External perfusion system and liquid path control method of microfluidic chip

Abstract

An external perfusion system and liquid path control method of a microfluidic chip belong to the technical field of microfluidic chip perfusion. The present application aims at the problem of unstable flow rate of the existing microfluidic chip perfusion method. The system comprises a liquid storage tank, a flow control tank and a micro peristaltic pump. The liquid inlet of the liquid storage tank is used for injecting culture solution. The liquid inlet of the liquid storage tank is communicated with the liquid outlet of the micro peristaltic pump, and the liquid inlet of the micro peristaltic pump is communicated with the liquid outlet of the flow control tank. The liquid inlet of the flow control tank is communicated with the liquid outlet of the microfluidic chip. One end of the liquid delivery pipeline connected to the liquid outlet of the liquid storage tank, and the other end of the liquid delivery pipeline is used for connecting the liquid inlet of the microfluidic chip. The liquid storage tank is arranged higher than the flow control tank in the spatial dimension, and the exhaust port of the liquid storage tank is communicated with the exhaust port of the flow control tank. The present application can realize stable and uninterrupted perfusion of the microfluidic chip.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microfluidic chip perfusion, and particularly relates to an external perfusion system of a microfluidic chip and a liquid path control method. BACKGROUND

[0002] A microfluidic chip is a technology platform for manipulating fluid at a micron scale, and the core is the precise control of the internal liquid path.

[0003] At present, microfluidic chips are widely used in the field of organ chips, and the commonly used way of external perfusion is to inject into the chip channel at a constant speed through a syringe pump, to pump liquid into the flow channel by using a peristaltic pump, or to make a liquid storage tank and to naturally perfuse by hydraulic pressure difference. The first method needs to stop for a period of time before reabsorbing liquid after the syringe pump completes one injection, and the cost is high. The second method is a dot matrix injection, which has the defects of discontinuous liquid flow and difficult control of flow rate. The capacity of the liquid storage tank in the third method is limited, and the hydraulic pressure difference will gradually decrease as the perfusion proceeds, resulting in unstable flow rate. At the same time, the liquid storage tank needs to be manually filled or replaced, which affects the overall stability.

[0004] And the chip for culturing organoids or cells often needs to be perfused with culture medium stably and continuously, and the current external perfusion system cannot meet the requirements. SUMMARY

[0005] In view of the problem of unstable flow rate of the existing perfusion method of a microfluidic chip, the application provides an external perfusion system of a microfluidic chip and a liquid path control method.

[0006] The application provides an external perfusion system of a microfluidic chip, which comprises a liquid storage tank, a flow control tank and a micro-peristaltic pump, and a liquid delivery pipeline is arranged between the liquid storage tank and the microfluidic chip; wherein,

[0007] The liquid inlet of the liquid storage tank is used for injecting culture liquid; the liquid inlet of the liquid storage tank is communicated with the liquid outlet of the micro-peristaltic pump, the liquid inlet of the micro-peristaltic pump is communicated with the liquid outlet of the flow control tank; and the liquid inlet of the flow control tank is communicated with the liquid outlet of the microfluidic chip.

[0008] The liquid outlet of the liquid storage tank is connected to one end of the liquid delivery pipeline, and the other end of the liquid delivery pipeline is connected to the liquid inlet of the microfluidic chip.

[0009] The liquid storage tank is arranged higher than the flow control tank in the spatial dimension, and the exhaust port of the liquid storage tank is communicated with the exhaust port of the flow control tank.

[0010] In one possible design, the external perfusion system of the microfluidic chip of the application further comprises a pressure control valve, which is arranged on the liquid delivery pipeline, and the liquid outlet of the pressure control valve is connected to the liquid inlet of the microfluidic chip.

[0011] In a possible design, the external perfusion system of the microfluidic chip also comprises a bubble remover, which is arranged on the infusion pipeline, and the liquid inlet of the bubble remover is connected to the liquid outlet of the liquid storage tank.

[0012] In a possible design, in the external perfusion system of the microfluidic chip, the liquid inlet and the exhaust port of the liquid storage tank are arranged at the top end of the liquid storage tank, and the liquid outlet is arranged at the bottom end of the liquid storage tank.

