Micro-fluidic chip for sorting living cells

Abstract

The present invention relates to a micro-fluidic chip for sorting living cells. A sample flow channel is in communication with a liquid intake end of a sorting flow channel; an air intake flow channel, a target flow channel and a non-target flow channel are in communication with a liquid output end of the sorting flow channel; an included angle between the target flow channel and the sorting flow channel is 100-130°; an included angle between the non-target flow channel and the sorting flow channel is 100-140°; and an intersection point between the axis of the air intake flow channel and the axis of the sorting flow channel is 0.02-0.05 mm away from an intersection point between the sorting flow channel, the target flow channel and the non-target flow channel. In the present solution, the micro-fluidic chip can enlarge a sorting area, and can prolong the retention time of cells in the sorting area, such that an airflow can accurately blow target cells into the target flow channel, thereby improving the cell sorting accuracy.

Description

A microfluidic chip for living cell sorting Technical Field

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

[0002] As research in the field of cells deepens, people's understanding of cells is increasing. When studying cells, cell sorting is a key step in studying cell physiology and pathology. Currently, the main technical means for cell sorting on the market is to use a combination of flow cytometry and microfluidic chips to sort target cells from a cell population. Cell sorting chips can use piezoelectric, magnetic, or pneumatic drive structures to drive cells to change their motion trajectory. Compared with other methods, pneumatic drive structures cause the least damage to cells. Therefore, when it is necessary to sort active cells, cell sorting chips with pneumatic drive structures are often chosen to sort target cells. For example, an existing sorting device that simultaneously detects multiple fluorescent signals in cells has a microfluidic chip that includes a detection area, a sorting area, an air inlet, a waste liquid pool, and a target cell pool. The detection area and the sorting area are connected by a first cell flow channel, the sorting area and the waste liquid pool are connected by a second cell flow channel, the air inlet and the sorting area are connected by a gas flow channel, and the target cell pool and the sorting area are connected by a sorting flow channel. The first cell flow channel, the second cell flow channel, the gas flow channel, and the sorting flow channel are arranged in a cross shape around the sorting area. This solution uses air jets to blow the target cells into the sorting channel. The gas causes less damage to the target cells when changing their path. However, the sorting area in this solution is too small. When the cell fluid flow rate in the sorting channel is too fast, the target cells stay in the sorting area too short, making it difficult to ensure that the airflow in the gas channel can accurately blow the target cells into the sorting channel, resulting in low cell sorting accuracy.

[0003] Summary of the Invention

[0004] The present invention addresses the problem in the prior art that the sorting zone of the microfluidic chip is too small. When the cell fluid flow rate in the sorting channel is too fast, the target cells spend too little time in the sorting zone, making it difficult to ensure that the airflow in the gas channel can accurately blow the target cells into the sorting channel, resulting in low cell sorting accuracy. The present invention provides a microfluidic chip for live cell sorting. This solution can further expand the area of ​​the sorting zone and extend the time target cells spend in the sorting zone, allowing them to be accurately blown into the target channel, thereby improving cell sorting accuracy.

[0005] The present invention employs a technical solution: a microfluidic chip for sorting living cells, comprising a sample area, a sample flow channel connected to the sample area, an electromagnetic air inlet valve, an air inlet channel connected to the electromagnetic air inlet valve, a target cell pool, a target flow channel connected to the target cell pool, a non-target cell pool, a non-target flow channel connected to the non-target cell pool, and a sorting flow channel. The sample flow channel is connected to the liquid inlet end of the sorting flow channel, the target flow channel and the non-target flow channel are connected to the liquid outlet end of the sorting flow channel, and the air inlet channel is connected to the sorting flow channel and is located on one end of the sorting flow channel near its liquid outlet. The inlet and non-target channels are located on one side of the sorting channel, while the target channel is located on the other side. The angle between the target channel and the sorting channel is 100°-130°, and the angle between the non-target channel and the sorting channel is 100°-140°. The axis of the inlet channel is perpendicular to the axis of the sorting channel. The distance d between the intersection of the inlet and sorting channel axes and the intersection of the sorting, target, and non-target channels is 0.02mm-0.05mm. The cell sorting zone is the end of the sorting channel that intersects the target, non-target, and inlet channels.

