Micro-fluidic chip for capturing and removing bubbles from liquid and use method of micro-fluidic chip

Abstract

The embodiment of the invention provides a micro-fluidic chip for capturing and removing bubbles from liquid and a use method, and relates to the technical field of micro-fluidic chips, the micro-fluidic chip is provided with a liquid buffer cavity, a breathable film cavity, a cavity structure, a liquid inlet flow channel and a liquid outlet flow channel; the upper end of the liquid buffer cavity is connected with the bottom of the breathable film cavity, and a breathable film is arranged between the liquid buffer cavity and the breathable film cavity; the cavity structure is provided with a first cavity with variable volume, and the first cavity is communicated with the breathable film cavity through a gas flow channel; one end of the liquid inlet flow channel is connected with the liquid buffer cavity; one end of the liquid outlet runner is connected with one side, far away from the breathable film cavity, of the liquid buffer cavity. According to the embodiment of the invention, the bubbles in the liquid can be removed, a device for generating negative pressure externally connected to the micro-fluidic chip is not needed, the complexity and the cost of removing the bubbles in the micro-fluidic chip are simplified, and the bubble removal efficiency can be improved based on the negative pressure generated in the first chamber.

Description

Technical Field

[0001] This application relates to the field of microfluidic chip technology, and in particular to a microfluidic chip for capturing and removing bubbles from liquids and a method of using it. Background Technology

[0002] Among related technologies, microfluidics is a technique for manipulating liquids in micrometer-scale channels, with "lab-on-a-chip" as its core. This technology is widely used in biomedicine (such as rapid diagnostics, single-cell analysis, organ-on-a-chip, DNA sequencing, etc.), chemical analysis (such as high-throughput drug screening, microreactors, nanomaterial synthesis, etc.), point-of-care testing (POCT) (such as portable on-site diagnostic devices), and environmental and food safety (such as trace pollutant detection) fields.

[0003] In practical applications, liquids easily trap air bubbles, necessitating their removal. Existing technologies for capturing and removing air bubbles in liquids are structurally complex, require external piping, and pose a risk of liquid entering the venting channels, potentially leading to reduced or failed bubble removal effectiveness. Furthermore, many bubble removal solutions utilize microfluidic chips made of PDMS material, leveraging their permeability to connect external positive or negative pressure mechanical devices for bubble removal. However, the external devices generating positive or negative pressure result in a complex overall system structure, high cost, and limitations on chip materials. The chip's fabrication process is complex, making mass production difficult and costly, thus restricting its application. Other solutions employ ultrasonic bubble removal. Ultrasonic bubble removal in microfluidic chips primarily relies on cavitation effects; however, ultrasonic components are expensive, and the ultrasonic process generates vibrations and heat, which can negatively impact cell growth, making it unsuitable for specific fields such as cell culture and organ culture. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a microfluidic chip and a method for capturing and removing bubbles from liquids, capable of removing bubbles from liquids.

[0005] An embodiment of the first aspect of this application provides a microfluidic chip for capturing and removing bubbles from a liquid, the microfluidic chip having a liquid buffer chamber, a breathable membrane chamber, a cavity structure, an inlet channel, and an outlet channel;

[0006] The upper end of the liquid buffer chamber is connected to the bottom of the breathable membrane chamber, wherein a breathable membrane is provided between the liquid buffer chamber and the breathable membrane chamber;

[0007] The cavity structure has a first chamber with a variable volume, and the first chamber is connected to the breathable membrane cavity through a gas flow channel;

[0008] One end of the liquid inlet channel is connected to the liquid buffer chamber;

[0009] One end of the liquid outlet channel is connected to the side of the liquid buffer chamber away from the breathable membrane chamber.

[0010] Furthermore, the microfluidic chip includes a substrate and an elastic membrane;

[0011] The substrate has an upper end face, and the upper end face is provided with a gas buffer cavity with an opening. The elastic membrane is disposed at the opening of the gas buffer cavity, and the elastic membrane and the gas buffer cavity enclose the first chamber.

[0012] Furthermore, the substrate has a lower end face, and the lower end face is provided with the liquid buffer cavity, the liquid inlet channel and the liquid outlet channel;

[0013] The microfluidic chip includes a sealing assembly, which includes a first sealing membrane and a second sealing membrane. The first sealing membrane is disposed on the upper end face, and the second sealing membrane is disposed on the lower end face.

