A microfluidic device, holder and method for plasma separation

Abstract

The application relates to a microfluidic device, a support and a plasma separation method for whole blood filtration, comprising a body, a filtration mechanism arranged in the body and a collection tank in communication with the filtration mechanism, the filtration mechanism is used for filtering red blood cells, and the collection tank is used for collecting plasma; the application further comprises a driving mechanism used for driving a sample in the body to move from a side where the filtration mechanism is located to a side where the collection tank is located. The driving mechanism can improve the flow speed of the sample, thereby improving the whole blood filtration speed, shortening the whole blood separation time and reducing the possibility of hemolysis. The microfluidic device provided by the embodiment can obtain plasma without a centrifuge, has a small device volume and is easy to operate.

Description

Technical Field

[0001] This invention relates to the field of biotechnology, and more particularly to a microfluidic device, a scaffold, and a method for plasma separation. Background Technology

[0002] Biochemical medical testing of human blood can provide important information reflecting a person's health status. Currently, most blood samples used in clinical practice are plasma, and plasma extraction largely relies on additional equipment, such as centrifuges. Centrifuges are mostly bulky and inconvenient to carry, which limits testing locations and is time-consuming, hindering rapid disease detection.

[0003] In the prior art, microfluidic devices for whole blood filtration can solve the above-mentioned technical problems. Existing microfluidic devices include a main body, a whole blood separation mechanism, a reservoir, and an outlet disposed on the chip body. The whole blood separation mechanism is used to filter and separate blood to obtain plasma. The reservoir is disposed between the whole blood separation mechanism and the outlet so that the separated plasma flows into the outlet.

[0004] However, existing microfluidic devices use capillary action to flow plasma, resulting in slow whole blood filtration.

[0005] Furthermore, existing technologies often use microcolumn arrays to filter red blood cells. Whole blood moves slowly within the microcolumn array, which often leads to hemolysis and inaccurate test results. In addition, after the whole blood is filtered, air bubbles are present in the plasma, which is detrimental to the testing of plasma samples. Summary of the Invention

[0006] One object of the present invention is to provide a microfluidic device to at least solve one of the above-mentioned technical problems.

[0007] To achieve the above objectives, a first aspect of the present invention provides a microfluidic device for whole blood filtration, comprising a body, a filtration mechanism disposed within the body, and a collection tank communicating with the filtration mechanism, wherein the filtration mechanism is used to filter red blood cells, the collection tank is used to collect plasma, and further comprising:

[0008] A driving mechanism is provided for driving the sample within the body to move from the side where the filtering mechanism is located to the side where the collection tank is located.

[0009] Optionally, the drive mechanism is used to introduce compressed air into the filter mechanism to drive the sample inside the body to move toward the collection tank.

[0010] Optionally, the drive mechanism is located on the side of the filter mechanism away from the collection tank.

[0011] Optionally, the main body has a drive cavity with an opening, the drive cavity is connected to the filter mechanism, and the drive mechanism includes a deformable membrane that covers the opening.

[0012] Optionally, the driving mechanism further includes a recovery driving element disposed in the driving cavity and capable of driving the deformable membrane to recover its deformation.

[0013] Optionally, the recovery drive element is an elastic element.

[0014] Optionally, the elastic element is at least one of sponge, sheet metal, and spring.

[0015] Optionally, the drive mechanism includes a vacuum component for creating a vacuum environment in the collection tank.

[0016] Optionally, the air extraction device is an air pump or a syringe.

[0017] Optionally, the main body has a receiving cavity, and the filtering mechanism is disposed in the receiving cavity. The filtering mechanism includes a primary filtration section, which can block and adsorb some red blood cells.

[0018] Optionally, the primary filtration section includes a filter membrane.

[0019] Optionally, the bottom of the receiving cavity is provided with a flow guiding structure for guiding the sample.

[0020] Optionally, the main body has an injection port communicating with the receiving cavity, the flow guiding structure includes a buffer zone and a filtration zone, at least part of the buffer zone is disposed opposite to the injection port, and the primary filtration section is disposed on the upper side of the filtration zone.

[0021] Optionally, the buffer zone is located on the side of the filtering area away from the collection tank.

[0022] Optionally, the flow guiding structure includes a first flow guiding structure, which is used to allow the sample to flow toward the side where the collection tank is located.

[0023] Optionally, the first flow guiding structure includes a plurality of spaced-apart first flow guiding columns, the first flow guiding columns being connected to the bottom of the receiving cavity, and the first flow guiding columns extending along the direction in which the filtering mechanism and the collecting groove are arranged sequentially.

[0024] Optionally, the flow guiding structure further includes a second flow guiding structure. In a first direction, at least one side of the first flow guiding structure is provided with the second flow guiding structure. The first direction is perpendicular to the direction in which the filtering mechanism and the collection tank are arranged in sequence, as well as the thickness direction of the microfluidic device. The second flow guiding structure is used to make the sample flow towards the side where the first flow guiding structure is located.

[0025] Optionally, the first flow guiding structure is provided with the second flow guiding structure on both sides along the first direction.

[0026] Optionally, the second flow guiding structure includes a plurality of spaced-apart second flow guiding columns, which are connected to the bottom of the receiving cavity and extend along the first direction.

[0027] Optionally, the bottom of the receiving cavity is connected to a first support portion, which is used to support the primary filter portion so that there is a first gap between the primary filter portion and the flow guiding structure.

[0028] Optionally, a limiting part is also provided in the receiving cavity. The limiting part is located on one side of the primary filter and is used to restrict the primary filter from moving towards the buffer zone.

[0029] Optionally, the filtration mechanism further includes a re-filtration section, which is located downstream of the primary filtration section and is used to filter red blood cells from the sample.

[0030] Optionally, the side of the re-filtration section closest to the primary filtration section is a curve or a broken line.

[0031] Optionally, the re-filtration section includes a first filtration zone, which includes a plurality of first micropillars arranged in an array.

[0032] Optionally, the re-filtration section further includes a second filtration section disposed downstream of the first filtration section, the second filtration section including a plurality of second micropillars arranged in an array.

[0033] Optionally, the spacing between two adjacent first micropillars is greater than the spacing between two adjacent second micropillars, and / or the cross-sectional area of ​​the first micropillar is greater than the cross-sectional area of ​​the second micropillar.

[0034] Optionally, the spacing between two adjacent second micropillars is 0.5 micrometers to 2 micrometers; and / or, the spacing between two adjacent first micropillars is 1 micrometer to 1.2 micrometers; and / or, the maximum dimension at the cross-section of the first micropillar is 10 micrometers to 1000 micrometers; and / or, the maximum dimension at the cross-section of the second micropillar is 10 micrometers to 500 micrometers.

[0035] Optionally, a flow guide is provided between the primary filtration section and the secondary filtration section, the flow guide being used to allow the sample to flow from the primary filtration section to the side where the secondary filtration section is located.

