Micro-channel structure, micro-channel chip and target particle aggregation method

Abstract

The invention discloses a micro-channel structure, a micro-channel chip and a target particle aggregation method. The micro-channel structure comprises at least one micro-channel unit, and each micro-channel unit comprises a plurality of bent channels and a plurality of steering channels. The multiple bent flow channels are arranged at intervals in the arrangement direction, and each steering flow channel is located between every two adjacent bent flow channels and enables every two adjacent bent flow channels to be communicated; and the two steering flow channels communicated with one bent flow channel are respectively positioned at two ends of the bent flow channel. Each bent flow channel is provided with a first side and a second side which are opposite in the arrangement direction, and each bent flow channel is bent towards a first position located on the second side. According to the micro-channel structure, particles with two or more sizes can be focused at different positions, so that separation can be realized; meanwhile, the micro-channel structure further has the advantages of being large in effective flow velocity interval redundancy, large in flow, high in separation efficiency, easy to manufacture, easy to operate, not prone to being interfered by impurities, insensitive to structural dependence, high in robustness and the like.

Description

Microfluidic structure, microfluidic chip and target particle aggregation method

[0001] This application claims priority to Chinese Patent Application No. 2022112738124 filed on October 18, 2022, and the contents of the above-mentioned Chinese patent application disclosure are hereby incorporated by reference in their entirety as a part of this application. Technical Field

[0002] Embodiments of the present disclosure relate to a microfluidic channel structure, a microfluidic channel chip, and a target particle aggregation method. Background Art

[0003] Among all passive sorting methods for unlabeled particles or granules (such as circulating tumor cells, CTCs) based on physical characteristics, inertial focusing technology uses fluid mechanics to focus and separate particles of different physical properties (such as size) by utilizing forces such as inertial lift generated by the shape of the inertial microfluidic channel. This method, which relies only on the shape of the device and not on external forces, makes the manufacturing process simple and easy to operate. Inertial focusing can achieve relatively high processing capacity, avoiding cell rupture caused by excessive shear force. It can also separate particles by relying solely on the inertial effect without the use of buffer, and is easy to combine with other separation methods. Inertial focusing has been at the forefront of scientific and applied research due to its advantages such as high throughput far higher than other methods and extremely high robustness.

[0004] Summary of the Invention

[0005] The disclosed embodiments provide a microfluidic structure and a microfluidic chip. This microfluidic structure can focus particles of two or more sizes at different locations, thereby enabling separation. Furthermore, the microfluidic structure features large redundancy in the effective flow rate range, high flow rate, high separation efficiency, simple fabrication, ease of operation, resistance to impurity interference, insensitivity to structural dependence, and high robustness, thus possessing broad application potential.

[0006] At least one embodiment of the present disclosure provides a microfluidic structure, comprising at least one microfluidic unit, each of the microfluidic unit comprising a plurality of curved channels arranged at intervals along the arrangement direction; and a plurality of turning channels, each of the turning channels being located between two adjacent curved channels and connecting the two adjacent curved channels, the two turning channels connected to one curved channel being respectively located at both ends of the curved channel, each of the curved channels having a first side and a second side opposite to each other in the arrangement direction, and each of the curved channels being bent toward a first position located on the second side.

[0007] For example, in the microchannel structure provided by an embodiment of the present disclosure, the plurality of first positions of the plurality of curved channels are located on the same side of the plurality of curved channels in the arrangement direction.

[0008] For example, in the microchannel structure provided in an embodiment of the present disclosure, the lengths of the plurality of curved channels gradually change along the arrangement direction.

[0009] For example, in the microchannel structure provided in an embodiment of the present disclosure, each of the curved channels is an arc-shaped channel, and the first position of each of the curved channels is the center of curvature of the curved channel.

[0010] For example, in the microchannel structure provided in an embodiment of the present disclosure, the plurality of first positions of the plurality of curved channels are located on the same straight line.

[0011] For example, in the microchannel structure provided in an embodiment of the present disclosure, the plurality of first positions of the plurality of curved channels overlap with each other.

[0012] For example, in the microchannel structure provided in one embodiment of the present disclosure, the lengths of the plurality of curved channels gradually decrease along the arrangement direction; among the plurality of curved channels, the arc radius of the longest curved channel is r max , the r max The value range of is 10mm to 50mm; the arc radius of the shortest curved flow channel is r min , the r min The value range is 1mm to 20mm.

[0013] For example, in the microchannel structure provided in an embodiment of the present disclosure, the number of the plurality of curved channels is N, and the value range of N is 2-50.

[0014] For example, in the microchannel structure provided in one embodiment of the present disclosure, the value range of N is 4-8.

[0015] For example, in the microchannel structure provided in one embodiment of the present disclosure, the lengths of the plurality of curved channels gradually decrease along the arrangement direction, the plurality of curved channels are equidistantly arranged, and the parameters of the microchannel units satisfy the following formula: (N-1)·d+N·D=r max -r min Wherein, N is the number of the plurality of curved channels, d is the spacing between two adjacent curved channels, D is the width of each of the plurality of curved channels, and in the plurality of curved channels, r max is the arc radius of the longest curved channel, and r min is the arc radius of the shortest curved flow channel.

[0016] For example, in the microchannel structure provided in one embodiment of the present disclosure, each of the turning channels includes an inner wall and an outer wall, the inner wall is arranged opposite to the outer wall, and is located on the side of the outer wall close to the gap between two adjacent curved channels.

[0017] For example, in the microchannel structure provided in one embodiment of the present disclosure, among the multiple turning channels located on the same side of the reference straight line extending along the arrangement direction and passing through the multiple curved channels, the outer wall of the first turning channel in the arrangement direction and the outer wall of the last turning channel both intersect with the first auxiliary straight line and are both located on the side of the first auxiliary straight line close to the reference straight line; among the multiple turning channels on the other side of the reference straight line, the outer wall of the first turning channel in the arrangement direction and the outer wall of the last turning channel both intersect with the second auxiliary straight line and are both located on the side of the second auxiliary straight line close to the reference straight line; the angle λ between the first auxiliary straight line and the second auxiliary straight line ranges from 10 degrees to 90 degrees.

[0018] For example, in the microchannel structure provided in an embodiment of the present disclosure, the value range of λ is 15 degrees to 30 degrees.

[0019] For example, in the microchannel structure provided in one embodiment of the present disclosure, the shape of the orthographic projection of the inner wall on the reference plane is a first arc, the shape of the orthographic projection of the outer wall on the reference plane is a second arc, and the reference plane is parallel to the arrangement direction and the extension direction of each of the curved channels.

[0020] For example, in the microchannel structure provided in one embodiment of the present disclosure, among the multiple turning channels located on the same side of a reference straight line extending along the arrangement direction and passing through the multiple curved channels, the outer wall of the first turning channel in the arrangement direction and the outer wall of the last turning channel have their orthographic projections on the reference plane tangent to the first straight line.

[0021] For example, the microchannel structure provided in one embodiment of the present disclosure also includes: an inlet channel, which is connected to the first curved channel in the arrangement direction; and an outlet channel, which is connected to the last curved channel in the arrangement direction, and the outlet channel and the first straight line are respectively located on both sides of a reference straight line extending along the arrangement direction and passing through the multiple curved channels, and the side wall of the last curved channel in the arrangement direction close to the first position and the orthographic projection of the side wall of the outlet channel close to the first straight line on the reference plane have an intersection, and the first position of the last curved channel in the arrangement direction and the intersection are located on a second straight line, and the first straight line and the second straight line have an angle θ, and the value range of θ is 10 degrees to 90 degrees.

[0022] For example, in the microchannel structure provided in one embodiment of the present disclosure, the value range of θ is 15 degrees to 30 degrees.

[0023] For example, in the microchannel structure provided in one embodiment of the present disclosure, the shape of the orthographic projection of the inner wall on the reference plane is a first straight line segment, and the shape of the orthographic projection of the outer wall on the reference plane is a second straight line segment, and the reference plane is parallel to the arrangement direction and the extension direction of each of the curved channels.

[0024] For example, in the microchannel structure provided in an embodiment of the present disclosure, among the multiple turning channels located on the same side of a reference straight line extending along the arrangement direction and passing through the multiple curved channels, the outer wall of the first turning channel in the arrangement direction and the outer wall of the last turning channel have their orthographic projections on the reference plane located on a fourth straight line. The microchannel structure also includes: an inlet channel connected to the first curved channel in the arrangement direction; and an outlet channel connected to the last curved channel in the arrangement direction, the outlet channel and the fourth straight line are respectively located on both sides of the reference straight line, the side wall of the last curved channel in the arrangement direction close to the first position and the orthographic projection of the side wall of the outlet channel close to the first straight line on the reference plane have an intersection, the first position of the last curved channel in the arrangement direction and the intersection are located on a second straight line, the fourth straight line and the second straight line have an angle β, and the value range of β is 10 degrees to 90 degrees.

[0025] For example, in the microchannel structure provided in one embodiment of the present disclosure, the value range of β is 15 degrees to 30 degrees.

[0026] For example, in the microchannel structure provided in an embodiment of the present disclosure, the second straight line segments of the turning channels located on the same side of a reference straight line extending along the arrangement direction and passing through the curved channels are parallel to each other.

[0027] For example, in the microchannel structure provided in one embodiment of the present disclosure, the ratio of the width to the height of the plurality of curved channels ranges from 1 to 20, and the height of the plurality of curved channels ranges from 10 μm to 150 μm.

[0028] For example, the microfluidic channel structure provided in one embodiment of the present disclosure further includes a connecting channel. The microfluidic channel structure includes a plurality of microfluidic channel units. The connecting channel is located between two adjacent microfluidic channel units and connects the two adjacent microfluidic channel units.

[0029] For example, in the microfluidic structure provided in one embodiment of the present disclosure, the multiple microfluidic units are arranged in sequence along an arc, and the arc bends toward a second position; the second position and the multiple first positions of the multiple curved channels of any one of the microfluidic units are located on the same side of the arc.

[0030] For example, in the microfluidic structure provided in one embodiment of the present disclosure, the multiple microfluidic units include a first microfluidic unit, a second microfluidic unit and a third microfluidic unit arranged in sequence in the extension direction of the arc line, the last curved channel of the first microfluidic unit in the arrangement direction is connected to the last curved channel of the second microfluidic unit in the arrangement direction through the connecting channel, and the first curved channel of the second microfluidic unit in the arrangement direction is connected to the first curved channel of the third microfluidic unit in the arrangement direction through the connecting channel.

[0031] For example, in the micro-channel structure provided in an embodiment of the present disclosure, the second position overlaps with a plurality of the first positions of the plurality of curved channels of any one of the micro-channel units.

[0032] For example, in the microfluidic channel structure provided in an embodiment of the present disclosure, the plurality of microfluidic channel units are arranged in sequence along a circumferential line.

[0033] At least one embodiment of the present disclosure provides a microfluidic chip, comprising a microfluidic structure according to any of the above descriptions; and a first separation structure, comprising a first sub-inlet and a plurality of first sub-outlets, wherein the microfluidic structure comprises an inlet and an outlet, and the first sub-inlet is connected to the outlet of the microfluidic structure.

[0034] At least one embodiment of the present disclosure provides a method for aggregating target particles, comprising: providing a sample solution comprising target particles; injecting the sample solution into the above-mentioned microfluidic structure, or injecting the sample solution into the microfluidic structure of the above-mentioned microfluidic chip; and focusing the target particles at an inertial equilibrium position in a channel of the microfluidic structure through the microfluidic structure.

[0035] For example, in the method provided in one embodiment of the present disclosure, the sample solution also includes other particles having a size different from that of the target particles, and focusing the target particles at an inertial equilibrium position in the channel of the microfluidic structure through the microfluidic structure includes: focusing the target particles and the other particles at different inertial equilibrium positions in the channel of the microfluidic structure through the microfluidic structure.

[0036] For example, the method provided in one embodiment of the present disclosure further includes: separating the target particles and the other particles located at different inertial equilibrium positions.

[0037] For example, in the method provided in one embodiment of the present disclosure, injecting the sample solution into the microfluidic structure or the microfluidic structure of the microfluidic chip includes: injecting the sample solution into the microfluidic structure or the microfluidic structure of the microfluidic chip at a set flow rate, and the flow rate range of the set flow rate is between 0 and 5 mL / min.

[0038] For example, in the method provided in one embodiment of the present disclosure, the sample solution including target particles includes whole blood or diluted blood.

[0039] For example, in the method provided in one embodiment of the present disclosure, the target particles include circulating tumor cells, human breast cancer cells, or T lymphocytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, rather than limiting the present disclosure.

[0041] FIG1A is a schematic top view of a spiral inertial focusing channel;

[0042] FIG1B is a schematic top view of a serpentine inertial focusing channel;

[0043] FIG1C is a schematic top view of a contraction-expansion inertial focusing channel;

[0044] FIG2A is a schematic structural diagram of a microfluidic unit of a microfluidic structure provided by an embodiment of the present disclosure;

[0045] FIG2B is a schematic top view of the microfluidic unit shown in FIG2A ;

[0046] FIG2C is a schematic top view of another microfluidic unit provided by an embodiment of the present disclosure;

[0047] FIG3A is a schematic top view of another microfluidic unit provided in one embodiment of the present disclosure;

[0048] FIG3B is a schematic top view of another microfluidic unit provided by an embodiment of the present disclosure;

[0049] FIG3C is a schematic top view of another microfluidic unit provided in one embodiment of the present disclosure;

[0050] FIG3D is a schematic top view of another microfluidic unit provided by an embodiment of the present disclosure;

[0051] FIG3E is a schematic top view of another microfluidic unit provided in one embodiment of the present disclosure;

[0052] FIG3F is a schematic top view of another microfluidic unit provided in one embodiment of the present disclosure;

[0053] FIG3G is a schematic top view of another microfluidic unit provided in one embodiment of the present disclosure;

[0054] FIG3H is a schematic top view of another microfluidic unit provided in one embodiment of the present disclosure;

[0055] FIG3I is a schematic top view of another microfluidic unit provided in one embodiment of the present disclosure;

[0056] FIG3J is a schematic top view of another microfluidic channel unit provided in one embodiment of the present disclosure;

[0057] FIG3K is a schematic top view of another microfluidic channel unit provided by an embodiment of the present disclosure;

[0058] FIG3L is a schematic top view of another microfluidic unit provided by an embodiment of the present disclosure;

[0059] FIG4 is a distribution simulation diagram of secondary flows caused by different turning flow channels provided by an embodiment of the present disclosure;

[0060] FIG5 is a schematic top view of a microfluidic channel structure provided by an embodiment of the present disclosure;

[0061] FIG6A is a schematic top view of another microfluidic channel structure provided by an embodiment of the present disclosure;

[0062] FIG6B is an experimental diagram showing the focusing position of particles in the microfluidic channel structure shown in FIG6A as the Reynolds number changes;

[0063] FIG6C is a diagram of the microchannel structure shown in FIG6A at r min Schematic diagram of the focusing position of three sizes of particles as the flow rate changes when β = 2 mm and β = 22.5 degrees;

[0064] FIG6D is a diagram of the microchannel structure shown in FIG6A at r min Schematic diagram of the focusing position of three sizes of particles as the flow rate changes when β = 6.05 mm and β = 22.5 degrees;

[0065] FIG6E is a diagram of the microchannel structure shown in FIG6A at r min Schematic diagram of the focusing position of three sizes of particles as the flow rate changes when β = 12.8 mm and β = 22.5 degrees;

[0066] FIG6F is a diagram of the microchannel structure shown in FIG6A at r min Schematic diagram of the focusing position of three-size particles as the flow rate changes when β = 6.05 mm and β = 30 degrees;

[0067] FIG6G is a diagram of the microchannel structure shown in FIG6A at r min Schematic diagram of the focusing position of three sizes of particles as the flow rate changes when β = 6.05 mm and β = 45 degrees;

[0068] FIG6H is a schematic top view of another microfluidic channel structure provided by an embodiment of the present disclosure;

[0069] 6I , 6J , and 6K are schematic diagrams of the focusing positions of particles of three sizes at different flow rates in the microfluidic channel structure shown in FIG. 6H ;

[0070] FIG6L is a schematic top view of another microfluidic channel structure provided by an embodiment of the present disclosure;

[0071] 6M , 6N , and 6O are schematic diagrams of the focusing positions of particles of three sizes at different flow rates in the microfluidic channel structure shown in FIG. 6L ;

[0072] FIG7A is a schematic top view of another microfluidic channel structure provided by an embodiment of the present disclosure;

[0073] FIG7B is a schematic top view of the microchannel structure shown in FIG7A after it has been repeated four times;

[0074] FIG7C is an experimental diagram of particle focusing positions of the microfluidic structure shown in FIG7A at different repetition numbers;

[0075] FIG8A is a schematic diagram of another microfluidic channel structure provided by an embodiment of the present disclosure;

[0076] FIG8B is a schematic diagram of another microfluidic channel structure provided by an embodiment of the present disclosure;

[0077] FIG9A is a schematic diagram of a microfluidic chip provided in one embodiment of the present disclosure;

