A microfluidic chip for sorting live cells

Abstract

The present invention relates to a microfluidic chip for sorting living cells. A sample flow channel communicates with the liquid supply end of a sorting flow channel, an intake air flow channel, a target flow channel, and a non-target flow channel are connected to the liquid discharge end of the sorting flow channel. The angle between the target flow channel and the sorting flow channel is 100° - 130°, the angle between the non-target flow channel and the sorting flow channel is 100° - 140°, and the intersection point of the axis of the intake air flow channel and the axis of the sorting flow channel is 0.02 mm to 0.05 mm away from the intersection point of the three of the sorting flow channel, the target flow channel, and the non-target flow channel. The microfluidic chip in this solution can expand the sorting area, extend the residence time of cells in the sorting area, and can accurately blow target cells into the target flow channel by an air flow, so the accuracy of cell sorting is improved.

Description

[Technical Field]

[0001] The present invention relates to the technical field of live cell sorting, and in particular to a microfluidic chip for sorting live cells. [Background technology]

[0002] As research in the field of cells advances, our understanding of cells is growing. When studying cells, cell sorting is an important link in the study of cell physiology and pathology. Currently, the main technological means of cell sorting on the market is to combine flow cytometry with microfluidic chips to select target cells from a cell population. Cell sorting chips can use piezoelectric, magnetic, or pneumatic drive structures to drive cells and change their trajectory. Compared with other methods, pneumatic drive structures cause minimal damage to cells. Therefore, when it is necessary to sort active cells, cell sorting chips with pneumatic drive structures are often selected to select target cells. For example, in existing sorting devices that simultaneously detect multiple intracellular fluorescent signals, the microfluidic chip includes a detection area, a sorting area, an intake port, a waste pool, and a target cell pool. The detection area and the sorting area are connected via a first cell channel, the sorting area and the waste pool are connected via a second cell channel, the intake port and the sorting area are connected via a gas channel, and the target cell pool and the sorting area are connected via a sorting channel. The first cell channel, the second cell channel, the gas channel, and the sorting channel are arranged in a cross shape around the sorting region. This solution uses gas injection into the gas channel to blow the target cells into the sorting channel, which reduces damage to the target cells caused by the gas when changing their path. However, this solution results in a low accuracy of cell sorting because the area of ​​the sorting region is too small and the flow rate of the cell solution in the sorting channel is too fast, resulting in a short residence time for the target cells in the sorting region, making it difficult to ensure that the air flow in the gas channel blows the target cells accurately into the sorting channel. Summary of the Invention [Means for solving the problem]

[0003] The present invention provides a microfluidic chip for sorting live cells to solve the problem of the above-mentioned existing technical solutions, in which the area of ​​the sorting region of the microfluidic chip is too small, and the flow rate of the cell solution in the sorting channel is too fast, resulting in a short residence time of the target cells in the sorting region, making it difficult for the air flow in the gas channel to ensure that the target cells are accurately blown into the sorting channel. This solution further expands the area of ​​the sorting region and extends the passage time of the cells in the sorting region, allowing the target cells to be accurately blown into the target channel and improving the accuracy of cell sorting.

[0004] The technical solution adopted in the present invention is a microfluidic chip for sorting living cells, which includes a sample region, a sample channel communicating with the sample region, an electromagnetic intake valve, an intake channel communicating with the electromagnetic intake valve, a target cell pool, a target channel communicating with the target cell pool, a non-target cell pool, non-target channels communicating with the non-target cell pool, and a sorting channel, where the sample channel is connected to a liquid supply end of the sorting channel, the target channel and the non-target channel are connected to a liquid discharge end of the sorting channel, and the intake channel is connected to the sorting channel and is located at an end of the sorting channel close to its liquid discharge port. The intake channel and non-target channel are located on one side of the sorting channel, and the target channel is located on the other side of the sorting channel, the angle between the target channel and the sorting channel is 100°-130°, the angle between the non-target channel and the sorting channel is 100°-140°, the axis of the intake channel is perpendicular to the axis of the sorting channel, and the distance d between the intersection of the axis of the intake channel and the axis of the sorting channel and the intersection of the sorting channel, target channel, and non-target channel is 0.02 mm to 0.05 mm. The cell sorting region is the end of the sorting channel where it intersects with the target channel, non-target channel, and intake channel.

