Nanometer spiral flow channel and preparation method and application thereof

Abstract

The invention relates to the technical field of nanometer manufacturing, and discloses a nanometer spiral flow channel and a preparation method and application thereof.The nanometer spiral flow channel comprises a silicon nitride layer and a graphene layer, the nanometer spiral flow channel is a spiral structure flow channel formed in the silicon nitride layer, and a silicon nitride nanometer hole is formed in the end, corresponding to the nanometer spiral flow channel, of the silicon nitride layer; a graphene nanopore is formed in the other end, corresponding to the nanometer spiral flow channel, of the graphene layer, and the silicon nitride nanopore and the graphene nanopore are through holes. According to the method, the nanoscale spiral flow channel can be prepared, a photoetching mask does not need to be designed and prepared in advance, and the preparation period is remarkably shortened.

Description

Technical Field

[0001] The present invention relates to the field of nano-manufacturing technology, and in particular to a nano-spiral flow channel and a preparation method and application thereof. Background Art

[0002] Spiral flow channels are one of the core structures of microfluidic chips. Microfluidics aims to manipulate tiny volumes of fluid to enable various analyses and processing in fields such as biology and chemistry. With the increasing performance requirements of microfluidic systems, more efficient and precise flow channel structures are needed to meet diverse application needs. Nanospiral flow channels have emerged as a result. Advances in nanotechnology have made it possible to fabricate nanoscale structures, providing technical support for the research of nanospiral flow channels. Nanofabrication techniques enable the precise fabrication of nanospiral flow channels with specific sizes and shapes, allowing exploration of their unique fluid dynamics properties and potential applications. Nanospiral flow channels provide an ideal platform for studying fluid dynamics phenomena at the nanoscale. At the nanoscale, fluid behavior differs significantly from that at the macroscale, with surface and quantum effects becoming prominent. Studying the flow of fluids within nanospiral flow channels can provide a deeper understanding of these unique phenomena and enrich and improve the theory of nanofluidics.

[0003] In the biomedical field, nanospiral channels can be used to efficiently separate biomolecules and cells, such as cancer cells and viral particles, due to differences in size, shape, and fluid dynamics. This allows for early detection and diagnosis of diseases. Furthermore, nanospiral channels prolong the residence time of the target in the detection zone. For example, fluorescently labeled biomolecules flowing through the spiral channel can pass through the excitation light zone multiple times, emitting more fluorescent signals and improving detection sensitivity, facilitating the detection of low-concentration target substances. In drug development, nanospiral channels can precisely control the movement of fluids and the particles within them. By adjusting parameters such as channel size, shape, and flow rate, manipulation of individual molecules or cells is possible. This allows for precise manipulation of biomolecules and cells for drug screening, toxicity testing, and other applications, accelerating drug development. They can also be used in cell therapy, such as precise manipulation and modification of immune cells, to enhance the effectiveness of cell therapy. Similarly, in chemical analysis, nanospiral channels can generate complex flow fields, creating secondary flows as fluids flow through the spiral path, promoting mixing between different fluids. This mixing effect is very important in biochemical reactions, chemical synthesis and other applications of microfluidic chips. It can ensure sufficient contact between reactants and improve reaction efficiency and uniformity.

[0004] Nanospiral channels, with their unique fluid manipulation capabilities, have become a research hotspot in microfluidics and nanotechnology. However, due to their nanoscale dimensions, nanospiral channels require extremely high processing precision. Photolithography is a commonly used method for preparing spiral channels. By designing photolithography masks and optimizing the photolithography process, nanospiral patterns can be formed on materials such as photoresist. This pattern can then be transferred to the substrate through subsequent processes such as etching, enabling the fabrication of nanospiral channels. However, at the nanoscale, photoresist has limited resolution, making it prone to image distortion and high edge roughness, which can affect the accuracy and performance of the channels. Summary of the Invention

[0005] In response to the deficiencies of the prior art, the present invention provides a nano-spiral flow channel and a preparation method and application thereof, which can prepare nano-scale spiral flow channels without the need for pre-design and preparation of photolithography masks, significantly shortening the preparation cycle.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In the first aspect, the present invention proposes a nano-spiral flow channel, which includes a silicon nitride layer and a graphene layer. The nano-spiral flow channel is a spiral structure flow channel opened on the silicon nitride layer. A silicon nitride nanopore is opened at one end of the nano-spiral flow channel on the silicon nitride layer, and a graphene nanopore is opened at the other end of the nano-spiral flow channel on the graphene layer. The silicon nitride nanopore and the graphene nanopore are both through holes.

