High-flux micro-droplet preparation device based on stepped structure and use method thereof

Abstract

The invention relates to the field of micro-fluidic chips, in particular to a high-flux micro-droplet preparation device based on a stepped structure, which comprises a liquid storage assembly and a micro-droplet preparation assembly, the liquid storage assembly comprises a base and a liquid storage shell, and the micro-droplet preparation assembly comprises a chip upper cover plate, at least one chip and a chip lower cover plate which are sequentially arranged from top to bottom. The chip lower cover plate is fixed above the base, and a plurality of micro-droplet preparation units which are uniformly distributed along the circumferential direction are arranged on the outer side part of the chip. According to the invention, through the stepped structure design of the micro-droplet preparation unit, the prepared micro-droplets are ensured to have relatively high size uniformity and relatively low particle size variation coefficient C.V.; the multi-layer assembled micro-droplet assembly is formed by means of the stackable chips, so that high-efficiency and high-flux micro-droplet preparation can be realized, and the micro-droplet preparation device is compact in overall design structure, high in space utilization rate, convenient to disassemble and beneficial to later maintenance.

Description

Technical Field

[0001] The invention belongs to the field of microfluidic chips, and particularly relates to a high-throughput micro-droplet preparation device based on a stepped structure and a use method thereof. Background Art

[0002] Emulsion is a mixture of two immiscible solutions and is commonly used in biomedicine, chemical analysis, cosmetics and other fields. Droplets can be used as independent reaction units and can be expanded to single-cell analysis, digital PCR and drug screening. They have the advantages of low reagent consumption and no cross-contamination. On this basis, by controlling the droplet size, generation frequency and morphology, it is more conducive to quantitative analysis of its internal reaction conditions and results.

[0003] Conventional emulsification techniques, such as stirring, ultrasound and homogenization, cut larger emulsions into small emulsions through physical shearing, which has the advantages of simple operation, low cost and high production efficiency, but the final output of droplets has low monodispersity, with a coefficient of variation CV>40%. In addition, excessive heat conversion or shear force during the emulsification process is likely to damage materials that are sensitive to heat or shear. To avoid the above problems, some researchers have prepared droplets through membrane emulsification technology. For example, in membrane emulsification technology, the dispersed phase is squeezed into the mobile phase through micropores, and the mobile phase applies shear force to shear the dispersed phase on the membrane to generate droplets, but due to the diameter of the circular membrane pores, the coefficient of variation CV of the particle size is about 10%. Some researchers have also used droplet microfluidics to prepare highly monodisperse microdroplets, such as using a single microdroplet generation unit with a T-type, confocal or flow focusing structure, to generate microdroplets at a frequency of up to 12kHz, and with a particle size variation coefficient CV <3%. However, the particle size of the microdroplets depends largely on the flow rates of the dispersed phase and the mobile phase. For example, when preparing microdroplets with a diameter of 50μm, the flux is usually less than 0.1mL / h.

[0004] In order to improve the overall microdroplet generation efficiency, high-throughput microdroplet preparation can be achieved through multi-channel parallel microdroplet generation units. Conventional microdroplet generation structures occupy a large area when performing multi-channel parallel operations, and the overall chip utilization rate is relatively low. In addition, the size of the microdroplets is highly dependent on the fluid flow rate, which greatly increases the difficulty of multi-channel parallel operations. To this end, some researchers have used multi-channel parallel high-potential difference step structures to prepare highly monodisperse microdroplets. This microdroplet generation method is achieved through Laplace pressure difference, and the formation of microdroplets is only driven by interfacial tension. Therefore, within a certain flow rate range, it is independent of the dispersed phase flow rate, such as edge-based droplet generation equipment and millipede devices reported in the literature. However, the above-mentioned high-throughput microdroplet generation strategy still faces the following problems: First, step emulsification relies on interfacial tension rather than shear force to form microdroplets, which will cause the microdroplets near the triangular nozzle to be crowded, leading to the fusion of microdroplets; second, due to the physical size, the number of parallel structures is still very limited, which is not conducive to the realization of higher-throughput microdroplet preparation. Summary of the invention

[0005] In view of the above problems, the present invention provides a high-throughput micro-droplet preparation device based on a stepped structure and a method for using the same.

