An all-silicon micro-chromatographic column with high aspect ratio and preparation method thereof

Abstract

The present invention provides an all-silicon micro-chromatographic column with a high aspect ratio and a preparation method thereof. Corresponding microchannels and microfluidic ports are formed in a first silicon substrate and a second silicon substrate respectively, and then a composite silicon substrate with closed microchannels and closed microfluidic ports is formed through a silicon-silicon bonding process, thereby forming an all-silicon micro-chromatographic column with only one silicon material, which is conducive to obtaining a uniform stationary phase and can form a closed microchannel with a high aspect ratio, so that the molecules of the component to be analyzed can quickly reach equilibrium between the stationary phase and the mobile phase, which is conducive to improving the separation performance and column capacity of the micro-chromatographic column.

Description

Technical Field

[0001] The invention belongs to the field of micro-electromechanical systems and relates to an all-silicon micro-chromatographic column with a high aspect ratio and a preparation method thereof. Background Art

[0002] The gas chromatography column is one of the core components of the gas chromatography system, which is mainly used to separate the components of the mixture. The traditional gas chromatography column is not conducive to the real-time and rapid analysis of complex gas components on site due to its large size, heavy weight, high power consumption and long separation time. With the development of MEMS (Micro-electro-mechanical systems, MEMS) technology, the miniaturization of the chromatographic column has been realized on silicon chips.

[0003] In the early days, the microchannels of microchromatographic columns were usually prepared by isotropic wet etching process, and the cross-section of the microchannels was circular or semicircular. However, the internal surface area of ​​the microchannels with circular or semicircular cross-sections was small, and the surface area available for carrying the stationary phase was small, and the separation performance was difficult to further improve. Subsequently, deep reactive ion etching (DRIE) technology was widely used to design and manufacture microchannels with rectangular cross-sections, and then silicon-glass bonding process was used to form closed microchannels.

[0004] Based on Golay's early theory, Glenn Spangler proposed a theory applicable to rectangular cross-section chromatographic columns, which predicts that the smaller the width of the rectangular cross-section microchannel, the smaller the theoretical plate height, and the higher the column efficiency of the microchromatographic column. However, as the width of the microchannel becomes smaller, the depth of the microchannel, especially the inlet and outlet, of the microchromatographic column manufactured by the silicon-glass bonding process is limited by the thickness of the silicon wafer, and the column capacity is difficult to increase. In order to increase the column capacity, semi-packed columns and multi-capillary columns have been proposed successively. For semi-packed columns, when the number of microcolumns in the microchannel increases, the column efficiency increases, but the inlet pressure also increases; for multi-capillary columns, stationary phase coating is a challenge and requires high inlet pressure. In addition, silicon and glass are two different materials with different surface properties, which also brings challenges to obtaining a uniform stationary phase in the microchannel.

[0005] In order to solve the above problems, it is necessary to provide an all-silicon micro-chromatographic column with a high aspect ratio and a preparation method thereof. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an all-silicon micro-chromatographic column with a high aspect ratio and a preparation method thereof, so as to solve the above-mentioned preparation problems faced by the micro-chromatographic column in the prior art.

[0007] To achieve the above object and other related objects, the present invention provides a method for preparing an all-silicon micro-chromatographic column with a high aspect ratio, comprising the following steps:

[0008] Providing a first silicon substrate and a second silicon substrate, and forming a patterned first mask layer on a surface of the first silicon substrate and forming a patterned second mask layer on a surface of the second silicon substrate;

[0009] Etching the first silicon substrate based on the first mask layer to form a first microchannel and a first microfluidic port connected to the first microchannel, and etching the second silicon substrate based on the second mask layer to form a second microchannel and a second microfluidic port connected to the second microchannel, wherein the first microchannel and the second microchannel have the same opening morphology, and the first microfluidic port and the second microfluidic port have the same opening morphology;

[0010] The first silicon substrate and the second silicon substrate are bonded to form a composite silicon substrate, and a closed microchannel located in the composite silicon substrate is formed based on the first microchannel and the second microchannel, and a closed microfluidic port connected to the closed microchannel is formed based on the first microfluidic port and the second microfluidic port.

