A device and method for preventing wall-adhering microdroplet generation based on multiphase flow synergistic lift control.
By introducing an auxiliary phase flow channel system into a microfluidic chip, and utilizing the flow channel topology design and multiphase fluid synergy, the problem of droplet wettability and adhesion within the flow channel is solved, enabling contactless droplet transport, improving chip stability and throughput, and making it suitable for high-throughput single-cell analysis and drug microsphere encapsulation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING TECH UNIV
- Filing Date
- 2025-04-26
- Publication Date
- 2026-07-17
AI Technical Summary
In existing microfluidic chips, droplets in the flow channel encounter wetting and adhesion problems due to contact with the wall surface caused by microgravity, resulting in microsphere morphology distortion, reduced collection rate and flow channel blockage. Traditional hydrophobic treatment methods are limited in terms of process complexity, durability and cost.
It adopts a three-layer substrate composite architecture and integrates an auxiliary phase flow channel system. Through the synergistic effect of flow channel topology design and multiphase fluid, the auxiliary phase fluid forms a dynamic fluid barrier at the bottom of the flow channel to prevent droplets from adhering to the wall and uses interfacial tension to bind the droplets, thus achieving contactless transmission.
It reduces system complexity and reagent costs, improves chip mechanical stability and reusability, and solves the problems of droplet deformation and throughput reduction caused by adhesion in inclined channels and low-viscosity systems. It is suitable for high-throughput single-cell analysis and drug microsphere encapsulation.
Smart Images
Figure CN120421056B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of microfluidics, specifically to a device and method for generating anti-adherent microdroplets based on multiphase flow synergistic lift regulation. Background Technology
[0002] Microfluidics, as a key technology for precisely manipulating micro and nanofluids, plays an irreplaceable role in fields such as controlled drug release, biomimetic cell culture, and high-throughput detection. It achieves fluid dynamics regulation through a precisely designed network of channels within a microfluidic chip. The controllable fabrication of monodisperse microspheres is considered a crucial application area, requiring the generated microspheres to meet stringent requirements for morphological uniformity and high recovery rates in targeted drug delivery and biosensing applications. However, the wettability issue caused by the interaction between droplets and channel walls during microsphere generation and transport remains a major bottleneck affecting chip performance.
[0003] When the plane on which the microfluidic chip is placed forms an angle with the direction of microgravity, under conditions of low flow rate and low viscosity, the droplet is subjected to microgravity (i.e., the resultant force of gravity and buoyancy, expressed as...). Droplets deflect towards the wall surface under microgravity, causing dynamic wetting behavior and even wall adhesion. This phenomenon can lead to microsphere morphology distortion, decreased collection efficiency, and channel blockage, severely limiting system reliability. To address this issue, existing technologies typically reduce droplet or microsphere adhesion to the wall surface by hydrophobic treatment of the channel surface. Commonly used techniques include:
[0004] 1. Hydrophobic Microstructure Fabrication: By constructing micron-scale papillary structures on the inner wall of the flow channel, the apparent contact angle is increased to over 150°, thereby inhibiting droplet expansion and adhesion on the wall surface. However, this technology suffers from poor uniformity in fabricating three-dimensional irregular flow channels, and the surface micro / nano structures are easily clogged by biomolecules or other suspended particles, resulting in a significant decrease in hydrophobic properties after cleaning. Furthermore, the use of such microstructures faces the challenge of subsequent cleaning, as liquid residue within the microstructure gaps may cause cross-contamination or reduce chip reusability.
[0005] 2. Surface Coating Treatment: By coating the flow channel surface with hydrophobic materials (such as silane or fluoride coatings), the hydrophobic properties are improved by reducing surface energy, thus reducing droplet adhesion to the flow channel walls. However, this coating technology has poor long-term stability. In actual operation, the coating is easily detached due to repeated liquid scouring or mechanical friction, leading to a rapid decline in the hydrophobic effect. Furthermore, some hydrophobic materials may react with the chip's chemical environment or the liquids being processed, further affecting its applicability and lifespan.
