A hynes jump quantitative controllable microfluidic chip and a working method thereof

Abstract

The application belongs to the technical field of microfluidics, and discloses a Haines jump quantitative controllable microfluidic chip and a working method thereof; wherein, in the Haines jump quantitative controllable microfluidic chip, a flow channel is arranged in the microfluidic chip body, and the flow channel is provided with a neck-down structure; one end of a control pipeline is used for introducing a liquid medium, and the other end of the control pipeline is used for packaging a gas medium under the joint action of the liquid medium and atmospheric pressure; the microfluidic chip body is further provided with a pipeline mounting channel for mounting the control pipeline; wherein, the Haines jump distance of the Haines jump generated at the neck-down structure and the stop time of the working fluid before the Haines jump occurs are controlled by adjusting the volume of the packaged gas medium. The technical scheme of the application can realize simulation control of the Haines jump process of the fluid, can improve the authenticity of the simulation of the fluid flow process, and can better assist in completing the simulation analysis of the fluid flow process.

Description

Technical Field

[0001] This invention belongs to the field of microfluidics technology, and specifically relates to a microfluidic chip with controllable jump quantity and its working method. Background Technology

[0002] Microfluidics is a technology for analyzing fluid flow in fields such as biology, chemistry, medicine, and geology. This technology integrates basic operational units such as sample preparation, reaction, separation, and detection onto a micrometer-scale chip, enabling the entire analysis process to be completed automatically. Among them, microfluidic chip technology has a wide range of applications. It uses the chip as an operating platform, is based on analytical chemistry, relies on microelectromechanical and micro-nano scale fabrication technology, has microchannel networks as its structural feature, and currently has many disciplines in the life sciences as its main application targets. It is the focus of current development in the field of micro total analysis systems.

[0003] Currently, most technologies that require microfluidic chips to simulate basic flow processes to explore corresponding mechanisms, such as underground carbon dioxide storage, energy extraction, and human blood flow research, all encounter the Haynes jump phenomenon during actual generation or microfluidic research. However, existing microfluidic chip designs generally do not consider the impact of the Haynes jump phenomenon on the flow process, resulting in poor realism in the simulated fluid flow. To explain further, some existing microfluidic chip designs use relatively rigid materials, increasing system stiffness and making it difficult to simulate the occurrence of Haynes jumps; conversely, other microfluidic chips using softer materials have not undergone careful calculation, making it difficult to unify system stiffness and control the occurrence of Haynes jumps.

[0004] In summary, designing a new microfluidic chip with quantitatively controllable jumps to better simulate more realistic fluid flow processes has become an urgent technical challenge. Summary of the Invention

[0005] The purpose of this invention is to provide a microfluidic chip with quantitatively controllable Haines jump and its operating method, thereby solving one or more of the aforementioned technical problems. The technical solution disclosed in this invention can simulate and control the Haines jump process of fluids, improving the realism of fluid flow process simulation and better assisting in the simulation and analysis of fluid flow processes.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a Haines microfluidic chip with controllable quantitation of jumps, comprising: a microfluidic chip body, a first syringe, a control channel, a second syringe, and a channel mounting channel; wherein, The microfluidic chip body has a flow channel with a necking structure; the inlet of the flow channel is connected to the injection port of the first syringe through an inlet pipe for introducing working fluid; the outlet of the flow channel is connected to the atmosphere through an outlet pipe. One end of the control pipe is connected to the injection port of the second syringe for introducing a liquid medium; the other end of the control pipe is used to encapsulate a certain volume of gas medium under the combined action of the liquid medium and atmospheric pressure. The microfluidic chip body is also provided with a pipe mounting channel for mounting the control pipe; wherein, one end of the pipe mounting channel is connected to the flow channel and is disposed between the inlet of the flow channel and the necking structure; the other end of the pipe mounting channel is used to enter the end of the control pipe encapsulated with a gas medium; The distance of the Haines jump generated at the necking structure and the dwell time of the working fluid before the Haines jump are controlled by adjusting the volume of the encapsulated gas medium.

[0007] A further improvement of the technical solution of the present invention is that the microfluidic chip body is made of a material with an elastic modulus greater than 10 MPa.

[0008] A further improvement of the technical solution of the present invention is that the material of the microfluidic chip body is quartz glass, silicon, polydimethylsiloxane, polymethyl methacrylate or cyclic olefin polymer.

[0009] A further improvement of the technical solution of the present invention is that the microfluidic chip body adopts an upper and lower splicing structure, including an upper body and a lower body, and one or both of the upper body and the lower body are transparent.

