A micro-droplet generation device and method

Abstract

The present invention discloses a micro-droplet generating device, which relates to the technical field of microfluidic devices and includes: a base, a cover plate, a nut cover, and a peek screw head. The base and the cover plate are rotating bodies sharing the same axis. A first through hole and a second through hole are respectively provided on the axes of the base and the cover plate. The middle of the nut cover is provided with an opening. A first groove is provided on the upper surface of the base, and an assembly hole is provided on the side surface. A second groove is provided at the bottom of the first groove, and the assembly hole communicates with the second groove. A gasket is placed at the bottom of the first groove. The present invention also discloses a method for generating micro-droplets using the above device. By replacing the capillary tubes a and b with different inner diameters and the gaskets 500 with different thicknesses, channel structures of different sizes can be obtained. By adjusting the flow rates of the continuous phase and the discontinuous phase, droplets of different particle sizes can be obtained, and good fluidity can be maintained when using polar solvents or non-polar solvents, and blockage is not likely to occur.

Description

Technical Field

[0001] The present invention relates to the technical field of microfluidic devices, and particularly to a micro-droplet generating device and method. Background Art

[0002] Microfluidics refers to a system that processes or manipulates tiny fluids (with volumes ranging from nanoliters (nL) to femtoliters (fL)) using microchannels (sized from dozens to hundreds of micrometers). The main fluid phenomena of fluids in microfluidic microchannels are laminar flow and droplets. When two immiscible liquids (oil and water) flow in a microfluidic channel, under the action of liquid / liquid interfacial tension and shear force, one of the fluid phases will form highly uniform discrete flow, that is, droplets, as shown in Figure 1 the attached figure.

[0003] Currently, in the droplet generation methods based on the microfluidic system, the most commonly used are the active type and the passive type. In the active type, external field driving forces such as heat, air pressure, piezoelectricity, microvalves, and magnetic fields are mainly used to achieve droplet generation. Compared with the active type, the passive generation method does not require the application of an external field. It directly uses the restriction of the microchannel geometric structure to cause the deformation of the flow field interface and the increase of interface instability, thereby generating discrete-phase droplets. The passive droplet generation technology can not only generate a continuous droplet string with uniform size, good monodispersity, and uniform spatial distribution, but also effectively avoid external interference and eliminate cross-contamination. According to different materials, the microfluidic devices in the passive type are mainly PDMS microfluidic chips and capillary microfluidic devices. However, the processing of PDMS chips is relatively complex, the cost is high, and PDMS has a swelling effect in non-polar solvents. Once blocked, it is difficult to dredge, the reuse rate is low, and the channel size is easily affected by pressure. The capillary microfluidic device has high requirements for the manufacturing accuracy of the capillary. According to different channel structure types, it is mainly divided into three types: T-type structure, coaxial type, and focused flow type.

[0004] In the T-type structure, the dispersed phase is sheared by the continuous phase at the joint and then broken into droplets. The volume of the formed micro-droplets depends on the flow rate ratio between the two-phase liquid flows, the flow rate between the two phases, the channel size, etc.; but if there is a large difference in the driving pressures of the two-phase liquid flows, then droplets cannot be formed, and the two-phase liquid flows will show laminar flow. This structure is prone to blockage.

[0005] In the co-flow structure, the dispersed phase is introduced into the internal channel, and the continuous phase flows into the external channel in the same direction. Then, the dispersed-phase and continuous-phase fluids meet in parallel flow, and the combined action of interfacial tension and shear force causes the dispersed phase to be squeezed and broken by the continuous phase to form uniform droplets. Inside this channel, the size of the droplets is affected by the fluid properties and flow rate. Among them, the flow rate is the main factor. In addition, the droplets inside this channel mainly exhibit two states. When the fluid flows at a low speed, droplets are periodically formed at the tip of the capillary orifice, which is called the dripping mode. The droplets generated in this mode are highly monodisperse. If the flow rate of any one of the fluids is increased to a certain critical value, the internal fluid is stretched and droplets are formed downstream, which is called the jet mode. Most of the droplets generated in the jet mode are polydisperse.