[0008] In combination with the first aspect, further, the cross section of the nano-spiral flow channel is a rectangular groove, the width of the rectangular groove is 50nm to 1000nm, and the depth is 5nm to 100nm.

[0009] In combination with the first aspect, further, the diameter of the silicon nitride nanopore is 2 nm to 100 nm.

[0010] In combination with the first aspect, further, the silicon nitride layer is a silicon nitride thin film with a thickness of 50 nm to 200 nm.

[0011] In combination with the first aspect, further, the material of the graphene layer may be one of molybdenum disulfide, boron nitride, tungsten disulfide and MXene.

[0012] In combination with the first aspect, further, the silicon substrate is double-sided polished, the silicon substrate can be either rectangular or circular, and the silicon substrate window opened at its center is a hollow structure with a side length of 100-200 μm.

[0013] In a second aspect, the present invention proposes a nanospiral flow channel chip comprising a silicon substrate and the aforementioned nanospiral flow channel. The silicon substrate, silicon nitride layer, and graphene layer are sequentially stacked, with a silicon substrate window defined below the silicon substrate corresponding to the nanospiral flow channel. The silicon nitride layer in the middle layer is a self-supporting suspended structure. The nanospiral flow channel chip of the present invention comprises a three-layer structure: a silicon substrate as the bottom layer; a silicon nitride layer as the middle layer; and a graphene layer as the third layer, which also serves as a covering layer.

[0014] In a third aspect, the present invention provides a method for preparing a nano-spiral flow channel, comprising the following steps:

[0015] Draw a planar image of the nano-spiral flow channel, convert the planar image into a graphic file that can be recognized by the focused ion beam operation device, and generate a scanning path of the focused ion beam;

[0016] A focused ion beam is used to etch spiral grooves on the silicon nitride layer along a scanning path to obtain a spiral flow channel;

[0017] A focused ion beam was used to sputter silicon nitride nanopores at one end of the spiral flow channel;

[0018] A wet transfer method is used to transfer the graphene layer onto the spiral flow channel;

[0019] A focused ion beam is again used to sputter a graphene nanopore on the graphene layer corresponding to the other end of the spiral flow channel, thereby obtaining a nano-spiral flow channel.

[0020] For nano-spiral flow channel cross-sections of different sizes, the ion beam current can be selected from 1pA to 80pA. The depth of the nano-spiral flow channel is determined by the focused ion beam etching time. The longer the etching time, the deeper the nano-spiral flow channel.

[0021] In conjunction with the third aspect, further, the silicon nitride nanopore is prepared by sputtering using a focused ion beam, with an ion beam current of 1pA to 40pA and a sputtering time of less than 1s. During the sputtering of the silicon nitride nanopore, the ion beam current determines the aperture size of the nanospiral flow channel entrance of the present invention, and the sputtering time is determined by the silicon nitride thickness. The graphene nanopore is prepared by sputtering using a focused ion beam, with an ion beam current of 1pA to 40pA and a sputtering time of less than 1s.

[0022] In a fourth aspect, the present invention provides a method for preparing a nano-spiral flow channel detection chip, including the above-mentioned method for preparing the nano-spiral flow channel, and further including the steps of preparing a silicon substrate and a silicon nitride layer before preparing the nano-spiral flow channel, specifically:

[0023] The silicon wafer is polished to obtain a silicon substrate; a silicon nitride layer is deposited on the surface of the silicon substrate by low-pressure chemical vapor deposition; and tetramethylammonium hydroxide is used for directionally etching to etch a silicon substrate window on the silicon substrate. The silicon nitride film in the silicon substrate window area forms a self-supporting structure.