[0005] When the microfluidic chip is in operation, target and non-target cells in the sample area enter the sample channel with the flow of cell solution and are arranged in a single straight line within the sample channel. As the cell solution continues to flow forward, target and non-target cells enter the sorting channel. The target cell signal identification device identifies cells that have entered the sorting channel. When a cell is identified as a target cell, it controls the electromagnetic intake valve to pump gas into the intake channel. When the target cell moves to the sorting area, the gas in the intake channel moves to the sorting area, blowing the target cell into the target channel. When the cell is identified as a non-target cell, the electromagnetic intake valve does not pump gas into the intake channel. After the non-target cell moves to the sorting area, it continues to flow into the non-target channel along with the cell solution.

[0006] In this solution, the target flow path, non-target flow path, and intake flow path are arranged to intersect with the sorting flow path, and when the distance d between the intersection of the axis of the intake flow path and the axis of the sorting flow path and the intersection of the intake flow path, target flow path, and non-target flow path is 0.02mm-0.05mm, by increasing the length of the sorting area, the residence time of the target cells in the sorting area becomes longer, the appropriate timing for pumping gas into the gas flow path becomes greater, the gas completes the work of blowing the target cells into the target flow path, and the accuracy of sorting the target cells becomes higher.

[0007] When the gas in the intake channel enters the sorting region, the gas exerts a deflection force on the cells perpendicular to their original path. After the target cells are subjected to the deflection force provided by the gas, their migration path changes and moves into a parabolic path toward the target cell channel. The shape of this parabola is determined by the flow velocity of the original cells and the magnitude of the intake pressure. The angle between the two asymptotes of this parabola is the angle between the sorting channel and the target channel. When target cells move within the sorting region, the distance d that the target cells travel along the axis of the sorting channel is required for them to enter the target cell channel. The direction of migration of the target cells is parallel to the axis of the target channel. A distance d of 0.02-0.05 mm and an angle of 100-130° between the target channel and the sorting channel ensures smooth entry of the target cell channel and ensures that the migration direction of the target cells is parallel to the axis of the target cell channel. Furthermore, the deflection force required to change the path of target cells when the angle between the destination channel and the sorting channel is 100°-130° is smaller than the deflection force required to change the path of target cells when the destination channel is perpendicular to the sorting channel. The cell sorting process can be completed even when the intake pressure in the present application is lower than that in the prior art. The lower the intake pressure, the less damage the gas causes to the target cells. Therefore, compared to the prior art, the present application causes less damage to the target cells. At the same time, when the angle between the non-destination channel and the sorting channel is 100°-140°, after the target cells are subjected to the deflection force provided by the gas in the intake channel, the angle between the direction of movement of the target cells and the axis of the non-destination channel becomes larger, further preventing the target cells from entering the non-destination channel.

[0008] Preferably, the sorting channel includes a first channel and a second channel, the first channel having a diameter of 0.1-0.12 mm, and the second channel having a diameter of 0.18-0.2 mm. The first channel is connected to the sample channel, and the second channel is connected to the target channel, the non-target channel, and the intake channel. The diameter of the second channel is larger than that of the first channel, which not only slows down the cell migration speed in the second channel but also prevents the gas flow in the gas channel from moving toward the first channel. If a portion of the gas flow moves toward the first channel, this portion cannot pass through the connecting end of the second channel and the first channel, preventing backflow from impacting the cells and causing cell damage.

[0009] Preferably, the end of the second flow path that is connected to the first flow path is tapered, so that the sample liquid in the first flow path can gently enter and fill the second flow path.