[0006] In the flow-focusing structure, based on hydrodynamic focusing, the continuous phase symmetrically shears the dispersed phase, causing the dispersed phase to break into droplets. Compared with the T-shaped device method, the method using flow focusing is easier to control the generation of micro-droplets. The droplet formation is relatively stable, and the particle size distribution of the formed droplets is wider. The Reynolds number of the micro-droplets formed by the flow-focusing method is very small, usually between 0.01 and 0.1. The main force is the interfacial tension, and the viscous force of the two-phase liquid flow is greater than the inertial force brought by the liquid flow velocity.

[0007] In comparison, the method of flow focusing is easier to control the generation of micro-droplets. The droplet formation is relatively stable, and the particle size distribution of the formed droplets is wider. However, whether it is a PDMS microfluidic chip or a capillary microfluidic device, the channel size of the same device is fixed and cannot be adjusted, resulting in the problem of a single structure. Summary of the Invention

[0008] The object of the present invention is to provide a micro-droplet generation device with adjustable channel size, and either a polar solvent or a non-polar solvent can be used as the continuous phase to solve the problems existing in the existing microfluidic devices.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A micro-droplet generation device includes: a base, a cover plate, a nut cover, and a peek screw head. The base and the cover plate are rotating bodies sharing the same axis. The base, the cover plate, the nut cover, and the peek screw head are detachably connected. A first through hole is provided on the axis of the base, a second through hole is provided on the axis of the cover plate, and the middle of the nut cover is open.

[0011] The upper surface of the base is provided with a first groove for placing a cover plate. The bottom of the first groove is provided with a second groove located outside the first through hole. The side surface of the base is provided with an assembly hole for installing a peek screw head, and the assembly hole communicates with the second groove.

[0012] The side surface of the cover plate is in close contact with the first groove. A gasket is placed at the bottom of the first groove outside the second groove. The nut cover is used to press the cover plate tightly in the first groove.

[0013] Preferably, when the nut cover is tightened, the upper surface of the cover plate is higher than the upper surface of the base, and at the same time, the upper surface of the base does not contact the inner surface of the nut cover.

[0014] Preferably, a tapered groove is provided in the middle of the first groove, and a tapered protrusion is provided at the bottom of the cover plate. The tapered groove, the tapered protrusion, and the first groove are coaxial.

[0015] Preferably, the central angles and heights of the tapered groove and the tapered protrusion are equal.

[0016] Preferably, a sealing washer is provided in the first groove, and the inner side of the sealing washer is in close contact with the cover plate.

[0017] Preferably, the base, the cover plate, the nut cover, and the gasket are all made of metal, and the peek screw head is made of plastic.

[0018] The present invention also provides a micro-droplet generation method. The micro-droplet generation method uses the above-mentioned micro-droplet generation device. The micro-droplet generation method based on the micro-droplet generation device includes the following steps:

[0019] S1: Pass the capillary a through the second through hole so that the lower end section of the capillary a is not higher than the lower surface of the cover plate and fix it.

[0020] S2: Place the cover plate with the capillary a in the first groove on the base, put on the nut cover and tighten it. Then insert another capillary b into the first through hole and push it up until it stops and fix it.

[0021] S3: Remove the nut cover, take out the cover plate with the capillary a, put a gasket and a sealing washer in the first groove, then reinstall the cover plate and the nut cover, and tighten the nut cover.

[0022] S4: Connect the capillary a to an injection device filled with a discontinuous phase, connect the capillary b to a collection tube, and at the same time place the lens of the microscope against the capillary b.

[0023] S5: Screw the peek screw head into the base, install the peek tube, with the other end of the peek tube connected to the continuous phase container, and the continuous phase container connected to the pressure pump.

[0024] S6: Start the pressure pump. When the continuous phase flows out of the capillary b, observe through a microscope whether there are bubbles in the continuous phase. When there are no bubbles, open the injection device to generate micro-droplets of the discontinuous phase in the continuous phase.

[0025] Preferably, in step S1, the lower end cross-section of the capillary a is flush with or protrudes from the lower surface of the cover slip.

[0026] Preferably, the capillary a and the capillary b are quartz capillaries, and the injection device is a syringe with an injection pump.

[0027] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0028] By adjusting the capillaries a and b with different inner diameters and the gaskets with different thicknesses, channel structures of different sizes can be formed, realizing the generation of multiple different channel structures on the same device, and solving the problem of the single channel structure of the capillary microfluidic device.

