A high-throughput microdroplet preparation device based on a stepped structure and its usage method

Abstract

This invention relates to the field of microfluidic chips, and particularly to a high-throughput microdroplet fabrication device based on a stepped structure. The device includes a liquid storage component and a microdroplet fabrication component. The liquid storage component includes a base and a liquid storage shell. The microdroplet fabrication component includes a chip upper cover plate, at least one chip, and a chip lower cover plate arranged sequentially from top to bottom. The chip lower cover plate is fixed above the base. Several microdroplet fabrication units are uniformly distributed circumferentially on the outer side of the chip. This invention, through the stepped structure design of the microdroplet fabrication units, ensures that the fabricated microdroplets have high size uniformity and a low coefficient of variation (CV). Furthermore, by utilizing stackable chips to form a multi-layered assembled microdroplet component, high-efficiency, high-throughput microdroplet fabrication can be achieved. The overall design is compact, with high space utilization, and easy disassembly for subsequent maintenance.

Description

Technical Field

[0001] This invention belongs to the field of microfluidic chips, and specifically relates to a high-throughput microdroplet preparation device based on a stepped structure and its usage method. Background Technology

[0002] Emulsions are mixtures of two immiscible solutions, commonly used in biomedicine, chemical analysis, and cosmetics. Droplets can serve as independent reaction units, extending their applications to single-cell analysis, digital PCR, and drug screening. They offer advantages such as low reagent consumption and no cross-contamination. Furthermore, by controlling droplet size, generation frequency, and morphology, it is easier to quantitatively analyze their internal reaction conditions and results.

[0003] Conventional emulsification techniques, such as stirring, ultrasonication, and homogenization, break down larger emulsions into smaller ones through physical shearing. These techniques offer advantages such as simplicity, low cost, and high production efficiency. However, the resulting droplets exhibit low monodispersity, with a coefficient of variation (CV) > 40%. Furthermore, excessive heat transfer or shear forces during emulsification can damage heat- or shear-sensitive materials. To avoid these problems, researchers have developed membrane emulsification techniques for droplet preparation. In membrane emulsification, the dispersed phase is extruded into the mobile phase through micropores, and the mobile phase applies shear force to shear the dispersed phase on the membrane, generating droplets. However, limited by the diameter of the circular membrane pores, the particle size variation (CV) is around 10%. Some researchers have also prepared highly monodisperse microdroplets using droplet microfluidics, such as single microdroplet generating units with T-shaped, confocal, or flow-focusing structures, which can generate microdroplets at frequencies up to 12 kHz and with a particle size variation coefficient (CV) of <3%. However, the microdroplet size largely depends on the flow rates of the dispersed and mobile phases. For example, when preparing microdroplets with a diameter of 50 μm, the flux is usually less than 0.1 mL / h.

[0004] To improve the overall efficiency of microdroplet generation, high-throughput microdroplet fabrication can be achieved through multi-parallel microdroplet generation units. Conventional microdroplet generation structures occupy a large area when multi-parallelized, resulting in relatively low overall chip utilization. Furthermore, the size of the microdroplets is highly dependent on the fluid flow rate, significantly increasing the difficulty of multi-parallelization. To address this, researchers have utilized multi-parallel high-gradient stepped structures to fabricate highly monodisperse microdroplets. This microdroplet generation method is achieved through Laplace pressure difference, and the formation of microdroplets is driven solely by interfacial tension. Therefore, within a certain flow rate range, it is independent of the dispersed phase flow rate, as seen in edge-based droplet generation devices and millipede-like devices reported in the literature. However, the aforementioned high-throughput microdroplet generation strategies still face the following challenges: First, stepped emulsification relies on interfacial tension rather than shear force to form microdroplets, which can lead to congestion of microdroplets near the triangular nozzle, resulting in microdroplet fusion. Second, due to physical size limitations, the number of parallel structures remains very limited, hindering the achievement of higher-throughput microdroplet fabrication. Summary of the Invention

[0005] To address the above problems, this invention provides a high-throughput microdroplet preparation device based on a stepped structure and its usage method.

