tensile force until it breaks, forming two electrodes with needle-like tips. At this time, the third heating operation and the second tensile operation are stopped, and the stretching time is 10s to 20s; Figure 5 As shown, it was observed that the drawn metal wire extended into the tip of the capillary glass tube without being broken.

[0073] Optionally, for a combination of a double-hole quartz glass capillary and a platinum wire, the gas flow rates of hydrogen and oxygen are set to 150 and 120 SCCM, respectively, and the stretching time is 10 s to 20 s.

[0074] After the drawing process is completed, the electrode tip formed by the drawn double-hole capillary glass tube with embedded metal wire is polished using a needle grinder or focused ion beam etching method to expose the metal wire in the double-hole capillary glass tube from the tip. The diameter of the polished metal wire tip is about 100 nm, and the distance between the two metal electrodes is about 4 μm. The prepared nanoelectrode is electrochemically characterized, and the electrolyte solution is set to 10 mmol / L potassium ferrocyanide solution. The cyclic voltammetry curve is scanned using the electrochemical workstation CHI760C, with the platinum wire as the counter electrode, Ag / AgCl as the reference electrode, and one end of the electrode as the working electrode. When part of the tip is cut off, the curve shows the S-shape current or hemispherical current of the nanoelectrode, indicating that the metal wire electrode has been exposed after part of the tip is cut off.

[0075] In other embodiments, the tip of the drawn capillary glass tube may not be polished. While the hole of the capillary glass tube at the electrode tip remains open, electrochemical deposition of gold plating solution is directly performed, and the hole position of the electrode tip is filled with deposited metal, so that the deposited gold is exposed from the tip, and further electrochemical deposition is performed until a nano-tunneling electrode is formed. At this time, the area size at the tip of the capillary glass tube is sub-hundred nanometers, and the partition between the double holes of the capillary glass tube is only a dozen nanometers thick. Therefore, the size of the metal electrode directly deposited to the exposed tip is also sub-hundred nanometers, and the gap between the electrode pairs is affected by the size of the glass partition and can be directly shortened to a size of more than ten nanometers, which is convenient for the subsequent electrochemical deposition process to prepare the tunneling electrode pair.

[0076] Among them, electrochemical deposition is performed on the nanoelectrode with the tip of the cut-off part to form a nanoelectrode pair with tunneling sensing function; the electrochemical deposition is carried out by a step-by-step deposition method, first pre-deposition is carried out on the tip surface to quickly form a deposited gold seed and shorten the distance between the metal electrodes at both ends, and then slow deposition is carried out by a feedback electrodeposition method until the distance between the two electrodes is shortened to within the tunneling distance range, which can be monitored by the tunneling current; the electroplating solution for electrodeposition is a diluted ECF64D gold plating solution (NH4AuSO3, (NH4)2SO3); the pre-deposition adopts a constant potential mode, with Ag / AgCl as the reference electrode and counter electrode, and the drawn metal wire as the working electrode for deposition; the feedback electrodeposition adopts a constant current mode, with one of the drawn metal wire electrodes as the reference electrode and counter electrode, and the other as the working electrode, alternating until the tunneling current is observed, that is, the electrochemical deposition process is stopped.

[0077] Example 2

[0078] The method for preparing a nanoelectrode provided by the present invention can be used to prepare a single metal wire nanoelectrode for research in the fields of basic electrochemistry, electrochemical scanning probe microscopy, etc.

[0079] Preparation of a gold wire nanoelectrode probe embedded in a single-hole borosilicate glass tube, the steps comprising:

[0080] Single-pore borosilicate glass capillaries were used as packaging carriers, and copper wires were used as metal electrode materials.

[0081] A single metal wire nanoelectrode device was prepared according to the packaging and drawing steps mentioned in Example 1.