[0011] Optionally, the aspect ratio R of the closed microchannel is in the range of 23≤R≤60.

[0012] Optionally, in the formed all-silicon micro-chromatographic column, patterns of the first silicon substrate and the second silicon substrate are symmetrically distributed about a bonding surface.

[0013] Optionally, the width of the formed closed microfluidic port is greater than the width of the closed microchannel, and the ratio T of the width of the closed microfluidic port to the width of the closed microchannel is in the range of 12≤T≤40.

[0014] Optionally, the method further comprises the following steps:

[0015] Perform dicing;

[0016] Providing a capillary, and fixing the capillary to the closed microfluidic port;

[0017] A stationary phase is applied, and the stationary phase comprises a PDMS stationary phase.

[0018] The present invention also provides an all-silicon micro-chromatographic column with a high aspect ratio, the all-silicon micro-chromatographic column comprising:

[0019] A composite silicon substrate, the composite silicon substrate comprising a first silicon substrate and a second silicon substrate bonded to each other, the first silicon substrate having a first microchannel and a first microfluidic port connected to the first microchannel, the second silicon substrate having a second microchannel and a second microfluidic port connected to the second microchannel, the first microchannel and the second microchannel having the same opening morphology, and the first microfluidic port and the second microfluidic port having the same opening morphology;

[0020] A closed microchannel, wherein the closed microchannel is located in the composite silicon substrate, and the closed microchannel is formed by bonding the first microchannel and the second microchannel;

[0021] A closed microfluidic port is located in the composite silicon substrate, and the closed microfluidic port is formed by bonding the first microfluidic port and the second microfluidic port.

[0022] Optionally, the aspect ratio R of the closed microchannel is in the range of 23≤R≤60.

[0023] Optionally, patterns of the first silicon substrate and the second silicon substrate in the all-silicon micro-chromatographic column are symmetrically distributed about a bonding surface.

[0024] Optionally, the width of the closed microfluidic port is greater than the width of the closed microchannel, and the ratio T of the width of the closed microfluidic port to the width of the closed microchannel is in the range of 12≤T≤40.

[0025] Optionally, the closed microchannels are distributed in a serpentine shape, a spiral shape or a wave shape.

[0026] As described above, the all-silicon microchromatographic column with a high aspect ratio and the preparation method thereof of the present invention respectively form corresponding microchannels and microfluidic ports in the first silicon substrate and the second silicon substrate, and then form a composite silicon substrate with closed microchannels and closed microfluidic ports through a silicon-silicon bonding process, thereby forming an all-silicon microchromatographic column with only one silicon material, which is conducive to obtaining a uniform stationary phase, and can form a closed microchannel with a high aspect ratio, so that the molecules of the component to be analyzed can quickly reach equilibrium between the stationary phase and the mobile phase, which is conducive to improving the separation performance and column capacity of the microchromatographic column. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Shown is a flow chart of the preparation process of an all-silicon micro-chromatographic column with a high aspect ratio in an embodiment of the present invention.

[0028] Figure 2 Shown is a schematic diagram of the structure of etching the first silicon substrate in an embodiment of the present invention

[0029] Figure 3Shown is a schematic structural diagram of a first silicon substrate formed in an embodiment of the present invention.

[0030] Figure 4 Shown is a scanning electron microscope schematic diagram of a first silicon substrate in an embodiment of the present invention.

[0031] Figure 5 It is a schematic diagram of the structure after the first silicon substrate and the second silicon substrate are bonded in an embodiment of the present invention.

[0032] Figure 6 Shown is a scanning electron microscope schematic diagram of a composite silicon substrate in an embodiment of the present invention.

[0033] Figure 7 Display as Figure 6 Schematic diagram of the enlarged structure of area A in FIG.

[0034] Figure 8 Shown is a Van Deemter curve diagram of the all-silica micro-chromatographic column in an embodiment of the present invention.

[0035] Fig. 9 Shown is a test chromatogram of the all-silicon micro-chromatographic column in an embodiment of the present invention.