[0036] Optionally, the drainage portion is disposed at the bottom of the receiving cavity;

[0037] Alternatively, the drainage section may have a second gap with the bottom of the receiving cavity, and / or the drainage section and the primary filtration section may be an integral structure.

[0038] Optionally, when the drainage portion has a second gap with the bottom of the receiving cavity, the body further includes a second support portion connected to the bottom of the receiving cavity, the second support portion being used to create the second gap between the drainage portion and the bottom of the receiving cavity.

[0039] Optionally, the size of the receiving cavity gradually decreases from the upstream side to the downstream side along the sample flow.

[0040] Optionally, a capillary channel is provided between the filtration mechanism and the collection tank, the capillary channel being used to allow plasma to flow from the filtration mechanism into the collection tank.

[0041] Optionally, the capillary channel is provided with an antifoaming mechanism, which is used to eliminate air bubbles in the plasma.

[0042] Optionally, the defoaming mechanism includes a plurality of baffles spaced apart along the length of the capillary channel, the baffles extending along the width of the capillary channel, the baffles having a third gap with the top wall of the capillary channel for allowing plasma to pass through, and the capillary channel having a first sidewall and a second sidewall in the width direction.

[0043] One end of the stop post is connected to the first side wall, and the other end is connected to the second side wall; or

[0044] The baffle includes a first baffle and a second baffle. One end of the first baffle is connected to the first sidewall of the capillary channel, and the other end is spaced apart from the second sidewall. The second baffle is connected to the second sidewall of the capillary channel, and the other end is spaced apart from the first sidewall. The first baffle and the second baffle are arranged alternately.

[0045] Optionally, the defoaming mechanism has a confluence slit at one end near the collection tank.

[0046] Optionally, the capillary channel is further provided with an acceleration mechanism for accelerating plasma flow, the acceleration mechanism being located downstream of the defoaming mechanism.

[0047] Optionally, the acceleration mechanism includes a plurality of spaced-apart third micropillars connected to the bottom wall of the capillary channel, and the surface of the third micropillars has a hydrophilic substance.

[0048] Optionally, the outlet end of the capillary channel is inclined downwards.

[0049] Optionally, the body also includes a sealing element for closing or opening the injection port.

[0050] Optionally, the body includes a base and a cover, the base having a receiving groove, and the cover covering the base to form the receiving cavity.

[0051] Optionally, the cover is made of single-sided adhesive.

[0052] Optionally, the surface of the collection tank is provided with a hydrophilic layer.

[0053] Another object of the present invention is to provide a microfluidic device to solve one of the above-mentioned technical problems.

[0054] To achieve this objective, the second aspect of the present invention adopts the following technical solution:

[0055] A bracket adapted to the microfluidic device, the bracket being used to place the microfluidic device at an acute angle or right angle to the horizontal plane, and to place the side where the collection tank is located lower than the side where the filtration mechanism is located.

[0056] Optionally, the support includes:

[0057] Base plate;

[0058] At least one column, the lower end of which is connected to the base plate;

[0059] An inclined plate is connected to the base plate and is set at an angle to the horizontal plane. One end of the microfluidic device, which has a collection groove, abuts against the inclined plate, and the other end of the microfluidic device abuts against the top of the column.

[0060] Another object of the present invention is to provide a plasma separation method to solve one of the above-mentioned technical problems.

[0061] To achieve this objective, the third aspect of the present invention adopts the following technical solution:

[0062] A plasma separation method adapted to the aforementioned microfluidic device and stent, wherein plasma is separated from whole blood by gravity induction and capillary action.

[0063] As can be seen from the above, the technical solution provided by this invention can increase the flow rate of the sample through the driving mechanism, thereby increasing the whole blood filtration rate, shortening the whole blood separation time, and reducing the possibility of hemolysis. The microfluidic device provided in this embodiment can obtain plasma without relying on a centrifuge, and the device is small in size and easy to operate.

[0064] The primary filtration section and the secondary filtration section work together to quickly filter whole blood to obtain plasma. The primary filtration section filters out most red blood cells, so the sample can flow quickly into the secondary filtration section. Due to the reduced sample concentration (because some red blood cells are filtered by the primary filtration section), the sample can flow more quickly in the secondary filtration section, increasing the flow rate of the sample, shortening the whole blood separation time, and avoiding hemolysis.

[0065] A defoaming mechanism is provided inside the capillary channel to eliminate air bubbles in the plasma.

[0066] The microfluidic device has capillary channels that accelerate plasma flow and shorten whole blood separation time; the outlet end of the capillary channel is set at an angle to form an anti-backflow channel to prevent plasma backflow. Attached Figure Description

[0067] Figure 1 This is a schematic diagram of the structure of the first microfluidic device provided in the embodiments of the present invention;

[0068] Figure 2 This is an exploded view of the first microfluidic device provided in the embodiments of the present invention;

[0069] Figure 3 This is a partial structural diagram of the first type of microfluidic device provided in the embodiments of the present invention. Figure 1 ;

[0070] Figure 4 This is a schematic diagram of the structure of the second microfluidic device provided in the embodiments of the present invention;

[0071] Figure 5 This is a partial structural diagram of the first type of microfluidic device provided in the embodiments of the present invention. Figure 2 ;

[0072] Figure 6 This is a cross-sectional view of the first microfluidic device provided in the embodiments of the present invention;

[0073] Figure 7 yes Figure 6 A magnified view of a section at point D;

[0074] Figure 8 Yes, yes Figure 3 A magnified view of a section at point A in the middle;

[0075] Figure 9This is an exploded view of the second microfluidic device provided in the embodiments of the present invention;

[0076] Figure 10 Yes, yes Figure 9 A magnified view of a section at point E in the middle;

[0077] Figure 11 Yes, yes Figure 9 A magnified view of a section at point G in the middle;

[0078] Figure 12 Yes, yes Figure 4 A magnified view of a section at point B in the middle;

[0079] Figure 13 This is a schematic diagram of the structure of the bracket provided in an embodiment of the present invention;

[0080] Figure 14 This is a schematic diagram of the structure of the microfluidic device supported by the bracket provided in an embodiment of the present invention. Figure 1 ;

[0081] Figure 15 This is a schematic diagram of the structure of the microfluidic device supported by the bracket provided in an embodiment of the present invention. Figure 2 .

