Micro-fluidic chip

Abstract

The utility model relates to the technical field of micro-fluidic chips, and provides a micro-fluidic chip which comprises a liquid drop fusion area, the liquid drop fusion area comprises a fusion channel and one to three bumps, and the bumps are arranged on the fusion channel. One of the depth size and the width size of the fusion channel is smaller than the diameter of a liquid drop to be fused, and the ratio of the cross sectional area of the fused liquid drop to the cross sectional area of the bump is 1: 1-1: 3; the electrode is arranged on one side of the bump and provides voltage for liquid drops to be fused in the bump.

Description

Technical Field

[0001] This utility model belongs to the field of microfluidic chip technology, and in particular relates to a microfluidic chip. Background Technology

[0002] Droplet microfluidics refers to the process within microchannels where interfacial tension and shear forces isolate one liquid phase from another or multiple phases, forming highly uniform, intermittent flow—droplets. This technology enables the high-throughput preparation of highly dispersed emulsion droplets in microfluidic channels, significantly improving the controllability of the droplet formation process. The aforementioned emulsion droplets refer to the metastable system formed by dispersing two immiscible liquids using microfluidics; for example, droplets formed by an oil phase coating a liquid phase are a type of emulsion droplet.

[0003] The generated droplets, uniform in size and shape, provide a stable microenvironment for biochemical reactions, and the parallel processing of a large number of droplets facilitates high throughput. Confining individual targets within droplets and isolating each target enables high-precision analysis.

[0004] If microfluidic droplets can function as microreactors, precise manipulation of the droplets is required. Currently, the functional units for droplet manipulation mainly include droplet generation, droplet incubation, droplet mixing, droplet injection, droplet output, droplet fusion, droplet splitting, droplet detection, and droplet sorting units.

[0005] Droplet fusion is a crucial technique in droplet microfluidics. It allows for the pairing and fusion of droplets carrying different reagents after droplet generation, enabling the orderly addition of samples and facilitating stable and efficient multi-step operations within the microdroplet. This is essential for applications requiring step-by-step reactions in chemical, biological, or enzymatic reactions (single-cell sequencing, kinetics, crystallization parameters, protein and biomolecule synthesis), material synthesis, and the selection of microbial engineered strains. For sequencing reactions, the order in which reagents are added is critical, which can be achieved by containing each reagent in a separate droplet and merging the droplets at appropriate times.

[0006] Therefore, providing a microfluidic chip for obtaining emulsion droplets, which are then paired and fused with droplets carrying different reagents, and subsequently used for applications such as multiplex digital nucleic acid reactions, single-cell sequencing, drug sensitivity analysis, and selection of microbial engineered strains, has significant practical implications.

[0007] In the prior art, patent CN112439467A discloses a chip and device for preparing emulsion droplets. The technical solution of this patent is as follows: a droplet containing a sample flows in a main channel, and a reagent injection region is provided on the main channel. The width of the main channel narrows within the reagent injection region, and the main channel within this region connects to a reagent injection end, through which reagent is injected into the droplet within the main channel. This technical solution increases the amount of reagent injected into the droplet by reducing the width of the main channel. However, the above method of injecting reagent into the droplet cannot precisely control the amount of reagent injected into the droplet. Utility Model Content

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a microfluidic chip that allows a droplet containing different samples or reagents to fuse with another droplet. By fusing droplets containing reagents and droplets containing samples, the amount of reagents and samples after fusion can be precisely controlled within the microfluidic chip.

[0009] To achieve this objective, the present invention adopts the following technical solution: a microfluidic chip, comprising:

[0010] The droplet fusion region includes a fusion channel and a bulge, wherein the fusion channel is provided with 1-3 bulges;

[0011] One of the depth and width dimensions of the fusion channel is smaller than the diameter of the droplet to be fused, and the ratio of the cross-sectional area of ​​the fused droplet to the cross-sectional area of ​​the bulge is 1:1 to 1:3.

[0012] An electrode is disposed on one side of the bulge, and the electrode provides a voltage to the droplets to be fused within the bulge.

[0013] Preferably, the ratio of the length to the width of the bump is in the range of 1:4 to 1:1.5, and the length of the bump is in the range of 100μm to 500μm, and the width of the bump is in the range of 150μm to 500μm.

[0014] Preferably, the length of the bulge is in the range of 100μm-200μm, and the width of the bulge is in the range of 150μm-300μm.

[0015] Preferably, the depth dimension of the bulge is the same as the depth dimension of the fusion channel, and the ratio of the width dimension of the bulge to the width dimension of the fusion channel is 2:1-3:1.

[0016] Preferably, when the number of bulges is not less than 2, the length-direction dimension between two adjacent bulges ranges from 25μm to 100μm.

[0017] Preferably, one of the width and depth dimensions of the fusion channel is 1-2 times the diameter of the large droplet to be fused;

[0018] And / or, the ratio of the depth dimension to the width dimension of the fusion channel is in the range of 1:1 to 1:6;

[0019] And / or, the width of the fusion channel ranges from 50μm to 150μm.

[0020] Preferably, the number of bulges is 2-3, and the electrode is disposed in the middle region on one side of any of the upstream bulges.

[0021] Preferably, the vertical distance between the discharge end of the electrode and the lower end of the bulge is in the range of 30μm-150μm along the width direction of the bulge.

[0022] Preferably, the microfluidic chip includes a substrate and an encapsulation layer. The encapsulation layer is disposed on one side surface of the substrate. An electrode channel groove is formed on the substrate. The electrode channel groove and the encapsulation layer form an electrode channel. The electrode channel and the droplet fusion region are located on the same side of the substrate.