[0006] A high-throughput micro-droplet preparation device based on a stepped structure, comprising a liquid storage component and a micro-droplet preparation component;

[0007] The liquid storage assembly comprises a base and a liquid storage shell, the inner side of the liquid storage shell is provided with a liquid storage cavity, the base is provided with a dispersed phase liquid inlet and a mobile phase liquid inlet and outlet, the mobile phase liquid inlet and outlet are connected to the liquid storage cavity, and the dispersed phase liquid inlet is connected to a circular accommodating cavity arranged in the base;

[0008] The micro-droplet preparation assembly comprises a chip upper cover plate, at least one chip and a chip lower cover plate which are arranged in sequence from top to bottom, the chip lower cover plate is fixed above the base, the cross-sections of the chip and the chip lower cover plate are both circular, and the middle parts of the chip and the chip lower cover plate are both provided with a circular opening for connecting the circular accommodating cavity;

[0009] The outer side of the chip is provided with a plurality of micro-droplet preparation units evenly distributed along the circumferential direction, and the micro-droplet preparation units include a liquid inlet, an intermediate flow channel and a liquid outlet connected in sequence, the width of the liquid inlet gradually decreases from the inside to the outside, and the width of the liquid outlet gradually increases from the inside to the outside.

[0010] Furthermore, the number of the chips is at least two, and two adjacent chips are stacked concentrically in a vertical direction.

[0011] Furthermore, in two adjacent chips, the liquid outlets of the micro-droplet preparation units on the upper chip and the liquid outlets of the micro-droplet preparation units on the lower chip are arranged in a staggered manner.

[0012] Furthermore, the liquid inlet and the liquid outlet are both triangular, the intermediate flow channel is long and strip-shaped, the angle range of the liquid inlet and the liquid outlet is 20°-60°, the depth range of the liquid inlet, the liquid outlet and the intermediate flow channel is 10μm-1000μm, and the width range of the liquid inlet, the liquid outlet and the intermediate flow channel is 10μm-1000μm.

[0013] Furthermore, the circular accommodating cavity is arranged in the middle of the base, an annular groove is arranged on the base, and the annular groove is arranged on the outside of the circular accommodating cavity, and the mobile phase inlet and outlet are opened on the bottom surface of the annular groove;

[0014] The bottom surface of the annular groove is lower than the liquid outlet of the micro-droplet preparation unit, and the height difference between the two is not less than at least ten times the depth of the micro-droplet preparation unit.

[0015] Furthermore, the liquid storage shell is detachably connected to the base, an annular stepped groove is provided at the outer edge of the lower surface of the base, a plurality of evenly arranged first threaded holes are provided on the bottom surface of the annular stepped groove, a second threaded hole adapted to the first threaded hole is provided at the bottom of the liquid storage shell, and then the base is connected to the liquid storage shell through the first threaded hole, the second threaded hole and screws;

[0016] A sealing gasket is provided at the connection between the liquid storage shell and the base;

[0017] The micro-droplet preparation component is detachably connected to the base, a third threaded hole is provided in the middle of the chip cover plate, and a fourth threaded hole is provided at the bottom of the circular accommodating cavity, and then the chip cover plate, the chip, and the chip lower cover plate are connected to the base through the third threaded hole, the circular opening in the middle of the chip, the circular opening in the middle of the chip lower cover plate, the fourth threaded hole and bolts.

[0018] Furthermore, the sealing gasket is made of one of silicone, nitrile, fluororubber, perfluoroether FFKM, and polytetrafluoroethylene PTFE.

[0019] A method for using a high-throughput micro-droplet preparation device based on a stepped structure. When preparing micro-droplets, under the drive of external pressure, the dispersed phase is filled into the circular accommodating cavity in the base through the dispersed phase liquid inlet, flows through the circular opening in the middle of the chip lower cover plate and the circular opening in the middle of the chip, and then enters the micro-droplet preparation unit on the outer side of the chip, and then is driven by interfacial tension at the liquid outlet of the micro-droplet preparation unit, thereby forming highly monodisperse micro-droplets in the liquid storage cavity filled with the mobile phase.

[0020] Furthermore, the mobile phase in the liquid storage chamber is in a static state or a flowing state.