[0013] In a possible design, in the external perfusion system of the microfluidic chip, the liquid inlet and the exhaust port of the liquid storage tank are arranged at the top end of the liquid storage tank, and the liquid outlet is arranged at the bottom end of the liquid storage tank.

[0014] In a possible design, in the external perfusion system of the microfluidic chip, the liquid inlet and the exhaust port of the liquid storage tank are arranged at the top end of the liquid storage tank, and the liquid outlet is arranged at the bottom end of the liquid storage tank.

[0015] The application also provides a liquid path control method of a microfluidic chip, which is used for controlling the liquid path of the external perfusion system of the microfluidic chip, and comprises the following steps:

[0016] Adjusting the rotation speed of the micro-peristaltic pump so that the flow rate of the micro-peristaltic pump is greater than the target flow rate.

[0017] Controlling the culture solution to be perfused into the microfluidic chip at the target flow rate under the action of the gravity pressure difference, so that the internal air self-circulation passage formed between the exhaust port of the liquid storage tank and the exhaust port of the liquid storage tank is balanced under the pressure balance of the internal air self-circulation passage, and the continuous constant-speed perfusion of the culture solution to the microfluidic chip is realized.

[0018] In a possible design, the liquid path control method of the microfluidic chip comprises the following steps:

[0019] Adjusting the height of the liquid storage tank relative to the liquid storage tank so that the culture solution is perfused into the microfluidic chip at the target flow rate under the action of the gravity pressure difference.

[0020] In some embodiments, the liquid path control method of the microfluidic chip comprises the following steps:

[0021] Determining the target height pressure difference between the liquid storage tank and the liquid storage tank according to the target flow rate and the total flow resistance of the system.

[0022] Adjusting the height of the liquid storage tank relative to the liquid storage tank according to the target height pressure difference.

[0023] In another possible design, the liquid path control method of the microfluidic chip comprises the following steps:

[0024] On the basis of fixing the height of the liquid storage tank relative to the flow control tank, the opening of the pressure control valve is adjusted, so that the culture solution is perfused into the microfluidic chip at a target flow rate under the action of gravity pressure difference.

[0025] In still another possible design, a liquid path control method of a microfluidic chip according to the present application controls the culture solution to be perfused into the microfluidic chip at a target flow rate under the action of gravity pressure difference, comprising:

[0026] The opening of the pressure control valve is coarsely adjusted, and then the height of the liquid storage tank relative to the flow control tank is finely adjusted, so that the culture solution is perfused into the microfluidic chip at a target flow rate under the action of gravity pressure difference.

[0027] In some embodiments, the liquid path control method of a microfluidic chip according to the present application coarsely adjusts the opening of the pressure control valve, and then finely adjusts the height of the liquid storage tank relative to the flow control tank, comprising:

[0028] A relationship between the target flow rate of the microfluidic chip and the height pressure difference between the liquid storage tank and the flow control tank and the total flow resistance of the system is obtained;

[0029] The opening of the pressure control valve is adjusted according to the target flow rate to change the total flow resistance of the system, so that the actual flow rate approaches the target flow rate;

[0030] The target height pressure difference between the liquid storage tank and the flow control tank is determined according to the target flow rate and the current total flow resistance, and the height of the liquid storage tank relative to the flow control tank is adjusted according to the target height pressure difference.

[0031] In some embodiments, the actual flow rate can be obtained by marking a scale line on the liquid storage tank, disconnecting the connection between the micro-peristaltic pump and the liquid inlet of the liquid storage tank, and calculating the actual flow rate according to the corresponding relationship between the remaining amount of the culture solution in the liquid storage tank and the time.

[0032] The beneficial effects of the present application: The external perfusion system provided by the present application realizes pressure balance under internal air self-circulation through the pipeline connection between the liquid storage tank and the flow control tank, which can prevent the introduction of pollution during cell culture. When the method of the present application is used for perfusion of a microfluidic chip, after adjusting the perfusion flow rate by adjusting the height of the liquid storage tank according to the needs of the microfluidic chip, self-circulation can be realized, and stable and uninterrupted perfusion of the microfluidic chip can be achieved.