[0014] A second chamber is defined between the first sealing membrane and the breathable membrane, and the gas flow channel is connected to the second chamber.

[0015] Furthermore, the liquid buffer cavity is formed by a recess on the side of the lower end face facing the upper end face.

[0016] Furthermore, the liquid inlet channel and the wall of the liquid buffer chamber transition smoothly.

[0017] Furthermore, the liquid buffer chamber has a first chamber wall and an outlet end;

[0018] The first cavity wall extends from the end of the liquid inlet channel toward the gas outlet.

[0019] Furthermore, the longitudinal cross-sectional profile of the liquid buffer cavity is square, triangular, trapezoidal, or includes an arc, wherein the longitudinal section is parallel to the thickness direction of the substrate.

[0020] Furthermore, the breathable membrane is made of a hydrophilic or hydrophobic material.

[0021] Furthermore, the liquid outlet channel is connected to the bottom of the side wall of the liquid buffer chamber.

[0022] An embodiment of the second aspect of this application provides a method for using a microfluidic chip, applied to the microfluidic chip as described above, comprising the following steps:

[0023] The volume of the first chamber is set to a first volume, which is smaller than the maximum volume of the first chamber.

[0024] Liquid is allowed to flow into the liquid buffer chamber through the inlet channel until the liquid in the liquid buffer chamber flows into the outlet channel, thereby adjusting the volume of the first chamber to a second volume, wherein the second volume is greater than the first volume;

[0025] The liquid continues to flow into the liquid buffer chamber through the inlet channel until the air pressure in the liquid buffer chamber is equal to the air pressure in the breathable membrane chamber.

[0026] As can be seen from the above technical solutions, the embodiments of this application have at least the following beneficial effects:

[0027] In the microfluidic chip and its usage method provided in this application, after liquid enters the liquid buffer chamber and simultaneously submerges the liquid flow channel, the air bubbles carried in the liquid gather at the upper end of the liquid buffer chamber under the action of liquid buoyancy. Subsequently, by changing the volume of the first chamber, the air pressure in the venting membrane chamber is made lower than the air pressure in the liquid buffer chamber, allowing the gas in the liquid buffer chamber to permeate through the venting membrane and flow into the venting membrane chamber, thereby achieving the purpose of removing air bubbles. The embodiments of this application do not require an external device for generating negative pressure, simplifying the complexity and cost of microfluidic chip capturing and removing air bubbles, and can improve the air bubble removal efficiency based on the negative pressure generated in the first chamber. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the overall structure of a microfluidic chip provided in one embodiment of this application;

[0030] Figure 2 This is an exploded view of a microfluidic chip provided in one embodiment of this application.

[0031] Figure 3 This is a schematic diagram of the upper surface of the substrate in a microfluidic chip provided in one embodiment of this application;

[0032] Figure 4 This is a schematic diagram of the lower end face of the substrate in a microfluidic chip provided in one embodiment of this application;

[0033] Figure 5 This is a schematic diagram of the cross-sectional structure of a microfluidic chip provided in one embodiment of this application;

[0034] Figure 6 for Figure 5 A magnified view of part A in the diagram.

[0035] Figure label:

[0036] 100, Substrate; 110, Upper end face; 111, Ventilation membrane cavity; 112, Gas flow channel; 113, First chamber; 114, Liquid inlet; 115, Liquid outlet; 120, Lower end face; 121, Liquid buffer chamber; 122, Liquid inlet flow channel; 123, Liquid outlet flow channel; 1211, First chamber wall; 1212, Side wall;

[0037] 200. Breathable membrane;

[0038] 300. Elastic membrane;

[0039] 410. First sealing membrane; 420. Second sealing membrane. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] See Figures 1 to 6 As shown, an embodiment of the first aspect of this application discloses a microfluidic chip. After liquid enters the liquid buffer chamber 121 and simultaneously submerges the liquid flow channel 123, the air bubbles carried in the liquid gather at the upper end of the liquid buffer chamber 121 under the action of liquid buoyancy. Subsequently, by changing the volume of the first chamber 113, the air pressure in the ventilated membrane chamber 111 is made lower than the air pressure in the liquid buffer chamber 121. During the subsequent continuous entry of liquid into the liquid buffer chamber 121, the gas in the liquid buffer chamber 121 can permeate through the ventilated membrane 200 and flow into the ventilated membrane chamber 111, thereby achieving the purpose of removing air bubbles. The embodiment of this application does not require an external device for generating negative pressure, simplifying the complexity and cost of air bubble removal in the microfluidic chip, and can improve the air bubble removal efficiency based on the negative pressure generated in the first chamber 113.