[0010] A further improvement of the technical solution of the present invention is that the liquid medium is an incompressible fluid that is not easily evaporated; the gas medium is a compressible ideal gas; and the working fluid is an incompressible fluid.

[0011] A further improvement of the technical solution of the present invention is that the liquid medium is hydraulic oil or water; the gas medium is air or nitrogen; and the working fluid is water, ethanol or glycerol.

[0012] A further improvement of the technical solution of the present invention is that both the first syringe and the second syringe are equipped with a micro-injection pump for controlling the injection volume.

[0013] A further improvement to the technical solution of the present invention is that it further includes: A microscope camera is used to obtain the jump distance of the Haines jump generated at the necking structure.

[0014] A further improvement of the technical solution of the present invention is that, in the step of controlling the distance of the Haines jump generated at the necking structure and the dwell time of the working fluid before the Haines jump occurs by adjusting the volume of the encapsulated gas medium, the relationship between the volume of the encapsulated gas medium and the jump distance of the Haines jump is expressed as follows: V 0= LhDP 2 / ( P 1- P 2); In the formula, V 0 represents the volume of the encapsulated gas medium; L This represents the jump distance of Haines. h The height of the microfluidic chip body; D The maximum diameter of the flow channel; P 1. To control the capillary pressure at the channel interface, P 2 represents the capillary pressure at the necking structure; P 1= P 0+ c cos( i (2 / ) d +2 / h ); P 2= P 0+ c cos( i (2 / ) D +2 / h ); In the formula, P 0 represents atmospheric environmental pressure; i、c These are the contact angle and surface tension of the working fluid, respectively. d The diameter is the smallest part of the necked structure.

[0015] In a second aspect, the present invention provides a method for operating a microfluidic chip with controllable hopping quantity, comprising: The working fluid in the first syringe is introduced into the flow channel inside the microfluidic chip body through the inlet pipe. The outlet of the flow channel is connected to the atmosphere, and the working fluid flows in the flow channel. The liquid medium in the second syringe is introduced into the control pipe through one end of the control pipe, and under the combined action of the liquid medium and atmospheric pressure, a certain volume of gas medium is sealed at the other end of the control pipe. The end of the control pipe containing the gas medium is installed into the pipe installation channel set in the microfluidic chip body and connected to the flow channel. The volume of the gas medium encapsulated in the control pipeline is adjusted to quantitatively control the Haines jump generated at the constriction structure; wherein, quantitative control includes controlling the jump distance of the Haines jump or controlling the dwell time of the working fluid before the Haines jump occurs.

[0016] Compared with the prior art, the present invention has the following beneficial effects: Investigating fluid flow behavior at the pore scale within porous media is a key issue in geology, biology, medicine, thermodynamics, and other fields. Existing technologies typically employ microfluidic methods to visualize pore-scale flow behavior. However, existing microfluidic chip technologies may suffer from missing Haynes jumps due to the use of rigid materials, or uncontrollable Haynes jumps due to the use of flexible materials. Both phenomena cause significant deviations from expected pore-scale infiltration behavior, complicating subsequent analysis. In view of these existing technical problems, this invention discloses a novel microfluidic chip with quantitatively controllable Haynes jumps. It introduces an encapsulated gaseous medium as a means to adjust the stiffness of the microfluidic chip body, thereby achieving precise, rapid, and low-cost quantitative control of Haynes jumps. This allows for the simulation of Haynes jump behavior under different application scenarios, greatly enhancing the accuracy of pore-scale fluid flow behavior and making research results more realistic and reliable. In summary, this invention improves the controllability of microfluidic chip simulation experiments and enhances the realism and reliability of the experiments. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a Haines microfluidic chip with controllable jump quantity in an embodiment of the present invention; The explanations of the reference numerals in the figure are as follows: 1. Microfluidic chip body; 2. Flow channel; 3. Inlet pipe; 4. Outlet pipe; 5. First injector; 6. Working fluid; 7. Neck structure; 8. Pipe installation channel; 9. Control pipe; 10. Second injector; 11. Gas medium; 12. Liquid medium. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention; obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Based on the technical solutions disclosed in the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0021] Please see Figure 1 This invention provides a Haines jump-quantitative controllable microfluidic chip, comprising: a microfluidic chip body 1, a first injector 5, a control channel 9, a second injector 10, and a channel mounting channel 8; wherein, The microfluidic chip body 1 is provided with a flow channel 2 for introducing working fluid 6. The flow channel 2 is provided with a necking structure 7. The inlet of the flow channel 2 is connected to the injection port of the first syringe 5 through an inlet pipe 3. The outlet of the flow channel 2 is connected to the atmosphere through an outlet pipe 4. One end of the control pipe 9 is connected to the injection port of the second syringe 10 for introducing liquid medium 12; the other end of the control pipe 9 is used to encapsulate a certain volume of gas medium 11 under the combined action of the liquid medium 12 and atmospheric pressure. The microfluidic chip body 1 is provided with a pipe mounting channel 8 for mounting the control pipe 9; wherein, one end of the pipe mounting channel 8 is connected to the flow channel 2 and is located between the inlet of the flow channel 2 and the necking structure 7; the other end of the pipe mounting channel 8 is used to pass through the end of the control pipe 9 encapsulated with gas medium 11. Explained, under the influence of the encapsulated gas medium 11, the stiffness of the microfluidic chip body 1 is adjustable, and a quantitatively controllable Haynes jump can be generated at the necking structure 7 of the flow channel 2; wherein, the jump distance of the Haynes jump generated at the necking structure 7 and the pause time of the liquid working fluid 6 before the Haynes jump occurs are controlled by adjusting the volume of the encapsulated gas medium 11.