[0023] Preferably, the depth of the electrode channel ranges from 20 to 50 μm.

[0024] Preferably, the electrode channel includes a positive electrode channel and a negative electrode channel. The positive electrode channel includes a first electrode material inlet, a first electrode material outlet, and a positive electrode material channel located between the two. The positive electrode material channel is filled with positive electrode material.

[0025] And / or, the negative electrode channel includes a second electrode material inlet, a second electrode material outlet, and a negative electrode material channel located between the two, the negative electrode material channel being filled with negative electrode material.

[0026] Preferably, the positive electrode channel and the negative electrode channel are located on the same side of the bulge and are symmetrically arranged about the center line of the bulge along the width direction.

[0027] Preferably, the microfluidic chip further includes a droplet supply region, which includes a droplet generation region and / or a droplet introduction region, wherein the droplet generation region is configured to generate a first droplet to the fusion channel in real time;

[0028] The droplet introduction region is configured to introduce a second droplet into the fusion channel.

[0029] Preferably, the depth dimensions of the bulge, the fusion channel, and the droplet supply region are the same.

[0030] Preferably, the droplet generation region includes an aqueous phase channel and an oil phase channel. The inlet of the oil phase channel is connected to two oil phase channels, which are symmetrical about the aqueous phase channel. The outlet of the oil phase channel coincides with the outlet of the two oil phase channels and is connected to the droplet fusion region.

[0031] And / or, the droplet introduction region includes a droplet injection channel and a dispersion oil phase channel, both of which are connected to the droplet fusion region.

[0032] Preferably, a buffer strip structure is provided at the inlet of the droplet injection channel, with one end of the buffer strip structure disposed on the substrate and the other end in contact with the encapsulation layer.

[0033] Preferably, the buffer strip structure includes multiple support columns arranged in a matrix, and the dimension between two adjacent sets of support columns is 1-3 times the diameter of the largest droplet.

[0034] Preferably, a filter structure is provided at the inlet of the aqueous phase channel and / or the inlet of the oil phase channel;

[0035] And / or a filter structure is provided at the inlet of the dispersed oil phase channel.

[0036] Preferably, the filtration structure includes multiple filtration zones, each of which includes multiple filter blocks arranged in an array.

[0037] Compared with the prior art, this invention has the following advantages: In this invention, different types of samples or reagents can form different droplets. Each droplet containing fusion contains one sample or reagent, and the amount of sample and reagent in each droplet is determined. The amount of reagent and sample in the fused droplet is also determined. The microfluidic chip described above has a bulge on the fusion channel. One of the depth and width dimensions of the fusion channel is smaller than the diameter of any droplet to be fused, ensuring that the droplets to be fused are compressed by the fusion channel, generating resistance and causing a change in the flow velocity of the two droplets within the fusion channel, allowing the two droplets to pair within the fusion channel.

[0038] The aforementioned fusion channel is equipped with 1-3 bulges. The ratio of the cross-sectional area of ​​the fused droplet to the cross-sectional area of ​​the bulge is 1:1-1:3. The cross-sectional area of ​​the bulge is larger than that of the fused droplet. The two droplets to be fused fuse in a free state, which improves the fusion rate. Conversely, if the bulge is not in a free state, the droplets to be fused are easily squeezed and broken, which affects the fusion rate of the droplets.

[0039] The aforementioned electrode is positioned on one side of the bulge. When two droplets to be fused fuse, the electrode discharges into the droplets to be fused inside the bulge, breaking the oil film of the two droplets and promoting their fusion. The fusion rate of the two droplets in this microfluidic chip can reach over 90%. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the microfluidic chip in this utility model;

[0041] Figure 2 This is a schematic diagram of the electrode and a bulge in this utility model;

[0042] Figure 3 This is a schematic diagram of the electrode and two bulges in this utility model;

[0043] Figure 4 This is a schematic diagram of the electrode and three bulges in this utility model;

[0044] Figure 5 In this utility model Figure 1 Enlarged view of the structure at point I in the diagram;

[0045] Figure 6 In this utility model Figure 1 Enlarged view of the structure at point II in the diagram;

[0046] Figure 7 This is an experimental diagram of real-time droplet generation in this invention;

[0047] Figure 8 This is an experimental diagram of the introduction of liquid droplets in this utility model;

[0048] Figure 9 This is an experimental diagram showing the real-time generation and introduction of droplets pairing in this invention;

[0049] Figure 10 This is an experimental diagram showing how paired droplets form a fused droplet within a bulge, as described in this invention.

[0050] Figure 11 This is an experimental diagram of the fused droplets in this invention;

[0051] Figure 12 This is a schematic diagram of the fabrication process of the microfluidic chip in this utility model.