[0042] The following will combine Figures 1 to 6 The microfluidic chip disclosed in the first aspect of this application will be described in detail.

[0043] See Figures 1 to 6The microfluidic chip disclosed in the first aspect of this application has a liquid buffer chamber 121, a breathable membrane chamber 111, a cavity structure, an inlet channel 122, and an outlet channel 123.

[0044] Specifically, the upper end of the liquid buffer chamber 121 is connected to the bottom of the ventilated membrane chamber 111. A ventilated membrane 200 is disposed between the liquid buffer chamber 121 and the ventilated membrane chamber 111. Under a certain air pressure, gas located on one side of the ventilated membrane 200 can pass through the ventilated membrane 200. It is worth mentioning that the ventilated membrane 200 allows gas to pass through while having a barrier effect on liquid, thus effectively preventing liquid in the liquid buffer chamber 121 from seeping into the ventilated membrane chamber 111.

[0045] The cavity structure has a first chamber 113 with a variable volume, which is connected to the breathable membrane cavity 111 via a gas flow channel 112. When the volume of the first chamber 113 increases, the air pressure inside the first chamber 113 decreases. Since the first chamber 113 is connected to the breathable membrane cavity 111, the air pressure difference between the breathable membrane cavity 111 and the liquid buffer cavity 121 can be changed by changing the volume of the first chamber 113, thereby driving the bubbles to migrate directionally through the breathable membrane 200. This process does not require an external negative pressure source.

[0046] One end of the inlet channel 122 is connected to the liquid buffer chamber 121. Specifically, the other end of the inlet channel 122 is connected to the inlet hole 114. The liquid to be treated can enter the inlet channel 122 through the inlet hole 114 and then flow into the liquid buffer chamber 121. When the liquid level in the liquid buffer chamber 121 rises to cover the inlet of the outlet channel 123, the air bubbles entrained in the liquid can gather at the top of the liquid buffer chamber 121 under the action of buoyancy.

[0047] One end of the liquid outlet channel 123 is connected to the side of the liquid buffer chamber 121 away from the ventilated membrane chamber 111. The other end of the liquid outlet channel 123 is connected to the liquid outlet hole 115, through which the treated bubble-free liquid is discharged.

[0048] In one embodiment, see Figures 1 to 3The microfluidic chip includes a substrate 100 and an elastic membrane 300. Specifically, the substrate 100 has an upper end surface 110 and a lower end surface 120. The upper end surface 110 is provided with a gas buffer cavity with an opening. The elastic membrane 300 is disposed at the opening of the gas buffer cavity, and the elastic membrane 300 and the gas buffer cavity enclose a first chamber 113. When the elastic membrane 300 is deformed by an external force, the volume of the first chamber 113 changes accordingly, thereby changing the gas pressure in the first chamber 113. In this embodiment, by first making the elastic membrane 300 concave towards the gas buffer cavity, and then releasing the elastic membrane 300 after the liquid has submerged the liquid inlet of the liquid flow channel 123, a negative pressure can be generated in the first chamber 113. This changes the gas pressure difference on both sides of the venting membrane 200, allowing the gas in the liquid buffer cavity 121 to pass through the venting membrane 200 and enter the venting membrane cavity 111.

[0049] It is worth mentioning that the deformation of the elastic membrane 300 can be achieved by manual pressing, mechanical driving or thermal deformation, so as to flexibly adapt to the bubble removal needs in different scenarios.

[0050] In one embodiment, see Figure 3 , Figure 5 and Figure 6 The substrate 100 has a lower end face 120, which is provided with a liquid buffer chamber 121, a liquid inlet channel 122, and a liquid outlet channel 123. The microfluidic chip includes a sealing assembly, which includes a first sealing membrane 410 and a second sealing membrane 420. The first sealing membrane 410 is disposed on the upper end face 110, and the second sealing membrane 420 is disposed on the lower end face 120. A second chamber is defined between the first sealing membrane 410 and the breathable membrane 200, and the gas channel 112 communicates with the second chamber.