[0010] Preferably, arc-shaped chamfers are provided between the second flow path, the intake flow path, the non-target flow path, and the target flow path, with the arc-shaped chamfer between the second flow path and the intake flow path being a first chamfer, the chamfer between the intake flow path and the non-target flow path being a second chamfer, the chamfer between the non-target flow path and the target flow path being a third chamfer, and the chamfer between the target flow path and the second flow path being a fourth chamfer. The radius of the first chamfer is 0.08mm-0.1mm, the radius of the second chamfer is 0.08mm-0.1mm, the radius of the third chamfer is 0.12mm-0.15mm, and the radius of the fourth chamfer is 0.18mm-0.2mm. The sidewalls where the secondary flow path, intake flow path, non-target flow path, and target flow path intersect are provided with arc-shaped chamfers at their intersections. The curvature of the chamfers matches the parabolic path of cells, guiding the cell's migration path and preventing cell damage even when the cells come into contact with the sidewalls. Experimental measurements have shown that the chamfers' guiding role for cells is maximized when the radius of the first chamfer is 0.08mm-0.1mm, the radius of the second chamfer is 0.08mm-0.1mm, the radius of the third chamfer is 0.12mm-0.15mm, and the radius of the fourth chamfer is 0.18mm-0.2mm.

[0011] Preferably, the sample flow path includes a cell flow path and a sheath fluid flow path, the sample region includes a mixed cell region and a sheath fluid region, the cell flow path is connected to the mixed cell region, the sheath fluid flow path is connected to the sheath fluid region, and the sheath fluid flow path and the cell flow path intersect at the liquid supply end of the sorting flow path. There are two sheath fluid flow paths, each located on opposite sides of the cell flow path and symmetrically arranged with the axis of the cell flow path as the axis of symmetry, with the diameter of the sheath fluid flow path being the same as the diameter of the cell flow path and the diameter of the non-target flow path being twice the diameter of the target flow path. The sheath fluid can envelop the cells so that they flow into the detection region of the cytometer in a single linear array. Because there are two sheath fluid flow paths, each located on either side of the cell flow path, cells flowing into the sorting flow path are located in the center of the sorting flow path. The diameter of the sheath fluid channel is the same as that of the cell channel, and the diameter of the non-target channel is twice that of the target channel. Therefore, the ratio of the cell suspension and the sheath fluid on both sides of it after entering the sorting channel is 1:1:1. If there is no external interference with the liquid in the sorting channel, the sheath fluid on the side closer to the target channel will flow into the target channel, and the cell suspension and sheath fluid on the other side will flow into the non-target channel, automatically completing the process of guiding the flow of non-target cells into the non-target channel.

[0012] Preferably, the length of the destination channel is 5 mm or less. The air pressure of the gas pumped into the intake channel must not be too high; if it is too high, the gas entering the microfluidic chip will crosstalk throughout the channel. The gas pushing force on the target cells is sufficient to allow the target cells to migrate long distances within the destination channel. If the destination channel is too long, the target cells will remain within the channel and will not be able to reach the target cell pool. Therefore, the length of the destination channel cannot be too long. Experimental measurements have shown that when the length of the destination channel is 5 mm or less, the gas pushing force on the target cells allows the target cells to smoothly pass through the destination channel and enter the target cell pool.

[0013] Preferably, the angle between the sheath fluid flow path and the cell flow path is 25 to 35°. The sheath fluid flow path is provided with a serpentine flow resistance segment to reduce the flow rate of the sheath fluid in the sheath fluid flow path. As the angle between the sheath fluid flow path and the cell flow path increases, the impact of the sheath fluid flow on the cell fluid flow after the sheath fluid and cell fluid merge increases, impacting the cells in the cell fluid flow. Experimental measurements have shown that when the angle between the sheath fluid flow path and the cell flow path is 25 to 35°, the sheath fluid can be gently mixed with the cell fluid. When the flow resistance is snake-shaped and the sheath fluid passes through the snake-shaped sheath fluid flow path, the kinetic energy of the sheath fluid decreases, reducing the flow rate of the sheath fluid. This further slows the flow rate of the sample fluid entering the first flow path, thereby slowing the migration rate of the cells.