[0024] In the fifth aspect, the present invention proposes a nano-spiral flow channel detection device, comprising a liquid pool, an Ag / AgCl electrode, a patch clamp amplifier and the above-mentioned nano-spiral flow channel chip, wherein the nano-spiral flow channel chip is arranged in the middle of the liquid pool and separates the liquid pool into two left and right parts, the liquid pools of the two parts are injected with potassium chloride solution, and a certain concentration of biological molecules is also injected into the liquid pool on one side of the silicon substrate window; an Ag / AgCl electrode is inserted in each of the left and right parts of the liquid pool, the Ag / AgCl electrode located in the liquid pool injected with biological molecules is connected to the negative pole of the patch clamp amplifier, and the Ag / AgCl electrode in the liquid pool on the other side is connected to the positive pole of the patch clamp amplifier.

[0025] In a sixth aspect, the present invention proposes an application of a nano-spiral flow channel in biomolecule detection.

[0026] This invention overcomes the technical difficulties of manufacturing and processing nanoscale spiral channels by further reducing the size of the spiral channel structure to the nanoscale, thus forming a nanofluidic chip. Compared to micron-scale spiral channels, nanoscale spiral channels exhibit a smaller size effect. At the nanoscale, intermolecular forces (such as electrostatic forces, van der Waals forces, hydration forces, and steric repulsion) play a dominant role. Therefore, when biomolecules flow in the nanoscale spiral channel, the action of the spiral channel wall effectively reduces the flow rate of the biomolecules.

[0027] Compared with the prior art, the present invention provides a nano-spiral flow channel and its preparation method and application, which have the following beneficial effects:

[0028] (1) The present invention adopts a focused ion beam etching process to prepare nano-spiral flow channels, which far exceeds the resolution limit of traditional photolithography technology and can accurately control the height, curvature radius and pitch of the spiral flow channels. In addition, the focused ion beam directly etches the target structure by controlling the ion beam path through a computer, without the need for pre-design and preparation of photolithography masks, significantly shortening the preparation cycle; the focused ion beam does not require mask alignment, avoiding structural offset caused by alignment errors.

[0029] (2) In the application of single-molecule detection, the nano-spiral flow channel of the present invention connects silicon nitride nanopores, nano-spiral flow channels and graphene nanopores in a serial structure for the first time, breaking through the single structure of traditional nanopore detection chips. Biomolecules pass through the nanopores at both ends of the nano-spiral flow channel in sequence. Compared with a single nanopore, the interaction between biomolecules and the nanopore wall is increased, the flow velocity is reduced, and thus the passing velocity of biomolecules is reduced, thereby improving the sensitivity of detection.

[0030] (3) In the application of single-molecule detection, the nano-spiral flow channel of the present invention generates two blocking current signals when the biological molecules pass through the two nanopores in sequence, which further improves the accuracy of detection. This is of great significance for single-molecule detection technology, cell biology research, etc.

[0031] (4) The nano-spiral flow channel of the present invention uses a silicon nitride substrate, which has higher hardness than the traditional PDMS spiral micro-fluidic channel. When preparing a high aspect ratio structure, it will not collapse and the structure is not easily deformed under stress, overcoming the difficulties in preparing high aspect ratio nano-spiral flow channels in the prior art. Therefore, the high aspect ratio nano-spiral flow channel prepared by the present invention is more conducive to the mixing of mixed reagents in chemical and biological reaction applications because the high aspect ratio spiral flow channel has more space; in heat dissipation applications, the high aspect ratio heat dissipation area is larger, which is more conducive to heat dissipation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the exploded structure of the nano-spiral flow channel chip in Example 1 of the present invention;

[0033] Figure 2 A schematic diagram of a spiral flow channel drawn by focused ion beam software during the preparation of a nano-spiral flow channel in Example 1 of the present invention;