[0078] FIG9B is a partially enlarged schematic diagram of the first separation structure shown in FIG9A ;

[0079] FIG9C is a schematic diagram of separation of particles of different sizes in the first separation structure shown in FIG9A ;

[0080] FIG9D is a diagram showing the enrichment of particles of different sizes collected at the four first sub-outlets shown in FIG9A ;

[0081] FIG10A is a schematic diagram of another microfluidic chip provided in one embodiment of the present disclosure;

[0082] FIG10B is a graph showing the capture efficiency of target particles in whole blood using the microfluidic chip shown in FIG10A ;

[0083] FIG10C is a diagram showing the enrichment of human breast cancer cells spiked into whole blood at the three outlets of the microfluidic chip shown in FIG10A ;

[0084] FIG11A is a schematic structural diagram of another microfluidic chip provided in one embodiment of the present disclosure;

[0085] FIG11B is a schematic diagram of separation of particles of different sizes at the first separation structure shown in FIG11A ;

[0086] FIG11C is a schematic diagram of separation of particles of different sizes at the second separation structure shown in FIG11A ;

[0087] FIG11D is a schematic diagram of separation of particles at the third separation structure shown in FIG11A ;

[0088] FIG11E is a schematic diagram showing the capture efficiency of target particles using the microfluidic chip shown in FIG11A under different conditions;

[0089] FIG11F is a diagram showing the enrichment of human breast cancer cells collected in phosphate-buffered saline using the microfluidic chip shown in FIG11A ;

[0090] FIG11G is a diagram of collecting human breast cancer cells and waste fluid from ten-fold diluted blood using the microfluidic chip shown in FIG11A ;

[0091] FIG11H is a schematic diagram of the focusing positions of particles of different sizes in the microfluidic channel structure of the microfluidic chip shown in FIG11A ;

[0092] FIG11I is a graph showing the capture efficiency of the microfluidic chip shown in FIG11A at different flow rates;

[0093] FIG11J is a schematic diagram of target particles before and after treatment using the microfluidic chip shown in FIG11A ;

[0094] FIG11K is a comparative diagram showing the treatment of circulating tumor cells in a blood sample using the microfluidic chip shown in FIG11A ;

[0095] FIG11L is a graph showing the capture efficiency of particles and circulating tumor cells in whole blood at different flow rates using the microfluidic chip shown in FIG11A ;

[0096] FIG12 is a schematic diagram of a microfluidic device provided in one embodiment of the present disclosure; and

[0097] FIG13 is a flow chart of a target particle aggregation method provided in one embodiment of the present disclosure. DETAILED DESCRIPTION

[0098] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0099] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0100] Unless otherwise defined, the features such as “parallel”, “perpendicular” and “identical” used in the embodiments of the present disclosure include situations such as “parallel”, “perpendicular” and “identical” in a strict sense, as well as situations such as “approximately parallel”, “approximately perpendicular” and “approximately identical” that contain a certain error. For example, the above-mentioned “approximately” may mean that the difference between the compared objects is 10% of the average value of the compared objects, or within 5%. When the number of a component or element is not specifically indicated below in the embodiments of the present disclosure, it means that the component or element may be one or more, or may be understood as at least one. “At least one” refers to one or more, and “plurality” refers to at least two.

[0101] Among all the passive separation and classification methods for unlabeled particles or particulate matters (such as circulating tumor cells) based on physical characteristics, the membrane filtration and strut filtration methods have problems due to their orthogonality, resulting in the inability to simultaneously meet the throughput and capture rate. At the same time, the inability to improve purity is also an important issue. The lateral flow, deterministic lateral displacement (DLD), and pinched flow fractionation (PFF) methods all inevitably require a large amount of buffer for processing, which has a great impact on subsequent cell analysis. In contrast, inertial focusing can achieve relatively high processing capabilities, avoid the rupture of particulate matters such as cells caused by excessive shear force, and can also separate cells by relying only on inertial effects without using buffer, and is easy to combine with other separation methods. One of the important application scenarios of this separation method is the separation of CTC. CTC can be used as a target for "liquid biopsy", providing a non-invasive method for the research, diagnosis, and treatment of metastatic cancer. The main technical challenge in enriching CTC from peripheral blood is that CTC is very rare in blood, and the usually estimated concentration is several CTCs among billions of red blood cells and millions of white blood cells in each milliliter of whole blood. Therefore, how to efficiently and selectively capture CTC is the first key step in the analysis.

[0102] Compared with traditional microfluidic technologies, inertial microfluidic technologies operate in the intermediate Reynolds number (Re) range between the Stokes flow region and the turbulent flow region (1 < Re < 100). In this intermediate range, both the inertial viscosity and the fluid viscosity are finite, and some interesting effects are generated, which form the basis of inertial microfluidics, including inertial migration and secondary flow. Cells in the channel are affected by these two effects, causing particles of different sizes to start separating.

[0103] Inertial migration refers to the phenomenon that randomly dispersed particles shift to multiple equilibrium positions after passing through a sufficient long distance at the entrance of a straight channel. The phenomenon of inertial migration was first observed in a circular tube in 1961, where particles or granules aggregate into a ring with a radius approximately 0.6 times the radius of the circular tube. The inertial lift force varies with the fourth power of the cell size and is responsible for focusing cells at different multiple equilibrium positions within the cross-section of the microchannel.

[0104] where ρ is the fluid density (kg / m 3 ), U is the average flow velocity (m / s), D H is the hydraulic diameter of the channel (m), f is the lift coefficient, which varies with the position of the particle in the channel, and a is the particle diameter (m).

[0105] Secondary flows are generated when a curved channel is introduced. The fluid flowing through the curved channel experiences radially outward centrifugal acceleration, resulting in the formation of two counter-rotating vortices in the upper and lower halves of the channel. The magnitude of these secondary flows is quantified by a dimensionless parameter, the Dean number (De), which is given by the following formula:

[0106] Where, ρ is the fluid density, U is the average flow velocity, μ is the viscosity of the fluid, R is the radius of curvature of the channel path (m), and D H is the channel hydraulic diameter (m), and Re is the flow Reynolds number (ratio of inertial to viscous forces).

[0107] Where ρ is the fluid density, υ is the flow velocity, μ is the viscosity of the fluid, and d is the characteristic length of the channel (m). D is commonly used. H The Reynolds number (Re) is a dimensionless number that can be used to characterize fluid flow conditions.

[0108] The relationship between the secondary flow velocity and the Dean number is:

[0109] Where ρ is the fluid density, μ is the fluid viscosity, and D H is the hydraulic diameter of the channel, and k is the empirically determined proportionality factor for these curvilinear channels, which is approximately 0.01. The value of k can be verified using a COMSOL model of the set channel.

[0110] The drag force on the particle in the secondary flow can be given by Stokes' law: D =3πμaU De

[0111] where μ is the viscosity of the fluid, a is the particle diameter, and U De is the velocity of the secondary flow.

[0112] As a first-order approximation, for particles or granules flowing in curved channels, we can assume that the effects of inertial transport and secondary flow are additive. This means that Dean drag in the secondary flow competes with the inertial lift force, acting on the particle and shifting its equilibrium position. The ratio of these two forces (inertial lift / Dean drag) is the key parameter describing the behavior of these systems.

[0113] in,

[0114] Among them, when R f→0, the inertial force is smaller than the resistance, so the particle will ignore the inertial equilibrium position and be carried by the secondary flow, and then remain in the secondary flow; and R f →∞, the particles are mainly dominated by inertial forces and will migrate to the inertial focusing equilibrium position without being affected by the secondary flow. f , the inertial equilibrium position produced by inertial focusing can be modified by secondary flows, resulting in interesting new focusing results. f >~0.04, R f The effect related to the particle size causes two particles of different sizes to exhibit different behaviors in the channel. The smaller particles are completely entrained by the secondary flow, while the larger particles are concentrated in the inertial equilibrium position. When we choose the channel shape and Reynolds number appropriately, we can achieve the separation of particles of different sizes.

[0115] In some systems with high-density particle collisions (e.g., blood), purity may be reduced when separating unlabeled particles (e.g., circulating tumor cells) from undiluted blood due to cell-cell collisions.

[0116] Existing inertial focusing devices mainly separate particle sizes through three shapes, namely spiral, serpentine and contraction-expansion shapes. Figure 1A is a top-down schematic diagram of a spiral inertial focusing channel; Figure 1B is a top-down schematic diagram of a serpentine inertial focusing channel; and Figure 1C is a top-down schematic diagram of a contraction-expansion inertial focusing channel.

[0117] As shown in Figure 1A, the spiral inertial focusing channel focuses particles of different sizes near the inner wall and separates them by using the difference in focusing positions. However, the focusing positions of particles of different sizes are very close, and their relative positions will change with the flow rate. In order to stably collect particles of a fixed size, it is necessary to add a second inlet at the inlet to introduce a buffer solution to enhance the intensity of the secondary flow, or to add an extended outlet at the outlet to expand the slightly different focusing positions and thus collect particles of the target size.

[0118] As shown in Figure 1B, a symmetrical or asymmetrical serpentine inertial focusing channel focuses large particles in the center of the channel ("single focusing" effect) and small particles on both sides of the channel ("double focusing" effect), separating particles of different sizes. This is very effective for separating two particles with a large size difference. However, for particles with a smaller size difference, if we want to select a certain cutoff diameter and collect particles larger or smaller than this size separately, it will be very difficult, because in the process from "double focusing" to "single focusing", the particles are basically in a defocused state, and particles of different sizes cannot be distinguished.

[0119] As shown in Figure 1C, for a symmetrical converging and expanding channel, the focusing effect is similar to that of a symmetrical serpentine structure: large particles are focused in the center, while small particles are focused on the sides. However, for an asymmetric structure, large particles and small particles are focused at different locations depending on whether buffer is added at the inlet and the channel shape. Selecting a specific cutoff diameter and separately collecting particles larger or smaller than that size would also be very difficult.

[0120] Among the existing inertial focusing technologies, one part is based on the improvement of the serpentine pattern. As mentioned above, the focusing effect of this part is mostly to focus larger particles or granules in the center of the channel, and smaller particles on both sides of the channel. Particles of different sizes can be separated within a small specific flow rate range. This method has a relatively stable separation effect for particles with a certain size difference, and the structure is easy to connect in series. However, this method has difficulty in separating particles of multiple sizes at the same time, and the separation effect for particles of similar sizes is poor. The other part is based on the improvement of the spiral pattern. The focusing effect of this part is mostly focused near the channel wall. Although the focusing effect is good, the separation of different sizes can only be achieved by using a buffer solution or a structure similar to PFF to amplify the tiny difference in focusing position, and it is very sensitive to changes in flow rate.

[0121] In addition, some designs (for example, maze-shaped inertial focusing channels) use a combination of irregular corners and arcs to achieve a certain focusing effect. However, these designs lack a reasonable theoretical support and effective improvement solutions. They are overly sensitive to the structure, resulting in low robustness, and the focusing efficiency is extremely sensitive to flow rate. In summary, the main problems with these designs are that it is difficult to control the impact of changes in factors such as flow rate, and there are few parameters that can be adjusted and controlled, making it impossible to achieve the expected results through parameter improvement.

[0122] Existing inertial focusing separation devices (such as serpentine or spiral focusing) also suffer from flow rate and structural sensitivity issues. This problem severely limits practical applications. In many existing inertial focusing separation device chips, a change in flow rate of 0.1 mL / min can lead to significant changes in separation efficiency and results, and a significant reduction in capture efficiency. Some existing inertial focusing separation device chips are also highly sensitive to structure. Due to factors such as errors, the optimal flow rate of chips from different batches of the same mold can vary significantly.

[0123] In this regard, the embodiments of the present disclosure provide a microfluidic structure and a microfluidic chip. The microfluidic structure includes at least one microfluidic unit, each microfluidic unit including a plurality of curved channels and a plurality of turning channels. The plurality of curved channels are arranged at intervals along the arrangement direction, each turning channel is located between two adjacent curved channels and connects the two adjacent curved channels; the two turning channels connected to a curved channel are respectively located at both ends of the curved channel. Each curved channel has a first side and a second side opposite to each other in the arrangement direction, and each curved channel bends toward a first position located on the second side.

[0124] The multiple curved channels in each microchannel unit of the microchannel structure provided by the embodiment of the present disclosure are arranged at intervals along the arrangement direction, and each curved channel has a first side and a second side relative to each other in the arrangement direction, and each curved channel is bent toward a first position located on the second side; according to the above theoretical basis, when particles of different sizes are introduced into the curved channel, secondary flow will be generated, and the fluid flowing through the curved channel experiences radially outward centrifugal acceleration, resulting in the formation of two counter-rotating vortices in the upper and lower halves of the curved channel; particles of smaller size are more easily entrained by the secondary flow, while particles of larger size are concentrated at the inertial equilibrium position. When particles pass through multiple curved channels, the radially outward centrifugal acceleration to which the particles are subjected in each curved channel deviates from the first position located on the second side. Therefore, after passing through multiple curved channels with the bends all facing the second side, the particles will gradually focus at a position deviating from the center of the curved channel; at the same time, under the action of the secondary flow of the curved channel and the turning channel, particles of different sizes deviate from the center of the curved channel to different degrees. In this way, particles of different sizes can be focused at different positions deviating from the center of the flow channel, thereby achieving the separation of particles of different sizes. Different from the serpentine channels in the prior art, the multiple curved channels in this microfluidic structure are all curved toward the first position located on the second side, so that particles of different sizes can be focused at positions deviating from the center of the curved channel. In the serpentine channels in the prior art, larger particles are all focused at the center of the channel, and particles focused at the center of the channel cannot be separated. Therefore, by using this microfluidic structure, particles of two or more sizes can be inertially focused at different positions, thereby achieving separation.

[0125] In addition, the effective flow rate range redundancy of the microfluidic unit of this microfluidic structure is large, so it can be applied to a wider flow rate range; at the same time, it also has the characteristics of large flow rate, high separation efficiency, simple production, easy operation, and not easily affected by impurities, which reduces the sensitivity of dependence on the microfluidic structure, making the microfluidic structure have good robustness and a broad application space.

[0126] The microfluidic structure and microfluidic chip provided by the embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0127] FIG2A is a schematic structural diagram of a microfluidic unit of a microfluidic structure provided by an embodiment of the present disclosure; FIG2B is a schematic top view of the microfluidic unit shown in FIG2A . As shown in FIG2A and FIG2B , the microfluidic structure 100 includes at least one microfluidic unit 110, and each microfluidic unit 110 includes a plurality of curved channels 111 and a plurality of turning channels 112. The plurality of curved channels 111 are arranged at intervals along the arrangement direction X, and each turning channel 112 is located between two adjacent curved channels 111 and connects the two adjacent curved channels 111; the two turning channels 112 connected to a curved channel 111 are respectively located at both ends of the curved channel 111. Each curved channel 111 has a first side SN and a second side SN' relative to each other in the arrangement direction X, where N is the number of curved channels 111 in the microchannel unit 110; for example, the first curved channel 111 in the arrangement direction X has a first side S1 and a second side S1', and the last curved channel 111 in the arrangement direction X (i.e., the sixth curved channel 111) has a first side S6 and a second side S6'. For example, the above-mentioned first side SN and second side SN' may be the left and right sides of each curved channel 111 in the arrangement direction X. It should be noted that although the number N of curved channels in the microchannel unit shown in Figures 2A and 2B is six, the embodiments of the present disclosure include but are not limited to this.

[0128] As shown in Figures 2A and 2B , each curved channel 111 curves toward a first position PN located on the second side SN'. For example, the first curved channel 111 in the arrangement direction X curves toward a first position P1 located on the second side S1', and the sixth curved channel 111 in the arrangement direction X curves toward a first position P6 located on the second side S6'. Figure 2B only illustrates the first side S1, second side S1', and first position P1 of the first curved channel 111 in the arrangement direction X, and the first side S6, second side S6', and first position P6 of the sixth curved channel 111. The first side SN, second side SN', and first position P1 of the other curved channels 111 are similar and are not labeled in the figure.

[0129] The multiple curved channels 111 in each microchannel unit 110 of the microchannel structure 100 provided in the embodiment of the present disclosure are arranged at intervals along the arrangement direction X. Each curved channel 111 has a first side SN and a second side SN' relative to each other in the arrangement direction X, and each curved channel 111 bends toward a first position PN located on the second side SN'. According to the aforementioned theoretical basis, when particles of different sizes are introduced into a curved channel, a secondary flow is generated. The fluid flowing through the curved channel experiences radially outward centrifugal acceleration, resulting in the formation of two counter-rotating vortices in the upper and lower halves of the curved channel; smaller particles are more easily entrained by the secondary flow, while larger particles are concentrated in the inertial equilibrium position. When particles pass through multiple curved channels 111, the radially outward centrifugal accelerations to which the particles are subjected in each curved channel 111 are all directed away from the first position PN located on the second side SN'. Therefore, after passing through multiple curved channels 111 that are all bent toward the second side SN', the particles will gradually focus at a position deviated from the center of the curved channel 111. At the same time, under the action of the secondary flows of the curved channel 111 and the turning channel 112, particles of different sizes deviate from the center of the curved channel 111 to different degrees. Thus, particles of different sizes can be focused at different positions deviated from the center of the channel, thereby achieving the separation of particles of different sizes. Unlike the serpentine channels in the prior art, the multiple curved channels 111 in the microfluidic structure 100 all bend toward the first position PN located on the second side SN', thereby allowing particles of different sizes to be focused at a position deviated from the center of the curved channel 111. In the serpentine channels in the prior art, larger particles are all focused at the center of the channel, and particles focused at the center of the channel cannot be separated. Therefore, by using the microfluidic channel structure 100 , particles of two or more sizes can be inertially focused at different positions, thereby achieving separation.

