Microfluidic chip

Abstract

The micro-fluidic chip comprises a liquid inlet and a liquid outlet, a micro-channel structure is arranged between the liquid inlet and the liquid outlet, the micro-channel structure comprises at least one micro-channel unit, each micro-channel unit comprises at least one main channel, one end of each main channel is communicated with the liquid inlet, and the other end of each main channel is communicated with the liquid outlet. The other end of each main channel is communicated with the liquid outlet, each main channel comprises at least two channel parts, and the adjacent channel parts are communicated to form a U shape; and the at least one liquid storage structure is positioned between the adjacent U-shaped channel parts and is respectively communicated with the two channel parts. According to the micro-fluidic chip disclosed by the embodiment of the invention, the micro-droplets are formed in the liquid storage structure, the liquid storage structure can be prevented from generating bubbles, and subsequent detection is facilitated.

Description

Technical Field

[0001] The present disclosure relates to the field of microfluid transport technology, and in particular to a microfluidic chip. Background Art

[0002] Microfluidics involves disciplines such as chemistry, fluid physics, microelectronics, new materials, biology and biomedical engineering. It refers to a system that uses microchannels with sizes ranging from tens to hundreds of microns to process or manipulate tiny fluids. It has the characteristics of miniaturization and integration.

[0003] The application of microfluidic technology in the biomedical field is mainly concentrated in two areas: clinical diagnostic instruments and in vitro bionic models. One of the applications in clinical diagnosis is microfluidic detection chips, which generally have the advantages of low sample consumption, fast detection speed, simple operation, multi-functional integration, small size and easy to carry, and have great potential to simplify the diagnostic process and improve medical results.

[0004] Since the behavior of tiny fluids in microchannels of microfluidics is different from that in macroscale channels, the control of fluid behavior is crucial to the realization of microfluidic detection. Tiny fluids flow spontaneously in microchannels mainly by capillary force. However, the magnitude of capillary force is limited by the transport distance, structure and size of the microchannel. When the microchannel is characterized by long distance and high throughput, capillary force may be difficult to support the flow of tiny liquids in the microchannel, which may cause bubbles to appear in the microchannel or fail to capture the target particles to be detected in the tiny fluid, making it difficult to carry out the detection smoothly.

[0005] Therefore, it is necessary to develop a new microfluidic chip. Summary of the invention

[0006] In order to solve the above problems, an embodiment of the present disclosure provides a microfluidic chip for forming microdroplets. The microfluidic chip includes a liquid inlet and a liquid outlet, and a microfluidic structure is included between the liquid inlet and the liquid outlet, and the microfluidic structure includes: at least one microfluidic unit. Each microfluidic unit includes: at least one main channel, one end of the main channel is connected to the liquid inlet, and the other end of the main channel is connected to the liquid outlet, each main channel includes at least two channel parts, and the corresponding ends of adjacent channel parts are connected to form a U shape; and at least one liquid storage structure is located between adjacent U-shaped channel parts and is respectively connected to the two channel parts.

[0007] In some embodiments, each liquid storage structure includes: a liquid storage tank, suitable for containing liquid to form microdroplets; a liquid storage tank channel, suitable for liquid to flow into the liquid storage tank; and a restriction channel connected to the liquid storage tank.

[0008] In some embodiments, the cross-sectional area of ​​the main channel is larger than the cross-sectional area of ​​the reservoir channel, and the cross-sectional area of ​​the reservoir channel is larger than the cross-sectional area of ​​the restricting channel.

[0009] In some embodiments, the cross-sections of the main channel, the reservoir channel, and the limiting channel are rectangular.

[0010] In some embodiments, the width of the limiting channel is 10 μm to 100 μm, and the depth of the limiting channel is 10 μm to 100 μm.

[0011] In some embodiments, the liquid reservoir is cylindrical, the diameter of the liquid reservoir is 50 μm to 1000 μm, and the depth of the liquid reservoir is 50 μm to 1000 μm.

[0012] In some embodiments, the width of the main channel is 50 μm to 1000 μm, and the depth of the main channel is 50 μm to 1000 μm.