[0051] In one embodiment, see Figures 4 to 6 The liquid buffer chamber 121 is formed by a recess from the lower end face 120 towards the upper end face 110. Furthermore, the liquid inlet channel 122 is connected to the liquid buffer chamber 121 near the lower end face 120, and the liquid outlet channel 123 is connected to the liquid buffer chamber 121 near the upper end face 110. In this way, the liquid can quickly submerge the inlet of the liquid outlet channel 123 and reduce the flow of air bubbles into the liquid outlet channel 123, thereby improving the bubble capture efficiency and bubble capture effect.

[0052] In one embodiment, see Figures 4 to 6 The inlet channel 122 and the wall of the liquid buffer chamber 121 transition smoothly. This helps to reduce the resistance of the liquid during the flow process, allowing the liquid to flow smoothly into the liquid buffer chamber 121 and reducing the generation and accumulation of bubbles.

[0053] Further reading is available upon request. Figures 4 to 6The liquid buffer chamber 121 has a first chamber wall 1211 and an outlet end; the first chamber wall 1211 extends from the end of the liquid inlet channel 122 towards the outlet end. As shown in the figure, the outlet end is connected to the ventilated membrane chamber 111, and the outlet end is located at the top of the liquid buffer chamber 121, while the end of the liquid inlet channel 122 is located at the bottom of the liquid buffer chamber 121, forming an upward liquid flow path. This structure, combined with buoyancy, allows bubbles to naturally float to the top outlet end and be discharged through the ventilated membrane 200, significantly improving the continuity and stability of degassing and helping to reduce bubble generation.

[0054] In one embodiment, the longitudinal cross-sectional profile of the liquid buffer cavity 121 is square, triangular, trapezoidal, or includes an arc shape, wherein the longitudinal section is parallel to the thickness direction of the substrate 100. The arc shape can be circular, or it can be a shape composed of arcs and straight line segments, but is not limited thereto.

[0055] In one possible implementation, the longitudinal cross-sectional profile of the liquid buffer chamber 121 is trapezoidal. Specifically, the trapezoidal design, which is narrower at the top and wider at the bottom, facilitates the collection of bubbles at the top of the liquid buffer chamber 121. Its sloping walls can also guide the bubbles to migrate smoothly along the chamber walls, reducing the occurrence of bubble retention or bubble generation, and further improving the degassing efficiency.

[0056] Furthermore, the trapezoidal sidewall 1212 is perpendicular to the base and top edge of the trapezoid, which reduces the risk of air bubbles in the liquid buffer chamber 121 entering the liquid outlet channel 123. Of course, the trapezoid can also be an isosceles trapezoid, with the sidewall 1212 coinciding with the waist of the trapezoid, that is, the sidewall 1212 is set at an angle to the base and fixed edge.

[0057] It is worth mentioning that the breathable membrane 200 is disposed within the breathable membrane cavity 111 and is tightly sealed to the cavity wall of the breathable membrane cavity 111. Under certain pressure, the breathable membrane 200 can block the passage of liquid but allow gas to pass through. In practical applications, the breathable membrane 200 can be connected to the cavity wall of the breathable membrane cavity 111 through sealing methods including but not limited to hot pressing, ultrasound, bonding, UV adhesive bonding, and embedding.

[0058] In one embodiment, the breathable membrane 200 is made of a hydrophilic or hydrophobic material. Specifically, the material of the breathable membrane 200 can be selected as either a hydrophilic or hydrophobic material depending on the liquid being processed.

[0059] In one embodiment, the liquid outlet channel 123 is connected to the bottom of the side wall 1212 of the liquid buffer chamber 121.

[0060] See below. Figures 1 to 6The process of collecting and removing air bubbles using a microfluidic chip according to a specific embodiment of this application is described in detail below. It should be noted that the following embodiment is merely illustrative and should not be construed as limiting the scope of this application.