[0034] Figure 3 The scanning electron microscope photos of the nano-spiral flow channel are taken during the preparation process of the nano-spiral flow channel in Example 1 of the present invention under different focused ion beam etching times with the same nano-spiral flow channel pattern; wherein, Figure 3 a to Figure 3 The focused ion beams in d are all 24pA ion beams, and the etching times are 5s, 20s, 60s, and 80s, respectively;

[0035] Figure 4 The scanning electron microscope photos of different stages of the nano-spiral flow channel preparation process in Example 1 of the present invention are shown in FIG. Figure 4 a is the SEM photo of the nano-spiral channel etched on the silicon nitride film. Figure 4 b is the SEM photo of the silicon nitride nano-spiral channel after sputtering silicon nitride nano-holes at one end. Figure 4 c is the SEM photo of the graphene cover layer after transferring it above the silicon nitride nano-spiral channel. Figure 4 d is the SME photo after sputtering graphene nanopores on the graphene cover layer;

[0036] Figure 5 This is a schematic diagram of the structure of the nano-spiral flow channel in Example 1 of the present invention for applications in nanofluid dynamics research and single-molecule detection;

[0037] Figure 6 This is an IV curve of the nano-spiral flow channel of the present invention in Example 1 of the present invention in KCl solutions of different concentrations;

[0038] Figure 7 This is a graph showing the conductivity change of the nano-spiral flow channel in Example 1 of the present invention under the action of positive and negative electric fields in KCl solutions of different concentrations;

[0039] Figure 8 This is a graph showing the current signal of 48Kb λ-DNA ions detected by the nano-spiral flow channel in Example 1 of the present invention.

[0040] The meanings of the reference numerals in the figures are:

[0041] 1-Silicon substrate; 2-Silicon nitride layer; 3-Graphene layer; 4-Silicon substrate window; 5-Nanospiral flow channel; 6-Silicon nitride nanopore; 7-Graphene nanopore; 8-Nanospiral flow channel chip; 9-Liquid reservoir; 10-KCl solution; 11-Ag / AgCl electrode; 12-Patch clamp amplifier. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 creative efforts are within the scope of protection of the present invention.

[0043] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. Technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may also include different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0044] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the protection content of the present invention.

[0045] Example 1

[0046] like Figure 1 As shown, the nano-spiral flow channel chip 8 of the present invention includes a silicon substrate 1, a silicon nitride layer 2 and a graphene layer 3 stacked in sequence, a nano-spiral flow channel 5 is provided on the upper part of the silicon nitride layer 2, a silicon nitride nanopore 6 is provided at one end of the nano-spiral flow channel 5, and a graphene nanopore 7 is provided at the other end of the graphene layer 3 adjacent to the nano-spiral flow channel 5; a silicon substrate window 4 is provided directly below the silicon substrate 1 corresponding to the nano-spiral flow channel 5, so that biological molecules can enter the silicon nitride nanopore 5 from the silicon substrate window 4.

[0047] In one specific embodiment of this embodiment, the nanospiral channel 5 has a rectangular groove cross-section with a width of 50 nm to 1000 nm, preferably 300 nm. The rectangular groove has a depth of 5 nm to 100 nm, preferably 50 nm. The pitch of the nanospiral channel 5 is 100 nm to 1000 nm, or even wider, with a preferred pitch of 500 nm. The diameter of the silicon nitride nanopore 6 at one end of the nanospiral channel 5 is 2 nm to 100 nm. The pore size of the graphene nanopore 6 at the other end of the nanospiral channel 5 is determined based on the size of the molecule to be detected.

[0048] In a specific implementation of this embodiment, the silicon nitride layer 2 is a silicon nitride thin film, which is an intermediate layer; the graphene layer 3 is a graphene thin film, which is a covering layer.