[0013] In some embodiments, the width of the liquid reservoir channel is 50 μm to 1000 μm, and the depth of the liquid reservoir channel is 50 μm to 1000 μm.

[0014] In some embodiments, the length of the reservoir channel is 100 μm to 500 μm, and the length of the restriction channel is 100 μm to 200 μm.

[0015] In some embodiments, the angle between the liquid reservoir channel and the flow direction of the liquid in the main channel is an acute angle.

[0016] In some embodiments, the angle between the liquid reservoir channel and the flow direction of the liquid in the main channel is 30° to 60°.

[0017] In some embodiments, the inner surfaces of the main channel, the reservoir channel, and the limiting channel are hydrophilic surfaces.

[0018] In some embodiments, there are multiple liquid reservoirs, which are evenly distributed between adjacent U-shaped channel portions.

[0019] In some embodiments, the distance between any two adjacent liquid reservoirs is 400 μm to 1000 μm.

[0020] In some embodiments, the microfluidic channel structure further includes: a liquid collection pool connected between the other end of the main channel and the liquid outlet.

[0021] In some embodiments, each of the main channels includes two channel portions connected to form a U-shape, one end of the U-shaped main channel is connected to the liquid inlet, and the other end is connected to the liquid collection tank.

[0022] In some embodiments, each of the main channels includes three channel portions connected to form an S-shape, one end of the S-shaped main channel is connected to the liquid inlet, and the other end is connected to the liquid collection tank.

[0023] In some embodiments, the microfluidic chip further includes: a first substrate disposed on a first side of the microfluidic structure to seal the first side of the microfluidic structure; and a second substrate disposed on a second side of the microfluidic structure to seal the second side of the microfluidic structure.

[0024] In some embodiments, a plurality of electrodes are disposed on the first substrate and / or the second substrate, and the plurality of electrodes are located at positions corresponding to the main channels.

[0025] In some embodiments, the plurality of electrodes are spaced apart from each other and distributed non-uniformly on the first substrate or the second substrate.

[0026] In some embodiments, a sample inlet is provided on the first substrate, which is connected to the liquid inlet and is suitable for adding liquid into the microfluidic channel structure through the sample inlet.

[0027] In some embodiments, a sample outlet is provided on the first substrate, which is connected to the liquid outlet and is suitable for discharging liquid out of the microfluidic channel structure through the sample outlet.

[0028] Compared with the prior art, the technical solution of the embodiment of the present disclosure has the following beneficial effects:

[0029] In the microfluidic chip of the embodiment of the present disclosure, the corresponding ends of adjacent channel parts are connected to form a U shape, at least one liquid storage structure is located between the adjacent channel parts and is respectively connected to the two channel parts, the liquid enters the liquid storage structure through the main channel and is retained in the liquid storage structure, while preventing bubbles from being generated in the liquid storage structure.

[0030] Furthermore, the liquid storage structure includes: a liquid storage tank, which is suitable for containing liquid to form micro-droplets; a liquid storage tank channel, which is suitable for liquid to flow into the liquid storage tank through it; and a restriction channel, which is connected to the liquid storage tank. The liquid enters the liquid storage tank through the main channel to form micro-droplets, and the liquid fills the liquid storage tank channel and the restriction channel at the same time. The cross-sectional area of ​​the main channel is larger than the cross-sectional area of ​​the liquid storage tank channel, and the cross-sectional area of ​​the liquid storage tank channel is larger than the cross-sectional area of ​​the restriction channel. In this way, the micro-droplets can be in a stable state in the liquid storage tank and will not flow to other channels.

