Micro-fluidic chip and manufacturing method therefor, and droplet preparation method

Abstract

A micro-fluidic chip, which is used for generating droplets. The micro-fluidic chip comprises a first substrate and a second substrate, which are stacked, and a sealing film, which bonds the first substrate and the second substrate. The first substrate comprises at least two liquid storage parts and at least two liquid input holes, one end of each liquid input hole communicates with one liquid storage part, one of the liquid storage parts is used for storing a continuous phase liquid, and the other liquid storage part is used for storing a dispersed phase liquid. A channel is provided on the side of the second substrate that faces the first substrate, the sealing film has at least two communicating holes, and each communicating hole connects one liquid input hole and the channel. The present application further relates to a manufacturing method for a micro-fluidic chip, and a droplet preparation method.

Description

Microfluidic chips and their fabrication methods, droplet preparation methods Technical Field

[0001] This application relates to the field of microfluidics, and in particular to a microfluidic chip, a method for fabricating the same, and a method for preparing droplets. Background Technology

[0002] In recent years, microfluidic systems, as platforms capable of integrating multiple functional modules, have been widely applied in the fields of biology and chemistry. Microfluidic chips, also known as lab-on-a-chip, can integrate routine biochemical reactions into a chip of just a few square centimeters. Among them, microdroplet-based microfluidic chips, through micrometer-scale channels, encapsulate single cells and reactants within picoliter-sized microdroplets, creating multiple interconnected micro-reaction systems for single-cell analysis. Because microfluidically prepared microdroplets require very little reagent to achieve ultra-high throughput, they are attracting increasing attention in cell research.

[0003] Due to the widespread application of microfluidic chips, controlling their cost and manufacturing difficulty, i.e., controlling the cost and difficulty of droplet preparation, is a challenge that needs to be overcome.

[0004] Summary of the Invention

[0005] In view of this, this application provides a microfluidic chip that can solve the above problems.

[0006] In addition, this application also provides a method for fabricating a microfluidic chip that can solve the above problems and a method for preparing droplets.

[0007] This application provides a microfluidic chip for generating droplets, comprising a first substrate and a second substrate stacked together, and a sealing film bonding the first substrate and the second substrate. The first substrate includes at least two liquid reservoirs and at least two liquid inlets, each liquid inlet having one end connected to one of the liquid reservoirs. One of the liquid reservoirs is used to store a continuous phase liquid, and the other liquid reservoir is used to store a dispersed phase liquid. The second substrate has a channel on its side facing the first substrate. The sealing film has at least two connecting holes, the channel being sealed by the sealing film and communicating with the liquid inlets via the connecting holes.

[0008] Based on the first aspect, in some possible implementations, the first substrate is an injection-molded part, and the second substrate is an injection-molded part.

[0009] Based on the first aspect, in some possible implementations, the first substrate includes a first surface and a second surface facing away from each other, the first surface being away from the second substrate and the second surface facing the second substrate, each of the liquid storage portions being disposed on the first surface, and each of the liquid inlet holes penetrating the second surface and communicating with one of the liquid storage portions.

[0010] Based on the first aspect, in some possible implementations, at least one of the liquid storage portions protrudes from the first surface.

[0011] Based on the first aspect, in some possible implementations, at least one of the liquid storage portions is recessed from the first surface toward the second surface.

[0012] Based on the first aspect, in some possible implementations, the second substrate is a dispersed phase material.

[0013] Based on the first aspect, in some possible implementations, the sealing film includes a first adhesive layer, a substrate layer and a second adhesive layer stacked sequentially, wherein the first adhesive layer is bonded to the first substrate and the second adhesive layer is bonded to the second substrate.

[0014] Based on the first aspect, in some possible implementations, the first adhesive layer and the second adhesive layer are pressure-sensitive adhesives, and the substrate layer is a rigid plastic film.

[0015] Based on the first aspect, in some possible implementations, the microfluidic chip further includes a dispersed phase membrane, which is bonded between the sealing membrane and the second substrate, and the dispersed phase membrane is provided with at least two connection holes, each of which connects to a connecting hole and the channel.

[0016] Based on the first aspect, in some possible implementations, the dispersed phase film is bonded to the second substrate.

[0017] Based on the first aspect, in some possible implementations, at least one of the liquid inlet holes is composed of a plurality of spaced micropores, each of the micropores penetrating the second surface and communicating with one of the liquid storage sections.

[0018] Based on the first aspect, in some possible implementations, the diameter of each micropore in the liquid inlet is 5 micrometers to 5 millimeters.

[0019] Based on the first aspect, in some possible implementations, at least one of the connecting holes comprises a plurality of spaced micropores, each of the micropores penetrating the sealing membrane and connecting one of the liquid storage portions and the channel.

[0020] Based on the first aspect, in some possible implementations, the diameter of each of the micropores in the connecting hole is 5 micrometers to 5 millimeters.

[0021] Based on the first aspect, in some possible implementations, at least one of the connecting holes comprises a plurality of spaced micropores, each of the micropores penetrating the loosely dispersed phase membrane and connecting one of the connecting holes and the channel.

[0022] Based on the first aspect, in some possible implementations, the diameter of each of the micropores in the connecting hole is 5 micrometers to 5 millimeters.

[0023] Based on the first aspect, in some possible implementations, the contact angle between the first substrate and the dispersed liquid is θ1, the contact angle between the sealing film and the dispersed liquid is θ2, the contact angle between the second substrate and the dispersed liquid is θ3, and the microfluidic chip satisfies: θ1<90°<θ3≤θ2.

[0024] Based on the first aspect, in some possible implementations, the microfluidic chip includes multiple droplet generation sub-units, which are independent of each other and spaced apart. Each droplet generation sub-unit includes at least two liquid storage sections and at least two liquid inlet holes, as well as a channel sealed by the sealing membrane and connected to the liquid inlet holes via the connecting hole.

[0025] A second aspect of this application provides a method for fabricating a microfluidic chip, comprising: obtaining a first substrate and a second substrate by injection molding, wherein the first substrate includes at least two liquid storage portions and at least two liquid inlet holes, one end of each liquid inlet hole is connected to one of the liquid storage portions, one of the liquid storage portions is used to store a continuous phase liquid, and the other liquid storage portion is used to store a dispersed phase liquid, and a channel is provided on one side of the second substrate; and hot-pressing the first substrate, a sealing film, and the second substrate in sequence to obtain a microfluidic chip, wherein the sealing film is bonded to the side of the second substrate with the channel and the first substrate, and the sealing film has at least two connecting holes, each of the connecting holes connecting one of the liquid inlet holes and the channel to connect the liquid storage portion and the channel.