[0014] Compared with the prior art, the beneficial effect of this solution is that the microfluidic chip in this solution does not damage cells during cell sorting. This solution enlarges the cell sorting area, increasing the residence time of target cells in the cell sorting area, allowing for more timely pumping and preventing target cells from entering the non-target cell pool due to too slow pumping, improving cell sorting accuracy. Using lower air pressure, the goal of pushing target cells into the target channel can be achieved. The sorting channel can slow down the cell migration speed and further prevent gas backflow, further improving cell sorting accuracy and avoiding cell damage. The side walls where the second channel, intake channel, non-target channel, and target channel intersect are provided with arc-shaped chamfers at the intersections to guide cells into the sorting area. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a structural diagram of a microfluidic chip for selecting living cells according to the present invention. [Figure 2] FIG. 2 is an enlarged view of part B in FIG. 1 of the microfluidic chip for sorting living cells of the present invention. [Figure 3]FIG. 2 is an enlarged view of part A in FIG. 1 of the microfluidic chip for sorting living cells of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The accompanying drawings are for illustrative purposes only and should not be understood as limiting the present patent, some elements in the accompanying drawings may be omitted, enlarged or reduced in size to better explain the present embodiment, and do not represent the dimensions of the actual product, and those skilled in the art will understand that some well-known structures and their descriptions may be omitted in the accompanying drawings, and the positional relationships shown in the drawings are for illustrative purposes only and should not be understood as limiting the present patent.

[0017] The same or similar symbols in the drawings of the embodiments of the present invention correspond to the same or similar parts. In the description of the present invention, the orientations or positional relationships indicated by the terms "upper," "lower," "left," "right," "long," "short," etc. are orientations or positional relationships indicated based on the drawings, and are only intended to facilitate and simplify the description of the present invention, and are not intended to indicate or imply that the referenced devices or elements necessarily have a specific orientation or are constructed and operated in a specific orientation. Therefore, the terms used to describe the positional relationships in the drawings are for illustrative purposes only and should not be construed as limiting the present patent. Those skilled in the art can understand the specific meanings of the above terms according to specific circumstances.

[0018] The technical solutions of the present invention will be further described in detail below through specific examples and in conjunction with the accompanying drawings.

[0019] Example 1 1 and 2 show Example 1 of a microfluidic chip for sorting live cells, which includes a sample region, a sample channel communicating with the sample region, an electromagnetic intake valve, an intake channel 1 communicating with the electromagnetic intake valve, a target cell pool 5, a target channel 2 communicating with the target cell pool 5, a non-target cell pool 6, a non-target channel 3 communicating with the non-target cell pool 6, and a sorting channel 4. The sample channel is connected to the liquid supply end of the sorting channel 4, the target channel 2 and the non-target channel 3 are connected to the liquid outlet end of the sorting channel 4, and the intake channel 1 is connected to the sorting channel 4 and is located at the end of the sorting channel 4 close to its liquid outlet. The intake channel 1 and the non-target channel 3 are located on one side of the sorting channel 4, and the target channel 2 is located on the other side of the sorting channel 4. The angle between the target flow path 2 and the sorting flow path 4 is 120°, the angle between the non-target flow paths 3 and the sorting flow path 4 is 128°, the axis of the intake flow path 1 is perpendicular to the axis of the sorting flow path 4, and the distance d between the intersection of the axis of the intake flow path 1 and the axis of the sorting flow path 4 and the intersection of the sorting flow path 4, the target flow path 2, and the non-target flow paths 3 is 0.05 mm. The sorting region is the end of the sorting flow path 4 where it intersects with the target flow paths 2, non-target flow paths 3, and the intake flow path 1.