[0052] The components are as follows: 1. Substrate; 2. Droplet fusion region; 21. Fusion channel; 22. Bulge; 3. Electrode; 31. Electrode channel; 311. Positive electrode channel; 3111. First electrode material inlet; 3112. First electrode material outlet; 322. Negative electrode channel; 3221. Second electrode material inlet; 3222. Second electrode material outlet; 4. Droplet generation region; 41. Aqueous phase channel; 411. Second inlet; 42. Oil phase channel; 421. First inlet; 43. Filter containment tank; 44. Real-time droplet generation channel; 45. Filter structure; 451. First-stage filtration zone; 452, Second-stage filtration zone; 453, Third-stage filtration zone; 5, Droplet introduction zone; 51, Droplet injection channel; 511, Third inlet; 53, Dispersed oil phase channel; 531, Fourth inlet; 57, Buffer zone groove; 58, Buffer zone structure; 581, Support column; 6, First loop channel; 7, Second loop channel; 8, Chip outlet; 100, Continuous oil phase; 200, Dispersed aqueous phase; 300, Real-time droplet generation; 400, Droplet introduction; 500, Paired droplets; 600, Melted droplets; 700, Dispersed oil phase. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0054] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0055] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0056] In the description of this utility model, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use. They are used only for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0057] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0058] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0059] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0060] like Figures 1-11 As shown, this embodiment provides a microfluidic chip that can achieve the fusion of two identical or two different types of emulsion droplets.

[0061] Specifically, the microfluidic chip includes a droplet fusion region 2 and an electrode 3. Both the droplet to be fused and the fused droplet within the fusion channel 21 are spherical. The droplet fusion region 2 includes a fusion channel 21 and bulges 22. The fusion channel 21 has 1-3 bulges 22. One of the dimensions of the fusion channel 21, either depth or width, is smaller than the diameter of the droplet to be fused. The cross-sectional area of ​​the fused droplet 600 is in a ratio of 1:1 to 1:3 to the cross-sectional area of ​​the bulge 22. The electrode 3 is located on one side of the bulge 22 and provides voltage to the droplet to be fused within the bulge 22.

[0062] In this embodiment, the surface on the microfluidic chip where the fusion channel 21 is located is defined as a horizontal surface. Figure 1 The paper surface in the image is horizontal. The length direction of the fusion channel 21 lies within the horizontal plane, and the direction of movement of the droplets to be fused within the horizontal plane is the length direction. The width of the fusion channel 21 is perpendicular to the length direction within the horizontal plane. The depth direction of the fusion channel 21 is perpendicular to the horizontal plane (i.e., the depth direction is perpendicular to the horizontal plane). Figure 1 The direction of the bulge 22 is perpendicular to the plane of the paper, and it is perpendicular to both the length and width directions of the fusion channel 21. In this embodiment, the depth direction of the bulge 22 is consistent with the depth direction of the fusion channel 21, the length direction of the bulge 22 is consistent with the length direction of the fusion channel 21, and the width direction of the bulge 22 is consistent with the width direction of the fusion channel 21. For example, the fusion channel 21 is a straight channel.

[0063] The depth or width dimension of the aforementioned fusion channel 21 is compared with the diameter of the droplet to be fused. The diameter of the droplet to be fused refers to its diameter in its free state, meaning the droplet is in a state free from the squeezing action of the fusion channel 21. The diameter of the droplet to be fused or the fused droplet mentioned below refers to its diameter in its free state. The cross-sectional area of ​​the droplet to be fused or the fused droplet 600 is the cross-sectional area at its maximum diameter in its free state. The cross-section of the bulge 22 refers to the surface perpendicular to its length.

[0064] Different types of samples or reagents can form different droplets. The microfluidic chip described above has a bulge 22 on the fusion channel 21. One of the dimensions of the depth and width of the fusion channel 21 is smaller than the diameter of any droplet to be fused, ensuring that the droplets to be fused are squeezed by the fusion channel 21 and generate resistance, so that the flow velocity of the two droplets to be fused in the fusion channel 21 changes, and the two droplets to be fused can pair up in the fusion channel 21.

[0065] For example, if the diameter of the droplet to be fused in the fusion channel 21 is 53 μm and it is located in front, and the diameter of the other droplet to be fused is 48 μm and it is located behind, the two droplets to be fused will experience different resistances and flow velocities in the fusion channel 21. The droplet to be fused in front will have a slower flow velocity, while the droplet to be fused behind will have a faster flow velocity than the droplet to be fused in front. The two droplets to be fused will then pair up one by one in the fusion channel 21.

[0066] In this embodiment, after two droplets of arbitrary diameters enter the fusion channel 21, they will pair up within the fusion channel 21 due to their respective flow rates and the resistance within the fusion channel 21.

[0067] Preferably, one of the depth dimension and the width dimension of the fusion channel 21 is smaller than the diameter of the droplet to be fused, and one of the depth dimension and the width dimension of the fusion channel 21 is larger than the diameter of the droplet to be fused, so that the droplet to be fused located in the fusion channel 21 is subjected to a certain resistance, which promotes droplet pairing, but does not reduce the efficiency of droplet pairing.

[0068] The aforementioned fusion channel 21 is provided with 1-3 bulges 22. The ratio of the cross-sectional area of ​​the fused droplet 600 to the cross-sectional area of ​​the bulge 22 is 1:1-1:3. The cross-sectional area of ​​the bulge 22 is larger than that of the fused droplet 600. The two droplets to be fused fuse in a free state, which improves the fusion rate. Conversely, it is easy for the droplets to be fused to be squeezed and broken, which affects the fusion rate of the droplets.

[0069] The electrode 3 is disposed on one side of the bulge 22. When two droplets to be fused fuse, the electrode 3 discharges into the droplets to be fused inside the bulge 22, breaking the oil film of the two droplets and promoting their fusion. In this embodiment, the fusion rate of droplets in the microfluidic chip can reach over 90%.