[0026] Based on the second aspect, in some possible implementations, the process of sequentially stacking and pressing the first substrate, a sealing film, and the second substrate to form a microfluidic chip specifically includes: sequentially stacking and pressing the first substrate, a sealing film, a loosely dispersed phase film, and the second substrate to form a microfluidic chip, wherein the sealing film bonds the first substrate and the loosely dispersed phase film, the side of the loosely dispersed phase film opposite to the sealing film is combined with the side of the second substrate where the channel is provided, the sealing film has at least two through holes, the loosely dispersed phase film has at least two connection holes, the channel is sealed by the sealing film and the channel is connected to the liquid inlet through the through holes.

[0027] Based on the second aspect, in some possible implementations, each of the connecting holes is formed by laser drilling.

[0028] Based on the second aspect, in some possible implementations, multiple spaced micropores are formed by laser drilling to constitute a connecting hole. Each micropore penetrates the sealing film to connect the liquid inlet hole and the channel after the first substrate, the sealing film and the second base layer are laminated.

[0029] Based on the second aspect, in some possible implementations, the diameter of each of the micropores in the connecting hole is 5 micrometers to 5 millimeters.

[0030] Based on the second aspect, in some possible implementations, multiple spaced micropores are formed by laser drilling to constitute a connecting hole. Each micropore penetrates the dispersed phase film to connect the connecting hole and the channel after the first substrate, the sealing film and the second base layer are laminated.

[0031] Based on the second aspect, in some possible implementations, the diameter of each of the micropores in the connecting hole is 5 micrometers to 5 millimeters.

[0032] Based on the second aspect, in some possible implementations, the second substrate is prepared by injection molding using a dispersed phase material.

[0033] Based on the second aspect, in some possible implementations, at least one of the liquid inlet holes is composed of a plurality of spaced micropores, each of the micropores being connected to one of the liquid storage portions and connected to the channel after the first substrate, the sealing film and the second base layer are laminated together.

[0034] Based on the second aspect, in some possible implementations, the diameter of each micropore in the liquid inlet is 5 micrometers to 5 millimeters.

[0035] Based on the second aspect, in some possible implementations, the sealing film includes a first adhesive layer, a substrate layer, and a second adhesive layer stacked sequentially, with each of the connecting holes penetrating the first adhesive layer, the substrate layer, and the second adhesive layer. Before the first substrate, the sealing film, and the second substrate are sequentially stacked and hot-pressed, the width of the portion of the connecting hole corresponding to the substrate layer is smaller than the width of the portion of the connecting hole corresponding to the first adhesive layer and smaller than the width of the portion of the connecting hole corresponding to the second adhesive layer.

[0036] Based on the second aspect, in some possible implementations, the first adhesive layer and the second adhesive layer are pressure-sensitive adhesives, and the substrate layer is a rigid plastic film.

[0037] A third aspect of this application provides a method for preparing droplets using a microfluidic chip. The microfluidic chip, used to generate droplets, includes a first substrate and a second substrate stacked together, and a sealing film bonding the first and second substrates. The first substrate includes at least two liquid reservoirs and at least two inlet holes, one end of each inlet hole connected to one of the liquid reservoirs. One liquid reservoir is used to store a continuous phase liquid, and the other liquid reservoir is used to store a dispersed phase liquid. The second substrate has a channel on its side facing the first substrate. The sealing film has at least two connecting holes, and the channel is sealed by the sealing film and communicates with the inlet holes via the connecting holes. The method for preparing droplets includes: adding the continuous phase liquid and the dispersed phase liquid to different liquid reservoirs respectively; and causing the continuous phase liquid and the dispersed phase liquid to converge in the channel and be collected in the form of droplets by changing the pressure within the microfluidic chip.

[0038] Based on the third aspect, in some possible implementations, the continuous phase liquid and the dispersed phase liquid are respectively added to the different reservoirs using a pipette or pipette.

[0039] Based on the third aspect, in some possible implementations, the microfluidic chip further includes a liquid outlet from which the formed droplets are collected. Changing the pressure within the microfluidic chip specifically includes using a power pump to generate negative pressure within the microfluidic chip through the liquid outlet to change the pressure within the microfluidic chip.

[0040] Based on the third aspect, in some possible implementations, changing the pressure within the microfluidic chip specifically includes: pressurizing each of the liquid storage portions using a power pump to change the pressure within the microfluidic chip.

[0041] Based on the third aspect, in some possible implementations, the power pump is a manual pump or an electric pump.

[0042] Based on the third aspect, some possible implementations further include: selecting the microfluidic chip according to the continuous phase liquid and the dispersed phase liquid, wherein the contact angle between the first substrate and the dispersed phase liquid is θ1, the contact angle between the sealing film and the dispersed phase liquid is θ2, the contact angle between the second substrate and the dispersed phase liquid is θ3, and the microfluidic chip satisfies: θ1<90°<θ3≤θ2.

[0043] Based on the third aspect, in some possible implementations, the second substrate is a dispersed phase material.

[0044] Based on the third aspect, in some possible implementations, the first substrate is an injection-molded part, and the second substrate is an injection-molded part.

[0045] Based on the third aspect, in some possible implementations, the first substrate includes a first surface and a second surface facing away from each other, the first surface being away from the second substrate and the second surface being facing the second substrate, and each of the liquid storage portions being formed by protruding from the first surface or recessed from the first surface toward the second surface.

[0046] Based on the third aspect, in some possible implementations, the sealing film includes a first adhesive layer, a substrate layer and a second adhesive layer stacked sequentially, wherein the first adhesive layer is bonded to the first substrate and the second adhesive layer is bonded to the second substrate.

[0047] Based on the third aspect, in some possible implementations, the first adhesive layer and the second adhesive layer are pressure-sensitive adhesives, and the substrate layer is a rigid plastic film.

[0048] Based on the third aspect, in some possible implementations, the microfluidic chip further includes a dispersed phase membrane, which is bonded between the sealing membrane and the second substrate, and the dispersed phase membrane is provided with at least two connection holes, each of which connects to a connecting hole and the channel.

[0049] Based on the third aspect, in some possible implementations, at least one of the connecting holes includes a plurality of spaced micropores, each of the micropores penetrating the sealing membrane to connect the liquid inlet hole with the channel.

[0050] Based on the third aspect, in some possible implementations, the diameter of each of the micropores in the connecting hole is 5 micrometers to 5 millimeters.

[0051] Based on the third aspect, in some possible implementations, at least one of the liquid inlet holes includes a plurality of spaced micropores, each of the micropores connecting one of the liquid storage sections to the channel.

[0052] Based on the third aspect, in some possible implementations, the diameter of each micropore in the liquid inlet is 5 micrometers to 5 millimeters.