[0036] Component number description

[0037] 100 Composite silicon substrate

[0038] 101 First Silicon Substrate

[0039] 102 Second silicon substrate

[0040] 110 Closed microchannel

[0041] 111 The First Microchannel

[0042] 112 Second Microchannel

[0043] 121 First microfluidic port

[0044] 201 First mask layer DETAILED DESCRIPTION

[0045] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0046] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0047] For ease of description, spatial relational terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatial relational terms are intended to include other directions of the device in use or operation in addition to the directions depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can be one or more intervening layers. As used herein, "between..." means including the end point values.

[0048] In the context of the present application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0049] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0050] like Figure 1 This embodiment provides a method for preparing an all-silicon micro-chromatographic column with a high aspect ratio, comprising the following steps:

[0051] S1: providing a first silicon substrate and a second silicon substrate, and forming a patterned first mask layer on a surface of the first silicon substrate and forming a patterned second mask layer on a surface of the second silicon substrate;

[0052] S2: etching the first silicon substrate based on the first mask layer to form a first microchannel and a first microfluidic port connected to the first microchannel, and etching the second silicon substrate based on the second mask layer to form a second microchannel and a second microfluidic port connected to the second microchannel, wherein the first microchannel and the second microchannel have the same opening morphology, and the first microfluidic port and the second microfluidic port have the same opening morphology;

[0053] S3: Bonding the first silicon substrate and the second silicon substrate to form a composite silicon substrate, and forming a closed microchannel located in the composite silicon substrate based on the first microchannel and the second microchannel, and forming a closed microfluidic port connected to the closed microchannel based on the first microfluidic port and the second microfluidic port.

[0054] In this embodiment, the corresponding first microchannel, second microchannel, first microfluidic port and second microfluidic port are formed in the first silicon substrate and the second silicon substrate respectively, and then the composite silicon substrate having the closed microchannel and the closed microfluidic port is formed by a silicon-silicon bonding process, so as to prepare the all-silicon microchromatographic column having only one silicon material, which is conducive to obtaining a uniform stationary phase and can form the closed microchannel with a high aspect ratio, so that the molecules of the component to be analyzed can quickly reach equilibrium between the stationary phase and the mobile phase, which is conducive to improving the separation performance and column capacity of the microchromatographic column.

[0055] The following is combined with Figure 2 to Figure 7 , the preparation of the all-silica micro-chromatographic column is further introduced, specifically including:

[0056] First, see Figure 2 , perform step S1, provide a first silicon substrate 101 and a second silicon substrate 102, and form a patterned first mask layer 201 on the surface of the first silicon substrate 101 and form a patterned second mask layer (not shown) on the surface of the second silicon substrate 102.

[0057] Specifically, the first mask layer 201 may be one or a combination of a silicon oxide mask layer, a silicon nitride mask layer and a photoresist mask layer. In this embodiment, the first mask layer 201 is a photoresist mask layer covering the first silicon substrate 101, and then photolithography is performed to form a patterned first mask layer 201. The material of the second mask layer may be the same as or different from that of the first mask layer 201, and no excessive limitation is made here.

[0058] Next, see Figure 3-4 , execute step S2, based on the first mask layer 201, etch the first silicon substrate 101 to form a first microchannel 111 and a first microfluidic port 121 connected to the first microchannel 111, and based on the second mask layer, etch the second silicon substrate 102 to form a second microchannel 112 and a second microfluidic port (not shown) connected to the second microchannel 112, and the first microchannel 111 and the second microchannel 112 have the same opening morphology, and the first microfluidic port 121 and the second microfluidic port have the same opening morphology.

[0059] Specifically, based on the first mask layer 201, the exposed first silicon substrate 101 can be etched by deep reactive ion etching (DRIE) to form the first microchannel 111 and the first microfluidic port 121 connected to the first microchannel 111 in the first silicon substrate 101, such as Figure 4 , wherein the width of the first microchannel 111 is recorded as W1 and the depth is recorded as H1, and the width of the first microfluidic port 121 is recorded as W2 and the depth is recorded as H2.

[0060] As an example, in the formed all-silicon micro-chromatographic column, the patterns of the first silicon substrate 101 and the second silicon substrate 102 are symmetrically distributed about the bonding surface.