[0082] Example 3

[0083] A method for preparing a double-pore borosilicate glass capillary embedded with a heterogeneous double metal wire nanoelectrode comprises the following steps:

[0084] Use conductive silver glue to connect the two ends of a copper wire and a constantan wire with similar melting points to another copper wire; insert the connected combined metal wires into a double-bore borosilicate glass capillary tube so that the copper wire and constantan wire are located in the middle of the double-bore borosilicate glass capillary tube;

[0085] Install the double-hole borosilicate glass capillary tube with the metal wire threaded into the slots of the first slide rail 201 and the second slide rail 202, and then fix and tighten it with the first tightening block 211 and the second tightening block 212. Put rubber tubes connected to the vacuum pump on both ends of the double-hole borosilicate glass capillary tube;

[0086] After the capillary glass tube is fixed, a pre-thinning operation is started, and the area to be processed of the capillary glass tube is prepared for the first heating. The gas flow rates of hydrogen and oxygen generated by the hydrogen generator are monitored in real time. For the combination of the double-pore borosilicate glass capillary tube, the copper wire and the constantan wire, the gas flow rates of hydrogen and oxygen are set to 60 SCCM and 15 SCCM respectively. An igniter is used to ignite at the gas outlet of the heating structure. A slight popping sound indicates that the ignition is successful. Then, the double-pore borosilicate glass capillary tube is heated, and the middle part of the double-pore borosilicate glass capillary tube can be observed to soften. At the same time, a first stretching operation is performed on the capillary glass tube. A programmable traction shaft applies tension to the double-pore borosilicate glass capillary tube through the stretching structure. The softened part in the middle of the double-pore borosilicate glass capillary tube is slowly stretched under the action of the tension. The stretching distance is determined by the programmable traction shaft. The stretching process of the middle part of the double-pore borosilicate glass capillary tube is observed by a monitoring device. When the stretching reaches the specified distance, heating and stretching are stopped.

[0087] After stopping the first heating operation and the first stretching operation, the vacuum pump is turned on to evacuate the air in the double-pore borosilicate glass capillary; the hydrogen and oxygen gas flows generated by the hydrogen generator are monitored in real time, and the hydrogen and oxygen gas flows are set to 60 SCCM and 15 SCCM, respectively. An igniter is used to ignite at the gas outlet, and the second heating of the to-be-processed area of the double-pore borosilicate glass capillary is started. It is observed that the middle part softens and collapses toward the middle under the action of atmospheric pressure, thereby achieving the encapsulation of the copper wire and constantan wire in the double-pore borosilicate glass capillary. After encapsulation, the second heating operation is stopped, and the encapsulation time is 10 seconds;

[0088] After encapsulation, use a vacuum pump to check the airtightness of the package. Remove the rubber tube at one end of the glass tube and pinch it with your hand. If the vacuum pump indicates a vacuum state, it indicates that the encapsulation of the double-hole borosilicate glass capillary with metal wire is complete. After encapsulation, the copper wire and constantan wire are not broken or melted in the encapsulation area, and the encapsulation effect is good.

[0089] After testing the airtightness of the capillary glass tube, the metal wires at both ends were fixed with a first fastener 209 and a second fastener 210, so that the metal wires and the capillary glass tube were subjected to the tension of the tensile structure simultaneously during the drawing process. The hydrogen and oxygen gas flows produced by the hydrogen generator were monitored in real time, with the hydrogen and oxygen gas flows set to 60 SCCM and 35 SCCM, respectively. After the glass capillary tube with the embedded metal wire was heated, it rapidly contracted in the middle under the action of tension until it broke, forming two electrodes with needle-like tips. The drawing time was 10 seconds.

[0090] The drawn electrode tip is polished using a needle grinder or focused ion beam etching method to expose the metal wire in the double-pore borosilicate glass capillary from the tip; the exposed tip is a heterogeneous metal nanoelectrode with a tip diameter of approximately 100 nm and a distance between heterogeneous electrodes of 3 μm to 5 μm; the drawn nanoelectrode is electrochemically characterized using a 10 mmol / L potassium ferrocyanide solution as the electrolyte solution, and a cyclic voltammetry curve scan is performed using an electrochemical workstation CHI760C, with a platinum wire as the counter electrode, Ag / AgCl as the reference electrode, and one end of the electrode as the working electrode; it is verified that the metal wire at the tip has been exposed from the glass capillary, and the heterogeneous metal nanoelectrode device can now be studied as a nanothermocouple device.