[0006] While the aforementioned methods alleviate the wettability problem between microdroplets and the wall surface to some extent, they still face many limitations in terms of process complexity, durability, cost, and reusability. Especially in applications requiring high throughput and long-term continuous operation, these traditional hydrophobic treatment methods cannot effectively meet the demands. Therefore, developing a more efficient, stable, easily implemented surface wettability solution suitable for complex chip structures has become a key technological breakthrough direction for improving the performance of microfluidic chips. Summary of the Invention
[0007] This invention provides a device and method for generating anti-adhering microdroplets based on multiphase flow synergistic lift control. It addresses the issue of droplet adhesion caused by microgravity contact with the wall surface during droplet movement within the microfluidic chip, while minimizing the introduction of a third-phase solution and reducing manufacturing and maintenance costs. The core innovation of this invention lies in achieving contactless droplet transport between the droplet and the wall surface through channel topology design and the synergistic effect of multiphase fluids. Specifically, this chip employs a three-layer substrate composite architecture, integrating an auxiliary phase flow channel system on the microgravity side of the droplet transport channel. When the discrete phase liquid flow is sheared by the symmetrically distributed continuous phase at the flow focusing structure to form monodisperse droplets, the geometric relationship between the auxiliary phase flow channel and the gravity direction is precisely designed (for example, in a water-in-oil system, because the density of the water phase is greater than that of the oil phase, the droplets are prone to sinking under the influence of microgravity, while the shear forces on both sides of the droplet are symmetrical and cancel each other out, preventing them from shifting to either side; therefore, the auxiliary phase flow channel is placed at the bottom of the channel). A dynamic fluid barrier is formed at the bottom of the transport channel using the auxiliary phase fluid. This barrier has a dual control mechanism: First, by adding an auxiliary phase flow channel at the bottom of the transport channel, the insolubility of the discrete phase and the auxiliary phase is utilized; when the droplet approaches the wall, the auxiliary phase prevents it from adhering to the wall through viscous support. Second, if the selected continuous phase and auxiliary phase are immiscible solutions, interfacial tension can be used to further bind the droplet to the interface, thereby enhancing the anti-adhesion effect. The advantage of this system lies in its high flexibility—the auxiliary phase and the continuous phase can be the same solution to reduce the introduction of a third phase, or they can be immiscible solutions to enhance the control effect. This not only reduces the system complexity and reagent cost, but also avoids physical modification designs such as micro-nano structures or coatings, enabling the chip to have both excellent mechanical stability and reusability, and significantly reducing manufacturing and maintenance costs.
[0008] To address the aforementioned problems, this invention provides the following technical solution: The first aspect of this disclosure provides a device for generating anti-wall-adhering microdroplets based on a multiphase flow synergistic lift control method, comprising a substrate, an upper substrate, a middle substrate, and a lower substrate. A concave flow channel is provided below the upper substrate, comprising a discrete phase flow channel, a continuous phase flow channel, and a droplet transport flow channel, all three located at the same horizontal level and interconnected. The continuous phase flow channel is symmetrically located on both sides of the discrete phase flow channel. An auxiliary phase flow channel is provided in a microgravity configuration on the middle substrate. Multiple porous outlets are uniformly distributed at the connection between the microgravity side of the droplet transport flow channel and the auxiliary phase flow channel near the droplet transport channel side. The porous outlet is connected to the droplet transport channel; one end of the discrete phase channel, the continuous phase channel, and the auxiliary phase channel is respectively provided with a discrete phase channel inlet, a continuous phase channel inlet, and an auxiliary phase channel inlet, and one end of the droplet transport channel is provided with a channel outlet; the discrete phase channel inlet and the continuous phase channel inlet are through holes in the upper substrate, through which the discrete phase and the continuous phase are respectively introduced; the auxiliary phase channel inlet is a through hole penetrating the upper substrate and the middle substrate, through which the auxiliary phase is introduced; the auxiliary phase introduced into the auxiliary phase channel forms a dynamic liquid film layer on the bottom surface of the droplet transport channel, and the microdroplets formed by the continuous phase shearing the discrete phase are kept at a certain height and flow out stably from the droplet transport channel outlet by the upward impact of the auxiliary phase.
[0009] Furthermore, the cross-section of the porous outlet is circular or rectangular, and it has at least two rows communicating with the droplet transport channel.
[0010] Furthermore, the solution introduced into the discrete phase channel is immiscible with the solution in the continuous phase channel, the solution introduced into the auxiliary phase channel is immiscible with the discrete phase solution, and the solution introduced into the continuous phase channel is either a miscible solution or an immiscible solution with the solution in the auxiliary phase channel.