[0006] A high-throughput microdroplet preparation device based on a stepped structure includes a liquid storage component and a microdroplet preparation component;

[0007] The liquid storage assembly includes 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 inlet and a mobile phase inlet and outlet. The mobile phase inlet and outlet are connected to the liquid storage cavity, and the dispersed phase inlet is connected to a circular receiving cavity disposed in the base.

[0008] The microdroplet fabrication assembly includes a chip top cover, at least one chip, and a chip bottom cover arranged sequentially from top to bottom. The chip bottom cover is fixed above the base. The cross-sections of the chip and the chip bottom cover are both circular, and the middle of the chip and the chip bottom cover is provided with a circular opening for communicating with the circular receiving cavity.

[0009] The outer side of the chip is provided with several microdroplet preparation units evenly distributed along the circumference. Each microdroplet preparation unit includes an inlet, an intermediate channel and an outlet connected in sequence. The width of the inlet gradually decreases from the inside to the outside, and the width of the outlet gradually increases from the inside to the outside.

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

[0011] Furthermore, in two adjacent chips, the liquid outlets of the microdroplet preparation unit on the upper chip and the microdroplet preparation unit on the lower chip are arranged in an alternating pattern.

[0012] Furthermore, both the inlet and outlet are triangular, the intermediate channel is elongated, the angles of the inlet and outlet are both between 20° and 60°, the depths of the inlet, outlet, and intermediate channel are all between 10μm and 1000μm, and the widths of the inlet, outlet, and intermediate channel are all between 10μm and 1000μm.

[0013] Furthermore, the circular receiving cavity is disposed in the middle of the base, the base is provided with an annular groove, and the annular groove is disposed on the outside of the circular receiving 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 outlet of the microdroplet preparation unit, and the height difference between the two is not less than at least ten times the depth of the microdroplet preparation unit.

[0015] Furthermore, the liquid storage shell is detachably connected to the base. The outer edge of the lower surface of the base is provided with an annular stepped groove. The bottom surface of the annular stepped groove is provided with a plurality of first threaded holes arranged in a uniform manner. The bottom of the liquid storage shell is provided with a second threaded hole that matches the first threaded hole. Thus, the base is connected to the liquid storage shell through the first threaded hole, the second threaded hole, and a screw.

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

[0017] The microdroplet preparation component is detachably connected to the base. The upper cover of the chip is provided with a third threaded hole in the middle, and the bottom of the circular receiving cavity is provided with a fourth threaded hole. The upper cover of the chip, the chip, and the lower cover of the chip 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 lower cover of the chip, the fourth threaded hole, and bolts.

[0018] Furthermore, the sealing gasket is made of one of the following materials: silicone, nitrile rubber, fluororubber, perfluoroether (FFKM), or polytetrafluoroethylene (PTFE).

[0019] A method for using a high-throughput microdroplet preparation device based on a stepped structure involves, during microdroplet preparation, the dispersed phase, driven by an external pressure, being filled into a circular cavity within a base through a dispersed phase inlet. The phase then flows through a circular opening in the center of the chip's lower cover plate and another circular opening in the center of the chip, before entering a microdroplet preparation unit on the outer side of the chip. Subsequently, driven by interfacial tension at the outlet of the microdroplet preparation unit, highly monodisperse microdroplets are formed within the reservoir filled with the mobile phase.

[0020] Furthermore, the mobile phase located in the liquid storage chamber is either in a static state or in 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, both the chip and the chip cover plate are made of hydrophobic materials or materials that can be modified to be hydrophobic.

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

[0024] The beneficial effects of this invention are:

[0025] (1) By using a multi-layer stepped microdroplet preparation unit, high-efficiency and high-throughput microdroplet preparation is achieved. The overall design is compact, with high space utilization and easy disassembly for later maintenance.

[0026] (2) The overall structural design of the device can uniformly disperse the dispersed phase solution into each microdroplet generation unit through the deep circular containment cavity, avoiding the problem of uneven liquid distribution, thereby avoiding uneven microdroplet preparation and generation.