[0022] The technical solution disclosed in this invention can control the magnitude and distance of the Haines jump generated in the microfluidic chip body. It can effectively simulate and analyze the influence of the size of the Haines jump on fluid flow. When necessary, this control method can also eliminate or reduce the influence of the Haines jump on fluid flow experiments, thereby improving the controllability of microfluidic chip simulation experiments and improving the reliability of the experiments.

[0023] In a specific exemplary technical solution of the present invention, the microfluidic chip body 1 is made of a material with an elastic modulus greater than 10 MPa, such as quartz glass, silicon, polydimethylsiloxane, polymethyl methacrylate, cyclic olefin polymer, etc.; in a further exemplary technical solution, the microfluidic chip body 1 adopts an upper and lower splicing structure, including an upper body and a lower body, one or both of the upper body and the lower body are transparent.

[0024] In a specific exemplary technical solution of this invention, the liquid medium 12 can be an incompressible fluid that does not easily evaporate, such as hydraulic oil or water; the gas medium 11 is a compressible ideal gas such as air or nitrogen; and the working fluid 6 is an incompressible fluid such as water, ethanol, or glycerol. In a specific exemplary technical solution, the control liquid medium 12 is hydraulic oil, which is less immiscible with the pressurized gas and can achieve better control; in addition, hydraulic oil has poor compressibility and will not introduce additional elastic deformation.

[0025] In a specific exemplary technical solution of the present invention, both the first syringe 5 and the second syringe 10 are equipped with a micro-injection pump for controlling the injection volume.

[0026] In the preferred technical solution disclosed in this invention, the overall system stiffness of the microfluidic chip body is limited by restricting the material of the microfluidic chip body; simultaneously, a gas volume control system is introduced, which can precisely adjust the volume of the encapsulated gas medium. The encapsulated gas medium is a compressible gas, and the stiffness of the microfluidic chip body can be flexibly adjusted by adjusting the volume of the pressurized gas medium. The gas volume control system and the rigid microfluidic chip constitute a microfluidic experimental system with adjustable system stiffness. In a one-dimensional system, the distance of the Haynes jump and the corresponding waiting time are determined only by the system stiffness. The distance of the Haynes jump and the pause time before the Haynes jump are linearly proportional to the deformation of the encapsulated gas system; therefore, by adjusting the system stiffness, the deformation of the overall system can be controlled, thereby controlling the distance of the Haynes jump and the pause time before the Haynes jump.

[0027] The technical solution disclosed in this invention is explained in principle as follows: A micro-injection pump controls the flow of working fluid within a first syringe. After passing through a control channel, the fluid seals the gas at the front end of the control channel, forming a sealed gas section. As the working fluid continues forward through the constriction structure, it is compressed. This creates a mutual compressive force between the working fluid and the gas medium sealed at the front end of the control channel. This force causes deformation of the sealed gas medium. Under the same force, the larger the original volume of the sealed gas medium, the greater the deformation; conversely, the smaller the original volume, the smaller the deformation. The degree of deformation affects the distance of the Haynes jump. Based on this theory, the position of the control liquid medium at the front end can be adjusted beforehand using a second syringe controlled by the micro-injection pump to adjust the volume of the sealed gas medium, thereby controlling the magnitude of the rebound force of the sealed gas medium during the Haynes jump and thus controlling the jump distance.

[0028] In summary, the technical solution of this invention utilizes the incompatibility of the gas-liquid interface. By controlling the volume of the sealed gas medium at the control channel connection, the jump distance of the Haynes jump can be controlled more effectively, thus achieving better regulation and control of minute pressures. Furthermore, this force is applied passively, offering better reliability and controllability compared to active pressure regulation methods. Simultaneously, due to the extremely short duration of the Haynes jump, the passive regulation method achieves more precise control. Moreover, the relationship between the volume of the sealed gas medium at the control channel connection and the jump distance of the Haynes jump can be obtained through calculation or experimentally determined using a testing device.