[0061] For details, see Figure 5 In this embodiment, in order to reduce the complexity of the preparation process, the all-silicon micro-chromatographic column is preferably a symmetrical structure, that is, the first silicon substrate 101 and the second silicon substrate 102 have the same material and structure, but it is not limited to this. In another embodiment, only the first microchannel 111 and the second microchannel 112 can be set to have the same opening morphology, and the first microfluidic port 121 and the second microfluidic port have the same opening morphology to facilitate subsequent alignment and bonding, but the depths of the first microchannel 111, the second microchannel 112, the first microfluidic port 121 and the second microfluidic port can be selected as needed.

[0062] Next, see Figure 5 to Figure 7 , execute step S3, bond the first silicon substrate 101 and the second silicon substrate 102 to form a composite silicon substrate 100, and form a closed microchannel 110 located in the composite silicon substrate 100 based on the first microchannel 111 and the second microchannel 112, and form a closed microfluidic port (not shown) connected to the closed microchannel 110 based on the first microfluidic port 121 and the second microfluidic port.

[0063] Specifically, since the all-silicon microchromatographic column needs to be connected to the closed microfluidic port using a capillary later, and there will be a dead volume phenomenon at the capillary connection, in order to minimize the dead volume, the width W2 of the closed microfluidic port is much larger than the width W1 of the closed microchannel 110. For example, if the width W2 of the closed microfluidic port is 810 μm and the width W1 of the closed microchannel 110 is 30 μm, if the width W2 of the closed microfluidic port is reduced, the outer diameter of the capillary will be smaller than the depth of the closed microchannel 110, which will cause the dead volume to be reduced later. The continuous molding material such as epoxy resin flows into the closed microchannel 110, thereby causing the clogging of the microchromatographic column. If the microchannel is prepared on only one silicon wafer, for example, the width W1 of the microchannel is 30 μm, in order to make the microchannel depth match the outer diameter of the capillary, such as 750 μm, based on the difference in deep reactive ion etching rates of different widths, the depth H2 of the microfluidic port with a larger width must reach at least 1400 μm, so that a particularly thick silicon wafer is required to prepare a microchannel with a high aspect ratio on a single wafer, which will increase the probability of clogging at the connection between the microchromatographic column and the capillary, increase the size of the device, and cause material waste.

[0064] In this embodiment, two silicon wafers are etched separately, and then the all-silicon micro-chromatographic column with a high aspect ratio is prepared by alignment and silicon-silicon bonding. The preparation process is simple, and because the material of the two silicon wafers is silicon, they have the same chemical surface properties, which is conducive to the subsequent acquisition of a uniform stationary phase. The closed microchannel 110 with a high aspect ratio can provide a larger surface area for carrying the stationary phase, increase the surface area in contact with the mobile phase, thereby increasing the maximum sample capacity of the chromatographic column, and the closed microchannel 110 with a high aspect ratio is conducive to the analyte to quickly reach equilibrium between the stationary phase and the mobile phase, thereby helping to improve its separation performance.

[0065] As an example, the aspect ratio R of the closed microchannel 110 may be in the range of 23≤R≤60.

[0066] Specifically, the aspect ratio R of the closed microchannel 110 may be 23, 30, 35, 40, 45, 50, 55, 60, etc., which may be selected according to needs.

[0067] As an example, the width of the closed microfluidic port formed is greater than the width of the closed microchannel 110, and the ratio T of the width of the closed microfluidic port to the width of the closed microchannel 110 is in the range of 12≤T≤40, wherein the value of T can be 12, 15, 20, 25, 30, 35, 40, etc., and can be selected according to needs.

[0068] As an example, the following steps may also be included:

[0069] Perform dicing;

[0070] Providing a capillary, and fixing the capillary to the closed microfluidic port;

[0071] A stationary phase is applied, and the stationary phase comprises a PDMS stationary phase.