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

[0028] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A partial structural exploded view of the present invention is shown;

[0031] Figure 2 A bottom view of the chip portion of the present invention is shown;

[0032] Figure 3 A 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 diagram: 100, liquid storage shell; 101, liquid storage cavity; 102, second threaded hole; 200, chip top cover plate; 201, third threaded hole; 300, chip; 301, circular opening; 302, liquid outlet; 303, intermediate flow channel; 304, liquid inlet; 400, chip bottom cover plate; 500, sealing gasket; 600, base; 601, mobile phase inlet / outlet connector; 602, dispersed phase inlet connector; 603, annular groove; 604, first threaded hole; 605, fourth threaded hole; 606, circular receiving cavity; 607, mobile phase inlet / outlet. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] like Figure 1-4 As shown, a high-throughput microdroplet fabrication device based on a stepped structure includes a liquid storage component and a microdroplet fabrication 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 inlet and a mobile phase inlet / outlet 607. The mobile phase inlet / outlet 607 is connected to the liquid storage cavity 101, and the dispersed phase inlet is connected to a circular receiving cavity 606 disposed in the base 600. The microdroplet fabrication component includes a chip upper cover plate 200, at least one chip 300, and a chip lower cover plate arranged sequentially from top to bottom. 400, the chip lower cover plate 400 is fixed above the base 600. The cross-section of both the chip 300 and the chip lower cover plate 400 is circular, and the middle of both the chip 300 and the chip lower cover plate 400 is provided with a circular opening for connecting the circular receiving cavity 606. Several microdroplet preparation units are provided on the outer side of the chip 300, which are evenly distributed along the circumference. The microdroplet preparation unit includes an inlet 304, an intermediate flow channel 303 and an outlet 302 connected in sequence. The width of the inlet 304 gradually decreases from the inside to the outside, and the width of the outlet 302 gradually increases from the inside to the outside. This invention features several uniformly distributed microdroplet preparation units on the outer side of the chip 300. Through the stepped structure design of the inlet 304, intermediate flow channel 303, and outlet 302 in the microdroplet preparation unit, the prepared microdroplets are guaranteed to have high size uniformity and low particle size variation coefficient (CV). Furthermore, by using the stackable chip 300 to form a multi-layer assembled microdroplet assembly, high-efficiency and high-throughput microdroplet preparation can be achieved. The overall design is compact, with high space utilization, and easy disassembly for subsequent maintenance.

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

[0039] The diameter of chip 300 is the same as the diameter of chip cover plate 400 to ensure the preparation effect of microdroplets and avoid the microdroplets being blocked by chip cover plate 400 during transfer.

[0040] Both the inlet 304 and outlet 302 are triangular, and the intermediate flow channel 303 is elongated. The angles of the inlet 304 and outlet 302 range from 20° to 60°. The depths of the inlet 304, outlet 302, and intermediate flow channel 303 range from 10 μm to 1000 μm, and the widths of the inlet 304, outlet 302, and intermediate flow channel 303 also range from 10 μm to 1000 μm, thereby achieving stable microdroplet preparation. Preferably, the angle of the outlet 302 is 38°.

[0041] A circular receiving cavity 606 is located in the middle of the base 600. An annular groove 603 is provided on the base 600, and the annular groove 603 is located on the outer side of the circular receiving cavity 606. A mobile phase inlet / outlet 607 is located 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 microdroplet preparation unit, and the height difference between the two is not less than at least ten times the depth of the microdroplet preparation unit. In this design, the mobile phase inlet / outlet 607 is located on the bottom surface of the annular groove 603, creating a height difference that keeps it away from the outlet 302 of the microdroplet preparation unit. This ensures that the liquid surface pressure of the mobile phase in the storage cavity 101 is relatively uniform near the outlet 302 of the microdroplet preparation unit, guaranteeing the uniformity of the microdroplets prepared by the microdroplet preparation unit.

[0042] To facilitate disassembly and assembly and subsequent maintenance, the liquid storage shell 100 is detachably connected to the base 600. Specifically, the outer edge of the lower surface of the base 600 is provided with an annular stepped groove, and the bottom surface of the annular stepped groove is provided with several evenly arranged first threaded holes 604. The bottom of the liquid storage shell 100 is provided with a second threaded hole 102 that matches the first threaded hole 604. The base 600 is then connected to the liquid storage shell 100 through the first threaded hole 604, the second threaded hole 102, and screws. The microdroplet preparation component is detachably connected to the base 600. Specifically, the middle part of the chip upper cover plate 200 is provided with a third threaded hole 201, and the bottom of the circular receiving cavity 606 is provided with a fourth threaded hole 605. The chip upper cover plate 200, chip 300, and chip lower cover plate 400 are then 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 bolts.