[0091] The above is a detailed introduction to the preparation method and preparation device of a nanoelectrode provided by the present application. For ordinary technicians in this technical field, several improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A method for preparing a nanoelectrode, characterized in that: include: Providing a capillary glass tube with a built-in metal wire; The capillary glass tube is first heated at a temperature higher than the softening point of the capillary glass tube and lower than the melting point of the metal wire, and the capillary glass tube is first stretched to pre-thin the capillary glass tube; Fixing the metal wire, evacuating the capillary glass tube, and performing a second heating on the to-be-processed region of the capillary glass tube at a temperature higher than the softening point of the capillary glass tube and lower than the melting point of the metal wire, so that the capillary glass tube pre-thinned in the to-be-processed region is bonded to the metal wire to achieve a packaging operation; The capillary glass tube-metal wire assembly in the area to be processed is heated for a third time, and the capillary glass tube-metal wire assembly is stretched for a second time, so that the area to be processed of the capillary glass tube is stretched and broken, forming a nanoelectrode with a nanotip. The third heating operation and the second stretching operation are performed simultaneously. At the beginning of the third heating operation, the heating temperature is higher than the softening point of the capillary glass tube but does not rise to the melting point of the metal wire, and a slow horizontal displacement is performed. The capillary glass tube with the embedded metal wire is only subjected to a uniform first tension. After the heating temperature rises to the melting point of the metal wire, the capillary glass tube with the embedded metal wire is subjected to a second tension, which is greater than the first tension, and the acceleration of the stretching motion increases, so that the softened capillary glass tube and the molten metal wire are rapidly stretched under the action of the tension until they are broken, forming a variable acceleration motion during the entire stretching process.

2. The method for preparing a nanoelectrode according to claim 1, wherein: The speed of the first stretching operation is lower than the speed of the second stretching operation.

3. The method for preparing a nanoelectrode according to claim 1, wherein: Also includes: While the hole of the capillary glass tube at the nano tip remains open and closed, electrochemical deposition is performed to fill the hole position of the electrode tip with deposited metal, so that the nano-deposited metal is exposed from the tip, and further electrochemical deposition is performed until a nanoelectrode is formed.

4. The method for preparing a nanoelectrode according to claim 1, wherein: Also includes: The nano-tip of the nano-electrode is polished using a needle grinder or focused ion beam etching method, so that the metal wire in the capillary glass tube is exposed from the tip to form a nano-electrode.

5. The method for preparing a nanoelectrode according to claim 1, wherein: The capillary glass tube is a single-hole capillary glass tube or a double-hole capillary glass tube, wherein the metal wires built into the double-hole capillary glass tube are metal wires made of the same material or metal wires made of different materials.

6. The method for preparing a nanoelectrode according to claim 5, wherein: The nanoelectrode is used to prepare a double-pore homogeneous metal tunneling nanoelectrode device, a single-pore metal nanoelectrode device or a double-pore heterogeneous metal tunneling nanoelectrode device.

7. A device for preparing a nanoelectrode using the method for preparing a nanoelectrode according to claim 1, characterized in that: include: A fixing structure, comprising a first fixing member and a second fixing member located in the same straight line and arranged separately, wherein the first fixing member and the second fixing member are used to fix the capillary glass tube and the metal wire; a heating structure, the heating structure being located between the first fixing member and the second fixing member and corresponding to the region of the capillary glass tube to be processed, and utilizing the heating structure to heat the region of the capillary glass tube to be processed; a stretching structure connected to the first fixing member and the second fixing member, and performing a stretching operation on the first fixing member and the second fixing member to move away from each other; An air extraction structure is used to be connected to the capillary glass tube to keep the capillary glass tube in a vacuum state.

8. The nanoelectrode preparation device according to claim 7, characterized in that: The stretching structure includes a traction rope, a magnetic traction block, a traction shaft, and a magnetic base; The first fixing member, the second fixing member and the magnetic traction block are connected to each other through a traction rope. The magnetic traction block is connected to the traction shaft by magnetism. The magnetic traction block applies a pulling force to the capillary glass tube under the magnetic force of the magnetic base below.

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