[0031] Furthermore, the microfluidic chip of the embodiment of the present disclosure also includes a first substrate and a second substrate, and a plurality of electrodes are provided on the first substrate and / or the second substrate, and the plurality of electrodes are located at positions corresponding to the main channel. Therefore, when the liquid flows, a voltage can be applied to the electrodes to form an electric field, and the liquid is charged in the main channel, the liquid reservoir channel and the restriction channel, and the flow of the liquid is promoted under the action of the electric field. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features and advantages of the present disclosure will be better understood through the following detailed description of the optional embodiments in conjunction with the accompanying drawings, in which the same reference numerals represent the same or similar components, wherein:

[0033] Figure 1 A schematic diagram of a top view of a microfluidic channel structure in a microfluidic chip according to an embodiment of the present disclosure is shown;

[0034] Figure 2 A partial enlarged schematic diagram of a microfluidic channel unit according to an embodiment of the present disclosure is shown;

[0035] Figure 3 A schematic diagram of the three-dimensional structure of a microfluidic chip according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0036] Embodiments of the present disclosure are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present disclosure, and cannot be understood as limiting the present disclosure.

[0037] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. In the description of the present disclosure, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present disclosure.

[0038] Since the behavior of tiny fluids in microchannels of microfluidics is different from that in macroscale channels, the control of fluid behavior is crucial to the implementation of microfluidic detection. In order to form microdroplets and capture target particles to be detected, the embodiments of the present disclosure provide a new microfluidic chip. The technical solution of the present disclosure is described in detail below in conjunction with the accompanying drawings.

[0039] Figure 1 FIG. 1 is a schematic diagram showing a top view of a microfluidic structure in a microfluidic chip according to an embodiment of the present disclosure. Figure 1 , an embodiment of the present disclosure provides a microfluidic chip for forming microdroplets, the microfluidic chip includes a liquid inlet 11 and a liquid outlet 12, a microfluidic structure 1 is included between the liquid inlet 11 and the liquid outlet 12, and the microfluidic structure 1 includes at least one microfluidic unit. Each microfluidic unit includes: at least one main channel 13, one end of the main channel 13 is connected to the liquid inlet 11, and the other end of the main channel 13 is connected to the liquid outlet 12, each main channel 13 includes at least two channel parts, and the corresponding ends of adjacent channel parts are connected to form a U shape; and at least one liquid storage structure 14 is located between adjacent U-shaped channel parts and is respectively connected to the two channel parts.

[0040] The liquid inlet 11 is used to allow liquid to flow into the microfluidic unit, and the liquid outlet 12 is used to discharge the liquid in the microfluidic unit.

[0041] In some embodiments, the microfluidic channel structure 1 further includes a liquid collection pool 15 connected between the other end of the main channel 13 and the liquid outlet 12 for storing liquid discharged from the main channel and discharging the liquid from the microfluidic channel structure 1 through the liquid outlet 12 .

[0042] In some embodiments, each of the main channels 13 includes two channel portions, and the corresponding ends of the two channel portions are connected to form a U-shape, one end of the U-shaped main channel is connected to the liquid inlet 11, and the other end of the U-shaped main channel is connected to the liquid outlet 12; in some embodiments, the microfluidic structure 1 also includes a liquid collection pool 15, one end of the U-shaped main channel is connected to the liquid inlet 11, the other end of the U-shaped main channel is connected to the liquid collection pool 15, and the liquid collection pool 15 is connected to the liquid outlet 12.

[0043] In some embodiments, each of the main channels 13 includes three channel portions (131, 132, 133), one end of the channel portion 132 is interconnected with the corresponding end of the adjacent channel portion 131, and the other end of the channel portion 132 is interconnected with the corresponding end of the adjacent channel portion 133 to form an S-shaped main channel, and the three channel portions (131, 132, 133) are connected in series to form an S-shaped main channel. In some embodiments, one end of the S-shaped main channel 13 is connected to the liquid inlet 11, and the other end of the S-shaped main channel is connected to the liquid outlet 12; in some embodiments, the microfluidic structure 1 also includes a liquid collection pool 15, one end of the S-shaped main channel 13 is connected to the liquid inlet 11, and the other end is connected to the liquid collection pool 15, and the liquid collection pool 15 is connected to the liquid outlet 12.