[0021] Furthermore, when the mobile phase is in a flowing state, its flow direction is from top to bottom or from bottom to top.

[0022] Furthermore, when preparing water-in-oil microdroplets, the chip and the chip lower cover are both made of hydrophobic material or hydrophobically modifiable material;

[0023] When preparing oil-in-water microdroplets, the chip and the chip lower cover are both made of hydrophilic material or hydrophilically modifiable material.

[0024] The beneficial effects of the present invention are:

[0025] (1) By using a multi-layer stepped micro-droplet preparation unit, high-efficiency and high-throughput micro-droplet preparation is achieved, and the overall design structure is compact, the space utilization rate is high, and the easy disassembly is conducive to later maintenance;

[0026] (2) The overall structural design of the device can evenly disperse the dispersed phase solution into each micro-droplet generation unit through the deep circular receiving cavity, avoiding the problem of uneven liquid distribution, thereby avoiding uneven micro-droplet preparation and generation;

[0027] (3) With the help of the density difference between the mobile phase and the dispersed phase, the microdroplets generated at the triangular nozzle can be quickly transferred from bottom to top or from top to bottom, avoiding the fusion of highly crowded microdroplets.

[0028] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A partial structural decomposition schematic diagram of the present invention is shown;

[0031] Figure 2 A bottom view schematically shows a chip of the present invention;

[0032] Figure 3 A schematic top view of the base of the present invention is shown;

[0033] Figure 4 A partial structural cross-sectional schematic diagram of the present invention is shown.

[0034] In the figure: 100, liquid storage shell; 101, liquid storage cavity; 102, second threaded hole; 200, chip upper cover; 201, third threaded hole; 300, chip; 301, circular opening; 302, liquid outlet; 303, intermediate flow channel; 304, liquid inlet; 400, chip lower cover; 500, sealing gasket; 600, base; 601, mobile phase inlet and outlet joints; 602, dispersed phase inlet joint; 603, annular groove; 604, first threaded hole; 605, fourth threaded hole; 606, circular accommodating cavity; 607, mobile phase inlet and outlet. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0036] Example 1

[0037] like Figure 1-4 As shown, a high-throughput micro-droplet preparation device based on a stepped structure includes a liquid storage component and a micro-droplet preparation component; the liquid storage component includes a base 600 and a liquid storage shell 100, the inner side of the liquid storage shell 100 is provided with a liquid storage cavity 101, the base 600 is provided with a dispersed phase liquid inlet and a mobile phase liquid inlet and outlet 607, the mobile phase liquid inlet and outlet 607 are connected to the liquid storage cavity 101, and the dispersed phase liquid inlet is connected to a circular accommodating cavity 606 arranged in the base 600; the micro-droplet preparation component includes a chip upper cover plate 200, at least one chip 300 and a chip lower cover plate arranged in sequence from top to bottom 400, the chip lower cover 400 is fixed on the top of the base 600, the cross-sections of the chip 300 and the chip lower cover 400 are both circular, and the middle parts of the chip 300 and the chip lower cover 400 are both provided with circular openings for connecting the circular accommodating cavity 606; a plurality of micro-droplet preparation units uniformly distributed along the circumferential direction are provided on the outer side of the chip 300, and the micro-droplet preparation unit includes a liquid inlet 304, an intermediate flow channel 303 and a liquid outlet 302 connected in sequence, the width of the liquid inlet 304 gradually decreases from the inside to the outside, and the width of the liquid outlet 302 gradually increases from the inside to the outside. The present invention arranges a plurality of uniformly distributed micro-droplet preparation units on the outside of the chip 300. The step structure design of the liquid inlet 304, the intermediate flow channel 303 and the liquid outlet 302 in the micro-droplet preparation unit ensures that the prepared micro-droplets have high size uniformity and low particle size variation coefficient CV. A multi-layer assembled micro-droplet assembly is formed by means of the stackable chip 300, thereby realizing high-efficiency and high-throughput micro-droplet preparation. The overall design has a compact structure, high space utilization, and is easy to disassemble for later maintenance.