[0053] Based on the third aspect, in some possible implementations, at least one of the connecting holes comprises a plurality of spaced micropores, each of the micropores penetrating the sparsely dispersed phase membrane to connect one of the connecting holes with the channel.

[0054] Based on the third aspect, in some possible implementations, the diameter of each of the micropores in the connecting hole is 5 micrometers to 5 millimeters.

[0055] Based on the third aspect, in some possible implementations, the microfluidic chip includes multiple droplet generation sub-units, which are independent of each other and spaced apart. Each droplet generation sub-unit includes at least two liquid storage sections and at least two liquid inlets, as well as a channel sealed by the sealing membrane and communicating with the liquid inlets via the connecting hole. The preparation method includes: adding the continuous phase liquid and the dispersed phase liquid to different liquid storage sections of the multiple droplet generation sub-units respectively; and causing the continuous phase liquid and the dispersed phase liquid to converge in the channel and be collected in the form of droplets by changing the pressure in the flow channel of the droplet generation sub-unit.

[0056] Based on the third aspect, in some possible implementations, the dispersed phase liquid of at least one of the droplet generating subunits is different from the dispersed phase liquid of the other droplet generating subunits.

[0057] This application separates the liquid reservoir and the channel onto a first substrate and a second substrate, respectively, and then seals the first and second substrates together with a sealing film. This separable design of the liquid reservoir and the channel allows for different precision requirements during the fabrication of the first and second substrates. Specifically, the channel typically requires higher precision, while the liquid reservoir requires significantly lower precision. Therefore, this design allows for the use of different precision processes and molds to fabricate the first and second substrates, thereby reducing manufacturing process requirements and costs. Furthermore, when generating large-capacity droplets, only the first substrate with the liquid reservoir needs to be replaced; the same second substrate can be used to accommodate first substrates with different capacity liquid reservoirs without requiring the replacement of the second substrate with the channel, further reducing the cost of the microfluidic chip. Moreover, this design allows for the differentiation of the materials of the first and second substrates according to actual requirements. For example, channels typically require dispersed phase properties such as hydrophobicity, and materials with dispersed phase properties are relatively more expensive than ordinary materials. Therefore, the differentiated design of the materials of the first and second substrates further helps to reduce the cost of the microfluidic chip. In addition, using a sealing film to achieve a sealed connection between the first and second substrates helps to reduce the requirements for process precision and save costs. Attached Figure Description

[0058] Figure 1 is a three-dimensional schematic diagram of a microfluidic chip provided in one embodiment of this application.

[0059] Figure 2 is a disassembly diagram of a microfluidic chip according to an embodiment of this application from one angle.

[0060] Figure 3 is a disassembly diagram of a microfluidic chip according to one embodiment of this application from another angle.

[0061] Figure 4 is a cross-sectional view of a microfluidic chip according to an embodiment of this application along IV-IV as shown in Figure 1.

[0062] Figure 5 is a perspective view of the first substrate according to an embodiment of this application.

[0063] Figure 6 is a disassembly diagram of a microfluidic chip according to an embodiment of this application.

[0064] Figure 7 is a disassembly diagram of a microfluidic chip according to an embodiment of this application.

[0065] Figure 8 is a perspective view of the sealing film according to an embodiment of this application.

[0066] Figure 9 is a cross-sectional view of the sealing film according to an embodiment of this application along IV-IV as shown in Figure 1.

[0067] Figure 10 is a disassembly diagram of a microfluidic chip according to an embodiment of this application.

[0068] Figure 11 is a disassembly diagram of a microfluidic chip according to an embodiment of this application.

[0069] Figure 12 is a three-dimensional schematic diagram of a microfluidic chip according to an embodiment of this application.

[0070] Figure 13 is a disassembly diagram of the microfluidic chip shown in Figure 12.

[0071] Figure 14 is a flowchart of the fabrication process of a microfluidic chip according to an embodiment of this application.

[0072] Figure 15 is a flowchart of droplet preparation according to an embodiment of this application.

[0073] Explanation of main component symbols

[0074] Microfluidic chip 100

[0075] First substrate 10

[0076] Second substrate 30

[0077] Sealing film 50

[0078] First surface 10a

[0079] Second surface 10b

[0080] Liquid storage part 11

[0081] Liquid inlet hole 13

[0082] Continuous phase liquid storage section 111

[0083] Dispersed phase storage section 113

[0084] Continuous phase inlet hole 131

[0085] Dispersed phase inlet hole 133

[0086] Channel 30a

[0087] Connecting hole 51

[0088] Continuous phase channel 31

[0089] Dispersed phase channel 33

[0090] Convergence Channel 35

[0091] Liquid outlet A

[0092] Liquid outlet 53

[0093] Collection tank B

[0094] Micropores 13a, 51a, 61a

[0095] First adhesive layer 501

[0096] Substrate layer 503

[0097] Second adhesive layer 505

[0098] First hole 51b

[0099] Second hole 51c

[0100] Dispersed phase membrane 60

[0101] Connection hole 61

[0102] Droplet generation subunit 100a

[0103] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0104] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0105] It should be noted that when a component is considered "set on" another component, it can be directly set on the other component or may have an intervening component present; when a component is considered "installed on" another component, it can be directly installed on the other component or may have an intervening component present. The term "and / or" as used herein includes all and any combination of one or more of the related listed items.

[0106] Please refer to Figure 1. One embodiment of this application provides a microfluidic chip 100 for droplet generation. Referring to Figures 2, 3, and 4, the microfluidic chip 100 includes a first substrate 10 and a second substrate 30 stacked together, and a sealing film 50 bonding the first substrate 10 and the second substrate 30.

[0107] The first substrate 10 includes a first surface 10a and a second surface 10b facing away from each other. The first surface 10a of the first substrate 10 is provided with at least two liquid storage portions 11 for storing liquid that forms droplets. The first substrate 10 also includes at least two liquid inlet holes 13, each liquid inlet hole 13 connecting a liquid storage portion 11 to the second surface 10b.

[0108] Specifically, at least two liquid storage sections 11 include a continuous phase liquid storage section 111 for storing a continuous phase liquid and a dispersed phase liquid storage section 113 for storing a dispersed phase liquid. At least two liquid inlets 13 include a continuous phase liquid inlet 131 corresponding to the continuous phase liquid storage section 111 and a dispersed phase liquid inlet 133 corresponding to the dispersed phase liquid storage section. In some embodiments, as shown in Figures 2 and 3, the first substrate 10 has one continuous phase liquid storage section 111 and one dispersed phase liquid storage section 113, and correspondingly, one continuous phase liquid inlet 131 and one dispersed phase liquid inlet 133. In other embodiments, the number of continuous phase liquid storage sections 111 and the number of dispersed phase liquid storage sections 113 are not limited; correspondingly, each continuous phase liquid storage section 111 corresponds to one continuous phase liquid inlet 131, and each dispersed phase liquid storage section 113 corresponds to one dispersed phase liquid inlet 133.