[0011] Furthermore, when the solution introduced into the continuous phase channel and the solution introduced into the auxiliary phase channel are miscible solutions, the solution introduced into the discrete phase channel is a sodium alginate solution, the solution introduced into the continuous phase channel is liquid paraffin or dimethyl silicone oil, and the solution introduced into the auxiliary phase channel is liquid paraffin or dimethyl silicone oil.
[0012] When the solution introduced into the continuous phase channel and the solution introduced into the auxiliary phase channel are immiscible solutions, the solution introduced into the discrete phase channel is pure water, the solution introduced into the continuous phase channel is fluorinated oil, and the solution introduced into the auxiliary phase channel is dimethyl silicone oil.
[0013] Furthermore, the flow cross-sectional shape of the discrete phase flow channel, the continuous phase flow channel, and the auxiliary phase flow channel can be circular or rectangular.
[0014] Furthermore, the upper substrate, middle substrate, and lower substrate are photosensitive resin or plexiglass with light transmittance.
[0015] Furthermore, it also includes a microfluidic chip, a solution supply bottle, a pressure pump, a beaker, and a microscope imaging device: the microfluidic chip is located below the microscope imaging device, the discrete phase flow channel inlet, the continuous phase flow channel inlet, and the auxiliary phase flow channel inlet are respectively connected to the solution supply bottle through hoses and are located below the liquid surface, the solution supply bottle is sealed, another hose is provided on the liquid surface of the solution supply bottle and is located above the liquid surface, the other end of which is connected to the pressure pump, and the droplet transport flow channel outlet is connected to the collecting beaker through a hose.
[0016] The second aspect of this disclosure provides a method for preventing the formation of wall-adhering microdroplets based on a multiphase flow synergistic lift control method, the method comprising:
[0017] Step 1: Introduce an auxiliary phase that is insoluble in or soluble in the continuous phase into the inlet of the auxiliary phase flow channel, and let it flow out from the porous outlet to pre-fill the droplet transport channel and form a dynamic liquid film.
[0018] Step 2: Next, drive the pressure pump to inject the continuous phase into the inlet of the continuous phase channel, adjust the flow rate ratio of the continuous phase to the auxiliary phase, form a stable interface channel, and form a dynamic liquid film layer at the bottom of the droplet transport channel.
[0019] Step 3: Finally, introduce the discrete phase into the inlet of the discrete phase channel and adjust the supply pressure values of the discrete phase and the continuous phase so that the discrete phase is sheared at the intersection of the discrete phase channel and the continuous phase channel to form a stable microdroplet.
[0020] Step 4: If the microdroplets sink due to microgravity, when the auxiliary phase (20) and the continuous phase (19) are miscible solutions, the auxiliary phase (20) is injected upward through the porous outlet (9) to form a viscous flow field opposite to that of the sinking microdroplets. The microdroplets are subjected to viscous lift force opposite to the direction of microgravity at the immiscible interface. , , For fluid viscosity, Let v be the velocity gradient, i.e., the rate of change of fluid velocity v in the vertical z direction with spatial position, and A be the area of action. By adjusting the flow rate of the auxiliary phase (20), the magnitude of the viscous lift can be linearly controlled to achieve dynamic equilibrium of the microdroplet suspension height. The microdroplets are collected after flowing out of the droplet transport channel outlet (8) together with the continuous phase (19) and the auxiliary phase (20). When the auxiliary phase (20) and the continuous phase (19) are immiscible solutions, the interfacial tension between the two is... In synergy with the flow rate of the auxiliary phase (20), the liquid film thickness is changed by adjusting the flow rate. , For liquid film thickness, To increase the flow rate of the auxiliary phase (20), the sinking microdroplets are confined within the potential well range of the liquid-liquid interface energy barrier, forming a stable two-dimensional suspension transport. They are collected after flowing out of the droplet transport channel outlet (8) together with the continuous phase (19) and the auxiliary phase (20). If the microdroplets float due to microgravity, the entire microfluidic chip (13) can be inverted with the porous outlet (9) on the upper side.
[0021] Furthermore, the microdroplets are water-in-oil microdroplets.