[0082] In the picture:

[0083] 1. Body; 11. Base; 111. Receiving cavity; 1111. Second sub-slot; 12. Cover; 121. Through port; 122. Injection port; 13. Drive cavity; 131. Drive groove; 14. Support bar; 15. First support part; 151. Support column; 16. Limiting part; 17. Sealing part; 18. Connecting groove; 19. Second support part;

[0084] 2. Filtration mechanism; 21. Filter membrane; 22. Re-filtration section; 221. First filtration zone; 2211. First microcolumn; 222. Second filtration zone; 2221. Second microcolumn; 23. Curve; 24. Broken line; 25. First gap; 26. Second gap;

[0085] 3. Capillary channel; 31. Outlet end; 32. Defoaming mechanism; 321. Baffle; 322. First baffle; 323. Second baffle; 324. Confluence inlet; 33. First sidewall; 34. Second sidewall; 35. Acceleration mechanism; 351. Third micro-column;

[0086] 4. Drive mechanism; 41. Deformable membrane; 42. Sponge;

[0087] 5. Flow guiding structure; 51. First flow guiding structure; 511. First flow guiding column; 512. First flow guiding groove; 52. Second flow guiding structure; 521. Second flow guiding column; 522. Second flow guiding groove; 53. Buffer zone; 54. Filtering zone;

[0088] 6. Collection tank;

[0089] 100. Microfluidic device; 200. Support; 201. Base plate; 202. Column; 203. Inclined plate;

[0090] W, first direction; L, second direction; T, third direction. Detailed Implementation

[0091] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings, not all of them.

[0092] This invention defines certain directional terms. Unless otherwise stated, the directional terms used, such as "up," "down," "left," "right," "inner," and "outer," are used for ease of understanding and therefore do not constitute a limitation on the scope of protection of this invention.

[0093] 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.

[0094] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0095] This embodiment provides a microfluidic device 100 for whole blood filtration, such as separating plasma from red blood cells in whole blood and collecting the plasma to improve the plasma separation speed, but it is not limited to this and can also be used to separate other substances to be detected.

[0096] like Figures 1-2As shown, the microfluidic device 100 provided in this embodiment includes a body 1, a filter mechanism 2 disposed in the body 1, and a collection tank 6 communicating with the filter mechanism 2. The filter mechanism 2 is used to filter red blood cells to obtain plasma, and the collection tank 6 is used to collect plasma.

[0097] Optionally, in order to accommodate the sample and the filtering mechanism 2, a receiving cavity 111 is provided on the main body 1, into which the sample can be injected, and the filtering mechanism 2 can be disposed in the receiving cavity 111. It is understood that the sample in this embodiment can be whole blood, whole blood with some red blood cells filtered, or plasma, and those skilled in the art can understand the meaning of the sample according to the actual situation.

[0098] Specifically, such as Figure 2 As shown, the main body 1 has an injection port 122 that communicates with the receiving cavity 111. The injection gun can pass through the injection port 122 to inject whole blood into the receiving cavity 111. Preferably, the injection port 122 is positioned opposite to the filter mechanism 2 so that the whole blood can directly enter the filter mechanism 2.

[0099] Optionally, the body 1 includes a base 11 and a cover 12. The base 11 has a receiving groove, and the cover 12 covers the base 11 to cover the receiving groove, thereby forming a receiving cavity 111. This type of body 1 facilitates the processing of the receiving cavity 111.

[0100] like Figure 2 As shown, and in combination Figure 1 For example, the collection slot 6 is formed on the base 11 and is not covered by the cover 12.

[0101] Optionally, the cover 12 is a single-sided adhesive, such as pressure-sensitive adhesive. The cover 12 is connected to the body 1 by adhesive bonding. The cover 12 makes the microfluidic device 100 easy to process, and the small thickness of the pressure-sensitive adhesive makes the microfluidic device 100 small in size.

[0102] Optionally, the injection port 122 is formed on the pressure-sensitive adhesive. To seal the injection port 122, the body 1 may also include a sealing member 17 for closing or opening the injection port 122. The sealing member 17 is preferably a sticker that can adhere to the body 1. The sticker is thin and relatively soft, thus allowing for better adhesion to the pressure-sensitive adhesive.

[0103] like Figure 1 and Figure 2As shown, for ease of explanation, this embodiment defines a first direction W, a second direction L, and a third direction T, all of which are perpendicular to each other. The third direction T represents the thickness direction of the microfluidic device 100, and the second direction L represents the orientation of the filter mechanism 2 and the collection groove 6; that is, the overall flow direction of the sample is consistent with the second direction L. For example, the first direction W is consistent with the length direction of the microfluidic device 100, and the second direction L is consistent with the width direction of the microfluidic device 100.

[0104] like Figure 2 As shown, after the sample is injected into the receiving cavity 111, in order to accelerate the downstream flow of the sample, the bottom of the receiving cavity 111 may be provided with a flow guiding structure 5 for guiding the sample. The flow guiding structure 5 can guide the sample to flow in a preset direction and increase the flow rate of the sample.

[0105] like Figure 2 As shown, the flow guiding structure 5 includes a buffer zone 53 and a filtration zone 54. At least a portion of the buffer zone 53 is disposed opposite to the injection port 122, and the filtration zone 54 is disposed opposite to at least a portion of the filtration mechanism 2. Optionally, at least a portion of the filtration mechanism 2 is located on the upper side of the filtration zone 54. That is, no filtration mechanism 2 is provided in the position directly opposite the injection port 122 within the receiving cavity 111. This allows the plasma to be quickly dispersed into the receiving cavity 111, preventing plasma from overflowing from the injection port 122. At the same time, the buffer zone 53 of the flow guiding structure 5 can guide whole blood to quickly enter the filtration zone 54 equipped with the filtration mechanism 2, and be adsorbed by the filter membrane 21 located on the upper side of the filtration zone 54.

[0106] Preferably, the buffer zone 53 is located on the side of the filtration zone 54 away from the collection tank 6, so that after the sample enters the receiving cavity 111, the sample flows along the second direction L, shortening the whole blood filtration time.

[0107] like Figure 2 As shown, a limiting part 16 is also provided inside the receiving cavity 111. The limiting part 16 is disposed on one side of the filtering mechanism 2 (specifically, the filter membrane 21 described below) and is used to restrict the movement of the filtering mechanism 2 (specifically, the filter membrane 21 described below) towards the buffer zone 53, thereby ensuring the buffering effect of the buffer zone 53. Specifically, the limiting part 16 is connected to the bottom of the receiving cavity 111. The limiting part 16 can be part of a cylinder extending along the first direction W (that is, the width direction of the receiving cavity 111). The tension between the surface of the cylinder and the sample is small, thereby reducing the amount of sample residue on the limiting part 16.

[0108] refer to Figure 3 and Figure 4 The flow guiding structure 5 includes a first flow guiding structure 51, which is used to make the sample flow towards the side where the collection tank 6 is located, thereby accelerating the flow speed of the sample along the second direction L.

[0109] Specifically, the first flow guiding structure 51 includes a plurality of spaced first flow guiding columns 511. The first flow guiding columns 511 are connected to the bottom of the receiving cavity 111. The first flow guiding columns 511 extend along the direction in which the filter mechanism 2 and the collection groove 6 are arranged in sequence (i.e., the second direction L, that is, the length direction of the microfluidic device 100). A first flow guiding groove 512 is formed between two adjacent first flow guiding columns 511, and the sample can flow along the first flow guiding groove 512.