[0006] When the microfluidic chip is working, the target cells and non-target cells in the sample area enter the sample flow channel with the flow of cell fluid and are arranged in a single linear pattern in the sample flow channel. As the cell fluid continues to flow forward, the target cells and non-target cells enter the sorting flow channel. The cell target signal device identifies the cells entering the sorting flow channel. When the cell is identified as a target cell, the electromagnetic air intake valve is controlled to pump air into the air intake channel. When the target cell moves to the sorting area, the gas in the air intake channel can just move to the sorting area and blow the target cell into the target flow channel. When the cell is identified as a non-target cell, the electromagnetic air intake valve does not pump air into the air intake channel. After the non-target cell moves to the sorting area, it continues to flow into the non-target flow channel with the cell fluid.

[0007] In this solution, when the target flow channel, non-target flow channel and inlet flow channel are arranged to intersect with the sorting flow channel and the distance d between the intersection of the inlet flow channel axis and the sorting flow channel axis and the intersection of the inlet flow channel, target flow channel and non-target flow channel is 0.02mm-0.05mm, the length of the sorting area is increased, and the target cells stay in the sorting area longer, so that there are more suitable opportunities to pump gas into the gas flow channel to complete the work of blowing the target cells into the target flow channel, and the accuracy of sorting the target cells is higher.

[0008] When the gas in the inlet flow channel enters the sorting zone, it exerts a deflection force on the cells perpendicular to their original path. This causes the target cells to change their path of movement after receiving the deflection force, becoming a parabolic path toward the target cell channel. The shape of this parabola is determined by the original cell flow rate and the inlet pressure. The angle between the two progressive parabolas is the angle between the sorting channel and the target channel. When the target cell moves within the sorting zone, it must ensure that when the target cell moves a distance d along the axis of the sorting channel, the target cell enters the target cell channel and the direction of movement of the target cell is parallel to the axis of the target channel. When the distance d is 0.02mm-0.05mm and the angle between the target channel and the sorting channel is 100°-130°, the target cell can successfully enter the target cell channel and the direction of movement of the target cell is parallel to the axis of the target cell channel. Moreover, since the deflection force required for the target cell to change its path when the target flow channel and the sorting flow channel are at an angle of 100°-130° is smaller than the deflection force required for the target cell to change its path when the target flow channel is perpendicular to the sorting flow channel. The cell sorting work can still be completed when the intake gas pressure in the present application is lower than the intake gas pressure in the prior art. The gas causes less damage to the target cells when the intake pressure is lower. Therefore, compared with the prior art, the present application causes less damage to the target cells. At the same time, when the angle between the non-target flow channel and the sorting flow channel is 100°-140°, after the target cell is subjected to the deflection force provided by the gas in the intake flow channel, the angle between the target cell's movement direction and the axis of the non-target flow channel is larger, further preventing the target cell from entering the non-target flow channel.

[0009] Preferably, the sorting channel includes a first channel and a second channel. The diameter of the first channel is 0.1mm-0.12mm; the diameter of the second channel is 0.18mm-0.2mm. 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 inlet channel. The diameter of the second channel is larger than that of the first channel, which can slow the movement of cells in the second channel and prevent the airflow in the inlet channel from moving toward the first channel. When some airflow moves toward the first channel, this airflow cannot pass through the connection between the second channel and the first channel, preventing backflow from impacting the cells and causing cell damage.

[0010] Preferably, the end of the second flow channel connected to the first flow channel is tapered. The connection between the first flow channel and the second flow channel is tapered, so that the sample liquid in the first flow channel can smoothly enter and fill the second flow channel.

[0011] Preferably, arc chamfers are provided between the second flow channel, the inlet flow channel, the non-target flow channel and the target flow channel, wherein the arc chamfer between the second flow channel and the inlet flow channel is the first chamfer; the chamfer between the inlet flow channel and the non-target flow channel is the second chamfer; the chamfer between the non-target flow channel and the target flow channel is the third chamfer; and the chamfer between the target flow channel and the second flow channel is the 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. An arc chamfer is provided at the intersection of the side walls intersecting the second flow channel, the inlet flow channel, the non-target flow channel and the target flow channel. The radii of the chamfers coincide with the parabolic movement path of the cells, which can guide the movement of the cells. The arc chamfers at the intersection of the side walls will not damage the cells when the cells abut against the side walls. Experimental measurements show that 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, the chamfer has the best guiding effect on cells.