[0109] Each liquid storage section 11 can protrude from the first surface 10a or be recessed from the first surface 10a. As shown in Figures 1 and 2, both the continuous phase liquid storage section 111 and the dispersed phase liquid storage section 113 can protrude from the first surface 10a. The shape of each liquid storage section 11 is not limited; for example, it can be cylindrical, cuboid, or other regular or irregular shapes. The shapes of any two liquid storage sections 11 can be the same or different. Any two liquid storage sections 11 can be completely independently spaced apart as shown in Figure 2, or they can be adjacent to each other and separated as shown in Figure 5. The capacity of each liquid storage section 11 can be selected as needed; for example, for liquids requiring a larger capacity, a liquid storage section 11 with a larger capacity (e.g., greater depth) can be selected.

[0110] The second substrate 30 has a channel 30a recessed inward on one side, and the sealing film 50 has at least two connecting holes 51. The channel 30a is sealed by the sealing film 50 and communicates with the liquid inlet hole 13 through the connecting holes 51.

[0111] Specifically, channel 30a includes a continuous phase channel 31, a dispersed phase channel 33, and a confluence channel 35. The continuous phase channel 31 is connected to the continuous phase inlet port 131, and the dispersed phase channel 33 is connected to the dispersed phase inlet port 133. The continuous phase channel 31 and the dispersed phase channel 33 converge at the confluence channel 35.

[0112] Because channels typically require high precision while reservoirs have relatively lower precision requirements, when both are located on the same substrate, the substrate itself often needs to meet the precision requirements of the channels, increasing the cost and manufacturing complexity of the microfluidic chip. Furthermore, channels often require dispersed phase properties such as hydrophobicity, while reservoirs do not. Therefore, when both are located on the same substrate, the entire substrate must be made of a material with high dispersed phase properties (hydrophobicity), further increasing the cost of the microfluidic chip. Moreover, sometimes when using microfluidic chips for droplet fabrication, some liquids require larger volumes, necessitating larger reservoirs. Even if the channel design remains unchanged, when both are located on the same substrate, it may require re-fabrication of the entire substrate or even the use of a completely new mold, further increasing the cost of the microfluidic chip and potentially affecting product yield. The microfluidic chip of this application, by independently designing a first substrate 10 with a liquid reservoir 11 and a second substrate 30 with a channel 30a, allows for different precision requirements during the fabrication of the first substrate 10 and the second substrate 30. Therefore, this design allows for the fabrication of the first substrate 10 and the second substrate 30 using processes and molds with different precision, thereby reducing manufacturing process requirements and costs. Furthermore, when generating large-capacity droplets, only the first substrate 10 with the liquid reservoir needs to be replaced; the same second substrate 30 can be used to match first substrates 10 with liquid reservoirs of different capacities without requiring the replacement of the second substrate 30 with the channel, further reducing the cost of the microfluidic chip. Moreover, this design can also differentiate the materials of the first substrate 10 and the second substrate 30 according to actual requirements, further reducing the cost of the microfluidic chip. Additionally, the sealing connection of the first substrate 10 and the second substrate 30 via the sealing film 50 helps reduce the requirements for process precision and saves costs.

[0113] Referring to Figures 2 to 4, the microfluidic chip 100 also includes an outlet A as a droplet outlet, which connects to the manifold channel 35. In some embodiments, as shown in Figures 2 and 4, the outlet A may be disposed on the first substrate 10. Correspondingly, the sealing film 50 also has an outlet hole 53 corresponding to the outlet A, which connects the outlet A and the manifold channel 35. In this embodiment, the first substrate 10 may also have a collection groove B corresponding to the outlet A. The collection groove B may protrude from the first surface 10a as shown in Figure 2, or it may be recessed from the first surface 10a toward the second surface 10b, for collecting the formed droplets. In other embodiments, the outlet A may also be directly disposed on the second substrate 30, for example, located on the side of the second substrate 30 away from the first substrate 10 and connected to the manifold channel 35, or located on the sidewall of the second substrate 30.

[0114] The continuous phase liquid in the continuous phase storage section 111 enters the continuous phase channel 31 through the continuous phase inlet hole 131, and the dispersed phase liquid in the dispersed phase storage section 113 enters the dispersed phase channel 33 through the dispersed phase inlet hole 133. At the junction of the dispersed phase channel 33 and the continuous phase channel 31, the dispersed phase liquid is cut into multiple water-in-oil droplets under the action of the shear force of the continuous phase liquid and the interfacial tension between the two phases. After passing through the confluence channel 35, the droplets flow out from the outlet A and are collected in the collection tank B.

[0115] In some embodiments, both the first substrate 10 and the second substrate 30 can be injection molded parts, which is beneficial for improving accuracy, reducing costs and facilitating mass production.

[0116] The material of the first substrate 10 and the second substrate 30 may be the same or different. In some embodiments, since the microfluidic chip has high requirements for the hydrophobicity of the channel 30a, the second substrate 30 may be made of a hydrophobic material, which is beneficial to the formation of droplets. In other embodiments, the second substrate 30, especially the channel 30a, can also achieve a good hydrophobic effect by modifying the surface of the second substrate 30.

[0117] As shown in Figure 6, at least one liquid inlet 13 can be composed of multiple spaced-apart micropores 13a, wherein each micropore 13a penetrates the second surface 10b and connects to the corresponding liquid storage section 11. This facilitates the filtration of impurities in the liquid in the liquid storage section 11, thereby preventing impurities from entering the channel 30a and causing channel blockage, reducing the impact on droplet formation, and facilitating the removal of impurities when they are present. The micropores 13a can be arranged regularly or irregularly, and any two micropores 13a can be the same or different in size. In this embodiment, referring to Figures 3 and 6, each liquid inlet 13, namely the continuous phase liquid inlet 131 and the dispersed phase liquid inlet 133, can be composed of multiple spaced-apart micropores 13a. In some embodiments, the pore size of each micropore 13a in the liquid inlet 13 can be from 5 micrometers to 5 millimeters.

[0118] As shown in Figure 7, in some embodiments, at least one connecting hole 51 in the sealing membrane 50 may be composed of multiple spaced micropores 51a. Each micropore 51a penetrates the sealing membrane 50 to connect to a channel 30a and a liquid inlet 13, which facilitates the filtration of impurities in the liquid in the liquid storage section 11. This helps prevent impurities from entering the channel 30a and causing blockage, reduces the impact on droplet formation, and facilitates removal of impurities when they are present. The micropores 51a can be arranged regularly or irregularly, and any two micropores 51a can be the same or different in size. In this embodiment, each connecting hole 51 is composed of multiple spaced micropores 51a. In some embodiments, the pore size of each micropore 51a in the connecting hole 51 can be from 5 micrometers to 5 millimeters.