[0130] In addition, the effective flow rate range redundancy of the microfluidic unit 110 of the microfluidic structure 100 is large, so it can be applied to a wider flow rate range; at the same time, it also has the characteristics of large flow rate, high separation efficiency, simple production, easy operation, and not easily affected by impurities, which reduces the sensitivity of dependence on the microfluidic structure, making the microfluidic structure have good robustness and a broad application space.

[0131] In some examples, as shown in FIG2A and FIG2B , the first positions PN of the plurality of curved channels 111 are located on the same side of the plurality of curved channels 111 in the arrangement direction X. That is, the plurality of curved channels 111 of each microfluidic channel unit 110 can be considered as a whole, and in the arrangement direction X of the plurality of curved channels 111 of the microfluidic channel unit 110, the whole has a first side S0 and a second side S0' opposite to each other, and the first position PN of each curved channel 111 is located on the same side of the whole, for example, on the first side S0 or the second side S0' of the whole; that is, the first position PN of each curved channel 111 of the microfluidic channel unit 110 does not fall within the interior of the whole.

[0132] In some examples, as shown in FIG2A and FIG2B , the lengths Len of the plurality of curved flow channels 111 gradually change along the arrangement direction X. For example, the lengths Len of the plurality of curved flow channels 111 of each microfluidic channel unit 110 may gradually decrease or gradually increase along the arrangement direction X. The disclosed embodiments are not limited thereto, and the lengths Len of the plurality of curved flow channels 111 of each microfluidic channel unit 110 may also be the same or may vary alternately, and the lengths Len of the plurality of curved flow channels 111 may be set as required.

[0133] In some examples, as shown in FIG. 2A and FIG. 2B , each curved channel 111 is an arc-shaped channel, and the first position PN of each curved channel 111 is the center of curvature of the curved channel 111 .

[0134] In some examples, the multiple first positions PN of the multiple curved channels 111 are located on the same straight line. Thus, the microfluidic channel structure 100 can make the different inertial equilibrium positions of particles of different sizes in the channel more stable, thereby improving the separation efficiency of the microfluidic channel structure 100 and increasing the redundancy of the effective flow rate range.

[0135] In some examples, as shown in FIG2B , the first positions PN of the plurality of curved channels 111 overlap. Thus, the microfluidic channel structure 100 can stabilize the different inertial equilibrium positions of particles of different sizes in the channel, thereby achieving higher separation efficiency and greater redundancy in the effective flow rate range.

[0136] In some examples, as shown in FIG2A and FIG2B , along the arrangement direction X, the lengths of the plurality of curved channels 111 gradually decrease. Among the plurality of curved channels 111, the arc radius of the longest curved channel 111 is r max , arc radius r max The value range of is 13mm to 20mm. The embodiment of the present disclosure does not limit this. For example, the arc radius r max The value range of can also be 10mm to 50mm, for example, the arc radius rmax It can be 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 25mm, 30mm, 35mm, 40mm, 45mm, for example, the arc radius r max It can be any value between 10mm and 50mm.

[0137] For example, as shown in FIG2A and FIG2B, the arc radius r max Alternatively, it may be the arc radius of the curved channel 111 farthest from the first position PN, or the radius of the first curved channel 111 in the arrangement direction X.

[0138] For example, as shown in FIG2A and FIG2B, along the arrangement direction X, the lengths of the plurality of curved channels 111 gradually decrease. Among the plurality of curved channels 111, the arc radius of the shortest curved channel 111 is r. min , arc radius r min The value range of is 3mm to 8mm. The embodiment of the present disclosure does not limit this. For example, the arc radius r min The value range of can also be 1mm to 20mm, for example, the arc radius r min It can be 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 15mm, 18mm, for example, the arc radius r min It can be any value between 1mm and 20mm.

[0139] For example, as shown in FIG2A and FIG2B, the arc radius r min It may also be the arc radius of the curved channel 111 closest to the first position PN, or the radius of the last curved channel 111 in the arrangement direction X.

[0140] In the micro-channel structure 100 provided in the embodiment of the present disclosure, different arc radii r max and the arc radius r min The influence on the focusing effect is different. The smaller the radius of the arc, the stronger the secondary flow generated, and the greater the influence on the result. max and the arc radius r min Parameterization can better adjust and optimize the arc radius r max and the arc radius r min , thus obtaining an effective improvement plan, effectively improving the separation effect and being applicable to a wider flow rate range.

[0141] In some examples, as shown in Figures 2A and 2B, the number of multiple curved channels 111 is N, and the value range of the number N is 4-8; for example, each microchannel unit may include four, five, six, seven or eight curved channels. Thus, after passing through N curved channels 111, the different inertial equilibrium positions of particles of different sizes in the curved channels 111 are more stable, thereby having a higher separation efficiency and being applicable to a wider range of flow rates. Of course, the embodiments of the present disclosure are not limited to this. For example, the value range of the number N can also be 2-50. For example, the number N can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 18, 20, 25, 30, 35, 40, 45. For example, N can be any positive integer between 2 and 50.

[0142] In some examples, as shown in Figures 2A and 2B, the distance between two adjacent curved channels 111 is d, and the value range of the distance d can be 300μm to 1000μm. The embodiment of the present disclosure does not limit the value range of the distance d. For example, the value range of the distance d can also be 100μm to 2000μm. For example, the distance d can be 200μm, 400μm, 600μm, 800μm, 1000μm, 1200μm, 1500μm, or 1800μm. The distance d can be any value between 100μm and 2000μm.

[0143] For example, as shown in FIG. 2A and FIG. 2B , the intervals d between the plurality of curved flow channels 111 may be equal.

[0144] In some examples, as shown in FIG2A and FIG2B , the plurality of curved channels 111 of the microfluidic unit 110 are arc-shaped channels, the first position PN of each curved channel 111 is the center of curvature of the curved channel 111, the plurality of first positions PN of the plurality of curved channels 111 overlap with each other, the lengths of the plurality of curved channels 111 gradually decrease along the arrangement direction X, the plurality of curved channels 111 are equidistantly arranged, and the parameters of the microfluidic unit 110 satisfy the following formula: (N-1)·d+N·D=r max -r min

[0145] Wherein, N is the number of the plurality of curved channels 111, d is the distance between two adjacent curved channels 111, and D is the width of the curved channel 111. In the plurality of curved channels 111, r max is the arc radius of the longest curved channel 111, r min The present disclosure is not limited thereto. For example, along the arrangement direction X, the lengths of the plurality of curved channels 111 may not be limited to gradually becoming smaller. In this case, r maxis the arc radius of the curved channel 111 farthest from the first position PN, or the arc radius of the first curved channel 111 in the arrangement direction X, r min is the arc radius of the curved channel 111 closest to the first position PN, or the arc radius of the last curved channel 111 in the arrangement direction X. Thus, the microchannel unit 110 of the microchannel structure 100 can be parameterized. By adjusting the values ​​of different parameters, a microchannel structure 100 suitable for different conditions can be obtained. At the same time, by adjusting the parameters, various parameters can be matched and optimized, thereby obtaining an effective improvement solution, thereby effectively improving the separation efficiency and being applicable to a wider flow rate range.

[0146] In some examples, as shown in FIG. 2A and FIG. 2B , each turning channel 112 includes an inner wall 112a and an outer wall 112b , wherein the inner wall 112a is disposed opposite to the outer wall 112b , and the inner wall 112a is located on a side of the outer wall 112b close to the gap between two adjacent curved channels 111 .

[0147] In some examples, as shown in Figures 2A and 2B , among the multiple turning channels 112 located on the same side of a reference line L0 extending along the arrangement direction X and passing through the multiple curved channels 111, the outer wall 112b of the first turning channel 112 and the outer wall 112b of the last turning channel 112 in the arrangement direction X both intersect with the first auxiliary line L6 and are both located on the side of the first auxiliary line L6 closer to the reference line L0. Among the multiple turning channels 112 located on the other side of the reference line L0, the outer wall 112b of the first turning channel 112 and the outer wall 112b of the last turning channel 112 in the arrangement direction X both intersect with the second auxiliary line L7 and are both located on the side of the second auxiliary line L7 closer to the reference line L0. The angle λ between the first auxiliary line L6 and the second auxiliary line L7 ranges from 10 degrees to 90 degrees. The angle λ affects the duration of the focusing effect of the curved channel 111. As a result, each microchannel unit 110 of the microchannel structure 100 can stabilize the different inertial equilibrium positions of particles of different sizes in the channel, thereby achieving higher separation efficiency and greater redundancy in the effective flow rate range. Furthermore, by parameterizing the angle λ, better adjustments and optimizations can be made based on particle sizes, resulting in an effective improvement solution that effectively enhances separation efficiency and accommodates a wider flow rate range.

[0148] In some examples, the value of the angle λ can be 15 degrees, 15.5 degrees, 17.5 degrees, 20 degrees, 22.5 degrees, 25 degrees, 27.5 degrees, 30 degrees, 32.5 degrees, 35 degrees, 37.5 degrees, 40 degrees, 45 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, etc. The angle λ can be any angle between 10 degrees and 90 degrees, which are not listed here one by one.

[0149] In some examples, as shown in Figures 2A and 2B, the orthographic projection of the inner sidewall 112a of each turning channel 112 on reference plane A is in the shape of a first circular arc, and the orthographic projection of the outer sidewall 112b of the turning channel 112 on reference plane A is in the shape of a second circular arc. Reference plane A is parallel to both the arrangement direction X and the extension direction of each curved channel 111. Thus, each turning channel 112 can cause particles of different sizes to deviate from the center of the channel to varying degrees, thereby achieving separation of particles of different sizes and, further, enabling particles of different sizes to be focused at different locations off-center under the action of the microfluidic channel structure 100.

[0150] For example, the radius of the first arc is r in , the radius of the second arc r out , the curvature radius of the second arc r out It can be approximately equal to the curvature radius r of the first arc in and the sum of the widths of the steering channel 112; for example, the centers of curvature of the first arc and the second arc may coincide. In this case, the width of the steering channel 112 is the same in the extension direction of the steering channel 112. The embodiment of the present disclosure does not impose any restrictions on the parameters of the first arc and the second arc.

[0151] In some examples, as shown in Figures 2A and 2B, the diameter of the first arc can be equal to the distance d between two adjacent curved channels 111. That is, the first arc is a semicircular arc. Similarly, the second arc can also be a semicircular arc. The present disclosure is not limited to this. For example, the first arc and the second arc can also be inferior arcs or superior arcs.

[0152] In some examples, as shown in FIG2A and FIG2B , the reference line L0 is a line extending along the arrangement direction X and passing through the plurality of curved channels 111. Among the plurality of turning channels 112 located on the same side of the reference line L0, the orthographic projections of the outer wall 112b of the first turning channel 112 and the outer wall 112b of the last turning channel 112 in the arrangement direction X on the reference plane A are tangent to the first line L1. That is, the first line L1 is the outer common tangent line of the orthographic projections of the outer wall 112b of the first turning channel 112 and the outer wall 112b of the last turning channel 112 on the reference plane A.

[0153] For example, as shown in FIG2A and FIG2B , among the plurality of turning channels 112 located on the same side of the reference line L0, the outer sidewall 112b of the turning channel 112 located between the first turning channel 112 and the last turning channel 112 in the arrangement direction X may also be tangent to the first line L1. That is, the outer sidewalls 112b of the plurality of turning channels 112 located on the same side of the reference line L0 have the same external common tangent line, which is the first line L1. Of course, embodiments of the present disclosure include but are not limited to this. The outer sidewall 112b of the turning channel 112 located between the first turning channel 112 and the last turning channel 112 in the arrangement direction X may be located on the side of the first line L1 closer to the reference line L0, or at least a portion of the outer sidewall 112b of the turning channel 112 located between the first turning channel 112 and the last turning channel 112 in the arrangement direction X may be located on the side of the first line L1 farther from the reference line L0, that is, beyond the first line L1.

[0154] In some examples, as shown in Figures 2A and 2B, each microfluidic unit 110 of the microfluidic structure 100 further includes an inlet channel 113 and an outlet channel 114, the inlet channel 113 is connected to the first curved channel 111 in the arrangement direction X; the outlet channel 114 is connected to the last curved channel 111 in the arrangement direction X, the outlet channel 114 and the first straight line L1 are respectively located on both sides of the reference straight line L0, that is, the outlet channel 114 is located on the side of the reference straight line L0 away from the first straight line L1, the side wall of the last curved channel 111 in the arrangement direction X close to the first position P6 and the side wall of the outlet channel 114 close to the first straight line L1 have an intersection Px on the reference plane A, the first position P6 of the last curved channel 111 in the arrangement direction X and the intersection Px are located on the second straight line L2, the first straight line L1 and the second straight line L2 have an angle θ, and the value range of the angle θ is 15 degrees to 30 degrees. The angle θ affects the duration of the arc's focusing effect. Consequently, each microchannel unit 110 of the microchannel structure 100 can stabilize the different inertial equilibrium positions of particles of different sizes within the flow channel, resulting in higher separation efficiency and greater redundancy within the effective flow rate range. Furthermore, by parameterizing the angle θ, better adjustments and optimizations can be made based on particle sizes, resulting in an effective improvement solution that effectively enhances separation efficiency and accommodates a wider flow rate range.

[0155] For example, the angle θ may also range from 10 degrees to 90 degrees. For example, the angle θ may be any angle between 10 degrees and 90 degrees. For example, the angle θ may be 15 degrees, 15.5 degrees, 17.5 degrees, 20 degrees, 22.5 degrees, 25 degrees, 27.5 degrees, 30 degrees, 32.5 degrees, 35 degrees, 37.5 degrees, 40 degrees, 45 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, etc., which are not listed here one by one.

[0156] In some examples, as shown in FIG. 2A and FIG. 2B , the orthographic projection of the sidewall 114 a of the outlet flow channel 114 close to the first straight line L1 (or close to the reference straight line L0 ) on the reference plane A may coincide with the second straight line L2 .

[0157] In some examples, the width of the inlet channel 113 is the same as the width of the curved channel 111. For example, the height of the inlet channel 113 is the same as the height of the curved channel 111.

[0158] In some examples, the width of the outlet flow channel 114 is the same as the width of the curved flow channel 111. For example, the height of the outlet flow channel 114 is the same as the height of the curved flow channel 111.

[0159] In some examples, as shown in Figures 2A and 2B , among the multiple turning channels 112 located on the side of the reference line L0 away from the first line L1, the orthographic projections of the outer wall 112b of the first turning channel 112 and the outer wall 112b of the last turning channel 112 in the arrangement direction X on the reference plane A are tangent to the third line L3. That is, the third line L3 is the outer common tangent line of the orthographic projections of the outer walls 112b of the two turning channels 112 on the reference plane A. The third line L3 and the first line L1 are located on either side of the reference line L0, respectively.

[0160] In some examples, the first straight line L1 and the third straight line L3 may be parallel, that is, the angle α between the first straight line L1 and the third straight line L3 is 0 degrees.

[0161] In some examples, as shown in Figures 2A and 2B, the first straight line L1 and the third straight line L3 may have an angle α, and the angle α of the two first straight lines L1 may range from 15 degrees to 30 degrees. Thus, each microfluidic unit 110 of the microfluidic structure 100 can make the different inertial equilibrium positions of particles of different sizes in the flow channel more stable, and thus the separation efficiency of the microfluidic structure 100 is higher, and the redundancy of the effective flow rate range is greater. At the same time, by parameterizing the angle α, it is also possible to make better adjustments and optimizations according to particles of different sizes, thereby obtaining an effective improvement scheme, effectively improving the separation effect, and being applicable to a wider flow rate range. The embodiment of the present disclosure does not limit the value of the angle α. For example, the value range of the angle α can also be 10 degrees to 90 degrees. For example, the angle α can be any value between 10 degrees and 90 degrees. For example, the value of the angle α can be 15 degrees, 15.5 degrees, 17.5 degrees, 20 degrees, 22.5 degrees, 25 degrees, 27.5 degrees, 30 degrees, 32.5 degrees, 35 degrees, 37.5 degrees, 40 degrees, 45 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, etc., which are not listed here one by one.

[0162] In some examples, as shown in FIG. 2A , the first straight line L1 may coincide with the first auxiliary straight line L6 defined above, and the third straight line L2 may coincide with the second auxiliary straight line L7 defined above, so that the angle α and the angle λ may be the same.

[0163] For example, as shown in FIG2A , the second straight line L2 may be parallel to the third straight line L3 or the second auxiliary line L7 , so that the angle θ and the angle α may be the same, or the angle θ and the angle λ may be the same, or the angle θ, the angle α and the angle λ are all the same.