[0012] Preferably, the sample flow channel includes a cell flow channel and a sheath fluid flow channel, the sample area includes a mixed cell area and a sheath fluid area, the cell flow channel is connected to the mixed cell area, the sheath fluid flow channel is connected to the sheath fluid area, and the sheath fluid flow channel and the cell flow channel intersect at the liquid inlet end of the sorting flow channel. There are two sheath fluid flow channels, which are respectively located on opposite sides of the cell flow channel and symmetrically arranged with the axis of the cell flow channel as the symmetry axis. The sheath fluid flow channel has the same diameter as the cell flow channel, and the diameter of the non-target flow channel is twice the diameter of the target flow channel. The sheath fluid can wrap the cells so that the cells are arranged in a straight line and flow into the cytometer detection area. There are two sheath fluid flow channels and are respectively located on both sides of the cell flow channel, so that the cells flowing into the sorting flow channel are located in the middle of the sorting flow channel. The diameters of the sheath fluid channel and the cell channel are the same, and the diameter of the non-target channel is twice that of the target channel, so that after entering the sorting channel, the ratio of the cell suspension to the sheath fluid on both sides is 1:1:1. When the liquid in the sorting channel is not disturbed by the outside world, the sheath fluid close to the target channel flows into the target channel, and the cell suspension and the sheath fluid on the other side flow into the non-target channel, automatically completing the guidance of the non-target cells into the non-target channel.

[0013] Preferably, the length of the target flow channel is no longer than 5 mm. Since the pressure of the gas pumped into the inlet flow channel cannot be too high, otherwise the gas entering the microfluidic chip will crosstalk in the entire flow channel. The thrust of the gas on the target cells is not enough to make the target cells travel too long a distance in the target flow channel. When the target flow channel is too long, the target cells will stay in the target flow channel and cannot reach the target cell pool. Therefore, the length of the target flow channel cannot be too long. Experimental measurements show that when the length of the target flow channel is no longer than 5 mm, the thrust of the gas on the target cells can enable the target cells to pass through the target flow channel smoothly and enter the target cell pool.

[0014] Preferably, the angle between the sheath liquid flow channel and the cell flow channel is 25°-35°. A serpentine flow resistance section is provided on the sheath liquid flow channel to reduce the flow rate of the sheath liquid in the sheath liquid flow channel. As the angle between the sheath liquid flow channel and the cell flow channel increases, the impact of the sheath liquid flow on the cell liquid flow becomes greater after the sheath liquid and the cell liquid converge, impacting the cells in the cell liquid flow. Experimental measurements have shown that when the angle between the sheath liquid flow channel and the cell flow channel is 25°-35°, the sheath liquid can be smoothly mixed with the cell liquid. The flow resistance is serpentine, and the sheath liquid will reduce its kinetic energy after passing through the serpentine sheath liquid flow channel, reduce the flow rate of the sheath liquid, and thereby slow down the flow rate of the sample solution entering the first flow channel, reducing the movement speed of the cells.

[0015] Compared with the prior art, the beneficial effect of the present invention is that the microfluidic chip in this solution will not cause damage to cells during cell screening. This solution expands the cell sorting area, so that the target cells stay in the cell sorting area for a longer time, and there are more suitable opportunities to pump air, which prevents the target cells from entering the non-target cell pool due to too slow pumping, thereby improving the accuracy of cell sorting, and using gas with a smaller air pressure to achieve the goal of pushing the target cells into the target flow channel. The sorting flow channel can reduce the speed of cell movement and prevent gas backflow, which can further improve the accuracy of cell sorting while avoiding cell damage. The side walls where the second flow channel, the inlet flow channel, the non-target flow channel and the target flow channel intersect are provided with arc chamfers at the intersection, which guide the cells entering the sorting area. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a schematic structural diagram of a microfluidic chip for living cell sorting according to the present invention;

[0017] FIG2 is an enlarged view of part B in FIG1 of a microfluidic chip for living cell sorting according to the present invention;

[0018] FIG3 is an enlarged view of part A in FIG1 of a microfluidic chip for living cell sorting according to the present invention. DETAILED DESCRIPTION

[0019] The drawings are for illustrative purposes only and should not be construed as limiting this patent. To better illustrate the embodiments, some parts in the drawings may be omitted, enlarged, or reduced in size, and do not represent actual product dimensions. Those skilled in the art will understand that some well-known structures and their descriptions may be omitted from the drawings. The positional relationships depicted in the drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0020] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0021] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0022] Example 1