[0110] The flow guiding structure 5 also includes a second flow guiding structure 52. At least one side of the first flow guiding structure 51 is provided with the second flow guiding structure 52 along the first direction W, i.e., the first flow guiding structure 51 and the second flow guiding structure 52 are arranged along the first direction W. The second flow guiding structure 52 is used to direct the sample towards the side where the first flow guiding structure 51 is located. The second flow guiding structure 52 can concentrate the sample in the middle of the receiving cavity 111 along the first direction W (i.e., the width direction of the receiving cavity 111), thereby accelerating the sample flow rate. In particular, when the amount of sample in the receiving cavity 111 is small, the second flow guiding structure 52 can guide the sample located at the edge to the middle of the receiving cavity 111, thereby reducing the amount of sample remaining in the receiving cavity 111.

[0111] Preferably, the first flow guiding structure 51 is provided with a second flow guiding structure 52 on both sides along the first direction W, thereby further concentrating the sample in the middle of the receiving cavity 111.

[0112] Specifically, the second flow guiding structure 52 includes a plurality of spaced second flow guiding columns 521. The second flow guiding columns 521 are connected to the bottom of the receiving cavity 111. The second flow guiding columns 521 extend along the first direction W, thereby forming a second flow guiding groove 522 between two adjacent second flow guiding columns 521. The sample can flow along the second flow guiding groove 522 to the first flow guiding structure 51.

[0113] Optionally, both the first guide column 511 and the second guide column 521 are part of a cylinder, and the tension between the surface of the cylinder and the sample is small, thereby reducing the amount of sample residue on the first guide column 511 and the second guide column.

[0114] like Figure 2 and Figure 5 As shown, the filtration mechanism 2 includes a primary filtration section, which can stop and adsorb some red blood cells. When whole blood is dripped into the receiving cavity 111, it contains a large number of red blood cells. The plasma will first pass through the primary filtration section, which can filter out some red blood cells. On the one hand, the primary filtration section can reduce the number of red blood cells in the sample through physical adsorption, thereby reducing the mechanical damage to red blood cells and lowering the probability of hemolysis. On the other hand, the primary filtration section also acts as a blood chromatography, transporting the blood into the microchannels.

[0115] Optionally, the primary filtration section includes a filter membrane 21. The filter membrane 21 has higher water absorption than the flow guiding structure 5, which facilitates the absorption of whole blood from the flow guiding mechanism 5 onto the filter membrane 21. Most of the red blood cells in the whole blood are blocked by the filter membrane 21, thus initially filtering the sample. The remaining sample (containing plasma and some red blood cells) continues to flow forward (i.e., downstream, i.e., on the side where the collection tank 6 is located). The filter membrane 21 can be a glass fiber filter membrane, a polyethersulfone filter membrane, a polytetrafluoroethylene filter membrane, etc. Optionally, the filter membrane 21 can also be modified with a red blood cell trapping agent, such as a lectin, to prevent red blood cells from detaching from the filter membrane 21 again.

[0116] Preferably, the filter membrane 21 is disposed on the upper side of the filter zone 54.

[0117] like Figure 4 , Figures 6-7 As shown, the bottom of the receiving cavity 111 is connected to a first support portion 15, which supports the filter membrane 21 so that there is a first gap 25 between the filter membrane 21 and the flow guiding structure 5. In this embodiment, the filter membrane 21 is approximately parallel to the flow guiding mechanism 5, and a first gap 25 is formed between the filter membrane 21 and the flow guiding mechanism 5. The first gap 25 serves to buffer whole blood and prevent blood from overflowing.

[0118] Optionally, the first support portion 15 includes a plurality of spaced-apart support columns 151, which are connected to the bottom of the receiving cavity 111 and located at the location of the first flow guiding structure 51. Furthermore, the first support portion 15 is located at the filtration zone 54. For example, there are three support columns 151, each located at one of the three vertices of a triangle, thereby effectively supporting the filter membrane 21. The support columns 151 can be cylindrical.

[0119] To better support the filter membrane 21, the body 1 may also include a support strip 14, which is connected to the bottom of the receiving cavity 111. Optionally, support strips 14 are provided at both ends of the bottom of the receiving cavity 111 in the width direction to avoid affecting the sample flow.

[0120] To accelerate sample flow, the filtration mechanism 2 may optionally include a drainage section located downstream of the primary filtration section. This drainage section facilitates sample flow from the filter membrane 21 towards the collection tank 6. It is understood that the drainage section is also located within the receiving cavity 111.

[0121] like Figure 5 and Figure 7As shown, in this embodiment, the drainage section and the bottom of the receiving cavity 111 have a second gap 26. Preferably, the drainage section and the primary filtration section are an integral structure. The sample from the primary filtration section flows directly onto the drainage section, that is, a part of the filter membrane 21 forms the drainage section. However, the main function of the filter membrane 21 here is not to filter the sample, but to guide the sample through capillary action and chromatography to increase the flow rate of the sample.

[0122] like Figure 3 , Figure 5 and Figure 7 As shown, optionally, the body 1 further includes a second support portion 19, which is connected to the bottom of the receiving cavity 111. The second support portion 19 is used to create a second gap 26 between the filter membrane 21 (i.e., the drainage portion) and the bottom of the receiving cavity 111. This allows for better sample flow while preventing the filter membrane 21 (i.e., the drainage portion) from contacting the bottom of the receiving cavity 111, thus preventing sample residue from remaining at the bottom of the cavity. The second support portion 19 can be an annular structure. For example, the annular structure is trapezoidal, or more specifically, an isosceles trapezoid. The second support portion 19 is connected to the sidewall of the receiving cavity 111, thereby supporting the edge portion of the filter membrane 21 (i.e., the drainage portion) and preventing sample residue.

[0123] Of course, in other alternative embodiments, the drainage portion is disposed at the bottom of the receiving cavity 111. In this case, the second support portion 19 may not be provided, and the drainage portion may be placed directly on the bottom of the cavity. In this case, the drainage portion and the filter membrane 21 may be an integral structure or a separate structure.

[0124] like Figure 4 As shown, the size of the receiving cavity 111 gradually decreases from the upstream side to the downstream side along the sample flow. More specifically, the cross-section of the receiving cavity 111 corresponding to the flow guiding structure 5 and the flow outlet is an isosceles trapezoid, with the lower base of the isosceles trapezoid located upstream of the upper base. In this way, the sample gradually converges towards the middle of the first direction W of the filter membrane 21, preparing the sample for further filtration.

[0125] like Figure 3 , Figure 8 and Figures 9-10 As shown, to further filter the sample and remove residual red blood cells, the filtration mechanism 2 also includes a re-filtration section 22, which is located downstream of the filter membrane 21 and is used to filter red blood cells from the sample. A capillary channel 3 may also be included downstream of the re-filtration section 22. Exemplarily, the primary filtration section, the drainage section, the re-filtration section 22, the collection tank 6, and the capillary channel 3 are arranged sequentially along the second direction L. The primary filtration section receives most of the red blood cells, the drainage section allows the sample to flow from the primary filtration section to the re-filtration section 22, the re-filtration section 22 filters out residual red blood cells, and the capillary channel 3 allows plasma to flow from the re-filtration section 22 into the collection tank 6, where the collection tank 6 collects the plasma.