[0049] In the present invention, the nano-spiral flow channel 5 is formed by a focused ion beam etching process. Before etching the nano-spiral flow channel 5 on the silicon nitride layer 2, a plane pattern of the spiral flow channel is first drawn, such as Figure 2 As shown, the spiral pitch and spiral length can be set according to actual needs. Figure 2 The white track in the middle etches the silicon nitride layer 2, and the depth of the nano-spiral channel 5 can be determined by the etching time. Figure 3 As shown in FIG. 3 , the depth of the nano-spiral channel 5 gradually increases with the etching time. Figure 3 a is obtained by etching with an ion beam current of 24 pA for 5 seconds, with a depth of about 10 nm; Figure 3 b is also obtained by etching with an ion beam current of 24pA for 20s, with a depth of about 20nm; Figure 3 c is an ion beam with a beam current of 24 pA and an etching time of 60 s, with a depth of about 60 nm; Figure 3 Figure d shows an ion beam with a beam current of 24 pA and an etching time of 80 s, resulting in an approximately 80 nm depth. In focused ion beam etching, the beam current directly determines the etching speed. When etching a nanohelical channel 5 of the same depth, a larger beam current results in a faster etching speed.

[0050] In this embodiment, the preparation method of the nano-spiral flow channel chip 8 includes the following steps:

[0051] In step S1, a 20-200 nm thick silicon nitride film, preferably 100 nm thick, is deposited on the upper surface of a silicon substrate 1 by low-pressure vapor deposition. Tetramethylammonium hydroxide (TMAH) is then used for directionally etching to form a square window (silicon substrate window 4) with a side length of 100-300 μm on the silicon substrate 1. The side length of silicon substrate window 4 is preferably 200 μm, thus forming a self-supporting silicon nitride film.

[0052] Step S2, use computer-aided design software to draw the plane pattern of the nano-spiral flow channel 5 to be etched, and import the plane pattern into the control software of the focused ion beam system. Start the focused ion beam system, and the ion beam bombards the surface of the silicon nitride film according to the predetermined plane pattern to complete the etching of the nano-spiral flow channel 5. Figure 4 The width of the nano-spiral channel 5 can be adjusted according to the size of the pattern, and the depth of the nano-spiral channel 5 can be adjusted by the ion beam etching time.

[0053] Step S3, a silicon nitride nanopore 6 is processed at one end of the nano-spiral flow channel 5 by using a focused ion beam sputtering technique. The nanopore serves as the entrance of the nano-spiral flow channel chip 8. Figure 4 As shown in b.

[0054] Step S4, using wet transfer technology to transfer the graphene layer 3 grown by chemical vapor deposition onto the silicon nitride film to cover the nano-spiral flow channel 5, as shown in FIG. Figure 4 As shown in c.

[0055] Step S5, a graphene nanopore 7 is sputtered on the graphene layer 3 using a focused ion beam. The nanopore needs to be processed on the graphene layer above the other end of the nano-spiral flow channel 5. The graphene nanopore 7 serves as the outlet of the nano-spiral flow channel chip 8. Figure 4 As shown in d.

[0056] Example 2

[0057] like Figure 5 As shown, this embodiment applies the nano-spiral channel 5 to the study of ion rectification effect in a nano-confined space, including the following steps:

[0058] First, the nano-spiral flow channel chip 8 of the present invention is installed in the center of the liquid pool 9 to separate the liquid pool 9 into left and right sides. The nano-spiral flow channel 5 and two nanopores on the nano-spiral flow channel chip 8 are the only channels on both sides of the liquid pool 9.

[0059] Then, KCl solutions 10 of different concentrations are injected on both sides of the nano-spiral flow channel chip 8, and an Ag / AgCl electrode 11 is inserted on both sides of the liquid pool 9. The other end of the Ag / AgCl electrode 11 is connected to a patch clamp amplifier 12, which is used to apply a bias voltage and collect the ion current signal in the nano-spiral flow channel 5.