[0164] In some examples, as shown in FIG2A , the height of the plurality of curved channels 111 is h, and the value range of the height h is 10 μm to 100 μm. The disclosed embodiments do not limit the value range of the height h. For example, the height h can be 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, or 140 μm. For example, the height h can also be any value between 10 μm and 150 μm.

[0165] In some examples, the height h of the curved flow channel 111 can be selected based on the size of the target particles or the particles to be obtained or the desired flow rate of the microfluidic structure 100. For example, based on multiple experiments, the height h of the multiple curved flow channels 111 of the microfluidic structure 100 can satisfy the following empirical formula:

[0166] Among them, a c is the minimum diameter that can be focused. cThe value of is used to preliminarily confirm the value range of the height h of the curved flow channel 111.

[0167] For example, in the embodiment of separating circulating tumor cells, the cutoff diameter of leukocytes is selected to be 8 μm, i.e., a c The value of is 8 μm. According to the above empirical formula, the value range of the height h can be confirmed. Then, according to the selection of other parameters, the height of the curved channel 111 is finally selected to be 75 μm.

[0168] 2A and 2B , the width of the plurality of curved channels 111 is D, and the ratio of the width D to the height h of the curved channels 111 ranges from 1 to 20. Of course, the embodiment of the present disclosure does not limit the range of the ratio of the width D to the height h.

[0169] In some examples, as shown in FIG2A and FIG2B , the width of the plurality of curved channels 111 is D, the ratio of the width D to the height h of the curved channels 111 ranges from 1 to 20, and the height h of the plurality of curved channels ranges from 10 μm to 150 μm. For example, the ratio of the width D to the height h can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, or 18.

[0170] In some examples, as shown in FIG2A and FIG2B , the width D of the plurality of curved flow channels 111 ranges from 10 μm to 800 μm. For example, the width D can also be any value from 10 μm to 800 μm. The present disclosure does not limit the range of the width D. For example, the width D can be 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 250 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, 1200 μm, or 1400 μm. For example, the width D can also range from 10 μm to 1500 μm.

[0171] In some examples, the width D of the curved channel 111 can be selected based on the size of the target particles or the particles to be obtained or the desired flow rate of the microfluidic structure 100. For example, in a curved channel 111 with a larger aspect ratio, the inertial lift is too weak in the middle part, making it difficult to focus the particles, while in a curved channel 111 with a smaller aspect ratio, because the height selection is limited, the Reynolds number range applicable to the microfluidic structure 100 is fixed, so the usable flow rate is lower. An appropriate aspect ratio should be selected to balance the flow rate and the focusing effect. For example, in an embodiment of separating circulating tumor cells, the width of the curved channel 111 is selected as 500 μm as the standard width, so that the available flow rate range of the microfluidic structure 100 is within the range of 1-4 mL / min. As a result, the microfluidic structure 100 can be applicable to a wider flow rate range, solving the problem of flow rate sensitivity.

[0172] FIG2C is a top view schematic diagram of another microfluidic unit provided in an embodiment of the present disclosure. As shown in FIG2C , the width of the turning channel 112 of the microfluidic unit 110 is not uniform in the extension direction of the turning channel 112. For example, in the extension direction of the turning channel 112, the width of the turning channel 112 first gradually increases and then gradually decreases, and the maximum width of the turning channel 112 is greater than the width of the curved channel 111. Thus, the turning channel 112 of the microfluidic unit 110 can better make particles of different sizes deviate from the center of the channel to different degrees, thereby achieving the separation of particles of different sizes, and further making particles of different sizes focused on different positions deviating from the center under the action of the microfluidic structure 100.

[0173] In some examples, as shown in FIG. 2C , the inlet channel 113 of the microfluidic channel unit 110 may be the same as the turning channel 112 , and the outlet channel 114 of the microfluidic channel unit 110 may also be the same as the turning channel 112 .

[0174] Figure 3A is a schematic top view of another microfluidic unit provided in one embodiment of the present disclosure. As shown in Figure 3A , the orthographic projection of the inner sidewall 112a of the diverting channel 112 on reference plane A is a first straight line segment, and the orthographic projection of the outer sidewall 112b of the diverting channel 112 on reference plane A is a second straight line segment. Thus, each diverting channel 112 can cause particles of different sizes to deviate from the center of the channel to varying degrees, thereby achieving separation of particles of different sizes and, further, enabling particles of different sizes to be focused at different locations off-center under the action of the microfluidic structure 100.

[0175] For example, the length of the second straight segment of the same diverting channel 112 can be greater than, equal to, or less than the length of the first straight segment. The second straight segment and the first straight segment of the same diverting channel 112 can be parallel, or the lines between the second and second straight segments can form an angle. The present embodiment does not limit the parameters of the first and second straight segments.

[0176] In some examples, as shown in FIG3A , the angle between the extension line of the first straight segment or the second straight segment and the extension direction of one of the two adjacent curved channels 111 is an acute angle, and the angle between the extension line of the first straight segment or the second straight segment and the extension direction of the other of the two adjacent curved channels 111 is an obtuse angle.

[0177] In some examples, as shown in FIG3A , the reference straight line L0 is a straight line extending along the arrangement direction X and passing through the plurality of curved channels 111. The plurality of first straight line segments of the plurality of turning channels 112 located on the same side of the reference straight line L0 are located on the same straight line. For example, the first straight line segments of all or some of the turning channels 112 located on the same side of the reference straight line L0 are located on the same straight line.

[0178] In some examples, as shown in FIG3A , the second straight line segments of the plurality of diverting channels 112 located on the same side of the reference line L0 are located on the same straight line. For example, the second straight line segments of all or some of the diverting channels 112 located on the same side of the reference line L0 are located on the same straight line.

[0179] In some examples, as shown in FIG3A , among the multiple turning channels 112 located on the same side of the reference line L0, the orthographic projections of the outer wall 112b of the first turning channel 112 and the outer wall 112b of the last turning channel 112 in the arrangement direction X on the reference plane A are located on the fourth line L4. For example, the outer wall 112b of the turning channel 112 located between the first turning channel 112 and the last turning channel 112 in the arrangement direction X may be located on the fourth line L4, or on the side of the fourth line L4 closer to the reference line L0, or on the side of the fourth line L4 farther from the reference line L0, that is, beyond the fourth line L4.

[0180] In some examples, as shown in Figure 3A, each microfluidic channel unit 110 of the microfluidic channel structure 100 further includes an inlet channel 113 and an outlet channel 114, the inlet channel 113 is connected to the first curved channel 111 in the arrangement direction X; the outlet channel 114 is connected to the last curved channel 111 in the arrangement direction X, the outlet channel 114 and the fourth straight line L4 are respectively located on both sides of the reference straight line L0, that is, the outlet channel 114 is located on the side of the reference straight line L0 away from the fourth straight line L4, the side wall of the last curved channel 111 in the arrangement direction X close to the first position P6 and the side wall 114a of the outlet channel 114 close to the fourth straight line L4 (or close to the reference straight line L0) have an intersection Px in their orthographic projections on the reference plane A, the first position P6 of the last curved channel 111 in the arrangement direction X and the intersection Px are located on the second straight line L2, the fourth straight line L4 and the second straight line L2 have an angle β, and the value range of the angle β is 15 degrees to 30 degrees. As a result, each microchannel unit 110 of the microchannel structure 100 can stabilize the different inertial equilibrium positions of particles of different sizes within the flow channel, thereby achieving higher separation efficiency and greater redundancy in the effective flow rate range. Furthermore, by parameterizing the angle β, better adjustments and optimizations can be made based on particle sizes, resulting in an effective improvement solution that effectively enhances separation efficiency and accommodates a wider flow rate range.

[0181] For example, the angle β may also range from 10 degrees to 90 degrees. For example, the angle β may be any angle between 10 degrees and 90 degrees. The angle β may be 15 degrees, 15.5 degrees, 17.5 degrees, 20 degrees, 22.5 degrees, 25 degrees, 27.5 degrees, 30 degrees, 32.5 degrees, 35 degrees, 37.5 degrees, 40 degrees, 45 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, etc., which are not listed here one by one.

[0182] In some examples, as shown in FIG. 3A , the orthographic projection of the sidewall 114 a of the outlet flow channel 114 close to the fourth straight line L4 (or close to the reference straight line L0 ) on the reference plane A may coincide with the second straight line L2 .

[0183] In some examples, the width of the inlet channel 113 is the same as the width of the curved channel 111. For example, the height of the inlet channel 113 is the same as the height of the curved channel 111.

[0184] In some examples, the width of the outlet flow channel 114 is the same as the width of the curved flow channel 111. For example, the height of the outlet flow channel 114 is the same as the height of the curved flow channel 111.

[0185] In some examples, as shown in FIG3A , among the multiple turning channels 112 located on the side of the reference line L0 away from the fourth line L4, the orthographic projections of the outer wall 112b of the first and last turning channels 112 in the arrangement direction X on the reference plane A lie on the fifth line L5. The fourth line L4 and the fifth line L5 are located on opposite sides of the reference line L0, respectively. In some examples, the fourth line L4 and the fifth line L5 may be parallel, that is, the angle γ between the fourth line L4 and the fifth line L5 is 0 degrees.

[0186] In some examples, as shown in FIG3A , the fourth straight line L4 and the fifth straight line L5 may have an angle γ, and the angle γ between the fourth straight line L4 and the fifth straight line L5 may range from 15 degrees to 30 degrees. Thus, each microfluidic unit 110 of the microfluidic structure 100 can stabilize the different inertial equilibrium positions of particles of different sizes in the flow channel, thereby achieving higher separation efficiency and greater redundancy in the effective flow rate range of the microfluidic structure 100. Furthermore, by parameterizing the angle γ, better adjustment and optimization can be performed based on particles of different sizes, thereby obtaining an effective improvement solution, effectively enhancing the separation effect, and being applicable to a wider flow rate range.

[0187] For example, the value range of the angle γ may also be 10 degrees to 90 degrees. For example, the angle γ may be any value between 10 degrees and 90 degrees. For example, the value of the angle γ may be 15 degrees, 15.5 degrees, 17.5 degrees, 20 degrees, 22.5 degrees, 25 degrees, 27.5 degrees, 30 degrees, 32.5 degrees, 35 degrees, 37.5 degrees, 40 degrees, 45 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, etc., which are not listed here one by one.

[0188] In some examples, as shown in FIG3A , the fourth straight line L4 may coincide with the first auxiliary straight line L6 defined above, and the fifth straight line L5 may coincide with the second auxiliary straight line L7 defined above, so that the included angle β is the same as the included angle λ.

[0189] In some examples, as shown in FIG3A , the first straight line L1 may coincide with the first auxiliary straight line L6 defined above, and the fourth straight line L4 may coincide with the second auxiliary straight line L7 defined above, so that the angle γ and the angle λ may be the same.

[0190] For example, as shown in FIG3A , the fourth straight line L4 may be parallel to the fifth straight line L5 or the second auxiliary straight line L7 , so that the angle β and the angle γ may be the same, or the angle β and the angle λ may be the same, or the angle β, the angle γ and the angle λ are all the same.

[0191] Figure 3B is a schematic top view of another microfluidic channel unit provided by one embodiment of the present disclosure. As shown in Figure 3B , reference line L0 is a line extending along the arrangement direction X and passing through the plurality of curved channels 111. The plurality of second straight line segments of the plurality of diverting channels 112 located on the same side of reference line L0 are mutually parallel. For example, the second straight line segments of all or some of the diverting channels 112 located on the same side of reference line L0 are mutually parallel.

[0192] In some examples, as shown in FIG3B , the first straight line segments of the plurality of diverting channels 112 on the same side of the reference line L0 are parallel to each other. For example, the first straight line segments L of all or some of the diverting channels 112 on the same side of the reference line L0 are parallel to each other.

[0193] 3B , the second straight line segments of the diverting channels 112 located on both sides of the reference line L0 are parallel to each other. For example, all or part of the second straight line segments of the diverting channels 112 may be parallel to each other.

[0194] 3B , the first straight line segments of the plurality of diverting channels 112 located on both sides of the reference line L0 are parallel to each other. For example, all or part of the first straight line segments of the diverting channels 112 may be parallel to each other.

[0195] In some examples, as shown in FIG3B , the multiple second straight line segments of the multiple diverting channels 112 located on one side of the reference line L0 are located on the same straight line, while the multiple second straight line segments of the multiple diverting channels 112 located on the other side of the reference line L0 are parallel to each other. For example, the multiple first straight line segments of the multiple diverting channels 112 located on one side of the reference line L0 are located on the same straight line, while the multiple first straight line segments of the multiple diverting channels 112 located on the other side of the reference line L0 are parallel to each other.

[0196] In some examples, among the plurality of second straight line segments of the plurality of turning channels 112 located on the same side of the reference straight line L0 , some of the second straight line segments are parallel to each other, and some of the second straight line segments are located on the same straight line.

[0197] Figure 3C is a schematic top view of another microfluidic unit provided in one embodiment of the present disclosure. As shown in Figure 3C , reference line L0 is a line extending along the arrangement direction X and passing through the multiple curved channels 111. The multiple second straight line segments of the multiple diverting channels 112 located on one side of reference line L0 are located on the same straight line, and the multiple second straight line segments of the multiple diverting channels 112 located on the other side of reference line L0 are located on the same straight line, and the two straight lines are parallel.

[0198] Figure 3D is a top view of another microfluidic channel unit 110 provided in one embodiment of the present disclosure. As shown in Figure 3D , the ends of the multiple second straight segments of the multiple diverting channels 112 can be connected to the curved channel 111 via circular arcs. For example, the multiple first straight segments of the multiple diverting channels 112 can also be connected to the curved channel 111 via circular arcs.

[0199] Figure 3E is a top schematic diagram of another microfluidic unit provided by an embodiment of the present disclosure; Figure 3F is a top schematic diagram of another microfluidic unit provided by an embodiment of the present disclosure; Figure 3G is a top schematic diagram of another microfluidic unit provided by an embodiment of the present disclosure; Figure 3H is a top schematic diagram of another microfluidic unit provided by an embodiment of the present disclosure; Figure 3I is a top schematic diagram of another microfluidic unit provided by an embodiment of the present disclosure; Figure 3J is a top schematic diagram of another microfluidic unit provided by an embodiment of the present disclosure; Figure 3K is a top schematic diagram of another microfluidic unit provided by an embodiment of the present disclosure; Figure 3L is a top schematic diagram of another microfluidic unit provided by an embodiment of the present disclosure.

[0200] As shown in FIG3E to FIG3L, by adjusting the arc radius r max 、arc radius r min , number N, width D, spacing d, angle β (or angle γ), etc., different microfluidic units 110 can be obtained. The embodiments of the present disclosure are not limited to this. By adjusting the above parameters (for example, also including angle θ and angle α, etc.), other forms of microfluidic units 110 can also be obtained. In this way, parametric adjustment of the microfluidic unit 110 can be achieved. By defining multiple parameters of the microfluidic unit 110, various parameters are matched and optimized, which can not only obtain parameterized microfluidic units suitable for different use conditions, but also realize controllable modification of the microfluidic unit and qualitative screening of particles above the cut-off size; it can also effectively improve the separation effect of the microfluidic unit 110, thereby effectively improving the separation efficiency, and can be applicable to a wider range of flow rates.

[0201] In some examples, the shape of the orthographic projection of one of the inner sidewall 112a and the outer sidewall 112b of the turning channel 112 on the reference plane A may be a straight line segment, and the shape of the orthographic projection of the other of the inner sidewall 112a and the outer sidewall 112b of the turning channel 112 on the reference plane A may be an arc.

[0202] FIG4 is a distribution simulation diagram of the secondary flow caused by different steering flow channels provided in an embodiment of the present disclosure. As shown in FIG4 , different steering flow channels are shown on the left, and a distribution simulation diagram of the secondary flow of the corresponding steering flow channel at the dotted position when the flow rate is 1 m / s is shown on the right. The color scale in the figure indicates the magnitude of the flow rate. The darker the color, the greater the flow rate. The steering flow channel will affect the overall focusing pattern. The influence of different steering flow channels on the secondary flow can be simulated using Comsol software. As shown in FIG4 , different steering flow channels, for example, the inner wall and the outer wall of the steering flow channel can be arcs or straight line segments. After the particles pass through the steering flow channel, secondary flow can be formed. However, different steering flow channels generate different sizes of secondary flow. Different steering flow channels can be selected according to the size of different particles and actual needs. Thus, under the action of the secondary flow of the steering flow channel, particles of different sizes deviate from the center to different degrees, and under the action of the curved flow channel, particles of different sizes can be focused on different positions deviating from the center of the flow channel, thereby achieving the separation of particles of different sizes.

[0203] For example, a diverting channel connects a curved channel and provides a larger secondary flow to rebalance particles of varying sizes. For example, when the inner and outer walls of the diverting channel are circular, the center of the secondary flow is further offset from the channel center, and the maximum secondary flow velocity is also reduced. For example, a diverting channel that is more suitable for the target particle size can be selected based on design requirements or experimental verification.