[0020] In this embodiment, when the microfluidic chip is operating, target and non-target cells in the sample area enter the sample channel with the flow of cell solution and are aligned in a single line within the sample channel. As the cell solution continues to flow forward, the target and non-target cells pass through the sorting channel 4 and enter the sorting area. The target cell signal identification device identifies the cells that enter the sorting channel 4. When a cell is identified as a target cell, the electromagnetic intake valve controls the pumping of gas into the intake channel 1. As the target cell moves to the sorting area at the end of the sorting channel 4, the gas in the intake channel 1 moves into the sorting area, blowing the target cell into the target channel. When a cell is identified as a non-target cell, the electromagnetic intake valve stops pumping gas into the intake channel 1. After the non-target cell moves to the sorting area at the end of the sorting channel 4, it continues to flow into the non-target channel 3 along with the cell solution.

[0021] [Table 1]

[0022] The cell sorting chip used in the control group is a microfluidic chip of a sorting device for simultaneously detecting multiple fluorescent signals in cells in the prior art, while the microfluidic chip used in this application is the microfluidic chip described in this solution. Comparing control group 1 and control group 2 with application 1 and application 2, for the same target cells, under the same intake pressure and cell flow rate, the accuracy of cell sorting in this application is much higher than that of the control group. Control group 1 and Control group 2 and When comparing the above, under the same cell flow rate, the higher the intake pressure, the higher the cell sorting accuracy. However, when comparing Control Group 1 and Control Group 2 with Application 1 and Application 2, the experimental air pressure of the two groups decreases by the same amount, and the cell sorting accuracy in the control group fluctuates more than that of the application. As can be seen from the above experimental data, by enlarging the cell sorting area and adjusting the angle between the target channel and the sorting channel, the cell sorting accuracy can be significantly improved. When using a smaller air pressure to drive and deflect the target cells, the impact of air pressure fluctuations on cell sorting accuracy is small, and good cell sorting results can be obtained.

[0023] The beneficial effect of this embodiment is that the cell sorting area is enlarged in this solution, which increases the residence time of target cells in the cell sorting area, increases the appropriate timing of pumping, and prevents target cells from entering the non-target cell pool due to too slow pumping, thereby improving cell sorting accuracy. Furthermore, when driving and deflecting cells, using gas with a smaller air pressure can achieve the goal of pushing target cells into the target channel, and the smaller the air pressure of the gas, the less damage to target cells caused by the gas flow and the higher the activity of the target cells.

[0024] Example 2 Example 2 of the microfluidic chip for sorting living cells is based on Example 1, and further restricts the structures of the sorting channel 4 and the sorting region, as shown in FIGS.

[0025] Specifically, the sorting flow path 4 includes a first flow path 401 and a second flow path 402, the first flow path 401 having a diameter of 0.1 mm and the second flow path 402 having a diameter of 0.2 mm, the first flow path 401 being connected to the sample flow path, and the second flow path 402 being connected to the target flow path 2, the non-target flow path 3 and the intake flow path 1.

[0026] Specifically, the end of second flow path 402 connected to first flow path 401 is tapered.

[0027] Specifically, arc-shaped chamfers are provided between the second flow path 402, the intake flow path 1, the non-target flow path 3, and the target flow path 2, with the arc-shaped chamfer between the second flow path 402 and the intake flow path 1 being the first chamfer 7, the chamfer between the intake flow path 1 and the non-target flow path 3 being the second chamfer 8, the chamfer between the non-target flow path 3 and the target flow path 2 being the third chamfer 9, and the chamfer between the target flow path 2 and the second flow path 402 being the fourth chamfer 10. The radius of the first chamfer 7 is 0.1 mm, the radius of the second chamfer 8 is 0.1 mm, the radius of the third chamfer 9 is 0.15 mm, and the radius of the fourth chamfer 10 is 0.2 mm.