[0033] During the liquid path control process, the perfusion flow rate is less than the flow rate of the peristaltic pump, so that the internal hydraulic pressure difference of the whole system remains stable. The stable pressure difference provides stable and uninterrupted directional liquid flow, so that the perfusion speed is stable and controllable. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a structural schematic diagram of an external perfusion system of a microfluidic chip provided by an embodiment of the present application;

[0035] Figure 2 is a flow chart of a liquid path control method of a microfluidic chip provided by an embodiment of the present application;

[0036] Figure 3 is a front view three-dimensional schematic diagram of a bubble remover involved in an embodiment of the present application;

[0037] Figure 4 is a side view three-dimensional schematic diagram of a bubble remover involved in an embodiment of the present application;

[0038] Figure 5 is a three-dimensional structural schematic diagram of an external perfusion system of a microfluidic chip provided by an embodiment of the present application;

[0039] Figure 6 is a schematic diagram of a rear view of Figure 5 . DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0041] DETAILED DESCRIPTION Figure 1 According to the first aspect of the present application shown in the accompanying drawings, an external perfusion system of a microfluidic chip 4 is provided, which comprises a liquid storage tank 1, a flow control tank 2 and a micro peristaltic pump 3. A liquid delivery pipeline is arranged between the liquid storage tank 1 and the microfluidic chip 4. The liquid inlet of the liquid storage tank 1 is used for injecting culture solution. The liquid inlet of the liquid storage tank 1 is connected to the liquid outlet of the micro peristaltic pump 3, and the liquid inlet of the micro peristaltic pump 3 is connected to the liquid outlet of the flow control tank 2. The liquid inlet of the flow control tank 2 is connected to the liquid outlet of the microfluidic chip 4.

[0042] The liquid outlet of the liquid storage tank 1 is connected to one end of the liquid delivery pipeline, and the other end of the liquid delivery pipeline is connected to the liquid inlet of the microfluidic chip 4.

[0043] The liquid storage tank 1 is arranged higher than the flow control tank 2 in the spatial dimension, and the exhaust port of the liquid storage tank 1 is connected to the exhaust port of the flow control tank 2.

[0044] Specifically, Figure 1 The upper left interface of the liquid storage tank 1 is the liquid inlet of the liquid storage tank 1. At the initial moment, the liquid inlet is opened, and the culture solution can be injected into the liquid storage tank 1 through a syringe. The height of the liquid storage tank 1 can be adjusted according to actual needs. The liquid in the liquid storage tank 1 is perfused into the microfluidic chip under the action of gravity pressure difference, and enters the flow control tank. The micro peristaltic pump pumps the liquid at the bottom of the flow control tank back into the liquid storage tank to complete the liquid path circulation.

[0045] In one example, the present embodiment further comprises a pressure control valve 5, which is arranged on the liquid delivery pipeline and has a liquid outlet connected to the liquid inlet of the microfluidic chip 4. The flow rate of the culture solution can be adjusted by adjusting the opening degree of the pressure control valve 5.

[0046] In one example, the present embodiment further comprises a bubble remover 6, which is arranged on the liquid delivery pipeline and has a liquid inlet connected to the liquid outlet of the liquid storage tank 1. The bubble remover 6 can effectively remove bubbles from the liquid, thereby improving the quality and stability of the liquid.

[0047] In one example, in the present embodiment, the liquid inlet and the exhaust port of the liquid storage tank 1 are located at the top end of the liquid storage tank 1, and the liquid outlet of the liquid storage tank 1 is located at the bottom end of the liquid storage tank 1.

[0048] The liquid inlet and the exhaust port of the flow control tank 2 are located at the top end of the flow control tank 2, and the liquid outlet of the flow control tank 2 is located at the bottom end of the flow control tank 2.

[0049] The bottom end of the liquid storage tank 1 is higher than the top end of the flow control tank 2 in the spatial dimension.

[0050] In the actual system, due to the characteristics of the micro-ceramic pump, the driving pressure difference is intermittent, so in the constant perfusion system, the driving pressure difference caused by the micro-ceramic pump needs to be excluded. Since the micro-ceramic pump plays a role in circulating the liquid circuit, it is necessary to retain the use of the micro-ceramic pump. In order to make the perfusion system liquid circuit stable and uninterrupted, a self-balancing compensation pressure difference needs to be introduced at both ends of the micro-ceramic pump.