[0043] The design of the annular stepped groove facilitates the screw insertion. Specifically, there are eight first threaded holes 604 and eight second threaded holes 102 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 reservoir 100 and the base 600 to prevent leakage of the mobile phase solution inside the device. Specifically, the sealing gasket 500 is made of one of the following materials: silicone, nitrile, fluororubber, perfluoroether (FFKM), or polytetrafluoroethylene (PTFE).

[0045] To facilitate the installation of the microdroplet fabrication components and the flow of the dispersed phase, the diameters of the circular opening 301 in the center of chip 300 and the circular opening in the center of the lower cover plate 400 are both larger than the diameter of the bolt. Furthermore, when there are at least two chips 300, the diameter of the circular opening 301 in the center of the lowermost chip 300 is no larger than the diameter of the circular opening in the center of the lower cover plate 400, and in two adjacent chips 300, the diameter of the circular opening 301 in the center of the upper chip 300 is no larger than the diameter of the circular opening 301 in the center of the lower chip 300. This facilitates the full inflow of the dispersed phase liquid into the chip 300 from bottom to top.

[0046] The dispersed phase inlet is connected to the dispersed phase inlet connector 602 via a thread, and the mobile phase inlet / outlet 607 is connected to the mobile phase inlet / outlet connector 601 via a thread, thereby facilitating the connection of the dispersed phase inlet connector 602 and the mobile phase inlet / outlet connector 601 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 microdroplet preparation device based on a stepped structure is described. During microdroplet preparation, under applied pressure, the dispersed phase is injected into the circular receiving cavity 606 within the base 600 through the dispersed phase inlet. It then 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, before entering the microdroplet preparation unit on the outer side of the chip 300. Subsequently, driven by interfacial tension at the outlet 302 of the microdroplet preparation unit, highly monodisperse microdroplets are formed within the reservoir 101 filled with the mobile phase. Using this microdroplet preparation device not only achieves high-efficiency, high-throughput microdroplet preparation but also ensures that the prepared microdroplets have high size uniformity and a low coefficient of variation (CV).

[0049] During the preparation of microdroplets, the mobile phase located in the storage chamber 101 is either stationary or in 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, based on the density difference between the dispersed phase and the mobile phase, the mobile phase is used to transfer the microdroplets from the upper part of the storage shell 100 or from the mobile phase inlet / outlet 607, thereby ensuring the continuous operation of the entire device.

[0050] When preparing water-in-oil microdroplets, both the chip 300 and the chip cover plate 400 are made of hydrophobic materials or materials that can be modified to be hydrophobic. Specifically, the chip 300 and the chip cover plate 400 are made of one of the following materials: hydrophobic polymer, metal, glass, or materials that can be modified to be hydrophobic. For example, the chip 300 and the chip cover plate 400 can be made of one of the following materials: hydrophobic polymethyl methacrylate (PMMA), cyclic olefin copolymer (COC), polycarbonate, stainless steel, aluminum alloy, or glass. Alternatively, when the chip 300 and the chip cover plate 400 are made of materials that can be modified to be hydrophobic, a hydrophobic agent is used to modify the material to be hydrophobic, thereby ensuring the rapid preparation of water-in-oil microdroplets.

[0051] When preparing oil-in-water microdroplets, both the chip 300 and the chip cover plate 400 are made of hydrophilic materials or hydrophilically modifiable materials. Specifically, the chip 300 and the chip cover plate 400 are made of one of the following materials: hydrophilic polymers, metals, glass, or hydrophilically modifiable materials. For example, the chip 300 and the chip cover plate 400 can be made of one of the following materials: hydrophilic polymethyl methacrylate (PMMA), cyclic olefin copolymer (COC), polycarbonate, stainless steel, aluminum alloy, or glass. Alternatively, when the chip 300 and the chip cover plate 400 are made of hydrophilically modifiable materials, the materials are modified into hydrophilic materials using a hydrophilic agent, thereby ensuring the rapid preparation of oil-in-water microdroplets.