[0029] The structures except the sealing gasket are made of metal materials, and good fluidity can be maintained when using polar solvents or non-polar solvents, and blockage is not likely to occur.

[0030] Due to the support of the gasket, a conical channel is formed between the cover slip and the base. The continuous phase fluid is focused into the slit between the capillaries a and b through the conical channel. Since the cross-sectional area of the channel becomes smaller, the fluid will be subjected to a squeezing force, causing the discontinuous phase to break into droplets. Description of the Drawings

[0031] Figure 1 It is a demonstration diagram of the micro-droplet generation process.

[0032] Figure 2 It is an exploded view of the micro-droplet generation device of the present invention.

[0033] Figure 3 It is an assembly diagram of the micro-droplet generation device of the present invention.

[0034] Figure 4 It is Figure 3 The enlarged views at A and B in Figure 3 The enlarged view at A in Figure 3 The enlarged view at B in

[0035] Figure 5 It is an enlarged view of the contact position of the capillaries a and b.

[0036] Figure 6Microscopic image and droplet size distribution diagram of Example 1.

[0037] Figure 7 Microscopic image and droplet size distribution diagram of Example 2.

[0038] Figure 8 Microscopic image and droplet size distribution diagram of Example 3.

[0039] Figure 9 Microscopic image and droplet size distribution diagram of Example 4.

[0040] Figure 10 Microscopic image and droplet size distribution diagram of Example 5.

[0041] Figure 11 Microscopic image and droplet size distribution diagram of Example 6.

[0042] Figure 12 Microscopic image and droplet size distribution diagram of Example 7.

[0043] Markings in the figure: 100, base; 200, cover glass; 300, nut cover; 400, peek screw head; 500, gasket; 600, sealing washer; 101, first through hole; 102, first groove; 103, second groove; 104, assembly hole; 105, tapered groove; 201, second through hole; 202, tapered protrusion. Detailed implementation mode

[0044] The present invention provides a micro-droplet generating device for preparing monodisperse micron-sized droplets. As shown in the figure, the device includes: a base 100, a cover glass 200, a nut cover 300, and a peek screw head 400. Among them, the base 100 and the cover glass 200 are rotating bodies sharing the same axis, and the base 100, the cover glass 200, the nut cover 300, and the peek screw head 400 are detachably connected. A first through hole 101 is provided on the axis of the base 100, and a second through hole 201 is provided on the axis of the cover glass 200. Both the first through hole 101 and the second through hole 201 are used for inserting a capillary tube. The middle of the nut cover 300 is opened to allow the capillary tube to pass through. Among them, the diameter of the first through hole 101 is 0.70 mm, the diameter of the second through hole 201 is 0.45 mm, and the diameter of the opening in the middle of the nut cover 300 is 12.00 mm.

[0045] The upper surface of the base 100 is provided with a first groove 102, whose shape is adapted to the cover plate 200 for placing the cover plate 200. The depth of the first groove 102 is less than the height of the cover plate 200. At the bottom of the first groove 102, at a position outside the first through hole 101, a second groove 103 is provided. An assembly hole 104 is provided on the side surface of the base 100. The assembly hole 104 is arranged in the horizontal direction for installing the peek screw head 400. The bottom of the second groove 103 communicates with the assembly hole 104 in the vertical direction.

[0046] A gasket 500 is placed at the bottom of the first groove 102. The thickness of the gasket 500 is preferably 10 - 30 μm. During use, the gasket 500 is placed outside the second groove 103. When the cover plate 200 is placed in the first groove 102 and tightened with the nut cover 300, a slit is formed between the cover plate 200 and the bottom of the first groove 102. The liquid in the second groove 103 can flow in this slit, and with different gasket thicknesses, the size of the slit is different.

[0047] Since the depth of the first groove 102 is less than the height of the cover plate 200, when the nut cover 300 is tightened, the upper surface of the cover plate 200 is higher than the upper surface of the base 100, and at the same time, the upper surface of the base 100 does not contact the inner surface of the nut cover 300, enabling the cover plate 200 to fully compress the gasket 500 to maintain good sealing performance. Of course, since the gasket 500 is placed below the cover plate 200, in other embodiments, the depth of the groove 102 can be equal to the height of the cover plate 200, or the upper surface of the cover plate 200 can be slightly higher than the upper surface of the base 100. Considering the extremely low thickness of the gasket 500, which may be less than the dimensional error between the cover plate 200 and the base 100, it is generally recommended that the depth of the groove 102 be more than 1 mm lower than the height of the cover plate 200.