[0204] FIG5 is a schematic top view of a microfluidic structure provided by an embodiment of the present disclosure. As shown in FIG5 , the microfluidic structure 100 further includes a connecting channel 120. The microfluidic structure 100 includes a plurality of microfluidic units 110. The connecting channel 120 is located between two adjacent microfluidic units 110 and connects the two adjacent microfluidic units 110. The balance of particles requires a certain distance. Therefore, the connection of multiple microfluidic units 110 can not only focus particles of two or more sizes at different positions and achieve the separation of particles of different sizes, but also make the inertial focusing position of the particles more stable, so that two or more sizes can achieve a stable separation effect with high separation efficiency, thereby further reducing the sensitivity of dependence on the microfluidic structure, so that the microfluidic structure has good robustness.

[0205] In addition, the microfluidic structure 100 further increases the redundancy of the effective flow rate range, thereby being applicable to a wider range of flow rates. For example, the stable and available flow rate range reaches 1 mL / min, which better solves the problem of flow rate sensitivity. At the same time, the connection of multiple microfluidic units 110 can further increase the flow rate of the microfluidic structure 100, thereby improving the processing efficiency of the microfluidic structure 100, thereby having the characteristics of high throughput and high efficiency. The microfluidic structure 100 is also simple to manufacture, easy to operate, and not easily interfered with by impurities, and has a wide range of applications.

[0206] In some examples, as shown in FIG5 , the orthographic projection of the connecting channel 120 on the reference plane A may be a straight line segment, a circular arc, a broken line segment, etc., which is not limited in the present disclosure.

[0207] For example, as shown in FIG. 5 , the connecting channel 120 connects the curved channels 111 of two adjacent micro-channel units 110 .

[0208] In some examples, as shown in FIG5 , the multiple microfluidic channel units 110 of the microfluidic channel structure 100 are sequentially arranged along an arc a1, which curves toward the second position PM. The second position PM and the multiple first positions PN of the multiple curved channels 111 of any microfluidic channel unit 110 are located on the same side of the arc a1. Thus, sequentially arranging the microfluidic channel units 110 along the arc a1 not only stabilizes the inertial focusing position of particles of different sizes and improves separation efficiency, but also achieves compact size, high space utilization, and high integration.

[0209] In some examples, as shown in FIG5 , the multiple microfluidic channel units 110 of the microfluidic channel structure 100 include a first microfluidic channel unit 110a, a second microfluidic channel unit 110b, and a third microfluidic channel unit 110c sequentially arranged in the extending direction of the arc a1. The last curved channel 111 of the first microfluidic channel unit 110a in the arrangement direction X is connected to the last curved channel 111 of the second microfluidic channel unit 110b in the arrangement direction X via a connecting channel 120. The first curved channel 111 of the second microfluidic channel unit 110b in the arrangement direction X is connected to the first curved channel 111 of the third microfluidic channel unit 110b in the arrangement direction X via the connecting channel 120. Thus, the multiple microfluidic channel units 110 are connected via the connecting channel 120.

[0210] In some examples, as shown in FIG. 5 , the lengths of the multiple curved channels 111 of any microchannel unit 110 of the microchannel structure 100 gradually decrease in the arrangement direction X of the microchannel unit 110 .

[0211] In some examples, as shown in FIG. 5 , the second position PM overlaps with the first positions PN of the plurality of curved channels 111 of any micro-channel unit 110 .

[0212] In some examples, as shown in Figure 5, the microfluidic structure 100 also includes an inlet 130 and an outlet 140, the inlet 130 is connected to the first microfluidic unit 110 in the extension direction of the arc a1, specifically, the first curved channel 111 of the microfluidic unit 110 in its arrangement direction X; the outlet 140 is connected to the last microfluidic unit 110 in the extension direction of the arc a1, specifically, the last curved channel 111 of the microfluidic unit 110 in its arrangement direction X.

[0213] Figure 6A is a top view schematic diagram of another microfluidic structure provided by an embodiment of the present disclosure. As shown in Figure 6A, multiple microfluidic units 110 can be arranged sequentially along a circumferential line, with two adjacent microfluidic units 110 connected by a connecting channel 120. Therefore, arranging them sequentially along the circumference not only makes the inertial focusing position of particles of different sizes more stable and improves separation efficiency; it also further improves space utilization and integration, and further reduces the size of the microfluidic structure while maintaining the same number of microfluidic units.

[0214] In some examples, as shown in FIG6A , two different microfluidic units 110 arranged sequentially along a circumference constitute a basic microfluidic structure 100 a. Multiple basic microfluidic structures 100 a are arranged sequentially along a circumference, and two adjacent basic microfluidic structures 100 a are connected via a connecting channel 120. This design allows for a better arrangement of the microfluidic units 110, further improving space utilization and integration. The present disclosure is not limited thereto, and the same microfluidic unit 110 may also be arranged sequentially along a circumference, or more than two different microfluidic units 110 may be arranged sequentially along a circumference.

[0215] In some examples, as shown in FIG6A , two different microfluidic units 110 that constitute a basic microfluidic structure 100 a have the same number N and arc radius r. max Other than that, the structures are the same.

[0216] In some examples, the multiple microfluidic units 110 in the basic microfluidic structure 100a may not be arranged along a circular line. For example, the multiple microfluidic units 110 in the basic microfluidic structure 100a may be arranged along an arc or in any direction, and then the basic microfluidic structure 100a is arranged in sequence along a circular line.

[0217] In some examples, as shown in Figure 6A, the multiple microfluidic channel units 110 include a first microfluidic channel unit 110a, a second microfluidic channel unit 110b and a third microfluidic channel unit 110c arranged in sequence on a circular line, and the last curved channel 111 of the first microfluidic channel unit 110a in its arrangement direction X is connected to the last curved channel 111 of the second microfluidic channel unit 110b in its arrangement direction X through a connecting channel 120, and the first curved channel 111 of the second microfluidic channel unit 110b in its arrangement direction X is connected to the first curved channel 111 of the third microfluidic channel unit 110c in its arrangement direction X through a connecting channel 120.

[0218] In some examples, as shown in FIG. 6A , the lengths of the multiple curved channels 111 of any micro-channel unit 110 gradually decrease in the arrangement direction X of the micro-channel unit 110 .

[0219] In some examples, as shown in FIG6A , the center O of the circumference along which the multiple microfluidic channel units 110 or the multiple basic microfluidic channel structures 100a are located overlaps with the multiple first positions PN of the multiple curved channels 111 of any microfluidic channel unit 110. This further improves space utilization and integration, and further reduces the size of the microfluidic channel structure.

[0220] 6A , the microfluidic channel structure 100 may further include an inlet 130 and an outlet 140. For example, the positions of the inlet 130 and the outlet 140 may be interchanged.

[0221] 6A , the widths of the inlet 130 and outlet 140 of the microfluidic channel structure 100 are the same as the width of the curved channel 111. For example, the heights of the inlet 130 and outlet 140 of the microfluidic channel structure 100 are the same as the height of the curved channel 111.

[0222] Figure 6B shows an experimental diagram of the particle focusing position in the microfluidic structure shown in Figure 6A as the Reynolds number changes. As shown in Figure 6B, fluorescent particles can be used to demonstrate the particle focusing position or focusing pattern as the Reynolds number or flow rate changes. The horizontal axis represents the Reynolds number (Re), and the vertical axis represents the particle focusing position in the flow channel at outlet 140. The middle position of the vertical axis represents the center of the flow channel, and the maximum position of the vertical axis represents the width of the flow channel. In the experiment, the particle focusing pattern can be divided into several stages as the Reynolds number (or flow rate) changes:

[0223] The first stage is the incomplete focusing stage, that is, when the Reynolds number is small, the particles are not completely aggregated due to the low flow rate. The particles are distributed on both sides of the flow channel but the focus is widened. The second stage is the "double focusing" stage. At a position close to the two sides of the flow channel but still some distance away, the focusing behavior dominated by inertial lift causes the particles to focus near the equilibrium position. The third stage is the transition stage, that is, the particles gradually transition from the "double focusing" of the previous stage to the "single focusing" of the latter stage. The particles will gradually move from the two sides to the center and transform from two focused flows to one focused flow. The fourth stage is the "single focusing" stage, that is, the particles focus on a focused flow close to the center of the flow channel. For symmetrical structures, the focusing position is at the center, and for asymmetric structures, the focusing position will be a certain distance away from the center. The fifth stage is the defocusing stage. As the Reynolds number increases, the influence of secondary flow on focusing becomes increasingly greater, and it is difficult for particles to maintain a focused state. In actual experiments, due to the limitations of the interface of the microfluidic structure and the pressure that the syringe pump can withstand, the measurement of this part is somewhat difficult.

[0224] As shown in Figure 6B, in the first and fifth stages, the particles failed to fully aggregate or were difficult to maintain in a focused state, making the measurement of this part somewhat difficult. States 1 to 4 are the second stage (also known as the "double focusing" stage), states 5 to 7 are the third stage (also known as the transition stage), and states 8 to 12 are the fourth stage (the single focusing stage). It can be concluded that after the Reynolds number (or flow rate) of this microchannel structure reaches a certain value, the particles can be focused at a certain position deviating from the center of the channel, and the corresponding Reynolds number (or flow rate) has a wide range of values, which can solve the problem of flow rate sensitivity.

[0225] FIG6C is a diagram of the microchannel structure shown in FIG6A at r min = 2 mm, β = 22.5 degrees, and the focusing position of particles of three sizes as the flow rate changes; FIG6D is a schematic diagram of the microchannel structure shown in FIG6A at r min = 6.05 mm, β = 22.5 degrees, and the focusing position of particles of three sizes as the flow rate changes; FIG6E is a schematic diagram of the microchannel structure shown in FIG6A at r min =12.8mm, β = 22.5 degrees; FIG6F is a schematic diagram of the focusing position of particles of three sizes as the flow rate changes; FIG6A shows the microchannel structure at r min = 6.05 mm, β = 30 degrees, and the focusing position of particles of three sizes as the flow rate changes; FIG6G is a schematic diagram of the microchannel structure shown in FIG6A at r min = 6.05 mm, β = 45 degrees, and the focusing position of particles of three sizes as the flow rate changes. max =16mm.

[0226] As shown in Figures 6C to 6F, using fluorescent particles of different sizes can demonstrate the focusing position or focusing pattern of the particles as the Reynolds number or flow rate changes. The horizontal axis represents the flow rate, the vertical axis represents the focusing position of the particles in the flow channel at the outlet 140, the middle position of the vertical axis is the center of the flow channel, and the maximum position of the vertical axis is the width of the flow channel. In order to more clearly show the focusing state, we plotted the focusing positions of particles of different sizes (15μm, 10μm, 7.5μm) in the flow channel based on the half-height width of the particle focus (that is, the half-height width of the fluorescence intensity distribution).

[0227] As shown in FIG6C to FIG6E, when the angle β is equal to 22.5 degrees, the arc radius r min The focusing effect of three sizes of particles (15μm, 10μm, 7.5μm) when the arc radius is equal to 2mm, 6.05mm, and 12.8mm respectively. min When the radius of the arc is equal to 6.05 mm, the three sizes of particles can be well focused and separated, and after the flow rate is greater than 1.8 mL / min, the stable flow rate range reaches 1 mL / min; min When the diameter is equal to 2mm, it is also possible to achieve good aggregation and separation of particles of three sizes within a variable flow rate range of 0.5mL / min; it solves the flow rate sensitivity problem (<0.1mL / min) of inertial focusing in the prior art, so the microfluidic structure under this parameter can be applied to a wider flow rate range, with a simple structure, stable effect and convenient manufacturing. The effects of arcs of different radii on the focusing effect are different. The smaller the radius, the stronger the secondary flow generated by the arc, and the greater the impact on the result. Therefore, the effect of the arc with the smallest radius on the result is obvious, and the arc radius r in the microfluidic structure can be simulated with the help of software. min The impact on the focusing state of particles of different sizes can be used to more conveniently and quickly select the optimal value range.

[0228] As shown in FIG6D, FIG6F and FIG6G, the arc radius r minWhen the angle β is equal to 6.05mm, the focusing effect of particles of three sizes (15μm, 10μm, 7.5μm) when the angle β is equal to 22.5 degrees, 30 degrees, and 45 degrees respectively, when the angle β is equal to 22.5 degrees and 30 degrees, the three sizes of particles can be well focused and separated, and after the flow rate is greater than 1.8mL / min, the stable and available flow rate range reaches 1mL / min; therefore, the microfluidic structure under this parameter can be applied to a wider flow rate range, solving the problem of flow rate sensitivity. At the same time, the angle β can achieve focusing and separation of particles of three sizes within a certain value range (for example, between 22.5 degrees and 30 degrees), thereby reducing the sensitivity of dependence on the microfluidic structure, making the microfluidic structure have good robustness. The angle β affects the time of the arc for the focusing effect. The larger the angle β, the longer it takes for the particles to pass through the arc, and the greater the impact on the focusing and separation results. The effect of the angle β in the microfluidic structure on the focusing state of particles of different sizes can be simulated with the help of software, so that the optimal value range can be selected more conveniently and quickly.

[0229] In some examples, other parameters in the microfluidic structure can also be adjusted, such as the arc radius r max , number N, width D, spacing d, etc., so that the parameterization of the microchannel structure can be achieved.

[0230] The following schematically describes two preparation processes used for the microfluidic channel structure shown in FIG6A of the present application. However, the present disclosure does not limit the preparation process of the microfluidic channel structure, and a preparation process commonly used in the art can be used.

[0231] The first preparation process:

[0232] (1) Based on theoretical calculations, the specific dimensions of the microchannel structure are designed for specific target particles (e.g., the length LEN, width D, angle θ or β, number N, and arc radius r of the curved channel). min 、r max , the number of repetitions of the microfluidic unit, etc.), and use drawing software such as AutoCAD to draw a drawing of the microfluidic structure;

[0233] (2) A chromium plate is used to make a mask, and a silicon wafer or chromium plate is used as a substrate. A mold is made on the substrate by applying a photoresist (e.g., SU-8 photoresist), pre-baking, exposing, post-baking, and developing;

[0234] (3) A mixture of polydimethylsiloxane (PDMS) A glue and B glue = 8:1 is poured onto the mold, heated and cured, and then cut and demolded to make a chip. After the chip is punched, it is bonded to the glass slide through air plasma treatment to form a microfluidic structure.

[0235] The second preparation process:

[0236] (1) Based on theoretical calculations, the specific dimensions of the microchannel structure (e.g., angle θ or β, N, arc radius r of the curved channel) are designed for specific target particles. min 、r max , the number of repetitions of the microfluidic unit, etc.), and use drawing software such as AutoCAD to draw a drawing of the microfluidic structure;

[0237] (2) A chrome plate is used to make a mask, and a silicon wafer is used as a substrate. The chip microstructure is made on the substrate through a process of coating (e.g., SU-8 photoresist), pre-baking, exposure, post-baking, and development. A metal mold is made through processes such as magnetron sputtering and electroplating.

[0238] (3) preparing an injection-molded chip through an injection molding process;

[0239] (4) The chip is packaged through processes such as surface treatment and thermal bonding to form a microfluidic structure.

[0240] Figure 6H is a top view schematic diagram of another microfluidic structure provided by an embodiment of the present disclosure. As shown in Figure 6H, a plurality of microfluidic units 110 can be arranged in sequence along a circumferential line, and two adjacent microfluidic units 110 are connected by a connecting channel 120. In this way, not only can the inertial focusing position of particles of different sizes be made more stable and the separation efficiency be high; it also further improves the space utilization and integration, and further reduces the size of the microfluidic structure under the premise of the same number of microfluidic units. This example schematically shows that a plurality of microfluidic units 110 are arranged in sequence along a circumferential line to form half a circle, but the embodiment of the present disclosure is not limited to this. For example, a quarter of a circle, two-fifths of a circle, or three-quarters of a circle, or the like can also be formed in sequence along a circumferential line.

[0241] In some examples, as shown in FIG6H , two different microfluidic units 110 arranged sequentially along a circumference constitute a basic microfluidic structure 100 a. Multiple basic microfluidic structures 100 a are arranged sequentially along a circumference, and two adjacent basic microfluidic structures 100 a are connected via a connecting channel 120. This design allows for a better arrangement of the microfluidic units 110, further improving space utilization and integration. The present disclosure is not limited thereto, and the same microfluidic unit 110 may also be arranged sequentially along a circumference, or more than two different microfluidic units 110 may be arranged sequentially along a circumference.

[0242] In some examples, as shown in FIG6H , two different microfluidic units 110 that constitute a basic microfluidic structure 100 a have the same number N and arc radius r. max Other than that, the structures are the same.

[0243] In some examples, as shown in Figure 6H, the multiple microfluidic channel units 110 include a first microfluidic channel unit 110a, a second microfluidic channel unit 110b and a third microfluidic channel unit 110c arranged in sequence on a circular line, and the last curved channel 111 of the first microfluidic channel unit 110a in its arrangement direction X is connected to the last curved channel 111 of the second microfluidic channel unit 110b in its arrangement direction X through a connecting channel 120, and the first curved channel 111 of the second microfluidic channel unit 110b in its arrangement direction X is connected to the first curved channel 111 of the third microfluidic channel unit 110c in its arrangement direction X through a connecting channel 120.