[0119] In some embodiments, as shown in FIG8, the sealing film 50 may include a first adhesive layer 501, a substrate layer 503, and a second adhesive layer 505 stacked sequentially. In conjunction with FIG4 and FIG8, the first adhesive layer 501 is bonded to the first substrate 10, and the second adhesive layer 505 is bonded to the second substrate 30. Each through hole 51 passes through the first adhesive layer 501, the substrate layer 503, and the second adhesive layer 505 sequentially.

[0120] To facilitate a sealed connection between the sealing film 50 and the first substrate 10 and the second substrate 30, the first adhesive layer 501 and the second adhesive layer 505 can be pressure-sensitive adhesives, thereby achieving a sealed connection by pressing the first substrate 10, the sealing film 50, and the second substrate 30 together. The pressure-sensitive adhesive can be, but is not limited to, acrylic pressure-sensitive adhesives, adhesive block copolymer pressure-sensitive adhesives, polyurethane pressure-sensitive adhesives, or vinyl acetate pressure-sensitive adhesives.

[0121] The substrate layer 503 can be a rigid plastic film. Firstly, rigid plastic films are readily available and have a low cost; secondly, rigid plastic films help to enhance the overall structural strength of the sealing film 50. The material of the rigid plastic film may include, but is not limited to, polyurethane, polystyrene, polyethylene, polymaleic anhydride, polypropylene, polycarbonate, or nylon.

[0122] In some embodiments, as shown in FIG9, when at least one connecting hole 51 in the sealing film 50 includes a plurality of spaced micropores 51a, the micropores 51a may penetrate only the substrate layer 503, and the connecting hole 51 also includes a first hole 51b penetrating the first adhesive layer 501 and a second hole 51c penetrating the second adhesive layer 505. The first hole 51b simultaneously connects to the plurality of spaced micropores 51a, and the second hole 51c simultaneously connects to the plurality of spaced micropores 51a.

[0123] As shown in Figure 10, in some embodiments, to further enhance the dispersed phase properties of the microchannels in the microfluidic chip, the microfluidic chip 100 may further include a dispersed phase membrane 60. The dispersed phase membrane 60 is bonded between the sealing membrane 50 and the second substrate 30, thereby enhancing the dispersed phase properties of the microchannels formed by the cooperation of the dispersed phase membrane 60 and the channels 30a of the second substrate 30. Accordingly, the dispersed phase membrane 60 is provided with at least two connecting holes 61, each connecting hole 61 connecting a connecting hole 51 and a channel 30a. Specifically, the dispersed phase membrane 60 is bonded to the second substrate 30, which is beneficial to improving the stability of the dispersed phase performance. Referring to Figures 3 and 10, when the outlet A is located on the first substrate 10, the dispersed phase membrane 60 is also provided with a connecting hole 61 corresponding to the outlet A. In some embodiments, the dispersed phase membrane 60 may be a hydrophobic membrane.

[0124] Furthermore, in some embodiments, as shown in FIG11, at least one connecting hole 61 is composed of a plurality of spaced micropores 61a, wherein each micropore 61a penetrates the loosely dispersed phase membrane and connects a connecting hole 51 and a channel 30a. In some embodiments, the pore size of each micropore 61a in the connecting hole 61 may be from 5 micrometers to 5 millimeters.

[0125] In some embodiments, as shown in Figures 6, 7, and 11, only one of micropores 13a, 51a, and 61a exists between each liquid reservoir 11 and the channel 30a, thus achieving filtration without affecting the passage of liquid. Furthermore, when both the first substrate 10 and the second substrate 30 are injection molded parts, since the formation of the sealing film 50 and the dispersed phase film 60 does not require a mold, the corresponding micropores 51a and 61a can be easily formed directly by laser drilling, making them easier to manufacture and ensuring higher yield, thereby helping to reduce the cost of microfluidic chips.

[0126] Furthermore, in the microfluidic chip, the selection of materials for structures such as the first substrate 10, the second substrate 30, and the sealing membrane 50 typically needs to consider the composition of the liquid that will subsequently use the microfluidic chip. To ensure the droplet generation effect of the microfluidic chip, the contact angles between the materials of each structure of the microfluidic chip and the continuous phase liquid, as well as the contact angles between the materials of each structure of the microfluidic chip and the dispersed phase liquid, are closely related. In some embodiments, the contact angle between the first substrate 10 and the dispersed phase liquid is defined as θ1, the contact angle between the sealing membrane 50 and the dispersed phase liquid is defined as θ2, and the contact angle between the second substrate 30 and the dispersed phase liquid is defined as θ3. Then, the microfluidic chip needs to satisfy: θ1 < 90° < θ3 ≤ θ2, which is beneficial to the subsequent droplet generation.

[0127] In some embodiments, as shown in Figures 12 and 13, the microfluidic chip 100 may include a plurality of independent and spaced-apart droplet generation subunits 100a, such as, but not limited to, the three shown in Figure 12. It should be understood that the term "spaced-apart" in this embodiment refers to the fluid spacing between the plurality of droplet generation subunits 100a, which may be integrally formed. Each droplet generation subunit 100a includes at least two liquid storage sections 11 and at least two liquid inlet holes 13, as well as a channel 30a sealed by a sealing membrane 50 and connected to the liquid inlet holes 13 via a connecting hole 51. Correspondingly, each droplet generation subunit 100a may also include structures such as an outlet A and a collection tank B. Any two droplet generation subunits 100a can be used to generate the same droplet or to generate different droplets simultaneously, thereby improving the efficiency of droplet preparation by the microfluidic chip 100 and increasing the device throughput.

[0128] Referring to Figure 14, one embodiment of this application also provides a method for manufacturing the above-described microfluidic chip 100, which includes the following steps:

[0129] Step S11: The first substrate 10 and the second substrate 30 are obtained by injection molding.

[0130] To improve the dispersed phase effect of the subsequent microfluidic chip 100, a dispersed phase material can be selected for injection molding when fabricating the second substrate 30. To further improve the dispersed phase effect of the microfluidic chip 100, a dispersed phase material can also be selected for injection molding when fabricating the first substrate 10. Since the fabrication of the first substrate 10 and the second substrate 30 is completely independent, the materials selected for the first substrate 10 and the second substrate 30 can be adjusted and matched as needed, thereby helping to save on the manufacturing cost of the microfluidic chip 100.