[0060] Figure 6 The voltammetric (IV) curves of 0.1M, 0.5M, 1M, 1.5M, and 2M KCl solutions at -500~500 mV are shown. From the IV curves of KCl solutions with different concentrations, it can be found that when the concentration is lower than 0.5M, the IV curve is linear, while when the concentration is higher than 1M, the IV curve shows a rectifying effect. Figure 7 As shown, the IV curves between 500-0 mV and 0-500 mV were fitted to calculate the conductivity under positive and negative electric fields at different concentrations. It is clearly found that at 0.1M and 0.5M KCl concentrations, the conductivity of the nanospiral flow channel 5 under positive and negative electric fields essentially overlap. At concentrations of 1M, 1.5M, and 2M, the conductivity of the nanospiral flow channel 5 under positive electric fields is significantly lower than that under negative electric fields, demonstrating a significant rectification effect, with a maximum rectification ratio of 2. This is attributed to the fact that the diameter (48nm) of the silicon nitride nanopore 6 at the entrance of the nanospiral flow channel 5 is approximately twice the diameter (24nm) of the graphene nanopore 7 at the exit of the nanospiral flow channel 5.

[0061] The nano-spiral flow channel 5 of the present invention is applied to the study of the rectification effect of nanofluids, breaking the flow symmetry and providing an innovative solution for micro-nanoscale energy conversion, precise fluid control, biomedical applications and environmental monitoring.

[0062] Example 3

[0063] In this embodiment, the nano-spiral flow channel chip 8 is applied to detect 48Kb λ-DNA molecules. Figure 5As shown, 1 mol / L KCl solution 10 is injected on both sides of the liquid pool 9, and 10 μl of 30 ug / L concentration of λ-DNA molecules is injected into the liquid pool 9 near the side of the silicon substrate window 4. The λ-DNA molecules first enter the silicon nitride nanopore 6 from the silicon substrate window 4 of the nano-spiral flow channel chip 8 of this embodiment, then flow through the nano-spiral flow channel 5, and then pass through the graphene nanopore 7 to enter the other side of the liquid pool 9.

[0064] The patch clamp amplifier 10 is used to monitor the ionic current signal of the entire process of the λ-DNA molecule passing through the nano-helical flow channel chip 8, such as Figure 8 As shown in Figure 2, with a 1V bias voltage applied, the average baseline current I0 is approximately 7nA. When the λ-DNA molecule enters the silicon nitride nanopore 6, the baseline current decreases, with the average ion current decrease, ΔI1 (blocking signal), being 0.75nA. When the λ-DNA molecule passes through the graphene nanopore 7, the baseline current decreases again, with the average ion current decrease, ΔI2 (blocking signal), being 3nA. ΔI2 is approximately four times larger than ΔI1. The entire process from λ-DNA entering the silicon nitride nanopore 6 to exiting the graphene nanopore 7 lasts up to 800ms, with a λ-DNA transit speed of 60 bases / ms, which is significantly slower than existing linear solid-state nanopore detection methods.

[0065] This embodiment demonstrates the integration of the silicon nitride nanopore 6, the nanospiral channel 5 on the silicon nitride layer 2, and the graphene nanopore 7. In biomolecule detection applications, biomolecules sequentially pass through the silicon nitride nanopore 6, the nanospiral channel 5, and the graphene nanopore 7. A primary blockage occurs when the biomolecule enters the silicon nitride nanopore 6, causing a decrease in the baseline current. As the biomolecule exits the graphene nanopore 7 through the nanospiral channel 5, a secondary blockage occurs, further reducing the baseline current. Furthermore, the blockage signal is significantly amplified as the biomolecule passes through the graphene nanopore 7. Compared to linear channels, the periodic curvature of the nanospiral channel 5 significantly increases the surface area of ​​the inner channel wall, thereby enhancing contact between biomolecules and the nanospiral channel 5 wall. This effectively reduces the biomolecule transit velocity and improves detection accuracy. If the depth of the nanospiral channel 5 is further reduced to sub-10 nm, the interaction between biomolecules and the nanospiral channel 5 wall will be further enhanced.