[0126] like Figure 9 As shown, to more clearly illustrate the positional relationship between the primary filtration section, the drainage section, and the re-filtration section 22, the receiving tank is divided into a first sub-tank, a second sub-tank 1111, and a third sub-tank. The flow guiding structure 5, the primary filtration section, the limiting section 16, the first support section 15, and the support bar 14 are disposed in the first sub-tank; the drainage section and the second support section 19 are disposed in the second sub-tank 1111; and the re-filtration section 22 is disposed in the third sub-tank. The first sub-tank, the second sub-tank 1111, and the third sub-tank are arranged sequentially along the second direction L. Optionally, the depth of the second sub-tank 1111 is greater than the depth of the third sub-tank, thereby confining the filter membrane 21 between the limiting section 16 and the sidewall of the second sub-tank 1111, preventing the filter membrane 21 from shifting along the second direction L.

[0127] like Figure 8 and Figure 10 As shown, the size of the re-filtration section 22 gradually decreases from the upstream side to the downstream side of the sample flow to guide the sample into the capillary channel 3.

[0128] like Figure 8 and Figure 10 As shown, the side of the re-filtration section 22 closest to the filter membrane 21, that is, the side of the re-filtration section 22 closest to the filter membrane 21, is a fold line 24 (as shown). Figure 8 ) or curve 23 (such as Figure 10 This facilitates the flow of samples to the re-filtering section 22.

[0129] Optionally, the refiltration section 22 includes a first filtration zone 221, which includes a plurality of first micropillars 2211 arranged in an array to filter red blood cells again through the plurality of spaced first micropillars 2211.

[0130] The refiltration section 22 also includes a second filtration section 222 disposed downstream of the first filtration section 221. The second filtration section 222 includes a plurality of second micropillars 2221 arranged in an array to allow red blood cells to pass through the plurality of spaced second micropillars 2221 again.

[0131] The spacing between two adjacent first micropillars 2211 is greater than the spacing between two adjacent second micropillars 2221, and / or the cross-sectional area of ​​the first micropillar 2211 is greater than the cross-sectional area of ​​the second micropillar 2221. This embodiment further filters red blood cells using an array of micropillars with different spacing and / or micropillars of different sizes.

[0132] Optionally, the spacing between two adjacent second micropillars 2221 is 0.5 micrometers to 2 micrometers; and / or, the spacing between two adjacent first micropillars 2211 is 1 micrometer to 1.2 micrometers; and / or, the maximum dimension at the cross-section of the first micropillar 2211 is 10 micrometers to 1000 micrometers; and / or, the maximum dimension at the cross-section of the second micropillar 2221 is 10 micrometers to 500 micrometers.

[0133] The shape of the first micropillar 2211 and / or the second micropillar 2221 includes, but is not limited to, at least one of cylinder, cube, cuboid, and prism.

[0134] In this embodiment, the primary filtration section and the secondary filtration section 22 work together to quickly filter whole blood to obtain plasma. The primary filtration section filters most of the red blood cells, so the sample can quickly flow into the secondary filtration section 22. The secondary filtration section 22 further filters the red blood cells through the steric hindrance of the microcolumn space (i.e., the first filtration zone 221 and the second filtration zone 222) to avoid hemolysis.

[0135] like Figure 9 As shown, optionally, a capillary channel 3 is disposed between the filtration mechanism 2 and the collection tank 6. The capillary channel 3 is used to allow plasma to flow from the filtration mechanism 2 into the collection tank 6. The capillary channel 3 can accelerate plasma flow, increase filtration speed, and shorten whole blood separation time through capillary action.

[0136] like Figure 11 As shown, the outlet end 31 of the capillary channel 3 is inclined downward, which increases the distance between the bottom wall of the outlet end 31 of the capillary channel 3 and the cover 12, so that air can circulate between the capillary channel 3 and the inside of the receiving cavity 111 and the collection tank 6 during the process of plasma flowing into the collection tank 6.

[0137] like Figure 9 As shown, exemplarily, the capillary channel 3 extends along the second direction L, with its length direction aligned with the second direction L and its width direction aligned with the first direction W. It is understood that the capillary channel 3 is not limited to extending along the second direction L; it can also be a curved channel. The width direction of the capillary channel 3 is perpendicular to both the flow direction of the plasma within the capillary channel 3 and the thickness direction of the microfluidic device 100. Therefore, its width direction is not limited to being aligned with the first direction W.

[0138] During the whole blood filtration process and the rapid flow of plasma, air bubbles can form within the plasma due to the flow of the whole blood. This hinders the testing of plasma samples. To eliminate these air bubbles, such as... Figure 8 and Figure 12As shown, optionally, a defoaming mechanism 32 is provided inside the capillary channel 3, which is used to eliminate air bubbles in the plasma. Furthermore, the defoaming mechanism 32 is located at one of the upstream ends of the capillary channel 3.

[0139] The defoaming mechanism 32 may include a plurality of baffles 321 spaced apart along the length of the capillary channel 3. The baffles 321 extend along the width of the capillary channel 3 (i.e., the first direction W). The baffles 321 and the top wall of the capillary channel 3 have a third gap for allowing plasma to pass through. That is, there is a third gap between the baffles 321 and the cover 12. The capillary channel 3 has a first sidewall 33 and a second sidewall 34 in the width direction.

[0140] like Figure 8 As shown, in this embodiment, the baffle 321 includes a first baffle 322 and a second baffle 323. One end of the first baffle 322 is connected to the first sidewall 33 of the capillary channel 3, and the other end is spaced from the second sidewall 34. The second baffle 323 is connected to the second sidewall 34 of the capillary channel 3, and the other end is spaced from the first sidewall 33. The first baffle 322 and the second baffle 323 are arranged alternately.

[0141] When the amount of plasma in the capillary channel 3 is small, the plasma flows slowly forward in the space formed between the first baffle 322 and the second baffle 323, between the first baffle 322 and the second sidewall 34, and between the second baffle 323 and the first sidewall 33. That is, the trajectory of the plasma flow is roughly serpentine, which is equivalent to slowing down the plasma flow speed, thereby reducing the bubbles generated during the rapid flow of plasma.

[0142] When there is a large amount of plasma in the capillary channel 3, since the first baffle 322 and the second baffle 323 are horizontal columns, they block the direction of plasma flow. When the plasma accumulates to a height higher than the first baffle 322 (or the second baffle 323), it will flow to the next second baffle 323 (or the first baffle 322). This is equivalent to slowing down the plasma flow speed, thereby reducing the bubbles generated during the rapid flow of plasma.