[0044] In some embodiments, each of the main channels 13 includes more than four channel portions. When the main channel 13 includes four channel portions, corresponding ends of two adjacent channel portions are connected to form a U-shape, so that the four channel portions are connected in series to form three U-shapes, and the opening of the middle U-shape is opposite to the two adjacent U-shaped openings; in some embodiments, one end of the main channel 13 is connected to the liquid inlet 11, and the other end is connected to the liquid outlet 12; in some embodiments, one end of the main channel 13 is connected to the liquid inlet 11, and the other end is connected to the liquid collection pool 15, and the liquid collection pool 15 is connected to the liquid outlet 12.

[0045] Figure 2 FIG. 1 shows a partially enlarged schematic diagram of a microfluidic unit according to an embodiment of the present disclosure. Figure 2 In some embodiments, each liquid storage structure 14 includes: a liquid reservoir 141, suitable for containing liquid to form micro-droplets; a liquid reservoir channel 142, suitable for liquid to flow into the liquid reservoir 141; and a limiting channel 143, which is connected to the liquid reservoir 141. The two ends of the liquid reservoir channel 142 are respectively connected to the liquid reservoir 141 and the channel portion 131, and the two ends of the limiting channel 143 are respectively connected to the liquid reservoir 141 and the channel portion 132.

[0046] In some embodiments, the angle between the liquid reservoir channel 142 and the flow direction of the liquid in the main channel 13 is an acute angle. In some embodiments, the angle a between the liquid reservoir channel 142 and the flow direction A1 of the liquid in the channel portion 131 of the main channel 13 is an acute angle; in some embodiments, the angle a ranges from 30° to 60°. In some embodiments, the angle b between the liquid reservoir channel 142 and the flow direction A2 of the liquid in the channel portion 132 of the main channel 13 is an acute angle; in some embodiments, the angle b ranges from 30° to 60°. The liquid reservoir channel 142 will not have liquid backflow.

[0047] In some embodiments, the angle between the restriction channel 143 and the flow direction of the liquid in the main channel 13 is approximately 90°.

[0048] In the microfluidic chip of the embodiment of the present disclosure, in order to achieve good micro-droplet storage effect and stability, the shapes and sizes of the main channel 13, the liquid storage tank channel 142 and the limiting channel 143 can be designed according to the requirements of actual applications, such as according to the liquid properties, the size of the target particles to be measured, etc.

[0049] In some embodiments, the length of the main channel 13 is 20 mm to 50 mm, the length of the reservoir channel 142 is 100 μm to 500 μm, and the length of the limiting channel 143 is 100 μm to 200 μm.

[0050] In some embodiments, the distance from the center of the liquid reservoir channel 142 to two adjacent channel portions is the same; in some embodiments, the distance from the center of the liquid reservoir channel 142 to the channel portion connected to the liquid reservoir channel 142 is different from the distance from the center of the liquid reservoir channel 142 to the channel portion connected to the limiting channel 143.

[0051] In some embodiments, the cross-sectional area of ​​the main channel 13 is larger than the cross-sectional area of ​​the liquid reservoir channel 142, that is, the cross-sectional area of ​​each channel portion is larger than the cross-sectional area of ​​the liquid reservoir channel 142; for the liquid reservoir channel 142 and the limiting channel 143 connected to the same liquid reservoir 141, the cross-sectional area of ​​the liquid reservoir channel 142 is larger than the cross-sectional area of ​​the limiting channel 143.

[0052] In some embodiments, the cross-sections of the main channel 13 , the liquid reservoir channel 142 , and the limiting channel 143 are rectangular, and specifically can be right-angled rectangles or rounded rectangles.

[0053] In some embodiments, the width of the main channel 13 with a rectangular cross-section is 50μm to 1000μm, for example, 250μm, 500μm or 750μm, etc.; the depth of the main channel 13 with a rectangular cross-section is 50μm to 1000μm, for example, 250μm, 600μm, 850μm or 950μm, etc.

[0054] In some embodiments, to ensure that the target particles in the liquid can pass through the liquid reservoir channel 142, the width of the liquid reservoir channel 142 with a rectangular cross-section is 50μm to 1000μm, for example, it can be 100μm, 500μm or 800μm, etc.; the depth of the liquid reservoir channel 142 with a rectangular cross-section is 50μm to 1000μm, for example, it can be 100μm, 600μm, or 900μm, etc.