[0061] 1. Before liquid is injected into the microfluidic chip, the elastic membrane 300 deforms into its cavity under external mechanical pressure; the degree of deformation can be controlled as needed. Simultaneously, some gas in the gas buffer chamber is discharged through the gas channel 112, the permeable membrane 200, the liquid buffer chamber 121, the liquid inlet channel 122, and the liquid outlet channel 123. The size, shape, thickness, and deformation of the elastic membrane 300, as well as the size and shape of the internal space of the gas buffer chamber, can all be designed or configured according to the volume and quantity of the liquid being processed.

[0062] 2. Under the action of liquid driving force, the liquid carrying air bubbles flows from the inlet hole 114 into the liquid buffer chamber 121 through the inlet channel 122. The longitudinal section of the liquid buffer chamber 121 is trapezoidal, and the side near the inlet channel 122 is an inclined surface with a certain angle, which allows the liquid flowing into the liquid buffer chamber 121 to gradually fill the internal space of the liquid buffer chamber 121. The liquid can be a hydrophilic liquid or a hydrophobic liquid.

[0063] 3. As the liquid continues to flow in, the liquid buffer chamber 121 gradually fills with liquid and air bubbles.

[0064] 4. Due to the buoyancy of the liquid, the bubbles will rise to the top of the liquid buffer chamber 121, meaning the bubbles are captured and aggregated at the top of the liquid buffer chamber 121 and come into contact with the breathable membrane 200. It is worth noting that for hydrophilic liquids, a hydrophobic breathable membrane 200 can be selected; for hydrophobic liquids, such as paraffin oil and mineral oil, a hydrophilic breathable membrane 200 can be selected.

[0065] 5. Continue injecting liquid until some liquid begins to enter the outlet channel 123. At this point, remove the external mechanical pressure applied to the elastic membrane 300. As a result, the elastic membrane 300 tends to return to its original state, thus creating a negative pressure in the gas buffer chamber, gas channel 112, and ventilated membrane chamber 111. This creates a pressure difference across the ventilated membrane 200, increasing the gas pressure (P) at the top of the liquid buffer chamber 121. 液体缓冲腔 The pressure inside the breathable membrane cavity 111 is greater than the pressure (P). 透气膜腔 ), that is, P 液体缓冲腔 >P 透气膜腔 ;

[0066] 6. As the liquid carrying air bubbles continuously flows into the liquid buffer chamber 121 from the inlet channel 122, gas continuously accumulates at the top of the liquid buffer chamber 121. The accumulated gas, under pressure, passes through the vent membrane 200 and enters the vent membrane chamber 111, further entering the gas buffer chamber through the gas channel 112. The liquid in the liquid buffer chamber 121, under this pressure difference, cannot pass through the vent membrane 200 or is insufficient to overcome the critical pressure (P) that the vent membrane 200 uses to block the liquid. 透气膜临界压力 ), that is, P 液体缓冲腔 -P 透气膜腔 <P 透气膜临界压力 ;

[0067] 7. At the same time, the liquid in the liquid buffer chamber 121 will continuously enter the liquid outlet channel 123 under the action of the liquid driving force, and flow out from the liquid outlet hole 115. The outflowing liquid has no obviously visible bubbles.

[0068] 8. As the gas entrained in the liquid continuously permeates through the permeable membrane 200 and enters the gas buffer chamber, the pressure difference across the permeable membrane 200 gradually decreases until it reaches a relative equilibrium state, i.e., P. 液体缓冲腔 ≈P 透气膜腔， When the air pressure on both sides of the breathable membrane 200 tends to be the same or the pressure difference is very small, the gas in the liquid buffer chamber 121 will no longer enter the gas buffer chamber.

[0069] 9. At this point, the microfluidic chip will lose its ability to remove bubbles by relying on the pressure difference on both sides of the breathable membrane 200. As the gas continues to accumulate at the top of the liquid buffer chamber 121 and the gas area gradually expands, it will come into contact with one end of the liquid outlet channel 123. The liquid in the liquid outlet channel 123 will once again carry the gas along with it, and the bubble removal process will end.

[0070] The second aspect of this application discloses a method for using a microfluidic chip, applied to the microfluidic chip as described above, comprising the following steps:

[0071] The volume of the first chamber 113 is set to a first volume, which is smaller than the maximum volume of the first chamber 113;

[0072] The liquid flows into the liquid buffer chamber 121 through the inlet channel 122 until the liquid flowing into the liquid buffer chamber 121 flows into the outlet channel 123, thereby adjusting the volume of the first chamber 113 to the second volume, which is greater than the first volume.