[0048] A conical groove 105 is provided in the middle of the first groove 102. At the same time, a conical protrusion 202 is provided at the bottom of the cover plate 200. The conical groove 105, the conical protrusion 202, and the first groove 102 are coaxial, and the central angles and heights of the conical groove 105 and the conical protrusion 202 are equal. During assembly, due to the support of the gasket 500, a height difference equal to the gasket thickness is formed between the conical groove 105 and the conical protrusion 202, thus forming a conical cavity. The liquid in the second groove 103 can enter this cavity.

[0049] To further improve the sealing performance, a sealing washer 600 is provided in the first groove 102, and the inner side of the sealing washer 600 is in close contact with the cover plate 200.

[0050] The peek screw head 400 is made of engineering plastics, specifically, semi-crystalline aromatic plastic engineering plastics; the base 100, the cover plate 200, the nut cover 300, and the gasket 500 are all made of 304 stainless steel, and other metal materials with high temperature resistance, corrosion resistance, and organic solvent resistance can replace the 304 stainless steel used in this embodiment.

[0051] The present invention also provides a micro-droplet generation method, which uses the above micro-droplet generation device to generate micro-droplets in the focusing flow mode. The method includes the following steps:

[0052] S1: Pass the capillary a through the second through hole 201, make the lower end section of the capillary a flush with the lower surface of the cover plate 200, and fix it with quick-drying glue;

[0053] S2: Place the cover plate 200 with the capillary a in the first groove 102 on the base 100, put on the nut cover 300 and tighten it. Then insert another capillary b into the first through hole 101 and push it up until it stops, and also fix it with quick-drying glue. The part of the capillary b exposed from the first through hole 101 should reserve enough length so that it can be attached to the lens of the microscope, generally not less than 80 mm, and can be adjusted according to the differences in the microscope model and lens position used;

[0054] S3: Remove the nut cover 300, take out the cover plate 200 with the capillary a, put the gasket 500 and the sealing washer 600 in the first groove 102, then reinstall the cover plate 200 and the nut cover 300, and tighten the nut cover 300;

[0055] S4: Connect the capillary a to the injection device filled with the discontinuous phase, connect the capillary b to the collection tube, and at the same time attach the lens of the microscope to the capillary b;

[0056] S5: Screw the peek screw head 400 into the base 100, and install the peek tube. The other end of the peek tube is connected to the continuous phase container, and the continuous phase container is connected to the pressure pump;

[0057] S6: Start the pressure pump. When the continuous phase flows out of the capillary b, observe through the microscope whether there are bubbles in the continuous phase. When there are no bubbles, open the injection device, and micro-droplets of the discontinuous phase can be generated in the continuous phase. By adjusting the flow rates of the continuous phase and the discontinuous phase, droplets with different particle sizes can be obtained.

[0058] In the above micro-droplet generation method, both the capillary a and the capillary b are quartz capillaries, and the injection device is a syringe with an injection pump.

[0059] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0060] Example 1

[0061] Quartz capillary a: outer diameter 375 μm, inner diameter 30 μm;

[0062] Quartz capillary b: outer diameter 665 μm, inner diameter 200 μm;

[0063] Thickness of gasket 500: 20 μm;

[0064] Continuous phase: 10 mL of mineral oil, 0.6 g of EM180, 40 μL of TEMED;

[0065] Discontinuous phase: 1 mL of TBSET buffer, 9 mL of Acryl / Bis 30% Solution (29:1), 0.06 g of APS;

[0066] Flow rate of continuous phase: 60.0 ml / min;

[0067] Flow rate of discontinuous phase: 0.3 ml / min;

[0068] Obtained droplet size: 56.8 μm, CV value: 3.2%.

[0069] Example 2

[0070] Quartz capillary a: outer diameter 375 μm, inner diameter 30 μm;

[0071] Quartz capillary b: outer diameter 665 μm, inner diameter 200 μm;

[0072] Thickness of gasket 500: 20 μm;

[0073] Continuous phase: 10 mL of mineral oil, 0.6 g of EM180, 40 μL of TEMED;

[0074] Discontinuous phase: 1 mL of TBSET buffer, 9 mL of Acryl / Bis 30% Solution (29:1), 0.06 g of APS;

[0075] Flow rate of continuous phase: 90.0 ml / min;

[0076] Flow rate of discontinuous phase: 0.3 ml / min;

[0077] Obtained droplet size: 33.3 μm, CV value: 3.0%.