[0028] The beneficial effect of this embodiment is that, because the diameter of second flow path 402 is larger than the diameter of first flow path 401, it is possible not only to slow down the migration speed of cells in second flow path 402, but also to prevent the gas flow in the intake flow path from moving toward first flow path 401. If a portion of the gas flow moves toward first flow path 401, this portion of the gas flow cannot pass through the connection end between second flow path 402 and first flow path 401, preventing the cells from being impacted by backflow and causing cell damage. Because the connection portion between first flow path 401 and second flow path 402 is tapered, the sample liquid in first flow path 401 can gently enter second flow path 402, filling it. The side walls where the second flow path 402, the intake flow path 1, the non-target flow path 3, and the target flow path 2 intersect have arc-shaped chamfers at the intersections to guide cells entering the sorting region. Since the shape of the chamfers is the same as the parabolic migration path of the cells, they can act as a guide for the cells that have entered the sorting region, making it easier for non-target cells to flow into the non-target flow path 3 and for target cells to flow into the target flow path 2.

[0029] Example 3 Example 3 of the microfluidic chip for sorting live cells is based on Example 1 or Example 2, and further limits the sample channel, target channel 2, and non-target channel 3, as shown in Figures 1 to 3.

[0030] Specifically, the sample flow path includes a cell flow path 11 and a sheath fluid flow path 12, the sample region includes a mixed cell region 13 and a sheath fluid region 14, the cell flow path 11 is connected to the mixed cell region 13, the sheath fluid flow path 12 is connected to the sheath fluid region 14, and the sheath fluid flow path 12 and cell flow path 11 intersect at the liquid supply end of the sorting flow path 4. There are two sheath fluid flow paths 12, which are located on opposite sides of the cell flow path 11 and are arranged symmetrically with respect to the axis of the cell flow path 12. The sheath fluid flow path 12 and the cell flow path 11 have the same diameter, and the diameter of the non-target flow path 3 is twice the diameter of the target flow path 2.

[0031] Specifically, the length of the destination flow path 2 is 4 mm or less. The angle between the sheath fluid flow path 12 and the cell flow path 11 is 25°. The sheath fluid flow path 12 is provided with a serpentine flow resistance segment (not shown) for reducing the flow velocity of the sheath fluid in the sheath fluid flow path 12.

[0032] The beneficial effect of this embodiment is that the diameter of the sheath fluid channel 12 is the same as that of the cell channel 11, and the diameter of the non-target channel 3 is twice that of the target channel 2. Therefore, after entering the sorting channel 4, the ratio of the cell suspension to the sheath fluid on both sides is 1:1:1. If there is no external interference with the liquid in the sorting channel 4, the sheath fluid on the side closer to the target channel 2 flows into the target channel 2, and the cell suspension and sheath fluid on the other side flow into the non-target channel 3, automatically guiding the inflow of non-target cells into the non-target channel 3. When the length of the target channel 2 is 4 mm, the pushing force of the gas on the target cells allows them to smoothly pass through the target channel 2 and enter the target cell pool 5. As the angle between the sheath fluid channel 12 and the cell channel 11 increases, the impact of the sheath fluid on the cell fluid stream after the sheath fluid and cell fluid merge becomes greater, impacting the cells in the cell fluid stream. Experimental measurements have shown that the sheath fluid can be gently mixed with the cell fluid when the angle between the sheath fluid flow path 12 and the cell flow path 11 is 25°. When the flow resistance is snake-shaped and the sheath fluid passes through the snake-shaped sheath fluid flow path 12, the kinetic energy of the sheath fluid decreases, the flow rate of the sheath fluid decreases, and the flow rate of the sample fluid that has entered the first flow path 401 also slows down, resulting in a slower migration rate of the cells.