[0022] This disclosure has at least the following advantages over the prior art:
[0023] Compared to traditional anti-adhesion solutions that rely on surface modification, this design achieves three major technical advantages through innovative flow channel structure and matching of fluid dynamic parameters: (1) It is compatible with auxiliary phase-continuous phase combinations of arbitrary solubility, which can reduce the introduction of a third phase (when the auxiliary phase is homogeneous with the continuous phase), thereby reducing system complexity and reagent costs; (2) It dynamically controls the droplet suspension state based on adjustable fluid parameters (flow rate, viscosity, interfacial tension), avoiding the limitations of working condition adaptability caused by fixed surface treatment; (3) The physical modification design without micro / nano structures or coatings gives the chip excellent mechanical stability and reusability, significantly reducing manufacturing and maintenance costs. This technology is particularly suitable for scenarios such as drug microsphere encapsulation with strict biocompatibility requirements and high-throughput single-cell analysis, and can effectively solve the problems of deformation, contamination, and throughput reduction caused by droplet adhesion in traditional microfluidic chips in inclined flow channels and low-viscosity systems. Attached Figure Description
[0024] To gain a more complete understanding of this disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, wherein:
[0025] Figure 1 This is a microfluidic chip structure diagram based on a multiphase flow synergistic lift control method according to an embodiment of the present invention.
[0026] Figure 2 yes Figure 1 The structure shown is a front view of the microfluidic chip after bonding.
[0027] Figure 3 yes Figure 1 The diagram shows a cross-sectional view of the chip shearing droplet position relationship.
[0028] Figure 4 This is a schematic diagram of a cross-section of a microfluidic chip's droplet transport channel.
[0029] Figure 5 This is a schematic diagram showing how microdroplets, under the influence of gravity, gradually deviate towards the wall and eventually suspend at the liquid film interface to continue transport.
[0030] Figure 6 This is a schematic diagram of the observation area of an optical microscope.
[0031] Figure 7 This is a schematic diagram of a microfluidic system for preventing wall adhesion based on the multiphase flow synergistic lift control method.
[0032] Explanation of reference numerals in the attached figures: 1. Upper substrate; 2. Middle substrate; 3. Lower substrate; 4. Discrete phase flow channel; 5. Continuous phase flow channel; 6. Auxiliary phase flow channel; 7. Droplet transport flow channel; 8. Droplet transport flow channel outlet; 9. Porous outlet; 10. Discrete phase flow channel inlet; 11. Continuous phase flow channel inlet; 12. Auxiliary phase flow channel inlet; 13. Microfluidic chip; 14. Liquid supply bottle; 15. Pressure pump; 16. Beaker; 17. Microscope imaging device; 18. Discrete phase; 19. Continuous phase; 20. Auxiliary phase; 21. Liquid film layer. Detailed Implementation
[0033] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.
[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.
[0035] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.
[0036] The following is combined Figures 1 to 7As shown, this embodiment of the invention provides a device for generating anti-wall-adhering microdroplets based on a multiphase flow synergistic lift control method, comprising a substrate, the substrate including an upper substrate 1, a middle substrate 2, and a lower substrate 3. The upper substrate 1 has a main flow channel, a shear flow channel, and a droplet transport flow channel 7 below it. The middle substrate 2 has an auxiliary phase flow channel 6 below it. The three substrates are combined to form the entire chip. A concave flow channel is provided below the upper substrate 1, the flow channel including a discrete phase flow channel 4, a continuous phase flow channel 5, and a droplet transport flow channel 7, all three located at the same horizontal level and interconnected. The continuous phase flow channel 5 is symmetrically located on both sides of the discrete phase flow channel 4. The shape is not limited and can be conical or rectangular; the continuous phase flow channels 5 on both sides converge at the discrete phase flow channel 4 to form a flow channel focusing structure; an auxiliary phase flow channel 6 is provided below the middle substrate 2, and the auxiliary phase flow channel 6 is located below the discrete phase flow channel 4 and the droplet transport flow channel 7; multiple porous outlets 9 are evenly distributed at the connection between the bottom side of the droplet transport flow channel 7 and the upper side of the auxiliary phase flow channel 6, and the porous outlets 9 communicate with the droplet transport flow channel 7; one end of the discrete phase flow channel 4, the continuous phase flow channel 5, and the auxiliary phase flow channel 6 is respectively provided with a discrete phase flow channel inlet 10, a continuous phase flow channel inlet 11, and an auxiliary phase flow channel inlet 12, as shown below. Figure 2 As shown, one end of the droplet transport channel 7 is provided with a channel outlet 8; the discrete phase channel inlet 10 and the continuous phase channel inlet 11 are through holes in the upper substrate 1 through which the discrete phase 18 and the continuous phase 19 are respectively introduced; the auxiliary phase channel inlet 12 is a through hole penetrating the upper substrate 1 and the middle substrate 2 through which the auxiliary phase 20 is introduced; the auxiliary phase 20 introduced into the auxiliary phase channel 6 forms a dynamic liquid film layer 21 on the bottom surface of the droplet transport channel 7, such as... Figure 5 As shown, under the influence of gravity, buoyancy, and other disturbing forces, the microdroplets gradually shift towards the bottom surface. The microdroplets formed by the shearing of the discrete phase 18 by the continuous phase 19 are held at a certain height and stably flow out from the droplet transport channel outlet 8 by the upward impact of the auxiliary phase 20. Figure 3 As shown.