[0070] Preferably, the ratio of the length to the width of the bulge 22 is between 1:4 and 1:1.2, and the length of the bulge 22 is between 100 μm and 500 μm, while the width is between 150 μm and 500 μm. The length and width of the bulge 22 are selected from the intersection of the aforementioned ratio ranges and the ranges of both length and width. Both the length and width simultaneously satisfy the above three conditions. This configuration ensures that the two droplets to be fused fuse in a free state within the bulge 22, and that the fused droplet 600 can flow freely within the bulge 22, allowing the paired droplets to be fused to fully fuse within the bulge 22.

[0071] More preferably, the ratio of the length to the width of the bump 22 is in the range of 1:4 to 1:1.2, and the length of the bump 22 is in the range of 100μm-200μm, while the width is in the range of 150μm-300μm. The length and width of the bump 22 are selected from the intersection of the aforementioned ratio range and the ranges of both length and width. Both the length and width simultaneously satisfy the above three conditions. This configuration ensures that when only one bump 22 is used, the paired droplets 500 can fuse rapidly, and the fusion rate can reach over 90%.

[0072] Specifically, in this embodiment, the length of the bump 22 is 165μm and the width of the bump 22 is 205μm.

[0073] The length and width of the bulge 22 ensure that the two droplets to be fused can flow freely within the bulge 22, and can fuse in a free state within the bulge 22 when the electrode 3 is discharged. The fused droplet 600 can also flow freely within the bulge 22 without being resisted by the bulge 22, and can flow quickly and smoothly to the chip outlet 8 through the fusion channel 21 between the bulge 22 and the chip outlet 8.

[0074] Preferably, when the width of the bulge 22 and the depth of the fusion channel 21 are the same, the ratio of the width of the bulge 22 to the width of the fusion channel 21 is 2:1-3:1, ensuring that the flow resistance of the fused droplet 600 in the bulge 22 and the fusion channel 21 of the chip outlet 8 does not change much.

[0075] Preferably, one of the depth and width dimensions of the fusion channel 21 is smaller than the diameter of the droplet to be fused. The cross-sectional area of ​​the fused droplet 600 is in the ratio of 1:1 to 1:3 to the cross-sectional area of ​​the bulge 22. There is one bulge 22. Through one bulge 22, the fusion rate of the two droplets in the bulge 22 can be more than 90%.

[0076] Preferably, when there are two or three bulges 22, the length-direction dimension between two adjacent bulges 22 ranges from 25 μm to 100 μm. Because an electrode 3 is disposed below the bulge 22, if the distance between two adjacent bulges 22 is too close, the electric field generated by the electrode 3 may affect the adjacent bulges 22, easily tearing apart the fused droplets 600. When two or three bulges 22 are provided, the fusion rate of paired droplets within the bulge 22 is above 90%. The fusion of paired droplets is mainly completed within the bulge 22 where the electrode 3 is located, and the fusion rate can reach above 90%. Adding bulges 22 after the electrode can further improve the fusion rate of paired droplets, increasing it by approximately 3%-5%.

[0077] Preferably, the droplets to be fused are spherical, and one of the width and depth dimensions of the fusion channel 21 is 1-2 times the diameter of the larger-diameter droplet to be fused. And / or, the ratio of the depth to the width of the fusion channel 21 ranges from 1:1 to 1:6. And / or, the width of the fusion channel 21 ranges from 50 μm to 150 μm. The aforementioned fusion channel 21 can accommodate the fusion of two droplets of arbitrary diameters. With the depth of the fusion channel 21 remaining constant, the closer the width of the fusion channel 21 is to the diameter of the larger-diameter droplet to be fused, the greater the success rate of fusion of the two droplets.

[0078] For example, the width of the fusion channel 21 is 85 μm, one of the droplets to be fused has a diameter range of 48 μm-52 μm, and the other droplet has a diameter range of 53 μm-57 μm. In the theoretical calculation, the diameter of the fused droplet 600 is 10 μm-20 μm larger than the diameter of the larger droplet to be fused.

[0079] Specifically, in the actual droplet fusion experiment in this embodiment, one of the droplets to be fused has a diameter of 48 μm, the other droplet to be fused has a diameter of 53 μm, and the diameter of the fused droplet 600 ranges from 65 μm to 75 μm.

[0080] like Figure 3 As shown, preferably, there are two bulges 22, and the electrode 3 is disposed in the middle region on one side of the first upstream bulge 22. Figure 4 As shown, when there are three bulges 22, the electrode 3 is positioned in the middle region on one side of the first or second bulge 22 upstream. Positioning the electrode 3 in the middle region of the bulge 22 ensures that the voltage of the electrode 3 can be applied uniformly to the droplets to be fused within the bulge 22, promoting the fusion of paired droplets and ensuring the fusion rate of the paired droplets.

[0081] Preferably, along the width direction of the bulge 22, the vertical distance between the discharge end of the electrode 3 and the lower end of the bulge 22 ranges from 30μm to 150μm. This ensures sufficient fusion of the two droplets while preventing the generated voltage from affecting droplets in adjacent areas, thus preventing the droplets from being torn apart by electric shock and increasing the droplet breakage rate. Specifically, in this embodiment, the distance between the electrode 3 and the bulge 22 is 50μm.

[0082] Preferably, the microfluidic chip includes a substrate 1 and an encapsulation layer. The encapsulation layer is disposed on one side surface of the substrate 1. An electrode channel groove is formed on the substrate 1. The electrode channel groove and the encapsulation layer form an electrode channel 31. The electrode channel 31 and the droplet fusion region 2 are located on the same side of the substrate 1, which facilitates the one-time processing of the electrode channel groove and the droplet fusion region groove forming the droplet fusion region 2, simplifies the overall processing steps, and reduces the difficulty of aligning the electrode channel 31 and the bulge 22, greatly improving the accuracy of the electric field strength and the arrangement position. Specifically, in this embodiment, the substrate 1 is a PDMS sheet, and the encapsulation layer is a glass sheet.