[0038] The number of the chips 300 is at least two, and two adjacent chips 300 are stacked concentrically in the vertical direction and can be installed and fixed by auxiliary tooling, thereby ensuring high-efficiency and high-throughput micro-droplet preparation.

[0039] The diameter of the chip 300 is the same as the diameter of the chip lower cover plate 400 to ensure the preparation effect of the micro-droplets and prevent the micro-droplets from being blocked by the chip lower cover plate 400 during transfer.

[0040] The liquid inlet 304 and the liquid outlet 302 are both triangular, the middle flow channel 303 is long, the angle range of the liquid inlet 304 and the liquid outlet 302 is 20°-60°, the depth range of the liquid inlet 304, the liquid outlet 302 and the middle flow channel 303 is 10μm-1000μm, and the width range of the liquid inlet 304, the liquid outlet 302 and the middle flow channel 303 is 10μm-1000μm, thereby achieving stable micro-droplet preparation. Preferably, the angle of the liquid outlet 302 is 38°.

[0041] The circular accommodating chamber 606 is arranged in the middle of the base 600, and the base 600 is provided with an annular groove 603, and the annular groove 603 is arranged outside the circular accommodating chamber 606, and the mobile phase inlet and outlet 607 is arranged on the bottom surface of the annular groove 603; the bottom surface of the annular groove 603 is lower than the outlet 302 of the micro-droplet preparation unit, and the height difference between the two is not less than at least ten times the depth of the micro-droplet preparation unit. In this design, the mobile phase inlet and outlet 607 is arranged on the bottom surface of the annular groove 603, so that it is away from the outlet 302 of the micro-droplet preparation unit to form a height difference, so that when the mobile phase in the liquid storage chamber 101 is close to the outlet 302 of the micro-droplet preparation unit, the liquid surface pressure of the mobile phase is relatively uniform, which ensures the uniformity of the micro-droplets prepared by the micro-droplet preparation unit.

[0042] In order to facilitate disassembly and assembly and facilitate later maintenance, the liquid storage shell 100 is detachably connected to the base 600. Specifically, an annular step groove is provided at the outer edge of the lower surface of the base 600, and a plurality of evenly arranged first threaded holes 604 are provided on the bottom surface of the annular step groove. The bottom of the liquid storage shell 100 is provided with a second threaded hole 102 adapted to the first threaded hole 604, and then the base 600 is connected to the liquid storage shell 100 through the first threaded hole 604, the second threaded hole 102 and the screw; the micro-droplet preparation component is detachably connected to the base 600. Specifically, a third threaded hole 201 is provided in the middle of the chip cover plate 200, and a fourth threaded hole 605 is provided at the bottom of the circular accommodating cavity 606, and then the chip cover plate 200, the chip 300, and the chip lower cover plate 400 are connected to the base 600 through the third threaded hole 201, the circular opening 301 in the middle of the chip 300, the circular opening in the middle of the chip lower cover plate 400, the fourth threaded hole 605 and the bolts.

[0043] The design of the annular stepped groove can facilitate screwing in of the screws. Specifically, the number of the first threaded holes 604 and the number of the second threaded holes 102 are both eight, so as to ensure a stable connection between the liquid storage shell 100 and the base 600.

[0044] A sealing gasket 500 is provided at the connection between the liquid storage shell 100 and the base 600 to prevent leakage of the mobile phase solution in the device. Specifically, the sealing gasket 500 is made of one of silica gel, nitrile, fluorine rubber, perfluoroether FFKM, and polytetrafluoroethylene PTFE.

[0045] In order to facilitate the installation of the micro-droplet preparation assembly and the circulation of the dispersed phase, the diameters of the circular opening 301 in the middle of the chip 300 and the circular opening in the middle of the chip lower cover plate 400 are both larger than the diameter of the bolt. In addition, when there are at least two chips 300, the diameter of the circular opening 301 in the middle of the lowest chip 300 is not larger than the diameter of the circular opening in the middle of the chip lower cover plate 400, and the diameter of the circular opening 301 in the middle of the upper chip 300 of two adjacent chips 300 is not larger than the diameter of the circular opening 301 in the middle of the lower chip 300, thereby facilitating the dispersed phase liquid to be fully poured into the chip 300 from bottom to top.