[0051] The conventional method is to connect the liquid storage tank 1 and the flow control tank 2 at both ends of the micro-ceramic pump to be open and connected with the outside atmosphere, so as to balance the intermittent pressure difference when the micro-ceramic pump works. Although this method can meet the stable perfusion requirement, the introduction of external air is easy to cause pollution inside the chip, even if an air filtration system is added, there is still a great risk of pollution after a long time of culture.

[0052] The present application sets an exhaust port on the liquid storage tank 1 and the flow control tank 2, and directly connects the two exhaust ports, which not only balances the intermittent pressure difference when the micro-ceramic pump works, but also prevents the pollution that may be caused by the external air.

[0053] Specific implementation two, combined Figure 1 and Figure 2 As shown in the specific implementation one, another aspect of the present application further provides a liquid circuit control method of a microfluidic chip 4, which controls the liquid circuit of the external perfusion system of the microfluidic chip, comprising:

[0054] Adjusting the rotation speed of the micro-ceramic pump 3 so that the flow rate of the micro-ceramic pump 3 is greater than the target flow rate;

[0055] The culture solution is controlled to flow into the microfluidic chip 4 under the action of gravity pressure difference at a target flow rate, so that the internal air self-circulation passage formed between the exhaust port of the storage tank 1 and the exhaust port of the flow control tank 2 is pressure balanced, and the culture solution is continuously and constantly perfused into the microfluidic chip 4.

[0056] Specifically, the liquid inlet of the storage tank 1 is opened, and the culture solution is injected into the storage tank 1 through a syringe. The height of the storage tank 1 can be adjusted according to actual needs. The liquid in the storage tank is perfused into the microfluidic chip under the action of gravity pressure difference, and enters the flow control tank, and the micro-ceramic pump pumps the liquid at the bottom of the flow control tank into the storage tank to complete the circulation of the liquid path.

[0057] In one example, the culture solution is controlled to flow into the microfluidic chip 4 under the action of gravity pressure difference at a target flow rate, comprising:

[0058] Adjusting the height of the storage tank 1 relative to the flow control tank 2 so that the culture solution flows into the microfluidic chip 4 under the action of gravity pressure difference at a target flow rate.

[0059] Further, adjusting the height of the storage tank 1 relative to the flow control tank 2 comprises:

[0060] According to the target flow rate and the total flow resistance of the system, a target height pressure difference between the storage tank 1 and the flow control tank 2 is determined;

[0061] According to the target height pressure difference, the height of the storage tank 1 relative to the flow control tank 2 is adjusted.

[0062] In another example, the culture solution is controlled to flow into the microfluidic chip 4 under the action of gravity pressure difference at a target flow rate, comprising:

[0063] A pressure control valve 5 is arranged on the liquid delivery pipeline between the storage tank 1 and the microfluidic chip 4;

[0064] On the basis that the height of the storage tank 1 relative to the flow control tank 2 is fixed, the opening degree of the pressure control valve 5 is adjusted so that the culture solution flows into the microfluidic chip 4 under the action of gravity pressure difference at a target flow rate.

[0065] In another example, the culture solution is controlled to flow into the microfluidic chip 4 under the action of gravity pressure difference at a target flow rate, comprising:

[0066] A pressure control valve 5 is arranged on the liquid delivery pipeline between the storage tank 1 and the microfluidic chip 4;

[0067] The opening degree of the pressure control valve 5 is coarsely adjusted, and then the height of the storage tank 1 relative to the flow control tank 2 is finely adjusted, so that the culture solution flows into the microfluidic chip 4 under the action of gravity pressure difference at a target flow rate.

[0068] Further, the opening degree of the pressure control valve 5 is coarsely adjusted, and then the height of the storage tank 1 relative to the flow control tank 2 is finely adjusted, comprising:

[0069] Obtain the relationship between the target flow rate of the microfluidic chip 4 and the height pressure difference between the liquid storage tank 1 and the flow control tank 2 and the total flow resistance of the system;

[0070] Adjust the opening of the pressure control valve 5 according to the target flow rate to change the total flow resistance of the system, so that the actual flow rate approaches the target flow rate; then, according to the target flow rate and the current total flow resistance of the system, determine the target height pressure difference between the liquid storage tank 1 and the flow control tank 2, and adjust the height of the liquid storage tank 1 relative to the flow control tank 2 according to the target height pressure difference.