[0143] like Figure 12 As shown, in another optional embodiment, the baffle 321 does not include the first baffle 322 and the second baffle 323. Instead, one end of the baffle 321 is connected to the first sidewall 33 and the other end is connected to the second sidewall 34. The baffle 321 and the top wall of the capillary channel 3 have a third gap for plasma to pass through. The plasma passes through the third gap. The baffle 321 is a transverse column structure (i.e., it extends along the width direction of the capillary channel 3 along the baffle 321), which blocks the direction of plasma movement. When the plasma accumulates to a height higher than the baffle 321, it will flow to the next baffle 321. This is equivalent to slowing down the plasma flow speed, thereby reducing the bubbles generated during the rapid flow of plasma.

[0144] Optionally, the baffle 321 is a cuboid baffle 321, which makes it easier for the bubble to burst when its edges come into contact with the bubble. The shape of the baffle 321 is not limited to this, and it can also be a hexahedron, pentahedron or other polygonal prism or cylinder.

[0145] like Figure 8 and Figure 12 As shown, the defoaming mechanism 32 is provided with a confluence cut 324 at one end near the collection tank 6. That is, the confluence cut 324 is located at the downstream end of the defoaming mechanism 32, so that the plasma gathers and then flows forward. When the plasma flows forward as a whole, the flow speed can be increased and the amount of plasma remaining on the substrate 11 can be reduced.

[0146] Optionally, the size of the manifold cut 324 along the width direction (i.e., the first direction W) of the capillary channel 3 gradually increases from the upstream side to the downstream side. For example, the manifold cut 324 is a triangular cut.

[0147] like Figure 12 As shown, the capillary channel 3 is also equipped with an acceleration mechanism 35 for accelerating plasma flow, which is located downstream of the defoaming mechanism 32. The acceleration mechanism 35 can increase the flow rate of plasma, thereby shortening the whole blood separation time.

[0148] For example, the accelerating mechanism 35 includes a plurality of spaced-apart third micropillars 351 connected to the bottom wall of the capillary channel 3. The surface of the third micropillars 351 is coated with a hydrophilic substance. The third micropillars 351 can increase the surface area in contact with plasma. The surface of the third micropillars 351 is covered with a hydrophilic substance containing hydrophilic groups. Therefore, when the plasma comes into contact with the hydrophilic groups, it is equivalent to the plasma being subjected to an attractive force, which propels the plasma forward, thereby shortening the whole blood separation time.

[0149] Optionally, the third micropillars 351 are arranged in an array. The third micropillars 351 can be cylinders with a diameter of 30 micrometers to 1000 micrometers, and the spacing between two adjacent third micropillars 351 is 20 micrometers to 1500 micrometers.

[0150] Of course, such as Figure 5 As shown, the acceleration mechanism 35 can also be omitted.

[0151] like Figure 1 and Figure 2As shown, the microfluidic device 100 provided in this embodiment also includes a driving mechanism 4, which drives the sample within the body 1 to move from the side where the filtering mechanism 2 is located to the side where the collection tank 6 is located. The driving mechanism 4 can increase the flow rate of the sample, thereby increasing the whole blood filtration rate, shortening the whole blood separation time, and reducing the possibility of hemolysis. The microfluidic device 100 provided in this embodiment can obtain plasma without relying on a centrifuge, and the device is small in size and easy to operate. In an optional embodiment, the driving mechanism 4, the filtering mechanism 2, and the collection tank 6 are arranged sequentially along the second direction L.

[0152] Optionally, the drive mechanism 4 is used to introduce compressed air into the filter mechanism 2 to drive the sample inside the body 1 to move towards the collection tank 6. By introducing compressed air into the filter mechanism 2, the drive mechanism 4 increases the pressure at the filter mechanism 2, thereby pushing the sample at the filter mechanism 2 towards the side where the collection tank 6 is located.

[0153] Furthermore, the drive mechanism 4 is located on the side of the filter mechanism 2 away from the collection tank 6, and is used to drive the sample in the body 1 to move towards the collection tank 6. By setting the drive mechanism 4 on the side of the filter mechanism 2 away from the collection tank 6, compressed air can push the sample on the side of the filter mechanism 2 away from the collection tank 6, that is, apply a force to the sample toward the collection tank 6, thereby increasing the downstream flow speed of the sample.

[0154] It is understood that the sample flows from the side where the filter mechanism 2 is located to the side where the collection tank 6 is located. Therefore, the position through which the sample flows first is upstream, and the position through which it flows later is downstream. For example, the filter mechanism 2 is located upstream of the collection tank 6.

[0155] like Figure 2 As shown, the main body 1 has a drive cavity 13 with an opening. For example, the base 11 has a drive groove 131, and the cover 12 has a through-hole 121 opposite to the drive groove 131. The cover 12 covers the base 11, and the drive groove 131 communicates with the through-hole 121 to form the drive cavity 13. The drive mechanism 4 includes a deformable membrane 41, which covers the opening to seal it.

[0156] The drive chamber 13 is connected to the filter mechanism 2, meaning that the space where the drive chamber 13 and the filter mechanism 2 are located is connected. By pressing the deformable membrane 41, the deformable membrane 41 moves into the drive chamber 13, which compresses the air in the drive chamber 13, thereby increasing the pressure in the drive chamber 13. This causes the compressed air in the drive chamber 13 to enter the filter mechanism 2, thereby driving the sample in the filter mechanism 2 to move towards the collection tank 6.

[0157] Optionally, the deformable film 41 is an elastic film, and the material of the elastic film can be selected from polyethylene film, polypropylene film, polyvinyl chloride film, PDMS film, thermoplastic polyurethane elastomer rubber film (i.e., TPU film), etc.

[0158] like Figure 2 As shown, in order to connect the driving cavity 13 with the receiving cavity 111, that is, to connect the driving cavity 13 with the filtering mechanism 2, a connecting groove 18 is provided on the base 11, and the opening of the connecting groove 18 is sealed by the cover 12. For example, the bottom of the connecting groove 18 is higher than the bottom of the receiving cavity 111 to prevent the sample in the receiving cavity 111 from flowing into the driving cavity 13 through the connecting groove 18.

[0159] To allow the deformable membrane 41 to recover its deformation, the driving mechanism 4 may optionally include a recovery driving member disposed in the driving cavity 13 and capable of driving the deformable membrane 41 to recover its deformation. Preferably, the recovery driving member is an elastic member. When the deformable membrane 41 is pressed, the elastic member is compressed. When the deformable membrane 41 is released, the elastic member recovers its deformation under the action of the restoring force, and drives the deformable membrane 41 to recover its deformation. For example, the elastic member is a sponge 42. Of course, in other optional embodiments, the elastic member may also be a sheet, a spring, or at least two of the following: sponge 42, sheet, and spring.

[0160] In this embodiment, when the deformable wall recovers its deformation, because the outlet end 31 of the capillary channel 3 is inclined, air enters the microfluidic device 100 from the capillary channel 3, thereby preventing the plasma in the collection tank 6 from being drawn back, that is, the outlet end 31 of the capillary channel 3 forms an anti-backflow pipe.