[0244] In some examples, as shown in FIG6H , the center O of the circumference along which the multiple microfluidic channel units 110 or the multiple basic microfluidic channel structures 100a are located overlaps with the multiple first positions PN of the multiple curved channels 111 of any microfluidic channel unit 110. This further improves space utilization and integration, and further reduces the size of the microfluidic channel structure.

[0245] 6H , the microfluidic channel structure 100 may further include an inlet 130 and an outlet 140. For example, the positions of the inlet 130 and the outlet 140 may be interchanged.

[0246] Figures 6I, 6J and 6K are schematic diagrams of the focusing positions of particles of three sizes at different flow rates in the microfluidic structure shown in Figure 6H. Figure 6I is a schematic diagram of the focusing positions of particles of three sizes (15μm, 10μm, 7.5μm) at 2.4mL / min. Figure 6J is a schematic diagram of the focusing positions of particles of three sizes (15μm, 10μm, 7.5μm) at 1.6mL / min. Figure 6K is a schematic diagram of the focusing positions of particles of three sizes (15μm, 10μm, 7.5μm) at 0.8mL / min. As shown in Figures 6I to 6K, at a flow rate of 2.4mL / min, particles of three sizes can be well focused and separated. As the flow rate decreases, the spacing between the three sizes of particles after focusing gradually decreases.

[0247] In this example, referring to FIG3A , the angle β of the microchannel structure shown in FIG6H is 22.5 degrees, and the arc radius of the shortest curved channel 111 is r min is 6.05 mm, and the arc radius of the longest curved channel 111 is r max This example only schematically verifies a set of angles β and arc radius r. min 、r max The focusing effect of the microchannel structure under different flow rates on three sizes of particles, however, the angle β and arc radius r in the previous embodiment are min 、r maxThe value range of is also applicable to the microchannel structure of FIG6H and can realize the focusing and separation of particles of different sizes, which will not be described in detail here.

[0248] For example, in this example, the angles β, γ, and λ are equal. Thus, when the angles γ and λ are 22.5 degrees, particles of three sizes can be well focused and separated.

[0249] Figure 6L is a top view schematic diagram of another microfluidic structure provided by an embodiment of the present disclosure. As shown in Figure 6L, a plurality of microfluidic units 110 can be arranged in sequence along a circumferential line to form a half circle, and two adjacent microfluidic units 110 are connected by a connecting channel 120. In this way, not only can the inertial focusing position of particles of different sizes be made more stable and the separation efficiency be high; it also further improves the space utilization and integration, and further reduces the size of the microfluidic structure under the premise of the same number of microfluidic units. The turning channel 112 of the microfluidic unit 110 of this example is an arc-shaped turning channel. The other structural descriptions of this example refer to the aforementioned embodiments and will not be repeated here.

[0250] Figures 6M, 6N and 6O are schematic diagrams of the focusing positions of three-sized particles of the microfluidic structure shown in Figure 6L at different flow rates. Figure 6M shows the focusing effect of three-sized particles (15μm, 10μm, 7.5μm) at 2.4mL / min. Figure 6N shows the focusing effect of three-sized particles (15μm, 10μm, 7.5μm) at 1.6mL / min. Figure 6O shows the focusing effect of three-sized particles (15μm, 10μm, 7.5μm) at 0.8mL / min. As shown in Figures 6M, 6N and 6O, at a flow rate of 2.4mL / min, the three-sized particles can be well focused and separated. As the flow rate decreases, the spacing between the three-sized particles after focusing gradually decreases.

[0251] In this example, referring to FIG. 2B , the angle θ of the microchannel structure shown in FIG. 6L is 22.5 degrees, and the arc radius of the shortest curved channel 111 is r min is 6.05 mm, and the arc radius of the longest curved channel 111 is r max This example only schematically verifies a set of angles θ and arc radius r. min 、r max The focusing effect of the microchannel structure under different flow rates on three sizes of particles, however, in the previous embodiment, the angle θ and the arc radius r min 、r max The value range of is also applicable to the microchannel structure of FIG6L and can realize the focusing and separation of particles of different sizes, which will not be described in detail here.

[0252] For example, in this example, the angles θ, α, and λ are equal. Thus, when the angles γ and λ are 22.5 degrees, particles of three sizes can also be well focused and separated.

[0253] The microfluidic unit 110 of the microfluidic structure shown in Figure 6H and Figure 6L has the same number of repetitions, and the angle β of the microfluidic unit 110 in Figure 6H is approximately the same as the angle α of the microfluidic unit 110 in Figure 6L (the angle β and the angle α are not shown in the figure, and can be referred to the definitions of the previous embodiment). The turning channel 112 of the microfluidic unit 110 shown in Figure 6H is a straight line segment, and the turning channel 112 of the microfluidic unit 110 shown in Figure 6L is a circular arc. The focusing positions of the three sizes of particles at different flow rates in the two groups of embodiments are approximately the same, and the focusing effects are also approximately the same. Therefore, the turning channel 112 using a straight line segment and the turning channel 112 using a circular arc have approximately the same focusing position and focusing effect. For example, the turning channel 112 can be selected as a straight line segment or a circular arc based on the material of the microfluidic structure, the difficulty of processing, or the structural requirements. The embodiment of the present disclosure does not limit the shape of the turning channel 112.

[0254] Referring to the microfluidic structure and the corresponding focusing effect shown in Figures 6A, 6H and 6L, the microfluidic structure can achieve effective separation of particles of different sizes by changing the number of microfluidic units 110 arranged in sequence, the shape of the turning channel 112, the angle β or angle α of the microfluidic unit 110, etc.

[0255] It should be noted that the embodiments corresponding to Figures 6D to 6G verify the influence of different angle β values ​​on the focusing and separation of particles of different sizes. When the angle β is equal to 22.5 degrees and 30 degrees, particles of three sizes can be well focused and separated. When the angle β is equal to 45 degrees, focusing and separation of particles of some sizes can be achieved, and after the flow rate is greater than 1.8 mL / min, the stable and available flow rate range reaches 1 mL / min. Referring to FIG3A and FIG6A , the angle β, the angle γ, and the angle λ are all the same or substantially the same, that is, the embodiments corresponding to FIG6D to FIG6G also verify that when the angle γ is equal to 22.5 degrees and 30 degrees, particles of three sizes can be well focused and separated, and when the angle γ is equal to 45 degrees, focusing and separation of particles of some sizes can be achieved, and after the flow rate is greater than 1.8 mL / min, the stable and usable flow rate range reaches 1 mL / min; the embodiments corresponding to FIG6D to FIG6G also verify that when the angle λ is equal to 22.5 degrees and 30 degrees, particles of three sizes can be well focused and separated, and when the angle λ is equal to 45 degrees, focusing and separation of particles of some sizes can be achieved, and after the flow rate is greater than 1.8 mL / min, the stable and usable flow rate range reaches 1 mL / min. No further details will be given here.

[0256] Referring to the conclusions drawn from the embodiments corresponding to Figures 6H and 6L, the steering channel 112 using a straight line segment and the steering channel 112 using an arc have approximately the same focusing effect, and referring to Figures 3A and 6L, the angle θ, the angle α and the angle λ are all the same or substantially the same. Therefore, the embodiments corresponding to Figures 6D to 6G can also be concluded that when the angle θ is equal to 22.5 degrees and 30 degrees, particles of three sizes can be well focused and separated. When the angle θ is equal to 45 degrees, particles of some sizes can be focused and separated, and after the flow rate is greater than 1.8 mL / min, the stable and usable flow rate range reaches 1 mL / min. When the angle α is equal to 22.5 degrees and 30 degrees, particles of three sizes can be well focused and separated. When the angle α is equal to 45 degrees, particles of some sizes can be focused and separated, and after the flow rate is greater than 1.8 mL / min, the stable and usable flow rate range reaches 1 mL / min. When the angle λ is equal to 22.5 degrees and 30 degrees, particles of three sizes can be well focused and separated. When the angle λ is equal to 45 degrees, particles of some sizes can be focused and separated, and after the flow rate is greater than 1.8 mL / min, the stable and usable flow rate range reaches 1 mL / min. No further details will be given here.

[0257] Figure 7A is a top view schematic diagram of another microfluidic structure provided by an embodiment of the present disclosure; Figure 7B is a top view schematic diagram of the microfluidic structure shown in Figure 7A after being repeated four times; and Figure 7C is an experimental diagram of the particle focusing position of the microfluidic structure shown in Figure 7A at different numbers of repetitions.

[0258] In some examples, as shown in Figures 7A and 7B, the microfluidic structure 100b shown in Figure 7A is arranged in sequence along the arc a1 to obtain the microfluidic structure 100c shown in Figure 7B; two adjacent microfluidic structures 100b are connected by a connecting channel 120. The center of curvature O of the arc a1 coincides with the first position PN of any microfluidic unit 110 of the microfluidic structure 100c. Figure 7B is a schematic diagram of the microfluidic structure 100b repeated four times, that is, the number of microfluidic structures 100b is 4. For example, the number of repetitions is represented by q, and when the number of repetitions q takes different values, different microfluidic structures correspond. For example, as shown in Figure 7B, the repeated microfluidic structures all have an inlet 130 and an outlet 140, and the width and height of the inlet 130 and the outlet 140 are respectively the same as the width and height of the curved channel 111.

[0259] In some examples, as shown in FIG7C , the microfluidic structure 100b shown in FIG7A is repeated multiple times, and the focus positions of the outlet 140 of the microfluidic structure 100c for particles of three sizes (15 μm, 10 μm, and 7.5 μm) at different numbers of repetitions q are plotted based on the half-width at half-maximum of the particle focus (i.e., the half-width at half-maximum of the fluorescence intensity). The horizontal axis is the number of repetitions, and the vertical axis is the focus position of the particle in the flow channel of the outlet 140. The flow channel width D of the microfluidic structure 100c is 500 μm, and the center position is at 250 μm on the vertical axis. As shown in FIG7C , when the number of microfluidic structure 100b shown in FIG7A is 4, that is, corresponding to the structure shown in FIG7B , the focus positions of the particles of the three sizes (15 μm, 10 μm, and 7.5 μm) are stably separated, that is, the particles of the three sizes can be focused at different positions off-center, thereby enabling effective separation. The equilibrium of the particles requires a certain distance, and thus a series of repetitions of the microfluidic channel structure 100 or the microfluidic channel unit 110 can be performed to achieve a stable separation effect of the particles.

[0260] In some examples, increasing the number of repetitions q can further increase the flow rate of the microfluidic structure 100, thereby improving the processing efficiency of the microfluidic structure 100, thereby achieving high throughput and high efficiency. For example, the flow rate of a single separation unit of the microfluidic structure 100 can reach 3 mL / min, reaching the maximum processing capacity of currently available technologies.

[0261] In some examples, the microfluidic structure described in Figure 6H, Figure 6L or Figure 7B can also be prepared using the two preparation processes used in Figure 6A. Of course, the embodiments of the present disclosure do not limit the preparation process of the microfluidic structure, and the preparation process commonly used in this field can be used.

[0262] FIG8A is a schematic diagram of another microfluidic structure provided by an embodiment of the present disclosure. As shown in FIG8A , the microfluidic unit 110 of the microfluidic structure 100 is arranged in sequence along a first direction Y, and the angle between the arrangement direction X of two adjacent microfluidic units 110 ranges from 0 degrees to 45 degrees.

[0263] In some examples, as shown in Figure 8A, two adjacent microfluidic channel units 110 include a first microfluidic channel unit 110a and a second microfluidic channel unit 110b, and the first microfluidic channel unit 110a and the second microfluidic channel unit 110b are adjacent to each other in the first direction Y; the last curved channel 111 of the first microfluidic channel unit 110a in its arrangement direction X is connected to the first curved channel 111 of the second microfluidic channel unit 110b in its arrangement direction X through a connecting channel 120.

[0264] FIG8B is a schematic diagram of a microfluidic structure provided by an embodiment of the present disclosure. As shown in FIG8B , the multiple microfluidic units 110 of the microfluidic structure 100 are arranged sequentially along the second direction Z, and the angle between the arrangement direction X of two adjacent microfluidic units 110 ranges from 145 degrees to 180 degrees.

[0265] In some examples, as shown in Figure 8B, two adjacent microfluidic channel units 110 include a first microfluidic channel unit 110a and a second microfluidic channel unit 110b, and the first microfluidic channel unit 110a and the second microfluidic channel unit 110b are adjacent to each other in the second direction Z; the last curved channel 111 of the first microfluidic channel unit 110a in its arrangement direction X is connected to the first curved channel 111 of the second microfluidic channel unit 110b in its arrangement direction X through a connecting channel 120.

[0266] In some examples, the microfluidic structure can be manufactured by molding, photolithography, electroforming, machining, chemical vapor deposition, etc. The embodiments of the present disclosure do not limit the processing and manufacturing methods of the microfluidic structure.

[0267] For example, the microfluidic structure in the disclosed embodiments can be fabricated using photolithography. Mask preparation is a key step in photolithography, serving to selectively block ultraviolet light on a surface, thereby enabling localized exposure of the photoresist. The mask's pattern and dimensions are designed using a computer, with commonly used design software such as L-Edit and AutoCAD. Common media for masks with patterned structures include transparent films and glass plates, and the patterned structure generally consists of transparent and opaque areas.

[0268] When resolution requirements are low, masks can be prepared using simple methods. The most common method is to use a high-resolution laser imagesetter (3000 dpi or higher) to print the image on transparent film. This method generally produces an error of 3-7 μm, depending on the accuracy of the laser imagesetter. Electron beam exposure can produce even higher-precision masks, with accuracy reaching 100 nm or even 10 nm.

[0269] Photoresist, composed of a mixture of photosensitive polymers or prepolymers dissolved in one or more organic solvents, is the key medium for precisely transferring the microstructures on a mask to a substrate using photolithography. Varieties with varying viscosities, optical properties, and physicochemical properties are available, depending on the application. Through photolithography, the pattern on the mask is transferred to a silicon wafer. In the exposure room, a pre-baked substrate is placed on an exposure table, and then a mask is placed on top. UV exposure is then performed, transferring the pattern on the mask to the substrate, thereby etching the substrate through photolithography.

[0270] For example, the microfluidic structure in the disclosed embodiments can also be injection molded and encapsulated using polydimethylsiloxane (PDMS) material. Polydimethylsiloxane, abbreviated as PDMS, commonly known as silicone rubber, is one of the most widely used materials for microfluidic structures. PDMS is widely used due to its unique elasticity, good light transmittance, high dielectric properties, chemical inertness, non-toxicity, ease of processing, and low price. PDMS is easily obtained into a solid state by thermal cross-linking of a prepolymer of a monomer and a cross-linking agent.

[0271] PDMS and PDMS sheets typically need to be sealed together, or PDMS and glass. Heat sealing is commonly used for sealing PDMS sheets. The two sheets are placed together, slightly pressured, and then heated in an incubator for 2-3 hours to seal. Plasma-assisted bonding is commonly used to seal PDMS sheets to glass (usually a glass slide). Bombarding the glass and PDMS surfaces with oxygen ions increases their surface activity, and then applying a certain amount of pressure creates a permanent bond between the two.

[0272] At least one embodiment of the present disclosure further provides a microfluidic chip. The microfluidic chip includes any of the above-mentioned microfluidic structures, thereby having corresponding beneficial effects of the microfluidic structure, which will not be described in detail here.

[0273] FIG9A is a schematic diagram of a microfluidic chip provided in one embodiment of the present disclosure; FIG9B is a partially enlarged schematic diagram of the first separation structure shown in FIG9A . As shown in FIG9A and FIG9B , the microfluidic chip 200 includes a microfluidic structure 100 and a first separation structure 210 . The microfluidic structure 100 includes an inlet 130 and an outlet 140 . The first separation structure 210 includes a first sub-inlet 211 and a plurality of first sub-outlets 212 . For example, as shown in FIG9A and FIG9B , the first separation structure 210 includes a first sub-inlet 211 and four first sub-outlets 212 , for example, the four first sub-outlets 212 are 212a , 212b , 212c , and 212d , respectively. The first sub-inlet 211 is connected to the outlet of the microfluidic structure 100 . Thus, particles of different sizes can be separated into different first sub-outlets 212 through the first separation structure 210 .

[0274] For example, as shown in Figures 9A and 9B, the size (width and height) of the inlet 130 of the microfluidic structure 100 is the same as the size (width and height) of the curved channel 111; for example, the size (width and height) of the outlet 140 of the microfluidic structure 100 is the same as the size (width and height) of the curved channel 111; for example, the size (width and height) of the first sub-inlet 211 of the first separation structure 210 is the same as the size (width and height) of the outlet 140 of the microfluidic structure 100.

[0275] For example, at least one sub-outlet 212 of the first separation structure 210 can be further connected to a separation structure; for example, the first separation structure can be sequentially connected to multiple separation structures. For example, at least one sub-outlet 212 of the first separation structure 210 can be simultaneously connected to multiple separation structures. Thus, by adding separation structures, the flow rate and separation efficiency of the microfluidic chip can be further improved. Furthermore, by adding separation structures, the separated particles can be concentrated to obtain highly concentrated particles.