[0083] Preferably, the depth dimension of the electrode channel 31 is in the range of 20μm-50μm. More preferably, the depth dimension of the electrode channel 31 is 25μm.

[0084] Preferably, the electrode channel 31 includes a positive electrode channel 311 and a negative electrode channel 322. The positive electrode channel 311 includes a first electrode material inlet 3111, a first electrode material outlet 3112, and a positive electrode material channel located between the two. The positive electrode material channel is filled with positive electrode material.

[0085] And / or, the negative electrode channel 322 includes a second electrode material inlet 3221, a second electrode material outlet 3222, and a negative electrode material channel located between the two, the negative electrode material channel being filled with negative electrode material.

[0086] In this embodiment, electrode 3 is designed as a contact flow channel electrode. The contact flow channel electrode is closer to the droplet within the flow channel, resulting in a lower voltage required to generate electrocoupling. Electrode 3 is made of gallium indium tin alloy (GaInT). GaInT is solid under normal conditions and has a low melting point, making electrode 3 easy to process. When heated, GaInT becomes liquid, allowing for easy distribution throughout the electrode channel 31. Furthermore, the solid state of GaInT at room temperature ensures connection strength and prevents leakage, making it easy to store, preserve, and facilitate experiments and cleaning. In addition, electrode channel 31 and other fluid channels of the microfluidic chip are on the same plane, allowing for a single photolithography step to create the entire microfluidic chip. This simplifies the overall process, reduces alignment difficulty, and significantly improves the electric field strength and placement accuracy. One end of the tin-bismuth alloy is heated to melt and introduced into the positive and negative ends of electrode 3. Under capillary action, the molten metal rapidly and uniformly spreads throughout the electrode channel 31.

[0087] In this embodiment, in order to stabilize the extension electrode 3 and prevent the electrode channel 31 from breaking due to stretching when the alligator clip wire is connected to the extension electrode 3 during the power-on process, AB glue is used to fix the extension electrode 3. The two phases of AB glue are mixed in a 1:1 ratio, stirred and then applied to the extension electrode 3 to increase stability.

[0088] Preferably, the positive electrode channel 311 and the negative electrode channel 322 are located on the same side of the bulge 22 and are symmetrically arranged about the center line of the bulge 22 along the width direction to ensure that the droplets in the bulge 22 are subjected to uniform voltage.

[0089] Preferably, the voltage range of electrode 3 is 200V-1000V. If the voltage of electrode 3 is too high, it will increase the breakage rate of surrounding droplets. If the voltage of electrode 3 is too low, it will result in a low droplet fusion rate.

[0090] To address the two droplet supply methods described above for entering the droplet fusion region 2, the microfluidic chip further includes a droplet supply region. This region may include a droplet generation region 4, configured to generate droplets 300 to the fusion channel 21 in real time. Alternatively, the droplet supply region may include a droplet introduction region 5, configured to introduce droplets to the fusion channel 21. Or, the droplet supply region may include both the droplet generation region 4 and the droplet introduction region 5, with the droplet generation region 4 configured to generate a first droplet to the fusion channel 21 in real time, and the droplet introduction region 5 configured to introduce a second droplet to the fusion channel 21.

[0091] In this embodiment, droplets 300 are generated in real time through droplet generation zone 4, and droplets to be fused are introduced through droplet introduction zone 5. In this embodiment, when the droplets in droplet introduction zone 5 enter the fusion channel 21, they are individual droplets with almost no dispersed oil phase 700.

[0092] The droplet generation region 4 may include an aqueous phase channel 41 and an oil phase channel 42. A first inlet 421 of the oil phase channel 42 connects to two oil phase channels 42, which are symmetrical about the aqueous phase channel 41. The outlets of the oil phase channels 42 coincide with the outlets of the two oil phase channels 42 and are connected to the droplet fusion region 2 via a real-time droplet generation channel 44. The first inlet 421 of the oil phase channel 42 is used to introduce a continuous oil phase 100, and the second inlet 411 of the aqueous phase channel 41 is used to introduce a sample or reagent of a dispersed aqueous phase 200.

[0093] The droplet introduction region 5 may include a droplet injection channel 51 and a dispersion oil phase channel 53, both of which are connected to the droplet fusion region 2. The third inlet 511 of the droplet injection channel 51 is used to inject droplets, which contain almost no dispersion oil phase 700. The fourth inlet 531 of the dispersion oil phase channel 53 is used to inject dispersion oil phase 700, where the continuous oil phase 100 is the same as the dispersion oil phase 700 introduced into the first inlet 421 of the aforementioned oil phase channel 42. Samples or reagents can be pre-formed into introduction droplets 400, which are introduced into the fusion channel 21 through the droplet introduction region 5. The dispersion oil phase 700 separates the introduction droplets 400 entering the fusion channel 21. Specifically, the droplets introduced through the droplet introduction region 5 are as follows: Figure 8 As shown.