[0055] In some embodiments, to ensure that target particles in the liquid cannot pass through the limiting channel 143, the width of the limiting channel 143 with a rectangular cross-section is 10μm to 100μm, and specifically, for example, it can be 30μm, 60μm or 90μm, etc.; the depth of the limiting channel 143 with a rectangular cross-section is 10μm to 100μm, and specifically, for example, it can be 30μm, 60μm or 90μm, etc.

[0056] In some embodiments, to ensure that only one target particle is stored in the liquid reservoir 141 to avoid errors in subsequent detection, liquid reservoirs 141 of different sizes are selected according to the particle size of the target particle. In some embodiments, the particle size of the target particle is 50 μm to 1000 μm. In some embodiments, the liquid reservoir 141 is cylindrical, and the circular diameter of the cylindrical top surface of the liquid reservoir 141 is 50 μm to 1000 μm, and specifically, it can be 100 μm, 500 μm or 800 μm, etc.; the depth of the liquid reservoir is 50 μm to 1000 μm, and specifically, it can be 100 μm, 600 μm, or 900 μm, etc. In some embodiments, the liquid reservoir 141 is a cube, and its volume is designed according to the size of the target particle. In some embodiments, the side length of the cube-shaped liquid reservoir 141 is 50 μm to 1000 μm, and specifically, it can be 100 μm, 600 μm, or 900 μm, etc.

[0057] In a specific embodiment, the width of the main channel 13 is 250 μm and the depth is 250 μm, the width of the liquid reservoir channel 142 is 100 μm and the depth is 100 μm, the width of the limiting channel 143 is 30 μm and the depth is 30 μm, the diameter of the liquid reservoir 141 is 100 μm and the depth is 100 μm, and the microfluidic chip is suitable for forming target particles with a particle size of 100 μm in the liquid reservoir 141.

[0058] In some embodiments, the main channel 13 , the liquid reservoir channel 142 and the limiting channel 143 of the microfluidic structure 1 are made of thermoplastic plastics such as PMMA and PC or glass, PDMS, etc., and have a porous structure.

[0059] In the microfluidic chip of the embodiment of the present disclosure, the microfluidic structure 1 may include a plurality of microfluidic units, and the plurality of microfluidic units are arranged in parallel between a liquid inlet 11 and a liquid outlet 12. Liquid enters the plurality of microfluidic units respectively through the liquid inlet 11. After the plurality of microfluidic units are filled with liquid, excess liquid enters a liquid collection pool 15 for storage and is discharged through the liquid outlet 12.

[0060] In some embodiments, a plurality of microfluidic units are arranged in parallel, and adjacent channel portions in the microfluidic units are connected in series. In practical applications, the number of main channels and the number of microfluidic units can be designed according to requirements.

[0061] In some embodiments, there are multiple liquid storage structures 141, that is, there are multiple liquid storage tanks 141, and the number of liquid storage tank channels 142 and limiting channels 143 corresponds to the number of liquid storage tanks 141. Multiple liquid storage tank channels 142 are distributed between adjacent U-shaped channel portions, and the spacing between any two adjacent liquid storage tanks 141 can be the same or different to meet the requirements of practical applications.

[0062] The density of the liquid reservoirs is set according to the detection requirements. In some embodiments, the distance between any two adjacent liquid reservoirs 141 is 400 μm to 1000 μm, and specifically may be 500 μm, for example.

[0063] refer to Figure 1 and Figure 2 The main channel 13 includes three channel parts (131, 132, 133), and the channel part 131, the channel part 132, and the channel part 133 are connected in series in an S shape. Figure 1 and Figure 2 The process of forming microdroplets in a microfluidic chip corresponding to the embodiment is described in detail.