[0276] For example, the first separation structure can further improve the separation efficiency of the microfluidic chip 200 by sequentially connecting multiple separation structures.

[0277] FIG9C is a schematic diagram of the separation of particles of different sizes in the first separation structure shown in FIG9A ; FIG9D is a diagram of the enrichment of particles of different sizes collected at the four first sub-outlets shown in FIG9A . As shown in FIG9C , particles of different sizes are focused at the focusing position or focusing mode of the microfluidic chip 200. The three sizes are 15 μm, 10 μm and 7.5 μm, respectively. The secondary flow of the microfluidic structure 100 of the microfluidic chip 200 affects the focusing position of the three sizes of particles, so that the three sizes of particles are focused at different positions off the center, thereby achieving effective focusing and separation. As shown in FIG9C , particles of 15 μm are focused near the center of the flow channel of the outlet 140 of the microfluidic structure 100, particles of 10 μm are focused off the center, and particles of 7.5 μm are focused on both sides farther off the center. After the three different sizes of particles pass through the first sub-inlet 211 and the four first sub-outlets 212 of the first separation structure 210, the separation of the particles is achieved. The 15 μm particles flow into the first sub-outlet 212b, the 10 μm particles flow into the first sub-outlet 212c, and the 7.5 μm particles flow into the first sub-outlets 212a and 212d. FIG9D shows an enrichment diagram of particles of three sizes collected through four first sub-outlets. Thus, the microfluidic chip 200 achieves separation and collection of particles of different sizes. Statistical analysis of FIG9D shows that the separation efficiency of particles of different sizes is as high as 99.8%. Thus, by appropriately adjusting the design parameters of the microfluidic structure 100 of the microfluidic chip 200 and the connection method between the microfluidic units 110 or between the microfluidic structures 100, a microfluidic chip 200 design for a specific cutoff diameter (i.e., the minimum diameter of particles to be collected) can be obtained. The secondary flow of the microfluidic chip 200 influences the focusing position of particles of different sizes, allowing particles of different sizes to be focused at different positions in the flow channel over a wide flow rate range and to be distributed in an orderly manner according to their size. At the same time, appropriate flow distribution is designed for the multiple first sub-outlets 212 of the first separation structure 210 to collect the desired size range. By matching the outlet flow resistance, separation of particles of different sizes can be achieved.

[0278] In some examples, as shown in Figures 9A and 9B, the multiple first sub-outlets 212 of the first separation structure 210 of the microfluidic chip 200 can also be designed with appropriate widths, as well as the position of the first separation structure 210 relative to the first sub-inlet 211, so as to collect and separate particles of different sizes focused at different positions, thereby allowing particles of different sizes focused at different positions to flow into different first sub-outlets 212.

[0279] In some examples, as shown in FIG9A , the microfluidic chip 200 may further include a filter structure 230 , which is in communication with the inlet 130 of the microfluidic structure 100 and configured to have a filtering function. For example, the filter structure 230 may filter impurities.

[0280] The following schematically describes two preparation processes used for the microfluidic chip shown in FIG9A of the present application. However, the present disclosure does not limit the preparation process of the microfluidic chip, and a commonly used preparation process in the art can be used.

[0281] The first preparation process:

[0282] (1) Based on theoretical calculations, the specific dimensions of the microfluidic chip are designed for specific target particles (e.g., the length LEN, width D, angle θ or β, number N, and arc radius r of the curved channel of the microfluidic structure). min 、r max , the number of repetitions of the microfluidic unit, etc.), and use drawing software such as AutoCAD to draw a drawing of the microfluidic chip;

[0283] (2) A chromium plate is used to make a mask, and a silicon wafer or chromium plate is used as a substrate. A mold is made on the substrate by applying a photoresist (e.g., SU-8 photoresist), pre-baking, exposing, post-baking, and developing;

[0284] (3) A mixture of polydimethylsiloxane (PDMS) A glue and B glue = 8:1 is poured onto the mold, heated and cured, and then cut and demolded to make a chip. After the chip is punched, it is bonded to the glass slide through air plasma treatment to form a microfluidic chip.

[0285] The second preparation process:

[0286] (1) Based on theoretical calculations, the specific dimensions of the microchannel structure (e.g., angle θ or β, N, arc radius r of the curved channel) are designed for specific target particles. min 、r max , the number of repetitions of the microfluidic unit, etc.), and use drawing software such as AutoCAD to draw a drawing of the microfluidic structure;

[0287] (2) A chrome plate is used to make a mask, and a silicon wafer is used as a substrate. The chip microstructure is made on the substrate through a process of coating (e.g., SU-8 photoresist), pre-baking, exposure, post-baking, and development. A metal mold is made through processes such as magnetron sputtering and electroplating.

[0288] (3) preparing an injection-molded chip through an injection molding process;

[0289] (4) The chip is packaged through processes such as surface treatment and thermal bonding to form a microfluidic chip.

[0290] FIG10A is a schematic diagram of another microfluidic chip provided in accordance with an embodiment of the present disclosure. As shown in FIG10A , this microfluidic chip 200 differs from the microfluidic chip 200 shown in FIG9A in that the first separation structure 210 is different. The first separation structure 210 shown in FIG10A has three first sub-outlets 212 , namely, first sub-outlets 212 a, 212 b, and 212 c.

[0291] Figure 10B is a graph showing the capture efficiency of target particles in whole blood using the microfluidic chip shown in Figure 10A; Figure 10C is a graph showing the enrichment of human breast cancer cells spiked into whole blood at the three outlets of the microfluidic chip shown in Figure 10A. As shown in Figure 10B, the capture efficiency of target particles (particle sizes of 10 μm and 15 μm) in undiluted whole blood was verified using the microfluidic chip 200 shown in Figure 10A. Particles of the two sizes were collected by the microfluidic chip 200 shown in Figure 10A at different flow rates (2.4 mL / min, 2.5 mL / min, and 2.6 mL / min). The capture efficiencies for the two sizes (10 μm and 15 μm) were 75% ± 3% and 81% ± 2%, respectively. Therefore, although the collision between cells in whole blood makes it extremely difficult to focus the target cells, and the focus of the target particles becomes wider, by using the microfluidic chip 200 shown in Figure 10A, it is also possible to achieve high-efficiency collection of target particles in whole blood, and by setting and matching the flow resistance at the multiple first sub-outlets 212 of the first separation structure 210, the optimal collection interval corresponding to particles of different sizes can be found, so that the target particles in undiluted whole blood can be effectively separated, thereby improving the separation efficiency.

[0292] In some examples, as shown in Figures 10B and 10C, human breast cancer cells were spiked into whole blood, and the capture efficiency of the human breast cancer cells was verified using the microfluidic chip 200 shown in Figure 10A. At three flow rates (2.4 mL / min, 2.5 mL / min, and 2.6 mL / min), the capture efficiency of the human breast cancer cells was approximately 70%, achieving high-efficiency collection of human breast cancer cells from whole blood. Figure 10C shows the enrichment graph of human breast cancer cells at the three sub-outlets of the microfluidic chip 200. As shown in the figure, the human breast cancer cells are essentially collected through the first sub-outlet 212b, achieving high collection efficiency.

[0293] Figure 11A is a schematic diagram of the structure of another microfluidic chip provided in one embodiment of the present disclosure; Figure 11B is a schematic diagram of the separation of particles of different sizes at the first separation structure shown in Figure 11A; Figure 11C is a schematic diagram of the separation of particles of different sizes at the second separation structure shown in Figure 11A; and Figure 11D is a schematic diagram of the separation of particles at the third separation structure shown in Figure 11A. As shown in Figures 11A to 11D, the microfluidic chip 200 includes a filtration structure 230, a microfluidic structure 100, a first separation structure 210, a second separation structure 220, a third separation structure 240, and multiple flow channel structures 250. The filtering structure 230 is connected to the inlet 130 of the microchannel structure 100. The first separation structure 210 includes a first sub-inlet 211a and three first sub-outlets 212a, 212b and 212c. The first sub-inlet 211a is connected to the outlet 140 of the microchannel structure 100. The first sub-outlets 212a, 212b and 212c are connected to the flow channel structure 250a, the flow channel structure 250b and the flow channel structure 250c respectively; the first sub-outlet 212c is connected to the second separation structure 220 through the flow channel structure 250c; the second separation structure 220 includes a second sub-inlet 221 and three second sub-outlets 222a, 222b and 222c. The second sub-inlet 221 is connected to the outlet of the flow channel structure 250c, the three second sub-outlets 222a, 222b and 222c are respectively connected to the flow channel structure 250d, the flow channel structure 250e and the flow channel structure 250f, and the second sub-outlet 222c is connected to the third separation structure 240 through the flow channel structures 250f and 250g; the third separation structure 240 includes a third sub-inlet 241 and three third sub-outlets 242a, 242b and 242c, the third sub-inlet 241 is connected to the outlet of the flow channel structure 250g, and the three third sub-outlets 242a, 242b and 242c are respectively connected to the flow channel structure 250h, the flow channel structure 250i and the flow channel structure 250j.

[0294] In some examples, as shown in Figures 11A to 11D, the flow channel structures 250c, 250f, and 250g may be serpentine flow channels. For example, the flow channel structures 250c, 250f, and 250g may be asymmetric serpentine structures.

[0295] In some examples, as shown in FIG. 11A to FIG. 11D , the flow channel structures 250 a , 250 b , 250 d , 250 e , 250 h , 250 i , and 250 j can be configured to function to match flow resistance.

[0296] For example, as shown in FIG. 11A to FIG. 11D , the flow channel structures 250 a , 250 b , 250 d , 250 e , 250 h , 250 i and 250 j may be serpentine structures, zigzag structures, and I-shaped structures, etc., which are not limited in the present disclosure.

[0297] In some examples, as shown in Figures 11A to 11D, particles of different sizes are used in the focusing position or focusing mode of the microfluidic chip 200. The sizes of the three particles are 15 μm, 10 μm, and 7.5 μm, respectively. The influence of the secondary flow of the microfluidic structure 100 of the microfluidic chip 200 on the focusing position can make the particles of the three sizes focused at different positions off the center, thereby achieving effective focusing and separation. As shown in Figures 11A and 11B, particles of 15 μm are focused near the center of the flow channel of the first sub-inlet 211 of the first separation structure 210, particles of 10 μm are focused off the center, and particles of 7.5 μm are focused farther off the center. Through the separation action of the first separation structure 210, particles of 15 μm and 10 μm flow into the first sub-outlet 212c, and particles of 7.5 μm flow into the first sub-outlet 212b.

[0298] For example, as shown in Figures 11A and 11C, the first sub-outlet 212c can be connected to the flow channel structure 250c, which is a serpentine flow channel. With the help of the serpentine flow channel structure 250c, the particles collected by the first sub-outlet 212c can be further focused and separated to increase the concentration ratio. For example, the collected particles can be further focused and separated based on the empirical parameters in the serpentine flow channel 250c to increase the concentration ratio. After further focusing and separation through the serpentine flow channel 250c, the 15μm and 10μm particles flow to the second sub-inlet 221 of the second separation structure 220. The 15μm particles flow into the second sub-outlet 222c, and the 10μm particles flow into the second sub-outlets 222b located on both sides.

[0299] For example, as shown in Figures 11A and 11D, second sub-outlet 222c can be connected to flow channel structure 250f, which is a serpentine flow channel. Serpentine flow channel structures 250f and 250g can be used to further focus and separate particles collected by second sub-outlet 222c, thereby further increasing the concentration factor. After further focusing and separation by serpentine flow channel structures 250f and 250g, particles sized 15 μm flow to third sub-inlet 241 of third separation structure 240. After passing through third separation structure 240, they flow into third sub-outlet 250j. By separating with multiple separation structures and further focusing separation with multiple serpentine flow channel structures, the concentration multiple of the particles finally obtained is greatly improved compared to separation by the separation structure alone; when separation is performed by the separation structure alone, the concentration multiple can only reach 3-4 times, which is difficult to improve further; the use of the above-mentioned microfluidic chip 200 can not only separate particles of different sizes, but also improve the concentration multiple of particles passing through the serpentine flow channel structure, especially the concentration multiple of particles obtained by the last separation structure is greatly improved, so that the particles can be concentrated at a high concentration. The embodiment of the present disclosure does not limit the serpentine flow channel structure for further focusing separation. For example, it can also be other forms of flow channel structures, and there is no limit on the number of further focusing separations.

[0300] In some examples, as shown in Figures 11A to 11D, the width D of the curved channel 111 of the microfluidic structure 100 of the microfluidic chip 200 is set to 500 μm. A pump is used to adjust the flow rate of the fluid flowing into the first separation structure 210 of the microfluidic chip 200 to between 2 and 3 mL / min, and the flow rate of the fluid flowing into the second separation structure 220 to between 0.6 and 0.9 mL / min. The width of the flow channel structure 250c connected to the first sub-outlet 212c of the first separation structure 210 is 260 μm. Passing through the 260 μm wide flow channel structure 250c, in a narrow flow rate range, large cells can be focused in the middle of the flow channel, and particles below the target size that are focused on both sides of the flow channel can be further removed. The flow rate into the third separation structure 240 is between 0.15-0.22 mL / min. In order to further focus and separate the collected particles, the width of the flow channel structure 250g is set to 500 μm, and the symmetry of the particle focusing is destroyed by adjusting the serpentine flow channel structure, so that the particles are focused on a single side of the flow channel and collected through the third sub-outlet 242c. At this time, the concentration multiple of the collected particles is about 80 times.

[0301] The flow rate range of the microfluidic structure 100 of the microfluidic chip 200 of the embodiment of the present disclosure can be between 0-5mL / min, and can be specifically selected and verified according to the structural form of the microfluidic structure 100, the size of the particles, and actual needs. For example, for the microfluidic structure 100 whose material is PDMS, 1.9-3.1ml / min is the preferred flow rate range, and within this preferred flow rate range, the microfluidic structure 100 can achieve focusing and separation of particles. For example, for the microfluidic structure 100 of the COC (Chip on Carrier) microfluidic chip 200, 3.2-4.2ml / min is the preferred flow rate range, and within this preferred flow rate range, the microfluidic structure 100 can achieve focusing and separation of particles. Therefore, the microfluidic structure 100 can be applicable to a wider flow rate range, and the stable and available flow rate range for particle focusing and separation can reach or even exceed 1 mL / min, that is, the length of the flow rate range reaches or even exceeds 1. The redundancy of the flow rate range is large, which solves the problem of flow rate sensitivity and reduces the sensitivity of dependence on the microfluidic structure, so that the microfluidic structure has good robustness and a broad application space.

[0302] Figure 11E is a schematic diagram illustrating the capture efficiency of target particles using the microfluidic chip shown in Figure 11A under different conditions. As shown in Figure 11E , using the microfluidic chip 200 shown in Figure 11A , the capture efficiency of particles (beads) of various sizes reached 99.8%. The capture efficiency of human breast cancer cells (MCF-7) in phosphate-buffered saline (PBS) was approximately 95%, and the capture efficiency of human breast cancer cells (MCF-7) in ten-fold diluted blood (10×blood) was approximately 85%. Thus, using this microfluidic chip 200, target particles can be collected effectively and with high capture efficiency.

[0303] Figure 11F is a diagram illustrating the enrichment of human breast cancer cells collected from a phosphate-buffered saline solution using the microfluidic chip shown in Figure 11A. As shown in Figure 11F, the microfluidic chip 200 shown in Figure 11A can not only separate human breast cancer cells from a phosphate-buffered saline solution, but also concentrate them to a high concentration.

[0304] Figure 11G shows the collection of human breast cancer cells and waste liquid from tenfold diluted blood using the microfluidic chip shown in Figure 11A. As shown in Figure 11G , from left to right, are the first-stage waste liquid from the first separation structure 210, the second-stage waste liquid from the second separation structure 220, the third-stage waste liquid from the third separation structure 240, and the collected liquid. Using the microfluidic chip 200 shown in Figure 11A , human breast cancer cells can be separated from tenfold diluted blood and concentrated to a high concentration.

[0305] FIG11H is a schematic diagram of the focusing position of particles of different sizes in the microfluidic structure of the microfluidic chip shown in FIG11A. As shown in FIG11A and FIG11H, the focusing position of the particles can be demonstrated using fluorescent particles. The horizontal axis of FIG11H represents the flow velocity of the microfluidic structure, and the vertical axis represents the focusing position of the particles in the flow channel at the outlet of the microfluidic structure 100. The width of the outlet flow channel is 500 μm, and the center position is at 250 μm on the vertical coordinate. Particles of three sizes (15 μm, 10 μm, 7.5 μm) can be focused at different positions of the flow channel in the flow rate range of 1.9 ml / min to 3.1 ml / min, thereby effectively separating particles of different sizes, and achieving a wide flow rate range for focusing and separation, which can solve the problem of flow rate sensitivity. In Figure 11H, in each flow rate segment, particles of 7.5 μm are focused near the outer side of the flow channel, particles of 15 μm are focused near the center of the flow channel, and particles of 10 μm are focused between the two. In order to more clearly show the focusing positions of particles of different sizes at different flow rates, the figure only schematically marks the focusing positions of particles of three sizes in two flow rate segments.