[0023] As shown in Figures 1 and 2, an embodiment 1 of a microfluidic chip for sorting living cells is shown, comprising a sample area, a sample flow channel connected to the sample area, an electromagnetic air inlet valve, an air inlet channel 1 connected to the electromagnetic air inlet valve, a target cell pool 5, a target flow channel 2 connected to the target cell pool 5, a non-target cell pool 6, a non-target flow channel 3 connected to the non-target cell pool 6, and a sorting flow channel 4 for cell sorting. The sample flow channel is connected to the liquid inlet end of the sorting flow channel 4, the target flow channel 2 and the non-target flow channel 3 are connected to the liquid outlet end of the sorting flow channel 4, and the air inlet channel 1 is connected to the sorting flow channel 4 and is the end of the sorting flow channel 4 near its liquid outlet. The air inlet channel 1 and the non-target flow channel 3 are located on one side of the sorting flow channel 4, and the target flow channel 2 is located on the other side of the sorting flow channel 4. The angle between target channel 2 and sorting channel 4 is 120°, and the angle between non-target channel 3 and sorting channel 4 is 128°. The axis of intake channel 1 is perpendicular to the axis of sorting channel 4. The distance d between the intersection of the axis of intake channel 1 and the axis of sorting channel 4 and the intersection of sorting channel 4, target channel 2, and non-target channel 3 is 0.05m. The sorting zone is the end of sorting channel 4 that intersects target channel 2, non-target channel 3, and intake channel 1.

[0024] The working principle or working process of this embodiment is as follows: when the microfluidic chip is working, the target cells and non-target cells in the sample area enter the sample channel with the flow of cell fluid and are arranged in a single linear pattern in the sample channel. As the cell fluid continues to flow forward, the target cells and non-target cells pass through the sorting channel 4 and enter the sorting area. The target cell identification signal device identifies the cells entering the sorting channel 4. When the cell is identified as a target cell, the electromagnetic air intake valve is controlled to pump air into the inlet channel 1. When the target cell moves to the sorting area at the end of the sorting channel 4, the gas in the inlet channel 1 can just move to the sorting area and blow the target cell into the target channel 2. When the cell is identified as a non-target cell, the electromagnetic air intake valve does not pump air into the inlet channel 1. When 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 with the cell fluid.

[0025] Table 1 Microfluidic chip control experiment

[0026] The cell sorting chip used in the control group is a microfluidic chip in a sorting device that simultaneously detects multiple fluorescent signals in cells in the prior art, and the microfluidic chip used in this application is the microfluidic chip described in this solution. Compared with control group 1 and control group 2 and present application 1 and present application 2, for the same target cells, under the same air intake pressure and cell flow rate, the accuracy of cell sorting in this application is much greater than the accuracy of cell sorting in the control group. Compared with control group 1 and present application 1 and control group 2 and present application 2, under the same cell flow rate, the greater the air intake pressure, the higher the accuracy of cell sorting. However, from the perspective of control group 1 and control group 2 and present application 1 and application 2, when the air pressure of the two groups of experiments is reduced by the same amount, the fluctuation of the accuracy of cell sorting in the control group is greater than the fluctuation of the accuracy of cell sorting in this application. From the above experimental data, it can be seen that after increasing the cell sorting area and adjusting the angle between the target flow channel and the sorting flow channel, the accuracy of cell sorting can be significantly improved. When using a smaller air pressure to drive the target cell deflection, the air pressure fluctuation has little effect on the accuracy of cell sorting, and good cell sorting effect can still be obtained.

[0027] The beneficial effects of this embodiment include: This solution expands the cell sorting zone, increasing the time target cells spend within the zone. This allows for more opportune moments to pump air, preventing slow pumping from causing target cells to enter the non-target cell pool, thereby improving cell sorting accuracy. Furthermore, when driving cell deflection, a lower gas pressure can be used to propel target cells into the target flow channel. This lower gas pressure minimizes damage to target cells, resulting in higher target cell activity.

[0028] Example 2

[0029] Embodiment 2 of a microfluidic chip for living cell sorting, as shown in FIG1 to FIG3 , further defines the structures of the sorting channel 4 and the sorting area on the basis of embodiment 1.