[0064] (1) Liquid is added from the liquid inlet 11, and the liquid flows to all microfluidic channel units respectively, first flowing into the channel portion 131 of the main channel 13 of the microfluidic channel unit, and continues to flow in the channel portion 131 along the direction A1;

[0065] (2) Since the cross section of the channel portion 131 is larger than the cross section of the reservoir channel 142, at the junction of the channel portion 131 and the reservoir channel 142, the cross section area becomes smaller, the capillary force increases, a part of the liquid flows into the reservoir channel 142 and flows into and fills the reservoir 141, and then enters and fills the restriction channel 143, and the liquid stops at the junction between the restriction channel 143 and the channel portion 132;

[0066] (3) The liquid flows along the channel portion 131 and gradually fills up all the liquid storage structures 14 connected to the channel portion 131;

[0067] (4) The liquid flows to the connection point between the channel portion 131 and the channel portion 132, enters the channel portion 132, and flows along the direction A2, gradually filling up all the liquid storage structures 14 between the channel portion 132 and the channel portion 133;

[0068] (5) The liquid flows to the connection point between the channel portion 132 and the channel portion 133, and flows into the channel portion 133. The liquid enters the liquid collecting tank 15 from the channel portion 133. All liquid storage structures 14 are eventually filled with liquid. Excess liquid is stored in the liquid collecting tank 15 and can be discharged in a timely manner. Micro-droplets are formed in the liquid storage tank 141. The micro-droplets include target particles, so that the target particles can be detected later.

[0069] To further enhance the fluidity of the liquid in the microfluidic structure 1, in some embodiments, the main component of the liquid is water, and the inner surface of the main channel 13, the inner surface of the reservoir channel 142, and the inner surface of the limiting channel 143 are hydrophilic surfaces to facilitate the expansion and flow of the liquid therein. The hydrophilic surface can be obtained by surface deposition treatment using polyvinyl alcohol or silicon dioxide, the hydrophilic property remains stable, and the hydrophilic surface has no effect on the visible light transmittance, and will not affect the detection effect when applied to fluorescence detection.

[0070] Figure 3 FIG. 1 shows a schematic diagram of a three-dimensional structure of a microfluidic chip according to an embodiment of the present disclosure. Figure 3 The microfluidic chip further comprises: a first substrate 2 and a second substrate 3 arranged opposite to each other. The first substrate 2 is arranged on a first side of the microfluidic structure 1 so as to seal the first side of the microfluidic structure 1. The second substrate 3 is arranged on a second side of the microfluidic structure 1 so as to seal the second side of the microfluidic structure 1.

[0071] In some embodiments, a plurality of electrodes are provided on the first substrate 2 or / and the second substrate 3, and the plurality of electrodes are located at positions corresponding to the respective channel portions of the main channel, and are suitable for being electrically connected to a power source so as to apply a voltage to generate an electric field. In the microfluidic channel structure 1, the inner walls of the main channel, the reservoir channel, and the limiting channel are porous, and the electrodes are charged by applying a voltage to generate an electric field in the area between the electrodes. In the electric field, the porous inner walls absorb positive and negative ions in the liquid, so that the liquid is relatively charged, and thus the liquid flows under the action of the electric field force.

[0072] In some embodiments, the electrode is a composite material of conductive powder such as Ag-PDMS / C-PDMS and a polymer material, has good conductivity and corrosion resistance, and does not chemically react when in contact with liquid.

[0073] In order to better enhance the fluidity of the liquid by the electric field force, the distribution of the electrodes can be distributed according to the fluidity properties of the liquid and the microfluidic structure 1, so as to form a uniform or non-uniform electric field in different parts of the microfluidic structure 1. The electrodes are connected to a power source, and the size and distribution of the electric field are adjusted by the density of the electrodes and the direction and size of the voltage applied to each electrode.

[0074] In some embodiments, a plurality of electrodes are disposed on the first substrate 2 or the second substrate 3 , and positions of the plurality of electrodes correspond to positions of respective channel portions of the main channel, and the intervals between two adjacent electrodes may be the same or different.

[0075] In some embodiments, voltages of different magnitudes and positive and negative voltages may be applied to different electrodes to make the electrodes positively or negatively charged, thereby forming electric fields of different magnitudes and directions in different regions.

[0076] In some embodiments, electrodes are disposed on both the first substrate 2 and the second substrate 3 .