[0094] In this embodiment, the speed of real-time droplet generation 300 is controlled by controlling the flow rates of the first inlet 421 of the aqueous phase channel 41 and the second inlet 411 of the oil phase channel 42. The flow rates of the real-time generated droplets 300 and the droplets injected into the droplet injection channel 51 are adjusted so that droplets of different diameters are paired in a set ratio in the fusion channel 21. Specifically, the droplet generation region 4 adopts a flow focusing structure. The dispersed aqueous phase 200 and the continuous oil phase 100 enter the cross-shaped tube through different channels. At the intersection point, the continuous oil phase 100 simultaneously squeezes the dispersed water phase from both sides, causing it to break and form droplets, i.e., real-time generated droplets 300. Because the continuous oil phase 100 simultaneously squeezes the dispersed aqueous phase 200 from both sides, the size of the real-time generated droplets is more uniform and controllable. Different types of samples or reagents can be introduced into the aqueous phase channel 41.

[0095] In this embodiment, a water-in-oil phenomenon is generated based on the principle of oil-water immiscibility. Monodisperse droplets are prepared using a flow focusing method. By setting the flow rates at the inlets of the aqueous phase channel 41 and the oil phase channel 42, droplets of the required size are generated in real time. Pre-prepared droplets are fluorescent, facilitating subsequent imaging and differentiation, and are re-injected into the chip. By controlling the width of the chip fusion channel 21 and the flow rates of the two types of droplets, one-to-one pairing of the two types is achieved. In this embodiment, the diameter of the real-time generated droplet 300 is 48–52 μm, and the diameter of the introduced droplet 400 is 53–57 μm.

[0096] In this embodiment, the flow rate of the aqueous phase in the aqueous phase channel 41 ranges from 0.5 μL / min to 5 μL / min, and the flow rate of the continuous oil phase 100 in the oil phase channel 42 ranges from 0.5 μL / min to 25 μL / min. The flow rate of the dispersed oil phase 700 in the dispersed oil phase channel 53 ranges from 0.5 μL / min to 5 μL / min. The flow rate of the introduced droplets 400 in the droplet injection channel 51 ranges from 0.1 μL / min to 5 μL / min.

[0097] The aforementioned aqueous phase channel 41, oil phase channel 42, droplet injection channel 51, and oil dispersion channel 53 are all located on the same side of the substrate 1. For example, the aqueous phase channel 41, oil phase channel 42, droplet injection channel 51, and oil dispersion channel 53 can each be fabricated with corresponding grooves on the substrate 1, and after covering the substrate 1 with an encapsulation layer, corresponding flow channels are formed.

[0098] The grooves corresponding to the aforementioned channels can be aligned with the electrode channel grooves to form each structure in a single process. Specifically, the depths of all the aforementioned channels are the same, and their bottom surfaces lie on the same plane.

[0099] A filter structure 45 is provided at the inlet of the aqueous phase channel 41 and / or the inlet of the oil phase channel 42. A filter structure 45 is also provided at the inlet of the dispersed oil phase channel 53.

[0100] A filter structure 45 is provided at the first inlet 421 of the oil phase channel 42 to filter impurities in the continuous oil phase 100 entering the oil phase channel 42. A filter structure 45 is provided at the second inlet 411 of the water phase channel 41 to filter impurities in the dispersed water phase 200 entering the water phase channel 41. A filter structure 45 is provided at the inlet of the dispersed oil phase channel 53 to filter impurities in the dispersed oil phase 700 entering the dispersed oil phase channel 53.

[0101] Specifically, the aforementioned filter receiving groove 43 is formed on the substrate 1. The depth of the filter receiving groove 43 is the same as the depth of each of the aforementioned channels, so as to facilitate one-time positioning and one-time processing of each channel on the microfluidic chip and the filter receiving groove 43. At the same time, the width of the filter receiving groove 43 is greater than the width of the channel in which it is located.

[0102] like Figure 5 As shown, a filter structure 45 is provided in the filter receiving tank 43 to filter the flowing phase in the channel. On the other hand, it prevents the chip from collapsing at this location by supporting the packaging layer within the filter receiving tank 43.

[0103] Specifically, the filter structure 45 includes multi-stage filtration zones, each of which comprises multiple filter blocks arranged in an array. Real-time generated droplets 300 and introduced droplets can pass through the filter blocks without disrupting the droplet's oil film. The filter blocks are used to filter impurities within the first and second droplets.

[0104] Preferably, the filter structure 45 includes a first-stage filter zone 451, a second-stage filter zone 452, and a third-stage filter zone 453 arranged in parallel. The size of the filter blocks in the first-stage filter zone 451 ranges from 80μm to 100μm, and the minimum distance between two adjacent filter blocks in the first-stage filter zone 451 ranges from 40μm to 50μm. The size of the filter blocks in the second-stage filter zone 452 ranges from 45μm to 55μm, and the minimum distance between two adjacent filter blocks in the second-stage filter zone 452 ranges from 20μm to 30μm. The side length of the filter blocks in the third-stage filter structure 45 ranges from 20μm to 30μm, and the minimum distance between two adjacent sets of filter blocks in the third-stage filter zone 453 ranges from 10μm to 20μm.

[0105] like Figure 6As shown, preferably, a buffer strip structure 58 is provided at the entrance of the droplet injection channel 51. The lower end of the buffer strip structure 58 is disposed on the substrate 1, and the upper end is in contact with the encapsulation layer. The buffer strip structure 58 is configured to prevent the microfluidic chip from collapsing.

[0106] Preferably, the buffer strip structure 58 includes a plurality of support columns 581 arranged in a matrix, and the size between two adjacent sets of support columns 581 is 1-3 times the diameter of the largest droplet, ensuring that the droplet can pass through the support columns 581 without damaging the structure of the droplet.