[0029] In this embodiment of the invention, the relationship between the volume of the sealing gas medium at the control channel connection and the jump distance of the Haines jump is obtained through calculation, including the following steps: Determining the Haines jump distance includes: determining the required controlled Haines jump distance based on the specific application and experimental distance needs. L Enter the results into the computer; Determining the geometric parameters of the necked structure includes: determining the minimum diameter of the necked structure based on the pore geometry parameters of the necked structure designed for the microfluidic chip. d Microfluidic chip body height h and the diameter at the maximum point of the flow channel D Enter the results into the computer; Determine the physical properties of the working fluid, including: determining the contact angle of the working fluid based on its physical characteristics. i and surface tension c Enter the results into the computer; Determine atmospheric environmental pressure P0. Enter the result into the computer; Calculate the capillary pressure at the control channel interface P 1 and capillary pressure at the constriction P 2. According to the Young-Laplace equation. P 1= P 0+ c cos( i (2 / ) d +2 / h ); P 2= P 0+ c cos( i (2 / ) D +2 / h ); Computational implementation of jump L Required bubble size V 0: LhD P 2 / ( P 1- P 2); Adjust the syringe piston position of the second micro-injection pump to maintain the remaining air volume at the control channel interface. V 0 is sufficient.

[0030] In this embodiment of the invention, the relationship between the volume of the sealed gas medium at the control channel connection and the jump distance of the Haines jump, obtained through experiments, includes the following steps: The relationship between the volume of the sealing gas at the control channel connection and the proximity of the Haines jump at the flow channel neck was determined using a microfluidic chip Haines jump testing device; wherein, In the microfluidic chip Haines jump test device, test flow channels are provided before and after the necking structure of the microfluidic chip body to be tested within the test microfluidic chip. Test necking structures are provided within these test flow channels to simulate the necking structure of the microfluidic chip body. One end of the test flow channel has an inlet connected to a test inlet pipe, and the other end has an outlet connected to a test outlet pipe. The test inlet pipe is connected to a syringe of a first micro-injection pump for testing, which contains working fluid. The test microfluidic chip is then fed into the syringe. A test control channel is vertically connected to the test flow channel located before the structure of the test neck. The test control channel has the same size as the simulated control channel and is externally connected to a test control pipe. The test control pipe is connected to the syringe of a test second micro-injection pump. A section of control gas is encapsulated at the junction of the front end of the test control channel and the test flow channel. The rear end of the test control channel and the corresponding syringe of the test second micro-injection pump are filled with control liquid. The test microfluidic chip is made of transparent material and a microscope camera is positioned directly above it.

[0031] In a preferred embodiment of the present invention, the experimental microfluidic chip and the microfluidic chip to be simulated in the microfluidic chip Haynes jump test device have the same front and rear position structure at the necking point. This allows them to simulate the Haynes jump control process. By observing and measuring with a microscope, a one-to-one correspondence can be obtained between the volume of the control gas at the front end of the control channel and the distance of the Haynes jump. Then, during actual control, the volume of the control gas can be adjusted according to this correspondence to control the distance of the Haynes jump.

[0032] Terminologically, the Haines jump refers to the physical phenomenon of fluid flow in porous media where the flow is not uniform but rather exhibits a dynamic, unbalanced state. When the fluid interface passes through irregular channels, its shape adjusts with changes in channel size, causing continuous changes in the interface curvature. This change not only affects the interface shape but also leads to continuous fluctuations in capillary pressure on both sides of the interface. Therefore, the meniscus expands and contracts intermittently, and due to the irregularity of the channels and the dynamic changes in the interface, the shape adjustment of the meniscus is usually abrupt. This leaping change indicates that the fluid does not flow uniformly through the porous medium but exhibits a leaping flow characteristic. This leaping phenomenon is called the Haines jump.