[0072] Specifically, the preparation of the all-silicon micro-chromatographic column may include but is not limited to the following steps:

[0073] First, a 15 μm layer of photoresist is spin-coated on two silicon wafers respectively, and then developed by photolithography;

[0074] The silicon wafer was etched using the DRIE process to form the corresponding microchannels of 30 μm × 375 μm and microfluidic ports, and the photoresist was removed;

[0075] The two etched silicon wafers were pre-aligned and bonded, and then annealed at 1100°C for 3 h to form a micro-channel with a width of 30 μm and a depth of 750 μm. Figure 6 ;

[0076] After dicing, epoxy resin was used to fix the connection between the capillary and the microfluidic port to obtain a microchromatographic column chip;

[0077] Prepare a polydimethylsiloxane (PDMS) solution with a mass fraction of 1.5%, and the solvent is n-pentane. At room temperature, connect the inlet of the pressure bottle containing the stationary phase solution to the high-pressure nitrogen bottle, and connect the outlet of the pressure bottle to the capillary inlet of the all-silicon microchromatographic column through an adapter; then inject the prepared stationary phase solution into the microchannel of the all-silicon microchromatographic column at 0.286MPa, and keep it for 20 minutes after the microchannel is filled with the stationary phase solution. Seal one end of the capillary of the all-silicon microchromatographic column with epoxy resin, and place it in a vacuum oven at 80°C for 60 hours. Wait for the solvent to evaporate, so that a 410nm PDMS stationary phase film is left in the microchannel. Figure 7 shown.

[0078] The obtained all-silica microchromatographic column was used to test a heavy hydrocarbon mixture (C7-C10). The Van Deemter curve of C10 obtained by the test was as follows: Figure 8 As shown, the chromatogram of C7-C10 measured at a constant temperature of 50°C and the optimal flow rate of C10 is as follows Fig. 9 shown.

[0079] The present embodiment further provides an all-silicon micro-chromatographic column with a high aspect ratio. The all-silicon micro-chromatographic column can be prepared by the above-mentioned preparation method, but is not limited thereto. In the present embodiment, the all-silicon micro-chromatographic column is prepared by the above-mentioned preparation method, so the structure, material, etc. of the all-silicon micro-chromatographic column can refer to the above description.

[0080] Specifically, Figure 3 to Figure 7The all-silicon micro-chromatographic column comprises a composite silicon substrate 100, wherein the composite silicon substrate 100 comprises a first silicon substrate 101 and a second silicon substrate 102 bonded to each other, wherein the first silicon substrate 101 comprises a first microchannel 111 and a first microfluidic port 121 connected to the first microchannel 111, wherein the second silicon substrate 102 comprises a second microchannel 112 and a second microfluidic port connected to the second microchannel 112, wherein the first microchannel 111 and the second microchannel 112 have the same opening morphology, and the first microfluidic port 121 and the second microfluidic port have the same opening morphology;

[0081] A closed microchannel 110, wherein the closed microchannel 110 is located in the composite silicon substrate 100, and the closed microchannel 110 is formed by bonding the first microchannel 111 and the second microchannel 112;

[0082] The closed microfluidic port is located in the composite silicon substrate 100 , and is formed by bonding the first microfluidic port 121 and the second microfluidic port.

[0083] As an example, the aspect ratio R of the closed microchannel 110 is in the range of 23≤R≤60, wherein the aspect ratio R of the closed microchannel 110 may be 23, 30, 35, 40, 45, 50, 55, 60, etc., and may be selected according to needs.

[0084] As an example, the patterns of the first silicon substrate 101 and the second silicon substrate 102 in the all-silicon micro-chromatographic column are symmetrically distributed about the bonding surface.

[0085] For details, see Figure 5 In this embodiment, in order to reduce the complexity of the preparation process, the all-silicon micro-chromatographic column is preferably a symmetrical structure, that is, the first silicon substrate 101 and the second silicon substrate 102 have the same material and structure, but it is not limited to this. In another embodiment, only the first microchannel 111 and the second microchannel 112 can be set to have the same opening morphology, and the first microfluidic port 121 and the second microfluidic port have the same opening morphology to facilitate subsequent alignment and bonding, but the depths of the first microchannel 111, the second microchannel 112, the first microfluidic port 121 and the second microfluidic port can be selected as needed.