[0131] In step S12, the first substrate 10, the sealing film 50, and the second substrate 30 are sequentially stacked and hot-pressed to obtain the microfluidic chip 100. After stacking, each connecting hole 51 on the sealing film 50 connects to a liquid inlet hole 13 on the first substrate 10 and a channel 30a on the second substrate 30, thereby connecting a liquid storage portion 11 on the first substrate 10 and a channel 30a on the second substrate 30.

[0132] The connecting hole 51 in the sealing film 50 can be formed by, but is not limited to, laser drilling or mechanical drilling. In this embodiment, the connecting hole 51 is formed by laser drilling.

[0133] Furthermore, in some embodiments, when the sealing film 50 includes a first adhesive layer 501, a substrate layer 503, and a second adhesive layer 505 stacked sequentially, and the connecting hole 51 sequentially penetrates the first adhesive layer 501, the substrate layer 503, and the second adhesive layer 505, since hot pressing increases the fluidity of the first adhesive layer 501 and the second adhesive layer 505, in order to reduce the risk of partial or complete blockage of the connecting hole 51 after hot pressing, before hot pressing, along the direction perpendicular to the stacking direction of the first adhesive layer 501, the substrate layer 503, and the second adhesive layer 505, the width of the portion of the connecting hole 51 corresponding to the substrate layer 503 is smaller than the width of the portion of the connecting hole 51 corresponding to the first adhesive layer 501, and the width of the portion of the connecting hole 51 corresponding to the substrate layer 503 is also smaller than the width of the portion of the connecting hole 51 corresponding to the second adhesive layer 505.

[0134] The sealing film 50 is made by, but not limited to, the following methods: for example, spraying or printing adhesive on opposite sides of a substrate layer 503 to form a first adhesive layer 501 and a second adhesive layer 505 respectively, and then laser drilling to form a connecting hole 51 that penetrates the first adhesive layer 501, the substrate layer 503 and the second adhesive layer 505; or forming a through hole in a substrate layer 503 by laser drilling, and spraying or printing adhesive on opposite sides of the substrate layer 503 to form a first adhesive layer 501 and a second adhesive layer 505 respectively, while shielding the through hole, so that the first adhesive layer 501 and the second adhesive layer 505 respectively form a hole portion corresponding to the through hole, and the two hole portions and the through hole constitute a connecting hole 51.

[0135] The aforementioned adhesive materials may include, but are not limited to, pressure-sensitive adhesives, which may be, but are not limited to, acrylic pressure-sensitive adhesives, viscous block copolymer pressure-sensitive adhesives, polyurethane pressure-sensitive adhesives, vinyl acetate pressure-sensitive adhesives, etc.

[0136] The substrate layer 503 may be, but is not limited to, a rigid plastic film. The material of the rigid plastic film may include, but is not limited to, polyurethane, polystyrene, polyethylene, polymaleic anhydride, polypropylene, polycarbonate, or nylon.

[0137] In some embodiments, before hot pressing in step S12, a loosely dispersed phase film 60 may be laminated between the sealing film 50 and the second substrate 30. After lamination, each connection hole 61 on the loosely dispersed phase film 60 connects to a connecting hole 51 and a channel 30a. The connection holes 61 in the loosely dispersed phase film 60 can be formed by, but is not limited to, laser drilling or mechanical drilling. In this embodiment, the connection holes 61 are formed by laser drilling.

[0138] Referring to Figure 15, one embodiment of this application also provides a method for preparing a droplet. This method can be performed using the microfluidic chip 100 described above, or using other microfluidic chip structures. The following description uses the microfluidic chip 100 as an example to illustrate the method for preparing the droplet, which includes:

[0139] Step S21: The continuous phase liquid and the dispersed phase liquid are respectively added to different liquid storage sections 11 of the microfluidic chip 100.

[0140] Specifically, a predetermined amount of continuous phase liquid and dispersed phase liquid can be measured using a pipette or pipette, and the measured continuous phase liquid is introduced into the continuous phase reservoir 111, while the measured dispersed phase liquid is introduced into the dispersed phase reservoir 113.

[0141] Step S22: By changing the pressure within the microfluidic chip 100, the continuous phase liquid and the dispersed phase liquid are caused to converge in the channel 30a and be collected in the form of droplets.

[0142] Specifically, in some embodiments, a power pump (not shown) can be used to connect to the outlet A. When the power pump is started, a negative pressure difference is formed between the pressure in the channel 30a, the connecting hole 51 and the inlet hole 13 and the atmospheric pressure through the outlet A. The pressure difference causes the continuous phase liquid and the dispersed phase liquid to flow into the channel 30a and merge to form droplets. The droplets flow out from the outlet A and are collected under the action of the pressure difference.

[0143] In other embodiments, a power pump can be used to pressurize each reservoir 11 to generate positive pressure in each reservoir 11, thereby forcing the continuous phase liquid in the continuous phase reservoir 111 and the dispersed phase liquid in the dispersed phase reservoir 113 into the channel 30a to flow and merge into droplets, and the droplets are collected by flowing out through the outlet A under the action of positive pressure.

[0144] The pump can be a manual pump or an electric pump. A manual pump can be, but is not limited to, a syringe or similar device that pulls or pushes.

[0145] When the microfluidic chip 100 includes multiple droplet generation subunits 100a, in step S21, a continuous phase liquid and a dispersed phase liquid are added to the liquid storage section 11 of each droplet generation subunit 100a. The continuous phase liquid added between any two droplet generation subunits 100a can be the same or different, and the dispersed phase liquid added between any two droplet generation subunits 100a can also be the same or different. In step S22, the pressure within each droplet generation subunit 100a is changed to cause the continuous phase liquid and dispersed phase liquid to converge in the channel 30a and be collected as droplets. Simultaneous droplet preparation by multiple droplet generation subunits 100a improves droplet preparation efficiency and also allows for the simultaneous preparation of different droplets.

[0146] The microfluidic chip, its fabrication method, and the droplet preparation method using the microfluidic chip disclosed in this application, through the independent design of a first substrate with a liquid reservoir and a second substrate with channels, allow for different precision requirements in the fabrication of the first and second substrates. Therefore, this design allows for the use of different precision processes and molds to fabricate the first and second substrates, thereby reducing production process requirements and costs. Furthermore, when producing large-capacity droplets, only the first substrate with the liquid reservoir needs to be replaced; the same second substrate can be used to match first substrates with different capacity liquid reservoirs without requiring replacement of the second substrate with channels, further reducing the cost of the microfluidic chip. Moreover, this design allows for the differentiation of materials for the first and second substrates according to actual requirements, further contributing to cost reduction. Additionally, the use of a sealing film to achieve a sealed connection between the first and second substrates helps reduce the requirements for process precision and saves costs.