[0037] In this embodiment, the flow channel is divided into upper and lower structures inside the substrate. The discrete phase flow channel 4, the continuous phase flow channel 5, and the droplet transport flow channel 7 are located below the upper substrate 1, and the auxiliary phase flow channel 6 is located below the middle substrate 2. Spatially, it is located below the discrete phase flow channel 4 and the droplet transport flow channel 7, and has a porous outlet 9 with two rows of circular holes in the flow channel, which communicates with the droplet transport flow channel 7 and covers the entire bottom surface of the droplet transport flow channel 7. The diameter of the circular holes is about 0.2-0.4 times the width of the droplet transport flow channel 7, and they are symmetrically distributed about the center line of the flow channel. The spacing between the circular holes along the flow channel direction is 1-2 circular hole diameters.
[0038] Specifically, the cross-section of the porous outlet 9 is circular, rectangular, triangular, etc., and it has at least two rows communicating with the droplet transport channel 7, such as... Figure 6As shown, the diameter of the circular holes is approximately 0.2-0.4 times the width of the droplet transport channel, and its size is less than 0.8 times the channel width. They are symmetrically distributed about the center line of the channel, and the spacing between the circular holes along the channel direction is 1-2 circular hole diameters. The number and arrangement rules of the multi-hole outlets 9 in this invention are not limited, and they can fill the entire channel according to the length of the droplet transport channel.
[0039] Specifically, the solution introduced into the discrete phase channel 4 is immiscible with the solution in the continuous phase channel 5, the solution introduced into the auxiliary phase channel 6 is immiscible with the discrete phase 18, and the solution introduced into the continuous phase channel 5 is either a miscible solution or an immiscible solution with the solution in the auxiliary phase channel 6.
[0040] Specifically, when the solution introduced into the continuous phase channel 5 and the solution introduced into the auxiliary phase channel 6 are miscible solutions, the solution introduced into the discrete phase channel 4 is a sodium alginate solution with a mass fraction of 1%, the solution introduced into the continuous phase channel 5 is liquid paraffin or dimethyl silicone oil containing 3% Span 80, and the solution introduced into the auxiliary phase channel 6 is liquid paraffin or dimethyl silicone oil containing 3% Span 80.
[0041] When the solution introduced into the continuous phase channel 5 and the solution introduced into the auxiliary phase channel 6 are immiscible solutions, the solution introduced into the discrete phase channel 4 is pure water, the solution introduced into the continuous phase channel 5 is fluorinated oil, and the solution introduced into the auxiliary phase channel 6 is dimethyl silicone oil.