[0071] Specifically, one method of obtaining the actual flow rate is to mark a scale line on the liquid storage tank 1; disconnect the connection between the micro-ceramic pump 3 and the liquid inlet of the liquid storage tank 1, and calculate the actual flow rate according to the corresponding relationship between the remaining amount of the culture solution in the liquid storage tank and the time.

[0072] Another method of obtaining the actual flow rate is to combine Figure 1 As shown in the figure, a flow rate detection module 7 can be arranged between the liquid storage tank 1 and the bubble remover 6, including a bubble generator and two bubble detection optocouplers. The bubble generator generates a small amount of bubbles at regular intervals, and the bubbles pass through the bubble detection optocouplers along with the liquid flow. By analyzing and calculating the time points at which the bubbles pass through the two detection optocouplers, the current flow rate in the pipeline can be obtained.

[0073] In one example, a bubble remover 6 can also be arranged on the liquid delivery pipeline between the liquid storage tank 1 and the microfluidic chip 4. The bubble remover 6 can effectively remove bubbles from the liquid, improving the quality and stability of the liquid.

[0074] The structure of the bubble remover 6 is shown in Figure 3 and Figure 4 As shown in the figure, Figure 3 In the figure, the fluid enters the bubble remover 6 from the liquid inlet 61 and flows out from the liquid outlet 62. The bubbles present in the fluid converge below the negative pressure chamber 63 of the liquid flow chamber, and a semi-permeable membrane exists between the negative pressure chamber 63 and the liquid flow chamber. The semi-permeable membrane allows gas molecules to pass through and blocks liquid. Under the action of the negative pressure chamber 63, the bubbles are expelled through the semi-permeable membrane.

[0075] Figure 5 and Figure 6 The specific structure of the height adjustment module for adjusting the liquid storage tank 1 is shown in

[0076] The stable flow rate automatic control step includes:

[0077] Manually adjust the opening of the pressure control valve to coarsely adjust the flow rate;

[0078] The flow rate is fine-tuned by the height adjustment module of the reservoir, and the flow rate is confirmed to be the target flow rate by the flow rate detection module, and the target flow rate is locked in the adjustment software.

[0079] The flow rate detection module periodically monitors the flow rate, and automatically adjusts the height of the reservoir according to the actual flow rate to reach the target flow rate.

[0080] If the target flow rate cannot be adjusted, the device will issue a warning and require manual intervention to adjust the opening degree of the pressure control valve, or check whether the liquid path is blocked.

[0081] As can be seen from the above, for controlling the culture solution to flow into the microfluidic chip 4 at a target flow rate under the action of gravity pressure difference, three flow rate adjustment methods are provided in the embodiment: the first is to adjust only the height of the reservoir 1 relative to the flow control tank 2; the second is to adjust only the opening degree of the pressure control valve 5; the third is to fine-tune the height of the reservoir 1 relative to the flow control tank 2 on the basis of coarse adjustment of the opening degree of the pressure control valve 5. It can be understood that the culture solution flow rate can also be controlled by other ways based on the external perfusion system of the microfluidic chip provided in the present application, and the present application is not limited.

[0082] Next, the specific control principle of the above-mentioned scheme is further introduced, and the theoretical formula derivation process of calculating the flow rate based on the pressure balance principle in fluid mechanics in the liquid path control is given below:

[0083] In the embodiment, the reservoir 1, the pressure control valve 5 and the micro-ceramic pump 3 jointly participate in the flow rate regulation.

[0084] Assuming that the perfusion system is in steady-state flow, the micro-ceramic pump 3 has a continuous and stable flow, then the flow rate can be expressed as:

[0085] ,

[0086] In the formula, is the height pressure difference between the reservoir 1 and the flow control tank 2, is the driving pressure difference generated by the micro-ceramic pump 3, is the total flow resistance of the system.