[0086] As an example, the width of the closed microfluidic port formed is greater than the width of the closed microchannel 110, and the ratio T of the width of the closed microfluidic port to the width of the closed microchannel 110 is in the range of 12≤T≤40, wherein the value of T can be 12, 15, 20, 25, 30, 35, 40, etc., and can be selected according to needs.

[0087] As an example, the closed microchannels may have a serpentine distribution, a spiral distribution, or a wave distribution, which may be specifically configured as required.

[0088] In summary, the all-silicon microchromatographic column with a high aspect ratio and the preparation method thereof of the present invention respectively form corresponding microchannels and microfluidic ports in the first silicon substrate and the second silicon substrate, and then form a composite silicon substrate with closed microchannels and closed microfluidic ports through a silicon-silicon bonding process, thereby forming an all-silicon microchromatographic column with only one silicon material, which is conducive to obtaining a uniform stationary phase, and can form a closed microchannel with a high aspect ratio, so that the molecules of the component to be analyzed can quickly reach equilibrium between the stationary phase and the mobile phase, which is conducive to improving the separation performance and column capacity of the microchromatographic column.

[0089] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing an all-silicon micro-chromatographic column with a high aspect ratio, characterized in that: The following steps are involved: Providing a first silicon substrate and a second silicon substrate, and forming a patterned first mask layer on a surface of the first silicon substrate and forming a patterned second mask layer on a surface of the second silicon substrate; Etching the first silicon substrate based on the first mask layer to form a first microchannel and a first microfluidic port connected to the first microchannel, and etching the second silicon substrate based on the second mask layer to form a second microchannel and a second microfluidic port connected to the second microchannel, wherein the first microchannel and the second microchannel have the same opening morphology, and the first microfluidic port and the second microfluidic port have the same opening morphology; The first silicon substrate and the second silicon substrate are bonded to form a composite silicon substrate, and a closed microchannel located in the composite silicon substrate is formed based on the first microchannel and the second microchannel, and a closed microfluidic port connected to the closed microchannel is formed based on the first microfluidic port and the second microfluidic port, and the width of the formed closed microfluidic port is greater than the width of the closed microchannel, the ratio T of the width of the closed microfluidic port to the width of the closed microchannel is in the range of 12≤T≤40, and the depth-to-width ratio R of the closed microchannel is in the range of 23≤R≤60; In the formed all-silicon micro-chromatographic column, the patterns of the first silicon substrate and the second silicon substrate are symmetrically distributed about the bonding surface.

2. The method for preparing an all-silicon micro-chromatographic column with a high aspect ratio according to claim 1, characterized in that: The following steps are also included: Perform dicing; Providing a capillary, and fixing the capillary to the closed microfluidic port; A stationary phase is applied, and the stationary phase comprises a PDMS stationary phase.

3. An all-silicon micro-chromatographic column with a high aspect ratio, characterized in that: The all-silicon micro-chromatographic column comprises: A composite silicon substrate, the composite silicon substrate comprising a first silicon substrate and a second silicon substrate bonded to each other, the first silicon substrate having a first microchannel and a first microfluidic port connected to the first microchannel, the second silicon substrate having a second microchannel and a second microfluidic port connected to the second microchannel, the first microchannel and the second microchannel having the same opening morphology, and the first microfluidic port and the second microfluidic port having the same opening morphology; A closed microchannel, wherein the closed microchannel is located in the composite silicon substrate, and the closed microchannel is formed by bonding the first microchannel and the second microchannel; A closed microfluidic port, wherein the closed microfluidic port is located in the composite silicon substrate, and the closed microfluidic port is formed by bonding the first microfluidic port and the second microfluidic port, and the width of the closed microfluidic port is greater than the width of the closed microchannel, and the ratio T of the width of the closed microfluidic port to the width of the closed microchannel is in the range of 12≤T≤40, and the depth-to-width ratio R of the closed microchannel is in the range of 23≤R≤60; The patterns of the first silicon substrate and the second silicon substrate in the all-silicon micro-chromatographic column are symmetrically distributed about the bonding surface.

4. The all-silicon micro-chromatographic column with a high aspect ratio according to claim 3, characterized in that: The closed microchannels are distributed in a serpentine shape, a spiral shape or a wave shape.

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