[0078] Example 3

[0079] Quartz capillary a: outer diameter 375 μm, inner diameter 30 μm;

[0080] Quartz capillary b: outer diameter 665 μm, inner diameter 200 μm;

[0081] Gasket 500 thickness: 20 μm;

[0082] Continuous phase: 10 mL mineral oil, 0.6 g EM180, 40 μL TEMED;

[0083] Discontinuous phase: 1 mL TBSET buffer, 9 mL Acryl / Bis 30% Solution (29:1), 0.06 g APS;

[0084] Continuous phase flow rate: 90.0 ml / min;

[0085] Discontinuous phase flow rate: 0.1 ml / min;

[0086] Obtained droplet size: 20.9 μm, CV value: 5.6%.

[0087] Example 4

[0088] Quartz capillary a: outer diameter 375 μm, inner diameter 30 μm;

[0089] Quartz capillary b: outer diameter 665 μm, inner diameter 200 μm;

[0090] Gasket 500 thickness: 20 μm;

[0091] Continuous phase: aqueous phase (1% SDS, 1% PVP);

[0092] Discontinuous phase: acrylamide dichloromethane solution (mass volume fraction 10%);

[0093] Continuous phase flow rate: 30.0 ml / min;

[0094] Discontinuous phase flow rate: 2.0 ml / min;

[0095] Obtained droplet size: 78.8 μm, CV value: 3.7%.

[0096] Example 5

[0097] Quartz capillary a: outer diameter 375 μm, inner diameter 15 μm;

[0098] Quartz capillary b: outer diameter 665 μm, inner diameter 200 μm;

[0099] Thickness of gasket 500: 20 μm;

[0100] Continuous phase: 10 mL of mineral oil, 0.6 g of EM180, 40 μL of TEMED;

[0101] Discontinuous phase: 1 mL of TBSET buffer, 9 mL of Acryl / Bis 30% Solution (29:1), 0.06 g of APS;

[0102] Flow rate of continuous phase: 60.0 ml / min;

[0103] Flow rate of discontinuous phase: 0.3 ml / min;

[0104] Obtained droplet size: 48.3 μm, CV value: 5.2%.

[0105] Example 6

[0106] Quartz capillary a: Outer diameter 375 μm, inner diameter 15 μm;

[0107] Quartz capillary b: Outer diameter 665 μm, inner diameter 200 μm;

[0108] Thickness of gasket 500: 10 μm;

[0109] Continuous phase: 10 mL of mineral oil, 0.6 g of EM180, 40 μL of TEMED;

[0110] Discontinuous phase: 1 mL of TBSET buffer, 9 mL of Acryl / Bis 30% Solution (29:1), 0.06 g of APS;

[0111] Flow rate of continuous phase: 60.0 ml / min;

[0112] Flow rate of discontinuous phase: 0.3 ml / min;

[0113] Obtained droplet size: 25.2 μm, CV value: 5.7%.

[0114] Example 7

[0115] Quartz capillary a: Outer diameter 375 μm, inner diameter 30 μm;

[0116] Quartz capillary b: Outer diameter 665 μm, inner diameter 150 μm;

[0117] Thickness of gasket 500: 20 μm;

[0118] Continuous phase: 10 mL mineral oil, 0.6 g EM180, 40 μL TEMED;

[0119] Discontinuous phase: 1 mL TBSET buffer, 9 mL Acryl / Bis 30% Solution (29:1), 0.06 g APS;

[0120] Flow rate of continuous phase: 90.0 ml / min;

[0121] Flow rate of discontinuous phase: 0.1 ml / min;

[0122] Obtained droplet size: 11.4 μm, CV value: 8.3%.

[0123] Figures 6 to 12 Among them, on the left is the microscopic image of the droplets in the capillary, in the middle is the microscopic image of the collected droplets, the horizontal line in the microscopic image is a scale bar with a length of 200 μm, and on the right is the picture of the droplet size distribution.