[0087] The height pressure difference is:

[0088] ,

[0089] In the formula, is the density of the culture solution, is the acceleration of gravity, is the height difference of the reservoir 1 relative to the flow control tank 2; by adjusting , the flow rate driven by the static pressure of the culture solution can be changed.

[0090] The driving pressure difference generated by the micro-peristaltic pump 3 is:

[0091] ,

[0092] wherein is the pressure-flow characteristic constant of the micro-peristaltic pump, is the set flow of the micro-peristaltic pump, which is related to the rotation speed.

[0093] The total flow resistance of the system is:

[0094] ,

[0095] wherein is the flow resistance of the pressure control valve, which can be changed by adjusting the opening degree; is the inherent flow resistance of the system, including the flow resistance generated by the pipeline, joint, etc. The total flow resistance of the system can be adjusted by adjusting the flow resistance of the pressure control valve .

[0096] The flow resistance of the pressure control valve is:

[0097] ,

[0098] wherein is the characteristic parameter of the pressure control valve, A is the current opening area of the pressure control valve, is the maximum opening area of the pressure control valve, is the adjustment characteristic index of the pressure control valve, wherein the linear valve is 1 and the percentage valve is 2.

[0099] Thus, the final theoretical formula of the flow rate is obtained:

[0100] .

[0101] Thus, the control strategy of the present application is obtained:

[0102] Increasing the height difference of the liquid storage tank 1 relative to the flow control tank 2 can increase the flow rate; increasing the current opening area of the pressure control valve can increase the flow rate.

[0103] In the actual system, due to the characteristics of the micro-peristaltic pump, the driving pressure difference is intermittent, so in the constant perfusion system, the driving pressure difference brought by the micro-peristaltic pump needs to be excluded. Since the micro-peristaltic pump plays a role in circulating the liquid circuit, the device cannot be discarded. In order to make the perfusion system liquid circuit stable and uninterrupted, a self-balancing compensation pressure difference needs to be introduced at both ends of the micro-peristaltic pump.

[0104] The conventional method is to connect the liquid storage tank 1 and the flow control tank 2 at both ends of the micro-peristaltic pump to the outside atmosphere to balance the intermittent pressure difference during the operation of the micro-peristaltic pump. Although this method can meet the stable perfusion requirements, the introduction of external air is easy to cause the pollution inside the chip. Even if an air filtration system is added, there is still a great risk of pollution after a long time of cultivation.

[0105] The present application sets an exhaust port on the liquid storage tank 1 and the flow control tank 2, and directly connects the two exhaust ports, which balances the intermittent pressure difference during the operation of the micro-peristaltic pump, and at the same time, the self-balancing air circulates inside, preventing the pollution that may be caused by the external air.

[0106] In summary, the system and method of the present application can be used for the stable and uninterrupted perfusion required by the chip for cultivating organoids or cells, and can realize the self-circulation of the liquid inside the microfluidic chip, the stable speed and uninterrupted continuous perfusion. The present application solves the problems existing in the current perfusion technology.

[0107] Although the present application is described herein with reference to particular embodiments, it should be understood that these examples are merely illustrative of the principles and applications of the present application. It should therefore be understood that numerous modifications can be made to the illustrative embodiments, and that other arrangements can be devised without departing from the spirit and scope of the present application as defined by the appended claims. It should be understood that the features described in connection with one embodiment can be used in conjunction with other embodiments described herein. It should also be understood that features described in connection with separate embodiments can be used in combination with each other.