[0073] The liquid continues to flow into the liquid buffer chamber 121 through the liquid inlet channel 122 until the air pressure in the liquid buffer chamber 121 is equal to the air pressure in the breathable membrane chamber 111.

[0074] After the liquid enters the liquid buffer chamber 121 and simultaneously submerges the liquid flow channel 123, the air bubbles carried in the liquid gather at the upper end of the liquid buffer chamber 121 under the action of liquid buoyancy. Then, by changing the volume of the first chamber 113, during the continuous flow of liquid into the liquid buffer chamber 121, the air pressure in the ventilated membrane chamber 111 is made lower than the air pressure in the liquid buffer chamber 121, so that the gas in the liquid buffer chamber 121 permeates through the ventilated membrane 200 and flows into the ventilated membrane chamber 111, thereby achieving the purpose of removing air bubbles.

[0075] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0076] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0077] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0078] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0079] It should be understood that although the steps in the flowcharts of the accompanying figures are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the accompanying figures may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

Claims

1. A microfluidic chip for capturing and removing gas bubbles from a liquid, characterized in that, The microfluidic chip has a liquid buffer cavity, a gas-permeable membrane cavity, a cavity structure, a liquid inlet channel and a liquid outlet channel; The upper end of the liquid buffer cavity is connected with the bottom of the gas-permeable membrane cavity, wherein a gas-permeable membrane is arranged between the liquid buffer cavity and the gas-permeable membrane cavity; The cavity structure has a first chamber with variable volume, and the first chamber is connected with the gas-permeable membrane cavity through a gas channel; One end of the liquid inlet channel is connected with the liquid buffer cavity; One end of the liquid outlet channel is connected with the side of the liquid buffer cavity away from the gas-permeable membrane cavity.

2. The microfluidic chip of claim 1, wherein, The microfluidic chip comprises a substrate and an elastic membrane; The substrate has an upper end face, and the upper end face is provided with a gas buffer cavity with an opening, and the elastic membrane is arranged at the opening of the gas buffer cavity, and the elastic membrane and the gas buffer cavity enclose the first chamber.

3. The microfluidic chip of claim 2, wherein, The substrate has a lower end face, and the lower end face is provided with the liquid buffer cavity, the liquid inlet channel and the liquid outlet channel; The microfluidic chip comprises a sealing assembly, and the sealing assembly comprises a first sealing membrane and a second sealing membrane, the first sealing membrane is arranged on the upper end face, and the second sealing membrane is arranged on the lower end face; The first sealing membrane and the gas-permeable membrane define a second chamber, and the gas channel is connected with the second chamber.

4. The microfluidic chip of claim 3, wherein, The liquid buffer cavity is recessed from the lower end face to the side of the upper end face.

5. The microfluidic chip of claim 3, wherein, The liquid inlet channel and the cavity wall of the liquid buffer cavity are smoothly connected.

6. The microfluidic chip according to any one of claims 2 to 5, wherein, The liquid buffer cavity has a first cavity wall and an air outlet end; The first cavity wall extends from the end of the liquid inlet channel to the air outlet end.

7. The microfluidic chip of claim 6, wherein, The longitudinal cross-sectional profile of the liquid buffer cavity is square, triangular, trapezoidal or a graph including an arc, wherein the longitudinal cross section is parallel to the thickness direction of the substrate.

8. The microfluidic chip of claim 1, wherein, The gas-permeable membrane is made of hydrophilic material or hydrophobic material.

9. The microfluidic chip of claim 1, wherein, The liquid outlet channel is connected with the bottom of the side wall of the liquid buffer cavity.

10. A method of using a microfluidic chip, the method comprising: The microfluidic chip is applied to the microfluidic chip of any one of claims 1 to 9, comprising the following steps: The volume of the first chamber is set to a first volume, which is smaller than the maximum volume of the first chamber; Liquid is flowed into the liquid buffer cavity through the liquid inlet channel until the liquid in the liquid buffer cavity flows into the liquid outlet channel, so that the volume of the first chamber is adjusted to a second volume, which is greater than the first volume; Liquid is continuously flowed into the liquid buffer cavity through the liquid inlet channel until the gas pressure in the liquid buffer cavity is equal to the gas pressure in the gas-permeable membrane cavity.

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