[0046] The dispersed phase liquid inlet is connected to the dispersed phase liquid inlet connector 602 through a thread, and the mobile phase liquid inlet and outlet connector 607 is connected to the mobile phase liquid inlet and outlet connector 601 through a thread, so that the dispersed phase liquid inlet connector 602 and the mobile phase liquid inlet and outlet connector 601 are conveniently connected to the dispersed phase liquid pipeline and the mobile phase liquid pipeline respectively.

[0047] Example 2

[0048] like Figure 1-4 As shown, a method for using a high-throughput micro-droplet preparation device based on a stepped structure is provided. When preparing micro-droplets, the dispersed phase is filled into the circular accommodating cavity 606 in the base 600 through the dispersed phase liquid inlet under the driving force of the external pressure, and flows through the circular opening in the middle of the chip lower cover plate 400 and the circular opening 301 in the middle of the chip 300, and then enters the micro-droplet preparation unit on the outer side of the chip 300, and then driven by the interfacial tension at the liquid outlet 302 of the micro-droplet preparation unit, so as to form highly monodispersed micro-droplets in the liquid storage cavity 101 filled with the mobile phase. When preparing micro-droplets using this micro-droplet preparation device, not only can high-efficiency and high-throughput micro-droplet preparation be achieved, but also the prepared micro-droplets can be guaranteed to have high size uniformity and low particle size variation coefficient CV.

[0049] When preparing micro-droplets, the mobile phase in the liquid storage chamber 101 is in a static state or a flowing state. When the mobile phase is in a flowing state, its flow direction is from top to bottom or from bottom to top. That is, according to the density difference between the dispersed phase and the mobile phase, the micro-droplets are transferred out from the upper part of the liquid storage shell 100 or from the mobile phase inlet and outlet 607 with the help of the mobile phase, thereby ensuring the continuous operation of the entire device.

[0050] When preparing water-in-oil micro-droplets, the chip 300 and the chip lower cover plate 400 are both made of hydrophobic materials or hydrophobically modifiable materials. Specifically, the material of the chip 300 and the chip lower cover plate 400 is one of a hydrophobic polymer, metal, glass material or a hydrophobically modifiable material, for example: the material of the chip 300 and the chip lower cover plate 400 can be one of hydrophobic polymethyl methacrylate PMMA, cycloolefin copolymer COC, polycarbonate, stainless steel, aluminum alloy, and glass material; or, when the material of the chip 300 and the chip lower cover plate 400 is a hydrophobically modifiable material, the material is modified into a hydrophobic material with the help of a hydrophobic agent, thereby ensuring the rapid preparation of water-in-oil micro-droplets.

[0051] When preparing oil-in-water micro-droplets, the chip 300 and the chip lower cover plate 400 are both made of hydrophilic materials or hydrophilically modifiable materials. Specifically, the material of the chip 300 and the chip lower cover plate 400 is a hydrophilic polymer, metal, glass material or a hydrophilically modifiable material, for example: the material of the chip 300 and the chip lower cover plate 400 can be a hydrophilic polymethyl methacrylate PMMA, cycloolefin copolymer COC, polycarbonate, stainless steel, aluminum alloy, glass material; or, when the material of the chip 300 and the chip lower cover plate 400 is a hydrophilically modifiable material, the material is modified into a hydrophilic material with the help of a hydrophilic agent, thereby ensuring the rapid preparation of the oil-in-water micro-droplets.

[0052] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-throughput micro-droplet preparation device based on a stepped structure, characterized in that: It includes a liquid storage component and a micro droplet preparation component; The liquid storage assembly comprises a base and a liquid storage shell, the inner side of the liquid storage shell is provided with a liquid storage cavity, the base is provided with a dispersed phase liquid inlet and a mobile phase liquid inlet and outlet, the mobile phase liquid inlet and outlet are connected to the liquid storage cavity, and the dispersed phase liquid inlet is connected to a circular accommodating cavity arranged in the base; The micro-droplet preparation assembly comprises a chip upper cover plate, at least one chip and a chip lower cover plate which are arranged in sequence from top to bottom, the chip lower cover plate is fixed above the base, the cross-sections of the chip and the chip lower cover plate are both circular, and the middle parts of the chip and the chip lower cover plate are both provided with a circular opening for connecting the circular accommodating cavity; The outer side of the chip is provided with a plurality of micro-droplet preparation units evenly distributed along the circumferential direction, and the micro-droplet preparation units include a liquid inlet, an intermediate flow channel and a liquid outlet connected in sequence, the width of the liquid inlet gradually decreases from the inside to the outside, and the width of the liquid outlet gradually increases from the inside to the outside.