[0124] As shown in Examples 1 to 7, the present invention forms different channel structures by adjusting the sizes of capillaries a, b and gasket 500, and adaptively adjusts the flow rates of the continuous phase and the discontinuous phase, thereby obtaining droplets with particle sizes ranging from 11.4 μm to 78.8 μm, solving the problems of the single structure and non-adjustability of the current micro-droplet generation device.

[0125] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A micro-droplet generating device, characterized in that, it includes: a base (100), a cover plate (200), a nut cover (300), and a peek screw head (400). The base (100) and the cover plate (200) are rotating bodies sharing the same axis. The base (100), the cover plate (200), the nut cover (300), and the peek screw head (400) are detachably connected. A first through hole (101) is provided on the axis of the base (100), a second through hole (201) is provided on the axis of the cover plate (200), and the middle of the nut cover (300) is provided with an opening; a first groove (102) is provided on the upper surface of the base (100), the first groove (102) is used for placing the cover plate (200), a second groove (103) is provided at the bottom of the first groove (102), the second groove (103) is located outside the first through hole (101), an assembly hole (104) is provided on the side surface of the base (100), the assembly hole (104) is used for installing the peek screw head (400), and the assembly hole (104) communicates with the second groove (103); the side surface of the cover plate (200) is in close contact with the first groove (102), a gasket (500) is placed at the bottom of the first groove (102), the gasket (500) is located outside the second groove (103), and the nut cover (300) is used to press the cover plate (200) tightly in the first groove (102).

2. The micro-droplet generating device according to claim 1, characterized in that, when the nut cover (300) is tightened, the upper surface of the cover plate (200) is higher than the upper surface of the base (100), and at the same time, the upper surface of the base (100) does not contact the inner surface of the nut cover (300).

3. The micro-droplet generating device according to claim 2, characterized in that, a conical groove (105) is provided in the middle of the first groove (102), a conical protrusion (202) is provided at the bottom of the cover plate (200), and the conical groove (105), the conical protrusion (202), and the first groove (102) are coaxial.

4. The micro-droplet generating device according to claim 3, characterized in that, the central angles and heights of the conical groove (105) and the conical protrusion (202) are equal.

5. The micro-droplet generating device according to claim 3, characterized in that, a sealing gasket (600) is provided in the first groove (102), and the inner side of the sealing gasket (600) is in close contact with the cover plate (200).

6. The micro-droplet generating device according to any one of claims 1 to 5, characterized in that, the base (100), the cover plate (200), the nut cover (300), and the gasket (500) are all made of metal material, and the peek screw head (400) is made of plastic material.

7. A micro-droplet generating method, characterized in that, the micro-droplet generating method uses the micro-droplet generating device according to claim 5 above. The micro-droplet generating method based on the micro-droplet generating device includes the following steps: S1: Pass the capillary a through the second through-hole (201) so that the lower end cross-section of the capillary a is not higher than the lower surface of the cover glass (200), and fix it. S2: Place the cover glass (200) with the capillary a in the first groove (102) on the base (100), put on the nut cover (300) and tighten it. Then insert another capillary b into the first through-hole (101) and push it up until it stops, and fix it. S3: Remove the nut cover (300), take out the cover glass (200) with the capillary a, put a gasket (500) and a sealing washer (600) in the first groove (102), then reinstall the cover glass (200) and the nut cover (300), and tighten the nut cover (300). S4: Connect the capillary a to the injection device filled with the discontinuous phase, connect the capillary b to the collection tube, and at the same time place the lens of the microscope against the capillary b. S5: Screw the peek screw head (400) into the base (100), and install the peek tube. The other end of the peek tube is connected to the continuous phase container, and the continuous phase container is connected to the pressure pump. S6: Start the pressure pump. When the continuous phase flows out of the capillary b, observe through the microscope whether there are bubbles in the continuous phase. When there are no bubbles, open the injection device, and micro-droplets of the discontinuous phase can be generated in the continuous phase.

8. The micro-droplet generation method according to claim 7, wherein, in step S1, the lower end cross-section of the capillary a is flush with or protrudes from the lower surface of the cover glass (200), and the protruding length does not exceed 5 mm.

9. The micro-droplet generation method according to claim 7 or 8, wherein, the capillary a and the capillary b are quartz capillaries, and the injection device is a syringe with an injection pump.

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