[0147] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although the preferred embodiment has been disclosed above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A microfluidic chip for generating droplets, characterized in that, The microfluidic chip comprises a first substrate, a second substrate and a sealing film, The first substrate comprises at least two liquid storage portions and at least two liquid inlet holes, one end of each of the liquid inlet holes is communicated with one of the liquid storage portions, one of the liquid storage portions is used for storing continuous phase liquid, and the other of the liquid storage portions is used for storing dispersed phase liquid; One side of the second substrate facing the first substrate is provided with a channel, The sealing film has at least two communication holes, the channel is sealed by the sealing film and communicated with the liquid inlet hole through the communication hole.

2. The microfluidic chip of claim 1, wherein, The first substrate is an injection molded part, and the second substrate is an injection molded part.

3. The microfluidic chip according to any one of claims 1 to 2, wherein, The first substrate comprises opposite first and second surfaces, the first surface faces away from the second substrate, and the second surface faces the second substrate, each of the liquid storage portions is arranged on the first surface, and each of the liquid inlet holes penetrates the second surface and is communicated with one of the liquid storage portions.

4. The microfluidic chip of claim 3, wherein, At least one of the liquid storage portions is convex on the first surface.

5. The microfluidic chip of claim 3, wherein, At least one of the liquid storage portions is concave from the first surface to the second surface.

6. The microfluidic chip according to any one of claims 1 to 5, wherein, The second substrate is made of a material that is not easy to be wetted by the dispersed phase.

7. The microfluidic chip according to any one of claims 1 to 6, wherein The sealing film comprises a first adhesive layer, a substrate layer and a second adhesive layer which are sequentially stacked, the first adhesive layer is bonded to the first substrate, and the second adhesive layer is bonded to the second substrate.

8. The microfluidic chip of claim 7, wherein, The first adhesive layer and the second adhesive layer are pressure sensitive adhesives, and the substrate layer is a hard plastic film.

9. The microfluidic chip according to any one of claims 1 to 8, wherein, The microfluidic chip further comprises a dispersed phase repellent film, the dispersed phase repellent film is combined between the sealing film and the second substrate, and the dispersed phase repellent film is provided with at least two connecting holes, each of the connecting holes is communicated with one of the communication holes and the channel.

10. The microfluidic chip of claim 9, wherein, The dispersed phase repellent film is bonded to the second substrate.

11. The microfluidic chip of claim 3, wherein, At least one of the liquid inlet holes is composed of a plurality of spaced-apart micropores, each of the micropores penetrates the second surface and is communicated with one of the liquid storage portions.

12. The microfluidic chip of claim 11, wherein, The diameter of each of the micropores in the liquid inlet hole is 5 microns to 5 millimeters.

13. The microfluidic chip of claim 1, wherein, At least one of the communication holes comprises a plurality of spaced-apart micropores, each of the micropores penetrates the sealing film and is communicated with one of the liquid storage portions and the channel.

14. The microfluidic chip of claim 13, wherein, The diameter of each of the micropores in the communication hole is 5 microns to 5 millimeters.

15. The microfluidic chip of claim 9, wherein, At least one of the connecting holes comprises a plurality of spaced-apart micropores, each of the micropores penetrates the dispersed phase repellent film and is communicated with one of the communication holes and the channel.

16. The microfluidic chip of claim 13, wherein, The diameter of each of the micropores in the communication hole is 5 microns to 5 millimeters.

17. The microfluidic chip of any one of claims 1 to 16, wherein, The contact angle of the first substrate with the dispersed phase liquid is θ1, the contact angle of the sealing film with the dispersed phase liquid is θ2, the contact angle of the second substrate with the dispersed phase liquid is θ3, and the microfluidic chip satisfies: θ1<90°<θ3≤θ2.

18. The microfluidic chip of any one of claims 1 to 17, wherein, The microfluidic chip comprises a plurality of droplet generation subunits, the plurality of droplet generation subunits are independent of each other and arranged at intervals, and each of the droplet generation subunits comprises the at least two liquid storage portions and the at least two liquid inlet holes, and the channel sealed by the sealing film and communicated with the liquid inlet hole through the communication hole.

19. A method of fabricating a microfluidic chip, the method comprising: The microfluidic chip comprises: The first substrate and the second substrate are obtained by injection molding, wherein the first substrate comprises at least two liquid storage parts and at least two liquid inlet holes, one end of each liquid inlet hole is communicated with one liquid storage part, one of the liquid storage parts is used for storing continuous phase liquid, and the other liquid storage part is used for storing dispersed phase liquid, and one side of the second substrate is provided with a channel; The first substrate, a sealing film and the second substrate are sequentially stacked and hot-pressed to obtain the microfluidic chip, wherein the sealing film is bonded to one side of the second substrate provided with the channel and the first substrate, and the sealing film has at least two communication holes, the channel is sealed by the sealing film and communicated with the liquid inlet hole through the communication hole.

20. The method of claim 19, wherein the microfluidic chip is fabricated by a method comprising: The first substrate, a sealing film and the second substrate are sequentially stacked and hot-pressed to obtain the microfluidic chip, wherein the sealing film is bonded to one side of the second substrate provided with the channel and the first substrate, and the sealing film has at least two communication holes, the channel is sealed by the sealing film and communicated with the liquid inlet hole through the communication hole. The first substrate, a sealing film, a dispersed phase repelling film and the second substrate are sequentially stacked and hot-pressed to obtain the microfluidic chip, wherein the sealing film is bonded to the first substrate and the dispersed phase repelling film, one side of the dispersed phase repelling film away from the sealing film is combined with one side of the second substrate provided with the channel, the sealing film has at least two communication holes, and the dispersed phase repelling film is provided with at least two connection holes, each liquid inlet hole is communicated with the channel through one communication hole and one connection hole in sequence.

21. The method of claim 19 or 20, wherein the microfluidic chip is fabricated by a method comprising: Each communication hole is formed by laser drilling.

22. The method of claim 19 or 20, wherein the microfluidic chip is fabricated by a method comprising: A plurality of interval distributed micropores are formed by laser drilling to constitute one communication hole, and each micropore penetrates the sealing film to communicate the liquid inlet hole with the channel after the first substrate, the sealing film and the second substrate are stacked and hot-pressed.

23. The method of claim 22, wherein the microfluidic chip is fabricated by a method comprising: The diameter of each micropore in the communication hole is 5 microns to 5 millimeters.

24. The method of claim 20, wherein the microfluidic chip is fabricated by a method comprising: A plurality of interval distributed micropores are formed by laser drilling to constitute one connection hole, and each micropore penetrates the dispersed phase repelling film to communicate the communication hole with the channel after the first substrate, the sealing film and the second substrate are stacked and hot-pressed.