[0033] Obviously, the above-described embodiments of the present invention are merely examples for the purpose of clarity and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications or changes based on the above description. It is not necessary or possible to cover all embodiments here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. The cell sorting system includes a sample area, a sample flow path communicating with the sample area, an electromagnetic intake valve, an intake flow path (1) communicating with the electromagnetic intake valve, a target cell pool (5), a target flow path (2) communicating with the target cell pool (5), a non-target cell pool (6), a non-target flow path (3) communicating with the non-target cell pool (6), and a sorting flow path (4), The sample flow path communicates with the liquid supply end of the sorting flow path (4), the target flow path (2) and the non-target flow path (3) communicate with the liquid discharge end of the sorting flow path (4), the intake flow path (1) communicates with the sorting flow path (4) and is located at an end of the sorting flow path (4) close to its liquid discharge port, the target flow path (2) is located on one side of the sorting flow path (4), and the intake flow path (1) and the non-target flow path (3) are located on the other side of the sorting flow path (4), the angle between the target flow path (2) and the sorting flow path (4) is 100°-130°, the angle between the non-target flow path (3) and the sorting flow path (4) is 100°-140°, the axis of the intake flow path (1) is perpendicular to the axis of the sorting flow path (4), and the intersection of the axis of the intake flow path (1) and the axis of the sorting flow path (4) is 0.02 mm to 0.05 mm away from the intersection of the sorting flow path (4), the target flow path (2), and the non-target flow path (3); The sorting flow path (4) includes a first flow path (401) and a second flow path (402), the diameter of the first flow path (401) is 0.1 mm to 0.12 mm, the diameter of the second flow path (402) is 0.18 mm to 0.2 mm, the first flow path (401) is in communication with the sample flow path, and the second flow path (402) is in communication with the target flow path (2), the non-target flow path (3), and the intake flow path (1).

2. 2. The microfluidic chip for sorting living cells according to claim 1, wherein the end of the second channel (402) connected to the first channel (401) is tapered.

3. 2. The microfluidic chip for sorting living cells according to claim 1, wherein arc-shaped chamfers are provided between the second flow path (402), the intake flow path (1), the non-target flow path (3), and the target flow path (2), the arc-shaped chamfer between the second flow path (402) and the intake flow path (1) being a first chamfer (7), the chamfer between the intake flow path (1) and the non-target flow path (3) being a second chamfer (8), the chamfer between the non-target flow path (3) and the target flow path (2) being a third chamfer (9), and the chamfer between the target flow path (2) and the second flow path (402) being a fourth chamfer (10).

4. The microfluidic chip for sorting living cells according to claim 3, characterized in that the radius of the first chamfer (7) is 0.08 mm to 0.1 mm, the radius of the second chamfer (8) is 0.08 mm to 0.1 mm, the radius of the third chamfer (9) is 0.12 mm to 0.15 mm, and the radius of the fourth chamfer (10) is 0.18 mm to 0.2 mm.

5. 2. The microfluidic chip for sorting living cells according to claim 1, wherein the sample flow path includes a cell flow path (11) and a sheath fluid flow path (12), the sample region includes a mixed cell region (13) and a sheath fluid region (14), the cell flow path (11) communicates with the mixed cell region (13), the sheath fluid flow path (12) communicates with the sheath fluid region (14), and the sheath fluid flow path (12) and the cell flow path (11) intersect at a liquid supply end of the sorting flow path (4).

6. 6. The microfluidic chip for sorting living cells according to claim 5, wherein there are two sheath fluid channels (12), the two sheath fluid channels (12) are located on opposite sides of the cell channel (11), and are arranged symmetrically with respect to the axis of the cell channel (11), the diameter of the sheath fluid channel (12) is the same as the diameter of the cell channel (11), and the diameter of the non-target channel (3) is twice the diameter of the target channel (2).

7. 7. The microfluidic chip for selecting living cells according to claim 6, wherein the length of the target channel is 5 mm or less.

8. 7. The microfluidic chip for sorting living cells according to claim 6, wherein the angle between the sheath fluid channel (12) and the cell channel (11) is 25-35°.

9. 9. The microfluidic chip for sorting living cells according to claim 8, wherein the sheath fluid flow path (12) is provided with a serpentine flow resistance segment (not shown) for reducing the flow velocity of the sheath fluid in the sheath fluid flow path (12).

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