[0161] like Figure 9 As shown, in other optional embodiments, the drive mechanism 4 may not have the structure described above. Instead, the drive mechanism 4 may include an air extraction component to create a vacuum environment in the collection tank 6. It is understood that a vacuum environment refers to a gaseous state where the pressure in the collection tank 6 is below one atmosphere. Since the pressure inside the filter mechanism 2 is not less than one atmosphere, the sample from the filter mechanism 2 can automatically flow into the collection tank 6. Optionally, the air extraction component can be an air pump or a syringe. The air inlet of the air pump or the air inlet of the syringe is sealed and covers the opening of the collection tank 6, thereby drawing in some of the air from the collection tank 6, thus creating a vacuum environment inside the collection tank 6.

[0162] To make it easier to collect plasma in the collection tank 6, a hydrophilic layer is provided on the surface of the collection tank 6. For example, the surface of the collection tank 6 is coated with a hydrophilic reagent or cured by ultraviolet light, or the surface of the collection tank 6 is subjected to plasma hydrophilic treatment to make its surface more hydrophilic. The plasma flows automatically into the plasma collection tank 6 without the need for an air pump.

[0163] For example, the process of filtering whole blood using the microfluidic device 100 provided in this embodiment is as follows:

[0164] 1. Open the sealing part 17, and inject whole blood into the receiving cavity 111 through the injection port 122. The whole blood enters the buffer zone 53 of the flow guiding structure 5. After the injection is completed, close the sealing part 17 again.

[0165] 2. Drive mechanism 4 operates to accelerate whole blood flow;

[0166] 3. The sample passes through the filter membrane 21, the first filter zone 221, the second filter zone 222 and the capillary channel 3 in sequence, and finally flows into the collection tank 6.

[0167] like Figure 13-15 As shown, this embodiment also provides a support 200 adapted to the microfluidic device 100 described above. The support 200 is used to place the microfluidic device 100 at an acute angle or right angle to the horizontal plane, and to make the side where the collection tank 6 is located lower than the side where the filter mechanism 2 is located. The support 200 can further accelerate the flow rate of the sample in the microfluidic device 100 under the action of gravity, thereby further shortening the whole blood separation time.

[0168] Optionally, the support 200 includes a base plate 201, an inclined plate 203, and at least one column 202. The lower end of the column 202 is connected to the base plate 201, and the inclined plate 203 is connected to the base plate 201 and is set at an angle to the horizontal plane. Preferably, the inclined plate 203 is inclined towards the side where the column 202 is located. One end of the microfluidic device 100 with a collection groove 6 abuts against the inclined plate 203, and the other end of the microfluidic device 100 abuts against the top of the column 202, so that the collection groove 6 is lower than the filter mechanism 2. The support 200 provided in this embodiment has a simple structure and is convenient for supporting the microfluidic device 100.

[0169] Optionally, multiple columns 202 are spaced apart along the direction of the inclined plate 203, so that multiple microfluidic devices 100 can be supported at the same time. For example, the inclined plate 203 extends along the first direction W, and the multiple columns 202 are spaced apart along the first direction W.

[0170] This embodiment also provides a plasma separation method adapted to the microfluidic device 100 and the stent 200 described above, which separates plasma from whole blood through gravity induction and capillary action. For example, during whole blood filtration, the microfluidic device 100 is tilted, with the collection tank 6 lower than the filtration mechanism 2, to achieve gravity induction. The filter membrane 21 and capillary channels 3 achieve capillary action.

[0171] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A microfluidic device for whole blood filtration, comprising a body (1), a filtration mechanism (2) disposed within the body (1), and a collection tank (6) communicating with the filtration mechanism (2), wherein the filtration mechanism (2) is used to filter red blood cells, and the collection tank (6) is used to collect plasma, characterized in that, Also includes: The driving mechanism (4) is used to drive the sample in the body (1) to move from the side where the filtering mechanism (2) is located to the side where the collection tank (6) is located; The main body (1) has a receiving cavity (111), and the bottom of the receiving cavity (111) is provided with a flow guiding structure (5) for guiding the sample; the flow guiding structure (5) includes a first flow guiding structure (51) and a second flow guiding structure (52), and the first flow guiding structure (51) and the second flow guiding structure (52) are perpendicular to each other; The filtration mechanism (2) is disposed in the receiving cavity (111). The filtration mechanism (2) includes a primary filtration section, which can block and adsorb some red blood cells. The filtration mechanism (2) also includes a secondary filtration section (22), which is disposed downstream of the primary filtration section and is used to filter red blood cells in the sample. A drainage section is also provided between the primary filtration section and the secondary filtration section (22), which is used to allow the sample to flow from the primary filtration section to the side where the secondary filtration section (22) is located.

2. The microfluidic device according to claim 1, characterized in that, The drive mechanism (4) is used to introduce compressed air into the filter mechanism (2) to drive the sample in the body (1) to move towards the collection tank (6).

3. The microfluidic device according to claim 2, characterized in that, The drive mechanism (4) is located on the side of the filter mechanism (2) away from the collection tank (6).

4. The microfluidic device according to claim 2 or 3, characterized in that, The main body (1) has a drive cavity (13) with an opening, the drive cavity (13) is connected to the filter mechanism (2), and the drive mechanism (4) includes a deformable membrane (41) covering the opening.

5. The microfluidic device according to claim 4, characterized in that, The drive mechanism (4) further includes a recovery drive element disposed in the drive cavity (13) and capable of driving the deformable membrane (41) to recover its deformation.

6. The microfluidic device according to claim 5, characterized in that, The recovery drive component is an elastic component.

7. The microfluidic device according to claim 6, characterized in that, The elastic element is at least one of sponge (42), sheet, and spring.

8. The microfluidic device according to claim 1, characterized in that, The drive mechanism (4) includes an air extraction component, which is used to create a vacuum environment in the collection tank (6).

9. The microfluidic device according to claim 8, characterized in that, The air extraction device is an air pump or a syringe.

10. The microfluidic device according to claim 1, characterized in that, The primary filtration section includes a filter membrane (21).

11. The microfluidic device according to claim 1, characterized in that, The main body (1) has an injection port (122) communicating with the receiving cavity (111). The flow guiding structure (5) includes a buffer zone (53) and a filtration zone (54). At least part of the buffer zone (53) is arranged opposite to the injection port (122). The primary filtration section is arranged on the upper side of the filtration zone (54).

12. The microfluidic device according to claim 11, characterized in that, The buffer zone (53) is located on the side of the filter zone (54) away from the collection tank (6).

13. The microfluidic device according to any one of claims 1, 11, or 12, characterized in that, The flow guiding structure (5) includes a first flow guiding structure (51), which is used to allow the sample to flow toward the side where the collection tank (6) is located.

14. The microfluidic device according to claim 13, characterized in that, The first flow guiding structure (51) includes a plurality of spaced first flow guiding columns (511), the first flow guiding columns (511) are connected to the bottom of the receiving cavity (111), and the first flow guiding columns (511) extend along the direction in which the filter mechanism (2) and the collection groove (6) are arranged in sequence.