[0306] Figure 11I is a capture efficiency graph of the microfluidic chip shown in Figure 11A at different flow rates. As shown in Figure 11I, the horizontal axis represents the flow rate of the microfluidic structure, and the vertical axis represents the capture efficiency of particles and human breast cancer cells in phosphate buffered saline (PBS). Thus, whether it is particles or human breast cancer cells, the microfluidic chip can achieve a capture efficiency of 90% between the flow rate range of 3.2ml / min and 4.2ml / min. Thus, the chip has a wide flow rate range for capture, which can solve the problem of flow rate sensitivity and can be mass-produced and applied. In this example, the particle type is a 15μm fluorescent particle made of polystyrene (PS).

[0307] FIG11J is a schematic diagram of the target particles before and after treatment using the microfluidic chip shown in FIG11A. As shown in FIG11J, FIG11J (1) represents the concentration rate of the particles after passing through the first separation structure 210, the second separation structure 220 and the third separation structure 240, respectively, and FIG11J (2) is a schematic diagram before treatment (upper half) and after treatment (lower half). Thus, using the microfluidic chip 200 shown in FIG11A, not only can the particles be focused and separated, but also the particles can be concentrated to a high concentration. The embodiment of the present disclosure does not limit the type of separated particles, and different types of particles can be extracted as needed. For example, the particles can be target particles in whole blood or diluted blood or phosphate buffered saline (PBS), for example, the target particles include but are not limited to circulating tumor cells, human breast cancer cells or T lymphocytes.

[0308] Figure 11K compares the processing of circulating tumor cells in a blood sample using the microfluidic chip shown in Figure 11A. As shown in Figure 11K , after processing using this microfluidic chip, the purity of circulating tumor cells in the blood reaches over 90%, enabling the extraction and enrichment of circulating tumor cells in blood samples.

[0309] Figure 11L shows the capture efficiency of particles and circulating tumor cells in whole blood at different flow rates using the microfluidic chip shown in Figure 11A. As shown in Figure 11L, the horizontal axis represents the flow rate of the microfluidic structure, and the vertical axis represents the capture efficiency. Thus, within the flow rate range of 3.2 ml / min to 3.6 ml / min, the capture efficiency for particles in whole blood exceeds 50%, and the capture efficiency for circulating tumor cells in whole blood exceeds 55%. This chip has a wide flow rate range for capturing particles and circulating tumor cells in whole blood, addressing the issue of flow rate sensitivity and enabling large-scale production and application.

[0310] The microfluidic chip of the disclosed embodiment can also be used to separate CTC cells from whole blood, for CAR-T cell quality control, etc. CAR-T cell therapy, also known as chimeric antigen receptor T cell therapy, is a new type of biological immunotherapy. T lymphocytes are important immune cells in the human body. CAR-T cell therapy is to separate and extract T lymphocytes from the patient's body, transform, process, and culture them through genetic engineering technology, activate the T lymphocytes, and install a positioning navigation device CAR (tumor chimeric antigen receptor). T lymphocytes use CAR to specifically identify tumor cells in the body and release a large number of multiple effector factors through immune action. CAR-T cells are returned to the body to eliminate cancer cells in the body and can effectively kill tumor cells. T lymphocytes are mostly enriched from the patient's peripheral blood. The microfluidic chip of the disclosed embodiment can quickly enrich T lymphocytes from the blood, providing convenient conditions for the implementation of CAR-T therapy.

[0311] In some examples, the microfluidic chip described in Figure 10A or Figure 11A can also be prepared using the two preparation processes used in Figure 9A. Of course, the embodiments of the present disclosure do not limit the preparation process of the microfluidic chip, and the preparation process commonly used in the field can be used.

[0312] At least one embodiment of the present disclosure further provides a microfluidic device. FIG12 is a schematic diagram of a microfluidic device provided in one embodiment of the present disclosure. As shown in FIG12 , the microfluidic device 300 includes any of the aforementioned microfluidic chips 200. Thus, the microfluidic device 300 can have corresponding beneficial effects as the microfluidic chip 200, which are not further described here.

[0313] At least one embodiment of the present disclosure further provides a target particle aggregation method. FIG13 is a flow chart of a target particle aggregation method provided by one embodiment of the present disclosure. As shown in FIG13 , the target particle aggregation method includes:

[0314] S100: providing a sample solution containing target particles;

[0315] S200: injecting a sample solution into any microfluidic structure provided by the embodiments of the present disclosure, or injecting a sample solution into the microfluidic structure of any microfluidic chip provided by the embodiments of the present disclosure;

[0316] S300: focusing the target particles at an inertial equilibrium position in a channel of the microfluidic structure through the microfluidic structure.

[0317] In the method provided in the embodiments of the present disclosure, the microfluidic structure can be used to focus target particles at the inertial equilibrium position of the microfluidic channel structure, thereby achieving the aggregation of target particles. This method has the same beneficial effects as the microfluidic structure or microfluidic chip described above, and will not be repeated here.

[0318] In some examples, the sample solution also includes other particles of a size different from the target particles, and focusing the target particles at an inertial equilibrium position in the channel of the microfluidic structure using the microfluidic structure includes focusing the target particles and other particles at different inertial equilibrium positions in the channel of the microfluidic structure using the microfluidic structure. The microfluidic structure of the disclosed embodiments can focus particles of multiple different sizes at different inertial equilibrium positions in the channel of the microfluidic structure, thereby achieving aggregation of not only the target particles but also other particles.

[0319] In some examples, the method further includes separating the target particles and other particles at different inertial equilibrium positions. For example, the separation of the target particles and other particles can be achieved by the separation structure of the microfluidic chip of the embodiment of the present disclosure, which will not be described in detail here.

[0320] In some examples, injecting the sample solution into the microfluidic structure or the microfluidic structure of the microfluidic chip includes: injecting the sample solution into the microfluidic structure or the microfluidic structure of the microfluidic chip at a set flow rate, and setting the flow rate interval between 0 and 5 mL / min. Thus, the flow rate interval of the microfluidic structure is large in redundancy, can be applied to a wider range of flow rates, can reduce the sensitivity of dependence on the microfluidic structure, so that the microfluidic structure has good robustness and a broad application space. For the experimental verification of the flow rate and the selection of the flow rate interval, please refer to the above description and will not be repeated here. For example, the preferred flow rate interval can also be between 0.5 and 4.5 mL / min. For example, the preferred flow rate interval can also be between 1 and 4 mL / min.

[0321] For example, the length of the flow rate interval for setting the flow rate may reach or even exceed 1 mL / min.

[0322] It should be noted that the flow rate interval in the present disclosure refers to a numerical set of all available flow rates for focusing the target particles at the inertial equilibrium position in the pipeline of the microfluidic structure.

[0323] For example, the sample solution containing the target particles may include whole blood or diluted blood, for example, ten-fold diluted blood.

[0324] For example, target particles include but are not limited to the circulating tumor cells, human breast cancer cells, T lymphocytes, etc. mentioned above.

[0325] Regarding this disclosure, the following points need to be explained:

[0326] (1) The drawings of the embodiments of the present disclosure only relate to the structures related to the embodiments of the present disclosure. Other structures may refer to conventional designs.

[0327] (2) The various components or structures in the drawings are not drawn strictly in proportion. For the sake of clarity, the sizes of the various components or structures may be exaggerated or reduced, but this should not be used to limit the scope of the present disclosure.

[0328] (3) In the absence of conflict, the embodiments of the present disclosure and the features therein may be combined with each other to form new embodiments.

[0329] The above are only specific embodiments of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A microfluidic channel structure, comprising at least one microfluidic channel unit, wherein: Each of the microfluidic channel units comprises: A plurality of curved flow channels are arranged at intervals along the arrangement direction; and A plurality of turning flow channels, each of which is located between two adjacent curved flow channels and connects the two adjacent curved flow channels. The two turning channels connected to one curved channel are respectively located at two ends of the curved channel. Each of the curved flow channels has a first side and a second side opposite to each other in the arrangement direction, and each of the curved flow channels bends toward a first position located on the second side.

2. The microfluidic channel structure according to claim 1, wherein: The plurality of first positions of the plurality of curved flow channels are located on the same side of the plurality of curved flow channels in the arrangement direction.

3. The microfluidic channel structure according to claim 1, wherein: Along the arrangement direction, the lengths of the plurality of curved flow channels gradually change.

4. The microfluidic channel structure according to claim 1, wherein: Each of the curved flow channels is an arc-shaped flow channel, and the first position of each of the curved flow channels is the center of curvature of the curved flow channel.

5. The microfluidic channel structure according to claim 4, wherein: The plurality of first positions of the plurality of curved flow channels are located on the same straight line.

6. The microfluidic channel structure according to claim 4, wherein: The first positions of the plurality of curved flow channels overlap with each other.

7. The microfluidic channel structure according to any one of claims 4 to 6, wherein: Along the arrangement direction, the lengths of the plurality of curved flow channels gradually decrease; Among the plurality of curved channels, the arc radius of the longest curved channel is r max , the r max The value range is 10mm to 50mm; the arc radius of the shortest curved flow channel is r min , the r min The value range is 1mm to 20mm.

8. The microfluidic channel structure according to any one of claims 1 to 7, wherein: The number of the plurality of curved flow channels is N, and the value range of N is 2-50.

9. The microfluidic channel structure according to claim 8, wherein: The value range of N is 4-8.

10. The microfluidic channel structure according to claim 6, wherein: Along the arrangement direction, the lengths of the plurality of curved channels gradually decrease, the plurality of curved channels are arranged at equal intervals, and the parameters of the microchannel units satisfy the following formula: (N-1)·d+N·D=r max -r min Wherein, N is the number of the plurality of curved channels, d is the distance between two adjacent curved channels, D is the width of each of the plurality of curved channels, and among the plurality of curved channels, r max is the arc radius of the longest curved channel, and r min is the arc radius of the shortest curved flow channel.

11. The microfluidic channel structure according to any one of claims 1 to 10, wherein: Each of the turning flow channels comprises an inner side wall and an outer side wall. The inner side wall is arranged opposite to the outer side wall and is located on a side of the outer side wall close to the interval between two adjacent curved flow channels.

12. The microfluidic channel structure according to claim 11, wherein: Among the plurality of turning channels located on the same side of a reference straight line extending along the arrangement direction and passing through the plurality of curved channels, the outer side wall of the first turning channel and the outer side wall of the last turning channel in the arrangement direction both intersect with the first auxiliary straight line and are both located on a side of the first auxiliary straight line close to the reference straight line. Among the multiple turning channels on the other side of the reference straight line, the outer wall of the first turning channel and the outer wall of the last turning channel in the arrangement direction both intersect with the second auxiliary straight line and are both located on the side of the second auxiliary straight line close to the reference straight line. The angle λ between the first auxiliary straight line and the second auxiliary straight line ranges from 10 degrees to 90 degrees.

13. The microfluidic channel structure according to claim 12, wherein: The value range of λ is 15 degrees to 30 degrees.

14. The microfluidic channel structure according to claim 11, wherein: The orthographic projection of the inner wall on the reference plane is a first arc, the orthographic projection of the outer wall on the reference plane is a second arc, and the reference plane is parallel to the arrangement direction and the extension direction of each curved flow channel.

15. The microfluidic channel structure according to claim 14, wherein: Among the multiple turning channels located on the same side of a reference straight line extending along the arrangement direction and passing through the multiple curved channels, the outer side wall of the first turning channel and the outer side wall of the last turning channel in the arrangement direction are projected on the reference plane tangent to the first straight line.

16. The microfluidic channel structure according to claim 15, further comprising: an inlet flow channel connected to the first curved flow channel in the arrangement direction; as well as The outlet flow channel is connected to the last curved flow channel in the arrangement direction. In which, the outlet flow channel and the first straight line are respectively located on both sides of a reference straight line extending along the arrangement direction and passing through the multiple curved flow channels, the side wall of the last curved flow channel in the arrangement direction close to the first position and the orthographic projection of the side wall of the outlet flow channel close to the first straight line on the reference plane have an intersection, the first position of the last curved flow channel in the arrangement direction and the intersection are located on a second straight line, the first straight line and the second straight line have an angle θ, and the value range of θ is 10 degrees to 90 degrees.

17. The microfluidic channel structure according to claim 16, wherein: The value range of θ is 15 degrees to 30 degrees.

18. The microfluidic channel structure according to claim 11, wherein: The shape of the orthographic projection of the inner wall on the reference plane is a first straight line segment, the shape of the orthographic projection of the outer wall on the reference plane is a second straight line segment, and the reference plane is parallel to the arrangement direction and the extension direction of each of the curved flow channels.

19. The microfluidic channel structure according to claim 18, wherein: Among the plurality of turning flow channels located on the same side of a reference straight line extending along the arrangement direction and passing through the plurality of curved flow channels, the outer side wall of the first turning flow channel and the outer side wall of the last turning flow channel in the arrangement direction have orthographic projections on the reference plane located on a fourth straight line. The microfluidic channel structure further includes: An inlet flow channel is connected to the first curved flow channel in the arrangement direction; and The outlet flow channel is connected to the last curved flow channel in the arrangement direction. In which, the outlet flow channel and the fourth straight line are respectively located on both sides of the reference straight line, the side wall of the last curved flow channel in the arrangement direction close to the first position and the orthographic projection of the side wall of the outlet flow channel close to the first straight line on the reference plane have an intersection, the first position of the last curved flow channel in the arrangement direction and the intersection are located on the second straight line, the fourth straight line and the second straight line have an angle β, and the value range of β is 10 degrees to 90 degrees.

20. The microfluidic channel structure according to claim 19, wherein: The value range of β is 15 degrees to 30 degrees.

21. The microfluidic channel structure according to claim 18, wherein: The second straight line segments of the turning channels that are located on the same side of a reference straight line extending along the arrangement direction and passing through the curved channels are parallel to each other.

22. The microfluidic channel structure according to any one of claims 1 to 21, wherein: The ratio of the width to the height of the plurality of curved flow channels ranges from 1 to 20, and the height of the plurality of curved flow channels ranges from 10 μm to 150 μm.

23. The microfluidic channel structure according to any one of claims 1 to 21, further comprising a connecting channel, in, The microfluidic channel structure includes a plurality of microfluidic channel units, and the connecting channel is located between two adjacent microfluidic channel units and connects the two adjacent microfluidic channel units.

24. The microfluidic channel structure according to claim 23, wherein: The plurality of micro-channel units are arranged in sequence along an arc line, and the arc line bends toward the second position; The second position and the first positions of the plurality of curved channels of any one of the micro-channel units are located on the same side of the arc.

25. The microfluidic channel structure according to claim 24, wherein: The plurality of micro-channel units include a first micro-channel unit, a second micro-channel unit and a third micro-channel unit which are sequentially arranged in the extending direction of the arc line. The last curved channel of the first microfluidic channel unit in the arrangement direction is connected to the last curved channel of the second microfluidic channel unit in the arrangement direction through the connecting channel, and the first curved channel of the second microfluidic channel unit in the arrangement direction is connected to the first curved channel of the third microfluidic channel unit in the arrangement direction through the connecting channel.

26. The microfluidic channel structure according to claim 25, wherein: The second position overlaps with a plurality of the first positions of the plurality of curved channels of any one of the micro-channel units.

27. The microfluidic channel structure according to claim 23, wherein: The plurality of micro-channel units are arranged in sequence along a circumferential line.

28. A microfluidic chip comprising: The microfluidic channel structure according to any one of claims 1 to 27; as well as The first separation structure includes a first sub-inlet and a plurality of first sub-outlets, The microchannel structure includes an inlet and an outlet, and the first sub-inlet is connected to the outlet of the microchannel structure.

29. A method for aggregating target particles, comprising: providing a sample solution including target particles; Injecting the sample solution into the microfluidic structure according to any one of claims 1 to 27, or injecting the sample solution into the microfluidic structure of the microfluidic chip according to claim 28; The target particles are focused on an inertial equilibrium position in a channel of the microfluidic channel structure through the microfluidic channel structure.

30. The method according to claim 29, wherein The sample solution also includes other particles of a size different from that of the target particles, Focusing the target particles at an inertial equilibrium position in a channel of the microfluidic structure through the microfluidic structure includes: The target particles and the other particles are focused on different inertial equilibrium positions in a channel of the microfluidic channel structure through the microfluidic channel structure.

31. The method of claim 30, further comprising: The target particles and the other particles located at different inertial equilibrium positions are separated.

32. The method of claim 29, wherein: The injecting the sample solution into the microfluidic structure or the microfluidic structure of the microfluidic chip comprises: Injecting the sample solution into the microfluidic structure or the microfluidic structure of the microfluidic chip at a set flow rate, The flow rate range of the set flow rate is between 0 and 5 mL / min.

33. The method according to any one of claims 29 to 31, wherein: The sample solution including target particles includes whole blood or diluted blood.

34. The method according to claim 33, wherein The target particles include circulating tumor cells, human breast cancer cells or T lymphocytes.

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