[0077] In some embodiments, a sample inlet 21 is disposed on the first substrate 2 and is connected to the liquid inlet 11 . Liquid can enter the liquid inlet 11 through the sample inlet 21 and then enter the microfluidic channel structure 1 .

[0078] In some embodiments, a sample outlet 22 is provided on the first substrate 2 and is communicated with the liquid outlet 12 , and the liquid is discharged from the microfluidic channel structure through the sample outlet 22 .

[0079] In some embodiments, the first substrate 2 and the second substrate 3 have high light transmittance, and the materials of the first substrate 2 and the second substrate 3 can be thermoplastic plastics such as polymethyl methacrylate, polycarbonate, or glass, polydimethylsiloxane, etc.

[0080] In some embodiments, the first substrate 2 and the second substrate 3 are connected and fixed, and the connection and fixing method can be adhesive bonding, ultrasonic welding, thermal compression bonding, etc.

[0081] The first substrate 2 and the second substrate 3 can be mass-produced through processes such as laser ablation, injection molding, micro-milling, etching, and photolithography.

[0082] In some embodiments, a plurality of electrodes are embedded through the first substrate 2 and fixed to the first substrate 2. In some embodiments, a plurality of electrodes are embedded through the second substrate 3 and fixed to the second substrate 3.

[0083] The microfluidic chip of the embodiment of the present disclosure can be applied to detection in the field of medical diagnosis. The application of the microfluidic chip to fluorescence detection is described below.

[0084] The specific steps include:

[0085] (1) Adding a test solution into the injection port 21, the test solution can be prepared by mixing a test sample with a reaction reagent having a fluorescent dye;

[0086] (2) The test solution flows into each main channel under the action of capillary force, enters and gradually fills each reservoir channel, reservoir and restriction channel, forms microdroplets in the reservoir, and the microdroplets include target particles, the main channel is filled with the test solution, and part of the test solution enters the collection tank;

[0087] (3) During the flow of the solution to be tested, a voltage is applied to at least part of the electrodes on the first substrate 2 or the second substrate 3. Since the solution to be tested has a certain charge, an electric field is formed between the electrodes after the electrodes are conductive, and the electric field force enhances the fluidity of the solution to be tested;

[0088] (4) After the main channel and the liquid storage structure are filled with the solution to be tested, a sealing liquid is added from the injection port 21. The sealing liquid is immiscible with the solution to be tested and is preferably a non-polar liquid such as silicone oil. The sealing liquid enters the main channel through capillary force and discharges the solution to be tested in the main channel.

[0089] (5) The sealing liquid fills the main channel, the solution to be tested fills the liquid storage structure, and the solution to be tested in the liquid collection pool is discharged from the sample outlet 22 through the liquid outlet 12.

[0090] (6) The sample inlet 21 and the sample outlet 22 are closed and fluorescence detection is performed.

[0091] Using the microfluidic chip of the embodiment of the present disclosure for detection can ensure that the solution to be tested forms microdroplets in the liquid reservoir in the microfluidic chip, the target particles are stored in the liquid reservoir, and the liquid reservoir, the restriction channel and the liquid reservoir channel are sealed with liquid sealing liquid to ensure smooth detection.

[0092] The above is only an exemplary embodiment used to illustrate the principle of the present disclosure, and is not intended to limit the scope of protection of the present disclosure. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also within the scope of protection of the present disclosure.

Claims

1. A microfluidic chip for forming microdroplets, comprising a liquid inlet and a liquid outlet, characterized in that: A microfluidic structure is included between the liquid inlet and the liquid outlet, and the microfluidic structure includes: At least one microfluidic unit, each microfluidic unit comprises: at least one main channel, one end of the main channel is connected to the liquid inlet, and the other end of the main channel is connected to the liquid outlet, each main channel comprises at least two channel parts, and corresponding ends of adjacent channel parts are connected to form a U shape; and at least one liquid storage structure is located between adjacent U-shaped channel parts and is respectively connected to the two channel parts.