25. The method of claim 24, wherein the microfluidic chip is fabricated by a method comprising: The diameter of each micropore in the connection hole is 5 microns to 5 millimeters.

26. The method of claim 19 to 25, wherein the microfluidic chip is fabricated by a method comprising: The second substrate is prepared by injection molding using a dispersed phase repelling material.

27. The method of claim 19 or 20, wherein the microfluidic chip is fabricated by a method comprising: At least one liquid inlet hole is composed of a plurality of interval distributed micropores, each micropore is communicated with one liquid storage part and communicated with the channel after the first substrate, the sealing film and the second substrate are stacked and hot-pressed.

28. The method of claim 27, wherein the microfluidic chip is fabricated by a method comprising: The diameter of each micropore in the liquid inlet hole is 5 microns to 5 millimeters.

29. The method of claim 19 to 28, wherein, The sealing film comprises a first adhesive layer, a substrate layer and a second adhesive layer which are sequentially stacked, each communication hole penetrates the first adhesive layer, the substrate layer and the second adhesive layer, and the width of the part of the communication hole corresponding to the substrate layer is smaller than the width of the part of the communication hole corresponding to the first adhesive layer and smaller than the width of the part of the communication hole corresponding to the second adhesive layer before the first substrate, the sealing film and the second substrate are sequentially stacked and hot-pressed.

30. The method of claim 29, wherein the microfluidic chip is fabricated by a method comprising: The first adhesive layer and the second adhesive layer are pressure sensitive adhesives respectively, and the substrate layer is a hard plastic film.

31. A method for preparing a droplet using a microfluidic chip, the method comprising: The microfluidic chip is used for generating droplets, comprising a first substrate and a second substrate which are laminated and a sealing film which bonds the first substrate and the second substrate, the first substrate comprises at least two liquid storage parts and at least two liquid inlet holes, one end of each of the liquid inlet holes communicates one of the liquid storage parts, wherein one of the liquid storage parts is used for storing continuous phase liquid and the other of the liquid storage parts is used for storing dispersed phase liquid; the second substrate is provided with a channel on the side facing the first substrate; The channel is sealed by the sealing film and communicates with the liquid inlet holes through the communication holes; The method for preparing the droplets comprises: The continuous phase liquid and the dispersed phase liquid are respectively added into different liquid storage parts; The continuous phase liquid and the dispersed phase liquid are caused to converge in the channel and are collected in the form of droplets by changing the pressure in the microfluidic chip.

32. The method of claim 31, wherein the droplet is prepared by The continuous phase liquid and the dispersed phase liquid are respectively added into different liquid storage parts by using a pipette or a pipet.

33. The method of claim 31 or 32, wherein the droplet is prepared by The microfluidic chip further comprises a liquid outlet, and the generated droplets are collected from the liquid outlet; The method for changing the pressure in the microfluidic chip comprises: A power pump is used to generate negative pressure in the microfluidic chip through the liquid outlet to change the pressure in the microfluidic chip.

34. The method of claim 31 or 32, wherein the droplet is prepared by The method for changing the pressure in the microfluidic chip comprises: A power pump is used to increase the pressure in the microfluidic chip to change the pressure in the microfluidic chip.

35. The method of claim 33 or 34, wherein the droplet is prepared by The power pump is a manual pump or an electric pump.

36. The method of claim 31 to 35, wherein, Further comprising: The microfluidic chip is selected according to the continuous phase liquid and the dispersed phase liquid, wherein the contact angle of the first substrate with the dispersed phase liquid is θ1, the contact angle of the sealing film with the dispersed phase liquid is θ2, the contact angle of the second substrate with the dispersed phase liquid is θ3, and the microfluidic chip satisfies: θ1<90°<θ3≤θ2.

37. The method of claim 31 to 36, wherein, The second substrate is made of a material which is poor in dispersing phase.

38. The method of claim 31 to 37, wherein, The first substrate is an injection molded part, and the second substrate is an injection molded part.

39. The method of claim 31 to 38, wherein, The first substrate comprises opposite first and second surfaces, the first surface faces away from the second substrate, and the second surface faces the second substrate, each of the liquid storage parts is convex on the first surface or is concave from the first surface to the second surface.

40. The method of claim 31 to 39, wherein, The sealing film comprises a first adhesive layer, a substrate layer and a second adhesive layer which are laminated in sequence, the first adhesive layer is bonded to the first substrate, and the second adhesive layer is bonded to the second substrate.

41. The method of claim 40, wherein the droplet is prepared by The first and second adhesive layers are pressure sensitive adhesives, and the substrate layer is a hard plastic film.

42. The method of claim 31 to 41, wherein, The microfluidic chip further comprises a dispersed phase poor film which is combined between the sealing film and the second substrate, and the dispersed phase poor film is provided with at least two connecting holes, each of the connecting holes communicates one of the communication holes with the channel.

43. The method of claim 31 to 42, wherein, At least one of the communication holes comprises a plurality of spaced apart micropores, each of the micropores penetrates the sealing film to communicate the liquid inlet hole with the channel.

44. The method of claim 43, wherein the droplet is prepared by The diameter of each of the micropores in the communication hole is 5 microns to 5 millimeters.

45. The method of claim 31 to 42, wherein, At least one of the liquid inlet holes comprises a plurality of micro-holes arranged at intervals, each of the micro-holes being connected to one of the liquid storage sections and the channel.

46. The method of claim 45, wherein the droplet is prepared by Each of the micro-holes in the communication hole has a diameter of 5 microns to 5 millimeters.

47. The method of claim 42, wherein the droplet is prepared by At least one of the connection holes comprises a plurality of micro-holes arranged at intervals, each of the micro-holes penetrating the sparse dispersed phase film to connect one of the communication holes and the channel.

48. The method of claim 47, wherein the droplet is prepared by Each of the micro-holes in the connection hole has a diameter of 5 microns to 5 millimeters.

49. The method of claim 31 to 48, wherein, The microfluidic chip comprises a plurality of droplet generation sub-units, the plurality of droplet generation sub-units being independent and arranged at intervals, each of the droplet generation sub-units comprising the at least two liquid storage sections, the at least two liquid inlet holes, and the channel sealed by the sealing film and connected to the liquid inlet holes through the communication holes; and the preparation method comprises: Respectively adding the continuous phase liquid and the dispersed phase liquid into different liquid storage sections of the plurality of droplet generation sub-units; By changing the pressure in the channel of the droplet generation sub-unit, the continuous phase liquid and the dispersed phase liquid are converged in the channel and collected in the form of droplets.

50. The method of claim 49, wherein the droplet is prepared by The dispersed phase liquid of at least one of the droplet generation sub-units is different from the dispersed phase liquid of the rest of the droplet generation sub-units.

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