[0066] The nanohelical flow channel 5 produced by the present invention not only provides a core device for nanofluid dynamics research but also offers a new platform for studying the rheological properties of fluids at the nanoscale. Compared to traditional linear nanofluidics, it exhibits unique physical properties and application advantages, particularly in controlling fluid behavior, enhancing interfacial interactions, and realizing complex functions. Furthermore, the nanohelical flow channel 5 of the present invention can be applied to single-molecule detection technology. The long path length and high surface area ratio of the nanohelical flow channel 5 can enhance the sensitivity of biosensors.

[0067] It should be noted that, in this application, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0068] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A nano-spiral flow channel, characterized by: The nano-spiral flow channel comprises a silicon nitride layer and a graphene layer. The nano-spiral flow channel is a spiral structure flow channel opened on the silicon nitride layer. A silicon nitride nanopore is opened at one end of the nano-spiral flow channel on the silicon nitride layer, and a graphene nanopore is opened at the other end of the nano-spiral flow channel on the graphene layer. Both the silicon nitride nanopore and the graphene nanopore are through holes.

2. The nano-helical flow channel according to claim 1, characterized in that: The cross section of the nano-spiral flow channel is a rectangular groove, the width of the rectangular groove is 50nm to 1000nm, and the depth is 5nm to 100nm.

3. The nano-helical flow channel according to claim 1, characterized in that: The diameter of the silicon nitride nanopore is 2nm to 100nm.

4. A nano-spiral flow channel chip, characterized in that , comprising a silicon substrate and the nano-spiral flow channel according to any one of claims 1 to 3, wherein the silicon substrate, the silicon nitride layer and the graphene layer are stacked in sequence, and a silicon substrate window is opened below the silicon substrate corresponding to the nano-spiral flow channel.

5. A method for preparing a nano-spiral flow channel, characterized in that: The following steps are involved: Draw a planar image of the nano-spiral flow channel, convert the planar image into a graphic file that can be recognized by the focused ion beam operation device, and generate a scanning path of the focused ion beam; A focused ion beam is used to etch spiral grooves on the silicon nitride layer along a scanning path to obtain a spiral flow channel; A focused ion beam was used to sputter silicon nitride nanopores at one end of the spiral flow channel; A wet transfer method is used to transfer the graphene layer onto the spiral flow channel; A focused ion beam is again used to sputter a graphene nanopore on the graphene layer corresponding to the other end of the spiral flow channel, thereby obtaining a nano-spiral flow channel.

6. The method for preparing the nano-spiral flow channel according to claim 5, characterized in that: The silicon nitride nanopore is prepared by sputtering with a focused ion beam, and the ion beam current used is 1pA to 40pA; the graphene nanopore is prepared by sputtering with a focused ion beam, and the ion beam current used is 1pA to 40pA.

7. A method for preparing a nano-spiral flow channel detection chip, characterized by: The method for preparing the nano-spiral flow channel according to claim 5 further comprises the steps of preparing a silicon substrate and a silicon nitride layer before preparing the nano-spiral flow channel, specifically: The silicon wafer is polished to obtain a silicon substrate; a silicon nitride layer is deposited on the surface of the silicon substrate; and a silicon substrate window is etched on the silicon substrate.

8. A nano-spiral flow channel detection device, characterized by: The invention comprises a liquid pool, an Ag / AgCl electrode, a patch clamp amplifier, and the nano-spiral flow channel chip according to claim 4, wherein the nano-spiral flow channel chip is arranged in the middle of the liquid pool and separates the liquid pool into two left and right parts, the liquid pools of the two parts are both injected with potassium chloride solution, and the liquid pool on one side of the silicon substrate window is also injected with a certain concentration of biomolecules; an Ag / AgCl electrode is inserted into each of the left and right parts of the liquid pool, the Ag / AgCl electrode located in the liquid pool injected with biomolecules is connected to the negative electrode of the patch clamp amplifier, and the Ag / AgCl electrode in the liquid pool on the other side is connected to the positive electrode of the patch clamp amplifier.

9. Use of the nanohelical flow channel according to any one of claims 1 to 3 in biomolecule detection.

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