2. The microfluidic chip according to claim 1, characterized in that: Each liquid storage structure includes: a liquid reservoir adapted to contain liquid to form microdroplets; a liquid reservoir channel, adapted for liquid to flow into the liquid reservoir through the channel; The restriction channel is communicated with the liquid storage tank.

3. The microfluidic chip according to claim 2, characterized in that: The cross-sectional area of ​​the main channel is larger than the cross-sectional area of ​​the liquid reservoir channel, and the cross-sectional area of ​​the liquid reservoir channel is larger than the cross-sectional area of ​​the limiting channel.

4. The microfluidic chip according to claim 3, characterized in that: The cross sections of the main channel, the liquid reservoir channel and the limiting channel are rectangular.

5. The microfluidic chip according to claim 4, characterized in that: The width of the limiting channel is 10 μm to 100 μm, and the depth of the limiting channel is 10 μm to 100 μm.

6. The microfluidic chip according to claim 5, characterized in that: The liquid reservoir is cylindrical, the diameter of the liquid reservoir is 50 μm to 1000 μm, and the depth of the liquid reservoir is 50 μm to 1000 μm.

7. The microfluidic chip according to claim 4, characterized in that: The width of the main channel is 50 μm to 1000 μm, and the depth of the main channel is 50 μm to 1000 μm.

8. The microfluidic chip according to claim 4, characterized in that: The width of the liquid reservoir channel is 50 μm to 1000 μm, and the depth of the liquid reservoir channel is 50 μm to 1000 μm.

9. The microfluidic chip according to claim 2, characterized in that: The length of the liquid storage channel is 100 μm to 500 μm, and the length of the restriction channel is 100 μm to 200 μm.

10. The microfluidic chip according to claim 2, characterized in that: The angle between the liquid storage channel and the flow direction of the liquid in the main channel is an acute angle.

11. The microfluidic chip according to claim 10, characterized in that: The angle between the liquid storage channel and the flow direction of the liquid in the main channel is 30° to 60°.

12. The microfluidic chip according to claim 2, characterized in that: The inner surfaces of the main channel, the liquid reservoir channel and the limiting channel are hydrophilic surfaces.

13. The microfluidic chip according to claim 2, characterized in that: There are multiple liquid storage tanks, which are evenly distributed between adjacent U-shaped channel parts.

14. The microfluidic chip according to claim 13, characterized in that: The distance between any two adjacent liquid storage tanks is 400 μm to 1000 μm.

15. The microfluidic chip according to any one of claims 1 to 14, characterized in that: Also includes: The liquid collecting pool is connected between the other end of the main channel and the liquid outlet.

16. The microfluidic chip according to claim 15, characterized in that: Each of the main channels includes two channel portions connected to form a U-shape, one end of the U-shaped main channel is connected to the liquid inlet, and the other end is connected to the liquid collecting tank.

17. The microfluidic chip according to claim 15, characterized in that: Each of the main channels includes three channel portions connected to form an S shape, one end of the S-shaped main channel is connected to the liquid inlet, and the other end is connected to the liquid collecting pool.

18. The microfluidic chip according to any one of claims 1 to 14, characterized in that: Also includes: A first substrate is disposed on a first side of the microfluidic channel structure so as to seal the first side of the microfluidic channel structure; The second substrate is disposed on the second side of the microfluidic channel structure so as to seal the second side of the microfluidic channel structure.

19. The microfluidic chip according to claim 18, characterized in that: A plurality of electrodes are disposed on the first substrate and / or the second substrate, and the plurality of electrodes are located at positions corresponding to the main channels.

20. The microfluidic chip according to claim 19, characterized in that: The plurality of electrodes are spaced apart from each other and distributed non-uniformly on the first substrate or the second substrate.

21. The microfluidic chip according to claim 18, characterized in that: The first substrate is provided with an injection port which is communicated with the liquid inlet and is suitable for adding liquid into the microfluidic channel structure through the injection port.

22. The microfluidic chip according to claim 18, characterized in that: The first substrate is provided with a sample outlet, which is communicated with the liquid outlet and is suitable for discharging the liquid out of the microfluidic channel structure through the sample outlet.

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