Claims

1. A liquid path control method of a microfluidic chip for performing liquid path control on an external perfusion system of a microfluidic chip, characterized by, The external perfusion system of the microfluidic chip comprises a liquid storage tank (1), a flow control tank (2) and a micro peristaltic pump (3), and a liquid delivery pipeline is arranged between the liquid storage tank (1) and the microfluidic chip (4). The liquid inlet of the liquid storage tank (1) is used for injecting the culture solution, and the liquid inlet of the liquid storage tank (1) is communicated with the liquid outlet of the micro peristaltic pump (3), and the liquid inlet of the micro peristaltic pump (3) is communicated with the liquid outlet of the flow control tank (2); the liquid inlet of the flow control tank (2) is communicated with the liquid outlet of the microfluidic chip (4); The liquid outlet of the liquid storage tank (1) is connected with one end of the liquid delivery pipeline, and the other end of the liquid delivery pipeline is connected with the liquid inlet of the microfluidic chip (4); The liquid storage tank (1) is arranged higher than the flow control tank (2) in the spatial dimension, and the exhaust port of the liquid storage tank (1) is communicated with the exhaust port of the flow control tank (2); The liquid route control method comprises: Adjusting the rotating speed of the micro peristaltic pump (3) to make the flow rate of the micro peristaltic pump (3) greater than the target flow rate; Controlling the culture solution to be perfused into the microfluidic chip (4) at the target flow rate under the action of the gravity pressure difference, so that the internal air self-circulation passage formed between the exhaust port of the liquid storage tank (1) and the exhaust port of the flow control tank (2) is balanced under the pressure balance, and the culture solution is continuously and constantly perfused into the microfluidic chip (4); Controlling the culture solution to be perfused into the microfluidic chip (4) at the target flow rate under the action of the gravity pressure difference, comprising: Adjusting the height of the liquid storage tank (1) relative to the flow control tank (2) to make the culture solution be perfused into the microfluidic chip (4) at the target flow rate under the action of the gravity pressure difference.

2. The method according to claim 1, wherein Further comprising a pressure control valve (5), the pressure control valve (5) is arranged on the liquid delivery pipeline, and the liquid outlet of the pressure control valve (5) is connected with the liquid inlet of the microfluidic chip (4).

3. The method according to claim 1 or 2, wherein Further comprising a bubble remover (6), the bubble remover (6) is arranged on the liquid delivery pipeline, and the liquid inlet of the bubble remover (6) is connected with the liquid outlet of the liquid storage tank (1).

4. The liquid route control method of the microfluidic chip according to claim 1, wherein: The liquid inlet and the exhaust port of the liquid storage tank (1) are located at the top end of the liquid storage tank (1), and the liquid outlet of the liquid storage tank (1) is located at the bottom end of the liquid storage tank (1); The liquid inlet and the exhaust port of the flow control tank (2) are located at the top end of the flow control tank (2), and the liquid outlet of the flow control tank (2) is located at the bottom end of the flow control tank (2); The bottom end of the liquid storage tank (1) is arranged higher than the top end of the flow control tank (2) in the spatial dimension.

5. The method according to claim 1, wherein Adjusting the height of the liquid storage tank (1) relative to the flow control tank (2) comprises: Determining the target height pressure difference between the liquid storage tank (1) and the flow control tank (2) according to the target flow rate and the total flow resistance of the system; Adjusting the height of the liquid storage tank (1) relative to the flow control tank (2) according to the target height pressure difference.

6. The method according to claim 1, wherein Controlling the culture solution to be perfused into the microfluidic chip (4) at the target flow rate under the action of the gravity pressure difference, comprising: On the basis that the height of the liquid storage tank (1) relative to the flow control tank (2) is fixed, adjusting the opening degree of the pressure control valve (5) to make the culture solution be perfused into the microfluidic chip (4) at the target flow rate under the action of the gravity pressure difference.

7. The method according to claim 1, wherein Controlling the culture solution to be perfused into the microfluidic chip (4) at the target flow rate under the action of the gravity pressure difference, comprising: Coarse adjustment of the opening of the pressure control valve (5), and then fine adjustment of the height of the liquid storage tank (1) relative to the flow control tank (2), so that the culture solution is perfused into the microfluidic chip (4) at a target flow rate under the action of gravity pressure difference.

8. The method according to claim 7, wherein Coarse adjustment of the opening of the pressure control valve (5), and then fine adjustment of the height of the liquid storage tank (1) relative to the flow control tank (2), including: Obtaining the relationship between the target flow rate of the microfluidic chip (4) and the height pressure difference between the liquid storage tank (1) and the flow control tank (2) and the total flow resistance of the system; Adjusting the opening of the pressure control valve (5) according to the target flow rate to change the total flow resistance of the system, so that the actual flow rate approaches the target flow rate; Then, according to the target flow rate and the current total flow resistance of the system, the target height pressure difference between the liquid storage tank (1) and the flow control tank (2) is determined, and the height of the liquid storage tank (1) relative to the flow control tank (2) is adjusted according to the target height pressure difference.

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