[0030] Specifically, the sorting channel 4 includes a first channel 401 and a second channel 402. The diameter of the first channel 401 is 0.1 mm; the diameter of the second channel 402 is 0.2 mm. The first channel 401 is connected to the sample channel, and the second channel 402 is connected to the target channel 2, the non-target channel 3 and the inlet channel 1.

[0031] Specifically, one end of the second flow channel 402 connected to the first flow channel 401 is tapered.

[0032] Specifically, arc chamfers are provided between the second flow channel 402, the intake flow channel 1, the non-target flow channel 3, and the target flow channel 2. The arc chamfer between the second flow channel 402 and the intake flow channel 1 is a first chamfer 7; the chamfer between the intake flow channel 1 and the non-target flow channel 3 is a second chamfer 8; the chamfer between the non-target flow channel 3 and the target flow channel 2 is a third chamfer 9; and the chamfer between the target flow channel 2 and the second flow channel 402 is a 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.

[0033] The beneficial effects of this embodiment are as follows: the diameter of the second flow channel 402 is larger than the diameter of the first flow channel 401, which can slow down the movement speed of cells in the second flow channel 402 and prevent the airflow in the inlet flow channel 1 from moving toward the first flow channel 401. When part of the airflow moves in the direction of the first flow channel 401, the airflow cannot break through the connection end of the second flow channel 402 and the first flow channel 401, which can prevent the backflow from impacting the cells and causing cell damage. The connection between the first flow channel 401 and the second flow channel 402 is conical, so that the sample liquid in the first flow channel 401 can smoothly enter and fill the second flow channel 402. The side walls that intersect between the second flow channel 402, the inlet flow channel 1, the non-target flow channel 3 and the target flow channel 2 are provided with an arc chamfer at the intersection. The shape of the arc chamfer is the same as the parabolic movement path of the cells, which can guide the cells flowing into the sorting area, making it easier for non-target cells to flow into the non-target flow channel 3 and target cells to flow into the target flow channel 2.

[0034] Example 3

[0035] Embodiment 3 of a microfluidic chip for living cell sorting, as shown in FIG1 to FIG3 , further defines the sample flow channel, the target flow channel 2 and the non-target flow channel 3 on the basis of embodiment 1 or embodiment 2.

[0036] Specifically, the sample flow channel includes a cell flow channel 11 and a sheath fluid flow channel 12. The sample area includes a mixed cell area 13 and a sheath fluid area 14. The cell flow channel 11 is connected to the mixed cell area 13, and the sheath fluid flow channel 12 is connected to the sheath fluid area 14. The sheath fluid flow channel 12 and the cell flow channel 11 intersect at the liquid inlet end of the sorting flow channel 4. There are two sheath fluid flow channels 12, which are located on opposite sides of the cell flow channel 11 and are symmetrically arranged with the axis of the cell flow channel 11 as the symmetry axis. The sheath fluid flow channel 12 and the cell flow channel 11 have the same diameter. The diameter of the non-target flow channel 3 is twice the diameter of the target flow channel 2.

[0037] Specifically, the length of the target flow channel 2 is 4 mm. The angle between the sheath fluid flow channel 12 and the cell flow channel 11 is 25°. A serpentine flow resistance section (not shown) is provided on the sheath fluid flow channel 12 to reduce the flow rate of the sheath fluid in the sheath fluid flow channel 12.

[0038] The beneficial effects of this embodiment are as follows: the sheath fluid channel 12 and the cell channel 11 have the same diameter, while the non-target channel 3 has a diameter twice that of the target channel 2. This results in a 1:1:1 ratio of cell suspension to sheath fluid on either side of the sorting channel 4. When the liquid within the sorting channel 4 is not disturbed by external factors, the sheath fluid on the side closest to the target channel 2 flows into the target channel 2, while the cell suspension and sheath fluid on the other side flow into the non-target channel 3, automatically guiding the non-target cells into the non-target channel 3. When the length of the target channel 2 is 4 mm, the thrust of the gas on the target cells allows them to pass smoothly through the target channel 2 and into 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 flow increases after the sheath fluid and cell fluid converge, impacting cells in the cell fluid flow. Experimental measurements have shown that when the angle between the sheath fluid channel 12 and the cell channel 11 is 25°, the sheath fluid can mix smoothly with the cell fluid. The flow resistance is serpentine. After the sheath fluid passes through the serpentine sheath fluid flow channel 12, the kinetic energy of the sheath fluid is reduced, the flow rate of the sheath fluid is reduced, and the flow rate of the sample solution entering the first flow channel 401 is slowed down, reducing the movement speed of the cells.