[0033] This invention discloses a microfluidic chip capable of quantitatively controlling the Haynes jump. Within the microfluidic chip body, a working fluid is controlled to pass through a constriction structure in the flow channel under pressure, generating a quantitatively controllable Haynes jump. A control channel is bypassed to the microfluidic chip body before the flow channel enters the constriction structure. After the working fluid flows past the control channel but before reaching the constriction, a lateral pressure is applied to the working fluid through a gas medium encapsulated in the control channel. By (pre-adjusting) the volume of the gas medium, the jump distance of the Haynes jump at the constriction structure is controlled. This invention enables the simulation and control of the Haynes jump process in fluids, thereby improving the realism of fluid flow simulation and better assisting in the simulation and analysis of fluid flow processes.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A microfluidic chip with controllable hopping quantity from the HAINS, characterized in that, include: The microfluidic chip body (1), the first syringe (5), the control channel (9), the second syringe (10), and the channel mounting channel (8) are included; among them, The microfluidic chip body (1) is provided with a flow channel (2), and the flow channel (2) is provided with a necking structure (7); the inlet of the flow channel (2) is connected to the injection port of the first syringe (5) through the inlet pipe (3) for introducing working fluid (6); the outlet of the flow channel (2) is connected to the atmosphere through the outlet pipe (4). One end of the control pipe (9) is connected to the injection port of the second syringe (10) for introducing liquid medium (12); the other end of the control pipe (9) is used to encapsulate a certain volume of gas medium (11) under the combined action of the liquid medium (12) and atmospheric pressure. The microfluidic chip body (1) is also provided with a pipe installation channel (8) for installing the control pipe (9); wherein, one end of the pipe installation channel (8) is connected to the flow channel (2) and is located between the inlet of the flow channel (2) and the necking structure (7); the other end of the pipe installation channel (8) is used to pass through the end of the control pipe (9) encapsulated with a gas medium (11); The distance of the Haines jump generated at the necking structure (7) is controlled by adjusting the volume of the encapsulated gas medium (11); the relationship between the volume of the encapsulated gas medium and the jump distance of the Haines jump is expressed as follows: V 0= LhDP 2 / ( P 1- P 2)； In the formula, V 0 represents the volume of the encapsulated gas medium; L This represents the jump distance of Haines. h The height of the microfluidic chip body; D The maximum diameter of the flow channel; P 1. To control the capillary pressure at the channel interface, P 2 represents the capillary pressure at the necking structure; P 1 = P 0+ γ cos( θ )(2 / d +2 / h ); P 2 = P 0+ γ cos( θ )(2 / D +2 / h ); In the formula, P 0 represents atmospheric environmental pressure; θ, γ These are the contact angle and surface tension of the working fluid, respectively. d The diameter is the smallest part of the necked structure.

2. The microfluidic chip with controllable hopping quantity according to claim 1, characterized in that, The microfluidic chip body (1) is made of a material with an elastic modulus greater than 10 MPa.

3. A microfluidic chip with controllable hopping speed according to claim 2, characterized in that, The microfluidic chip body (1) is made of quartz glass, silicon, polydimethylsiloxane, polymethyl methacrylate or cyclic olefin polymer.

4. A microfluidic chip with controllable hopping speed according to claim 2, characterized in that, The microfluidic chip body (1) adopts an upper and lower splicing structure, including an upper body and a lower body, and one or both of the upper body and the lower body are transparent.

5. A microfluidic chip with controllable hopping speed according to claim 1, characterized in that, The liquid medium (12) is an incompressible fluid that is not easily evaporated; The gas medium (11) is a compressible ideal gas; the working fluid (6) is an incompressible fluid.

6. A microfluidic chip with controllable hopping speed according to claim 5, characterized in that, The liquid medium (12) is hydraulic oil or water; the gas medium (11) is air or nitrogen; and the working fluid (6) is water, ethanol or glycerol.

7. A microfluidic chip with controllable hopping speed according to claim 1, characterized in that, Both the first syringe (5) and the second syringe (10) are equipped with a micro-injection pump for controlling the injection volume.

8. A microfluidic chip with controllable hopping speed according to claim 1, characterized in that, Also includes: A microscope camera was used to obtain the jump distance of the Haines jump generated at the constricted structure (7).

9. A method for operating the Haines jump-quantitatively controllable microfluidic chip as described in claim 1, characterized in that, include: The working fluid (6) in the first syringe (5) is introduced into the flow channel (2) inside the microfluidic chip body (1) through the inlet pipe (3), and the working fluid (6) flows in the flow channel (2); The liquid medium (12) in the second syringe (10) is introduced into the control pipe (9) through one end of the control pipe (9), and under the combined action of the liquid medium (12) and atmospheric pressure, a certain volume of gas medium (11) is sealed at the other end of the control pipe (9). One end of the control pipe (9) containing the gas medium (11) is installed into the pipe installation channel (8) set in the microfluidic chip body (1) and connected to the flow channel (2); The volume of the gas medium (11) encapsulated in the control pipe (9) is adjusted to quantitatively control the Haines jump generated at the constriction structure (7); wherein, quantitative control includes the control of the jump distance of the Haines jump.

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