15. The microfluidic device according to claim 13, characterized in that, The flow guiding structure (5) further includes a second flow guiding structure (52). In the first direction (W), the second flow guiding structure (52) is provided on at least one side of the first flow guiding structure (51). The first direction (W) is perpendicular to the direction in which the filter mechanism (2) and the collection tank (6) are arranged in sequence, as well as the thickness direction of the microfluidic device. The second flow guiding structure (52) is used to make the sample flow towards the side where the first flow guiding structure (51) is located.

16. The microfluidic device according to claim 15, characterized in that, The first flow guiding structure (51) has a second flow guiding structure (52) on both sides along the first direction (W).

17. The microfluidic device according to claim 15, characterized in that, The second flow guiding structure (52) includes a plurality of spaced second flow guiding columns (521), the second flow guiding columns (521) are connected to the bottom of the receiving cavity (111), and the second flow guiding columns (521) extend along the first direction (W).

18. The microfluidic device according to any one of claims 1, 11, or 12, characterized in that, The bottom of the receiving cavity (111) is connected to a first support (15), which is used to support the primary filter section so that there is a first gap (25) between the primary filter section and the flow guiding structure (5).

19. The microfluidic device according to claim 11, characterized in that, The receiving cavity (111) is also provided with a limiting part (16), which is located on one side of the primary filter and is used to restrict the primary filter from moving toward the buffer zone (53).

20. The microfluidic device according to claim 19, characterized in that, The side of the re-filtration section (22) near the primary filtration section is a curve (23) or a broken line (24).

21. The microfluidic device according to claim 19, characterized in that, The re-filtration section (22) includes a first filtration zone (221), which includes a plurality of first micropillars (2211) arranged in an array.

22. The microfluidic device according to claim 21, characterized in that, The re-filtration section (22) further includes a second filtration section (222) disposed downstream of the first filtration section (221), the second filtration section (222) including a plurality of second micropillars (2221) arranged in an array.

23. The microfluidic device according to claim 22, characterized in that, The distance between two adjacent first micropillars (2211) is greater than the distance between two adjacent second micropillars (2221), and / or the cross-sectional area of ​​the first micropillar (2211) is greater than the cross-sectional area of ​​the second micropillar (2221).

24. The microfluidic device according to claim 22, characterized in that, The spacing between two adjacent second micropillars (2221) is 0.5 μm to 2 μm; and / or, the spacing between two adjacent first micropillars (2211) is 1 μm to 1.2 μm; and / or, the maximum dimension at the cross-section of the first micropillar (2211) is 10 μm to 1000 μm; and / or, the maximum dimension at the cross-section of the second micropillar (2221) is 10 μm to 500 μm.

25. The microfluidic device according to claim 1, characterized in that, The drainage section is disposed at the bottom of the receiving cavity (111); Alternatively, the drainage section and the bottom of the receiving cavity (111) may have a second gap (26), and / or the drainage section and the primary filtration section may be an integral structure.

26. The microfluidic device according to claim 25, characterized in that, When the drainage portion has a second gap (26) with the bottom of the receiving cavity (111), the body (1) further includes a second support portion (19), which is connected to the bottom of the receiving cavity (111) and is used to make the drainage portion have the second gap (26) with the bottom of the receiving cavity (111).

27. The microfluidic device according to any one of claims 1, 10-12, characterized in that, The size of the receiving cavity (111) gradually decreases from the upstream side to the downstream side along the sample flow.

28. The microfluidic device according to any one of claims 1-3 and 8-12, characterized in that, A capillary channel (3) is also provided between the filtration mechanism (2) and the collection tank (6), the capillary channel (3) being used to allow plasma to flow from the filtration mechanism (2) into the collection tank (6).

29. The microfluidic device according to claim 28, characterized in that, The capillary channel (3) is provided with a defoaming mechanism (32), which is used to eliminate air bubbles in the plasma.

30. The microfluidic device according to claim 29, characterized in that, The defoaming mechanism (32) includes a plurality of baffles (321) spaced apart along the length of the capillary channel (3), the baffles (321) extending along the width of the capillary channel (3), the baffles (321) having a third gap with the top wall of the capillary channel (3) for allowing plasma to pass through, and the capillary channel (3) having a first sidewall (33) and a second sidewall (34) in the width direction. One end of the stop post (321) is connected to the first side wall (33), and the other end is connected to the second side wall (34); or The baffle (321) includes a first baffle (322) and a second baffle (323). One end of the first baffle (322) is connected to the first sidewall (33) of the capillary channel (3), and the other end is spaced from the second sidewall (34). The second baffle (323) is connected to the second sidewall (34) of the capillary channel (3), and the other end is spaced from the first sidewall (33). The first baffle (322) and the second baffle (323) are staggered.

31. The microfluidic device according to claim 29, characterized in that, The defoaming mechanism (32) has a flow inlet (324) at one end near the collection tank (6).

32. The microfluidic device according to claim 29, characterized in that, The capillary channel (3) is also provided with an acceleration mechanism (35) for accelerating plasma, which is located downstream of the defoaming mechanism (32).

33. The microfluidic device according to claim 32, characterized in that, The acceleration mechanism (35) includes a plurality of spaced third micropillars (351), which are connected to the bottom wall of the capillary channel (3) and have a hydrophilic substance on their surface.

34. The microfluidic device according to claim 28, characterized in that, The outlet end (31) of the capillary channel (3) is inclined downward.

35. The microfluidic device according to claim 11, characterized in that, The body (1) also includes a sealing element (17) for closing or opening the injection port (122).

36. The microfluidic device according to any one of claims 1, 10-12, characterized in that, The main body (1) includes a base (11) and a cover (12). The base (11) has a receiving groove, and the cover (12) covers the base (11) to form the receiving cavity (111).

37. The microfluidic device according to claim 36, characterized in that, The cover (12) is made of single-sided adhesive.

38. The microfluidic device according to any one of claims 1-3 and 8-12, characterized in that, The surface of the collection tank (6) is provided with a hydrophilic layer.

39. A support adapted for use with the microfluidic device according to any one of claims 1-38, characterized in that, The bracket is used to place the microfluidic device at an acute angle or right angle to the horizontal plane, and to make the side where the collection tank (6) is located lower than the side where the filter mechanism (2) is located.

40. The stent according to claim 39, characterized in that, The support includes: Base plate (201); At least one column (202) is provided, the lower end of which is connected to the base plate (201). An inclined plate (203) is connected to the base plate (201) and is set at an angle to the horizontal plane. One end of the microfluidic device with a collection groove (6) abuts against the inclined plate (203), and the other end of the microfluidic device abuts against the top of the column (202).

41. A plasma separation method adapted to the microfluidic device according to any one of claims 1-38 and the stent according to any one of claims 39-40, characterized in that, Plasma is separated from whole blood through gravity induction and capillary action.

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