[0107] Preferably, the cross-section of the support column 581 is circular, triangular, or rectangular. The cross-section of the support column 581 refers to a plane parallel to the horizontal plane mentioned above.

[0108] The aforementioned buffer groove 57 is formed on the substrate 1. The depth of the buffer groove 57 is the same as the depth of each channel and the filter receiving groove 43, so as to facilitate one-time positioning and one-time processing of each channel, filter receiving groove 43 and buffer groove 57 on the microfluidic chip. At the same time, the width of the buffer groove 57 is greater than the width of the channel in which it is located.

[0109] Preferably, a first loop-shaped channel 6 can be provided in the channel between the droplet generation region 4 and the droplet fusion region 2. A second loop-shaped channel 7 can be provided in the channel between the buffer band structure 58 and the droplet fusion region 2. The first loop-shaped channel 6 and the second loop-shaped channel 7 can offset some of the fluid pressure changes, making the droplet flow more stable in the fusion channel 21.

[0110] The depth of the first loop channel 6 and the second loop channel 7 opened on the substrate 1 is the same as the depth of the above-mentioned channels, so as to facilitate one-time positioning and one-time processing of the above-mentioned channels, filter receiving groove 43, buffer band groove 57, first loop channel 6 and second loop channel 7 on the microfluidic chip.

[0111] like Figure 10 As shown, in this embodiment, the actual experiment used one microfluidic chip bulge 22. The bulge 22 has a length of 150 μm and a width of 200 μm. The fusion channel 21 has a width of 85 μm. The voltage of electrode 3 is 500 V. The distance between the discharge end of electrode 3 and the bottom of bulge 22 is 50 μm. (The last sentence appears to be incomplete and possibly refers to a different example.) Figure 11 As shown, the microfluidic chip collected 600 fused droplets for fluorescence imaging. Four droplet fusion tests were conducted using droplets of four different fluorescent colors. The experimental results showed that the fusion efficiency of each droplet fusion test reached more than 90%.

[0112] like Figure 12 The following is a detailed fabrication process for microfluidic chips:

[0113] Step 1: The silicon wafers used for photolithography are cleaned and then blown away with high-pressure nitrogen gas to remove them from their moisture state.

[0114] Step 2: Place the cleaned silicon wafer obtained in Step 1 into a plasma machine for plasma treatment.

[0115] Step 3: Spin coat. Apply photoresist to the silicon wafer and spin coat it evenly on a spin coater.

[0116] Step 4: Pre-baking. Place the silicon wafer after photoresist homogenization on a heated stage to allow the solvent in the photoresist to evaporate. Steps S1-S4 above constitute the pre-treatment of the silicon wafer.

[0117] Step 5: As Figure 12 As shown in a.1, after the pre-baked silicon wafer is cooled, the mask and the silicon wafer are aligned. The mask already contains schematics of the various structures of the microfluidic chip, as shown below. Figure 12 As shown in a.2, a suitable exposure time is selected to perform ultraviolet lithography in a lithography machine.

[0118] Step 6: As Figure 12 As shown in a.2, post-baking involves placing the photolithographically etched silicon wafer on a heating stage to promote cross-linking reactions, ensuring a tight bond between the photoresist and the silicon wafer and preventing the photoresist from detaching during subsequent development.

[0119] Step 7: As Figure 12 As shown in a.3, development involves immersing the cooled post-baked silicon wafer in the developer solution and shaking it at a low, uniform speed on a shaker while observing the development process. Development is complete when the microstructure appears and its outline is clear, and there is no excess white flocculent residue of SU-8 adhesive. After development, a template for the microfluidic chip is formed on the silicon wafer.

[0120] Step 8: Hardening the film. Place the developed silicon wafer in an oven and heat at 150°C for more than 1 hour, then cool to room temperature.

[0121] Step 9: As Figure 12 As shown in a.4, PDMS molding is performed. The PDMS:initiator ratio is prepared at 10:1. After removing air bubbles, the silicon wafer is cast and then baked in an oven at 85°C. Figure 12 As shown in a.5, PMDS is cast onto the microfluidic chip template formed above, and the various structures designed on the mask drawing are realized on the PDMS board.

[0122] Step 10: As Figure 12 As shown in a.6, in chip fabrication, after demolding, PDMS undergoes cutting, drilling, plasma surface treatment, and bonding with glass, and is then baked in an 85℃ oven. Figure 12As shown in a.7, the PDMS chip is packaged to form a microfluidic chip.

[0123] Step 11: Fill electrode 3. After heating the chip to 85°C, place it on a heating plate and heat it to 180°C for 3 minutes. Then insert low-temperature melting solder wire into the inlet of the positive electrode channel 311 and the inlet of the negative electrode channel 322 above the chip to fill the entire electrode 3 channel with solder.

[0124] The microfluidic chip provided in this embodiment can form tiny droplets using different samples or reagents, and can fuse multiple micro-droplets within the chip. It can precisely control the volume ratio of droplet and reagent fusion, and does not achieve droplet fusion by precisely controlling the droplet speed. The chip is simple to operate and does not require high operational skills from the operator.

[0125] In this embodiment, the provided microfluidic chip enables precise droplet fusion, achieving the goal of analyzing small sample volumes and reducing reagent usage. It also facilitates further applications such as multiplex digital nucleic acid reactions, single-cell sequencing, immunoassay, drug sensitivity analysis, and selection of engineered microbial strains.