2. A high-throughput micro-droplet preparation device based on a stepped structure as claimed in claim 1, characterized in that: The number of the chips is at least two, and two adjacent chips are stacked concentrically in a vertical direction.

3. A high-throughput micro-droplet preparation device based on a stepped structure as claimed in claim 1, characterized in that: The liquid inlet and the liquid outlet are both triangular, the middle flow channel is long and strip-shaped, the angle range of the liquid inlet and the liquid outlet is 20°-60°, the depth range of the liquid inlet, the liquid outlet and the middle flow channel is 10μm-1000μm, and the width range of the liquid inlet, the liquid outlet and the middle flow channel is 10μm-1000μm.

4. A high-throughput micro-droplet preparation device based on a stepped structure as claimed in claim 1, characterized in that: The circular accommodating cavity is arranged in the middle of the base, an annular groove is arranged on the base, and the annular groove is arranged on the outside of the circular accommodating cavity, and the mobile phase inlet and outlet are opened on the bottom surface of the annular groove; The bottom surface of the annular groove is lower than the liquid outlet of the micro-droplet preparation unit, and the height difference between the two is not less than at least ten times the depth of the micro-droplet preparation unit.

5. A high-throughput micro-droplet preparation device based on a stepped structure as claimed in claim 1, characterized in that: The liquid storage shell is detachably connected to the base, an annular stepped groove is provided at the outer edge of the lower surface of the base, a plurality of evenly arranged first threaded holes are provided on the bottom surface of the annular stepped groove, a second threaded hole matching the first threaded hole is provided at the bottom of the liquid storage shell, and the base is connected to the liquid storage shell through the first threaded hole, the second threaded hole and screws; A sealing gasket is provided at the connection between the liquid storage shell and the base; The micro-droplet preparation component is detachably connected to the base, a third threaded hole is provided in the middle of the chip cover plate, and a fourth threaded hole is provided at the bottom of the circular accommodating cavity, and then the chip cover plate, the chip, and the chip lower cover plate are connected to the base through the third threaded hole, the circular opening in the middle of the chip, the circular opening in the middle of the chip lower cover plate, the fourth threaded hole and bolts.

6. A high-throughput micro-droplet preparation device based on a stepped structure as claimed in claim 5, characterized in that: The sealing gasket is made of one of silicone, nitrile, fluororubber, perfluoroether FFKM, and polytetrafluoroethylene PTFE.

7. A method for using a high-throughput micro-droplet preparation device based on a stepped structure according to any one of claims 1 to 6, characterized in that: When preparing micro-droplets, driven by external pressure, the dispersed phase is filled into the circular containing cavity in the base through the dispersed phase liquid inlet, and flows through the circular opening in the middle of the chip lower cover and the circular opening in the middle of the chip, and then enters the micro-droplet preparation unit on the outer side of the chip, and is then driven by interfacial tension at the liquid outlet of the micro-droplet preparation unit, thereby forming highly monodisperse micro-droplets in the liquid storage cavity filled with the mobile phase.

8. The method for using the high-throughput micro-droplet preparation device based on a stepped structure as claimed in claim 7, characterized in that: The mobile phase in the liquid storage cavity is in a static state or a flowing state.

9. The method for using the high-throughput micro-droplet preparation device based on a stepped structure as claimed in claim 8, characterized in that: When the mobile phase is in a flowing state, its flow direction is from top to bottom or from bottom to top.

10. The method for using the high-throughput micro-droplet preparation device based on a stepped structure as claimed in claim 7, characterized in that: When preparing water-in-oil microdroplets, the chip and the chip lower cover are both made of hydrophobic material or hydrophobically modifiable material; When preparing oil-in-water microdroplets, the chip and the chip lower cover are both made of hydrophilic material or hydrophilically modifiable material.

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