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

Claims

1. A high-throughput microdroplet preparation device based on a stepped structure, characterized in that, Includes liquid storage components and microdroplet preparation components; The liquid storage assembly includes 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 inlet and a mobile phase inlet and outlet. The mobile phase inlet and outlet are connected to the liquid storage cavity, and the dispersed phase inlet is connected to a circular receiving cavity disposed in the base. The microdroplet fabrication assembly includes a chip top cover, at least one chip, and a chip bottom cover arranged sequentially from top to bottom. The chip bottom cover is fixed above the base. The cross-sections of the chip and the chip bottom cover are both circular, and the middle of the chip and the chip bottom cover is provided with a circular opening for communicating with the circular receiving cavity. The outer side of the chip is provided with several microdroplet preparation units evenly distributed along the circumference. Each microdroplet preparation unit includes an inlet, an intermediate channel and an outlet connected in sequence. The width of the inlet gradually decreases from the inside to the outside, and the width of the outlet gradually increases from the inside to the outside. The circular receiving cavity is located in the middle of the base, and the base is provided with an annular groove, which is located on the outside of the circular receiving cavity. 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 outlet of the microdroplet preparation unit, and the height difference between the two is not less than at least ten times the depth of the microdroplet preparation unit.

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

3. The high-throughput microdroplet preparation device based on a stepped structure as described in claim 1, characterized in that, Both the inlet and outlet are triangular, the intermediate channel is elongated, the angles of the inlet and outlet are both between 20° and 60°, the depths of the inlet, outlet, and intermediate channel are all between 10μm and 1000μm, and the widths of the inlet, outlet, and intermediate channel are all between 10μm and 1000μm.

4. The high-throughput microdroplet preparation device based on a stepped structure as described in claim 1, characterized in that, The liquid storage shell is detachably connected to the base. The outer edge of the lower surface of the base is provided with an annular stepped groove. The bottom surface of the annular stepped groove is provided with a plurality of first threaded holes arranged in a uniform manner. The bottom of the liquid storage shell is provided with a second threaded hole that matches the first threaded hole. The base is then connected to the liquid storage shell through the first threaded hole, the second threaded hole, and a screw. A sealing gasket is provided at the connection between the liquid storage shell and the base; The microdroplet preparation component is detachably connected to the base. The upper cover of the chip is provided with a third threaded hole in the middle, and the bottom of the circular receiving cavity is provided with a fourth threaded hole. The upper cover of the chip, the chip, and the lower cover of the chip 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 lower cover of the chip, the fourth threaded hole, and bolts.

5. The high-throughput microdroplet preparation device based on a stepped structure as described in claim 4, characterized in that, The sealing gasket is made of one of the following materials: silicone, nitrile rubber, fluororubber, perfluoroether (FFKM), or polytetrafluoroethylene (PTFE).

6. A method of using the high-throughput microdroplet preparation device based on a stepped structure as described in any one of claims 1-5, characterized in that, During the preparation of microdroplets, under the drive of external pressure, the dispersed phase is filled into the circular cavity of the base through the dispersed phase inlet, and flows through the circular opening in the middle of the chip's lower cover plate and the circular opening in the middle of the chip before entering the microdroplet preparation unit on the outer side of the chip. Subsequently, driven by interfacial tension at the outlet of the microdroplet preparation unit, highly monodisperse microdroplets are formed in the reservoir filled with the mobile phase.

7. The method of using the high-throughput microdroplet preparation device based on a stepped structure as described in claim 6, characterized in that, The mobile phase located in the liquid storage chamber is either in a static state or in a flowing state.

8. The method of using the high-throughput microdroplet preparation device based on a stepped structure as described in claim 7, 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.

9. The method of using the high-throughput microdroplet preparation device based on a stepped structure as described in claim 6, characterized in that, When preparing water-in-oil microdroplets, both the chip and the chip cover plate are made of hydrophobic materials or materials that can be modified to be hydrophobic. When preparing oil-in-water microdroplets, both the chip and the chip cover plate are made of hydrophilic materials or hydrophilically modifiable materials.

Images