[0126] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A microfluidic chip, characterized by, include: The droplet fusion region (2) includes a fusion channel (21) and a bulge (22). The fusion channel (21) is provided with a bulge (22), and the number of bulges (22) is 1-3. One of the depth dimension and width dimension of the fusion channel (21) is smaller than the diameter of the droplet to be fused, and the cross-sectional area of ​​the fused droplet (600) is in the ratio of 1:1 to 1:3 to the cross-sectional area of ​​the bulge (22). An electrode (3) is disposed on one side of the bulge (22), and the electrode (3) provides voltage to the droplets to be fused inside the bulge (22).

2. The microfluidic chip of claim 1, wherein, The ratio of the length to the width of the bulge (22) is in the range of 1:4 to 1:1.5, and the length of the bulge (22) is in the range of 100μm to 500μm, and the width of the bulge (22) is in the range of 150μm to 500μm.

3. The microfluidic chip of claim 2, wherein, The length of the bulge (22) ranges from 100μm to 200μm, and the width of the bulge (22) ranges from 150μm to 300μm.

4. The microfluidic chip according to any one of claims 1-3, wherein, The depth dimension of the bulge (22) is the same as the depth dimension of the fusion channel (21), and the ratio of the width dimension of the bulge (22) to the width dimension of the fusion channel (21) is 2:1-3:

1.

5. The microfluidic chip according to any one of claims 1-3, wherein, When the number of the bulges (22) is not less than 2, the size range between two adjacent bulges (22) along the length direction is 25μm-100μm.

6. The microfluidic chip according to any one of claims 1-3, wherein, One of the width and depth dimensions of the fusion channel (21) is 1-2 times the diameter of the large droplet to be fused; And / or, the ratio of the depth dimension to the width dimension of the fusion channel (21) is in the range of 1:1 to 1:6; And / or, the width of the fusion channel (21) is in the range of 50μm-150μm.

7. The microfluidic chip according to any one of claims 1-3, wherein, The number of the bulges (22) is 2-3, and the electrode (3) is disposed in the middle region on one side of any of the bulges (22) upstream.

8. The microfluidic chip of claim 7, wherein, Along the width direction of the bulge (22), the vertical distance between the discharge end of the electrode (3) and the lower end of the bulge (22) ranges from 30μm to 150μm.

9. The microfluidic chip according to any one of claims 1-3, wherein, The microfluidic chip includes a substrate (1) and an encapsulation layer. The encapsulation layer is disposed on one side surface of the substrate (1). An electrode channel groove is formed on the substrate (1). The electrode channel groove and the encapsulation layer form an electrode channel (31). The electrode channel (31) and the droplet fusion region (2) are located on the same side of the substrate (1).

10. The microfluidic chip of claim 9, wherein, The depth dimension of the electrode channel (31) ranges from 20 to 50 μm.

11. The microfluidic chip of claim 9, wherein, The electrode channel (31) includes a positive electrode channel (311) and a negative electrode channel (322). The positive electrode channel (311) includes a first electrode material inlet (3111), a first electrode material outlet (3112), and a positive electrode material channel located between the two. The positive electrode material channel is filled with positive electrode material. And / or, the negative electrode channel (322) includes a second electrode material inlet (3221), a second electrode material outlet (3222), and a negative electrode material channel located between the two, the negative electrode material channel being filled with negative electrode material.

12. The microfluidic chip of claim 11, wherein, The positive electrode channel (311) and the negative electrode channel (322) are located on the same side of the bulge (22) and are symmetrically arranged about the center line of the bulge (22) along the width direction.

13. The microfluidic chip of claim 9, wherein, The microfluidic chip also includes a droplet supply area, which includes a droplet generation area (4) and / or a droplet introduction area (5). The droplet generation area (4) is configured to generate a first droplet to the fusion channel (21) in real time. The droplet introduction region (5) is configured to introduce a second droplet into the fusion channel (21).

14. The microfluidic chip of claim 13, wherein, The depth dimensions of the bulge (22), the fusion channel (21), and the droplet supply area are the same.

15. The microfluidic chip of claim 14, wherein, The droplet generation region (4) includes an aqueous phase channel (41) and an oil phase channel (42). The inlet of the oil phase channel (42) is connected to two oil phase channels (42). The two oil phase channels (42) are symmetrical about the aqueous phase channel (41). The outlet of the oil phase channel (42) coincides with the outlet of the two oil phase channels (42) and is connected to the droplet fusion region (2). And / or, the droplet introduction region (5) includes a droplet injection channel (51) and a dispersion oil phase channel (53), both of which are connected to the droplet fusion region (2).

16. The microfluidic chip of claim 15, wherein, A buffer strip structure (58) is provided at the entrance of the droplet injection channel (51). One end of the buffer strip structure (58) is disposed on the substrate (1), and the other end is in contact with the encapsulation layer.

17. The microfluidic chip according to claim 16, characterized in that, The buffer strip structure (58) includes multiple support columns (581) arranged in a matrix, and the size between two adjacent sets of support columns (581) is 1-3 times the diameter of the largest droplet.

18. The microfluidic chip of claim 15, wherein, A filter structure (45) is provided at the inlet of the water phase channel (41) and / or the inlet of the oil phase channel (42); And / or a filter structure (45) is provided at the inlet of the dispersed oil phase channel (53).

19. The microfluidic chip of claim 18, wherein, The filtration structure (45) includes multiple filtration zones, each of which includes multiple filter blocks arranged in an array.

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