[0039] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A microfluidic chip for sorting living cells, characterized in that: The invention comprises a sample area, a sample flow channel connected to the sample area, an electromagnetic air intake valve, an air intake channel (1) connected to the electromagnetic air intake valve, a target cell pool (5), a target flow channel (2) connected to the target cell pool (5), a non-target cell pool (6), a non-target flow channel (3) connected to the non-target cell pool (6), and a sorting flow channel (4); The sample flow channel is connected to the liquid inlet end of the sorting flow channel (4), the target flow channel (2) and the non-target flow channel (3) are connected to the liquid outlet end of the sorting flow channel (4), the inlet flow channel (1) is connected to the sorting flow channel (4) and is located on one end of the sorting flow channel (4) close to its liquid outlet, the target flow channel (2) is located on one side of the sorting flow channel (4), the inlet flow channel (1) and the non-target flow channel (3) are located on the other side of the sorting flow channel (4), and the target flow channel (2) and the non-target flow channel (3) are located on the other side of the sorting flow channel (4). The angle between the flow channel (2) and the sorting flow channel (4) is 100°-130°, the angle between the non-target flow channel (3) and the sorting flow channel (4) is 100°-140°, the axis of the inlet flow channel (1) is perpendicular to the axis of the sorting flow channel (4); the intersection of the axis of the inlet flow channel (1) and the axis of the sorting flow channel (4) is 0.02mm-0.05mm away from the intersection of the sorting flow channel (4), the target flow channel (2) and the non-target flow channel (3).

2. The microfluidic chip for living cell sorting according to claim 1, characterized in that: The sorting flow channel (4) comprises a first flow channel (401) and a second flow channel (402), wherein the diameter of the first flow channel (401) is 0.1 mm-0.12 mm; the diameter of the second flow channel (402) is 0.18 mm-0.2 mm, the first flow channel (401) is connected to the sample flow channel, and the second flow channel (402) is connected to the target flow channel (2), the non-target flow channel (3) and the inlet flow channel (1).

3. The microfluidic chip for living cell sorting according to claim 2, characterized in that: One end of the second flow channel (402) connected to the first flow channel (401) is tapered.

4. The microfluidic chip for living cell sorting according to claim 2, characterized in that: Circular chamfers are provided between the second flow channel (402), the intake flow channel (1), the non-target flow channel (3) and the target flow channel (2), wherein the circular chamfer between the second flow channel (402) and the intake flow channel (1) is a first chamfer (7); the chamfer between the intake flow channel (1) and the non-target flow channel (3) is a second chamfer (8); the chamfer between the non-target flow channel (3) and the target flow channel (2) is a third chamfer (9); and the chamfer between the target flow channel (2) and the second flow channel (402) is a fourth chamfer (10).

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

6. The microfluidic chip for living cell sorting according to claim 1, characterized in that: The sample flow channel comprises a cell flow channel (11) and a sheath fluid flow channel (12); the sample area comprises a mixed cell area (13) and a sheath fluid area (14); the cell flow channel (11) is connected to the mixed cell area (13); the sheath fluid flow channel (12) is connected to the sheath fluid area (14); the sheath fluid flow channel (12) and the cell flow channel (11) intersect at the liquid inlet end of the sorting flow channel (4).

7. The microfluidic chip for living cell sorting according to claim 6, characterized in that: There are two sheath fluid channels (12), which are respectively located on opposite sides of the cell flow channel (11) and are arranged symmetrically with the axis of the cell flow channel (11) as the axis. The diameter of the sheath fluid flow channel (12) is the same as that of the cell flow channel (11), and the diameter of the non-target flow channel (3) is twice the diameter of the target flow channel (2).

8. The microfluidic chip for living cell sorting according to claim 7, characterized in that: The length of the target flow channel (2) is not longer than 5 mm.

9. The microfluidic chip for living cell sorting according to claim 7, characterized in that: The angle between the sheath fluid flow channel (12) and the cell flow channel (11) is 25°-35°.

10. The microfluidic chip for living cell sorting according to claim 9, characterized in that: The sheath liquid flow channel (12) is provided with a serpentine flow resistance section for reducing the flow rate of the sheath liquid in the sheath liquid flow channel (12).

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