[0042] In this embodiment, an auxiliary phase channel 6 is added at the bottom of the transport channel to restrict droplet adhesion to the wall and does not restrict the solubility relationship between the auxiliary phase 20 and the continuous phase 19; they can be the same solution or immiscible solutions. When the discrete phase 18 is sheared into individual microdroplets at the channel junction, due to the symmetry of the continuous phase channels 5 on both sides, the shear forces on both sides of the microdroplets are large and cancel each other out, so they hardly adhere to the sides. In the vertical direction, due to the influence of microgravity, the microdroplets will shift towards the microgravity side, so the auxiliary phase channel 6 is located on the microgravity side. The examples described in this invention are all water-in-oil droplets, so the auxiliary phase channel 6 is located at the bottom. Compared with the conventional anti-adhesion microfluidic chip 13, the microfluidic chip 13 in this invention does not restrict the solubility relationship between the auxiliary phase 20 and the continuous phase 19, which can reduce the introduction of a third phase solution, greatly expanding the types of continuous phase 19 that can be used and the separation and recycling of the mixture. When the continuous phase 19 and the auxiliary phase 20 are the same liquid, when the microdroplet approaches the microgravity sidewall under the influence of microgravity, the microdroplet will be impacted upward by the auxiliary phase 20 flowing out from the porous outlet 9. Since the microdroplet and the auxiliary phase 20 are a liquid phase, they can provide the microdroplet with a vertically upward viscous support force, which is sufficient to overcome microgravity and thus make the microdroplet suspend. The magnitude of this viscous force can be controlled by adjusting the flow rate of the auxiliary phase 20. If the continuous phase 19 and the auxiliary phase 20 are immiscible, the microdroplet can be further bound to the liquid film interface by interfacial tension. The thickness of the dynamic liquid film layer 21 can be controlled by adjusting the flow rate of the auxiliary phase 20, thereby adjusting the height of the microdroplet suspended in the flow channel.
[0043] Specifically, the flow cross-sectional shape of the discrete phase flow channel 4, the continuous phase flow channel 5, and the auxiliary phase flow channel 6 can be circular or rectangular, and their size is not limited.
[0044] Specifically, the upper substrate 1, the middle substrate 2, and the lower substrate 3 are made of light-transmitting resin or plexiglass.
[0045] Specifically, it also includes a microfluidic chip 13, a liquid supply bottle 14, a pressure pump 15, a beaker 16, and a microscope imaging device 17: such as Figure 6 and Figure 7 As shown, the microfluidic chip 13 is located below the microscope imaging device 17. The pressure pump 15 drives each liquid supply bottle 14 to introduce liquid into each phase inlet. The pressure value is adjusted to a stable state. The condition of the droplet transport channel 7 is observed using the microscope imaging device 17. The discrete phase channel inlet 10, the continuous phase channel inlet 11, and the auxiliary phase channel inlet 12 are connected to the solution supply bottle 14 via Teflon tubing and are located below the liquid surface. The solution supply bottle 14 is sealed. Another tubing is located above the liquid surface of the solution supply bottle 14, with the other end connected to the pressure pump 15. The droplet transport channel outlet 8 is connected to the collecting beaker 16 via tubing. Figure 3 ,4 As shown in Figure 5, when the microdroplets sink under the influence of microgravity, the auxiliary phase 20 flows out from the bottom of the droplet transport channel 7, giving the droplets an upward lift force and forming a dynamic liquid film layer 21. The interface formed by the liquid film layer 21 and the continuous phase 19 further slows down the sinking of the microdroplets, enabling the droplets to achieve a suspension effect, preventing them from adhering to the wall and forming a flow, and finally entering the beaker 16 in a suspended state.
[0046] In one embodiment, the geometry of the anti-wall-adhering microfluidic chip 13 based on the multiphase flow synergistic lift control method is not limited, and can be a thin cuboid, a thin cylinder, etc. The material used to manufacture it can be a non-metallic material with good light transmittance, such as plexiglass, acrylic glass, glass, PDMS, etc., or it can be an opaque metallic material. Using a transparent material facilitates observation.
[0047] In one embodiment, the microfluidic chip substrate 1 can be engraved on the substrate using an engraving machine and then bonded together; or a mold can be manufactured using 3D printing technology and then cast with PDMS; or etching can be performed.
[0048] Another aspect of this disclosure provides a method for preventing the formation of wall-adhering microdroplets based on a multiphase flow synergistic lift control method, which employs, as follows: Figure 1 The microfluidic chip 13 shown is implemented using a method that specifically includes the following steps:
[0049] Step 1: Introduce auxiliary phase 20, which is insoluble in or soluble in continuous phase 19, into auxiliary phase inlet 12 and let it flow out from porous outlet 9, pre-filling droplet transport channel 7 to form a dynamic liquid film.
[0050] Step 2: Next, drive the pressure pump to inject continuous phase 19 into the inlet 11 of the continuous phase channel. Adjust the flow rate ratio between continuous phase 19 and auxiliary phase 20. Due to the flow rate difference, a stable interface channel can be formed at the bottom of the droplet transport channel 7, forming a dynamic liquid film layer 21 at the bottom of the droplet transport channel 7. Figure 4 As shown;
[0051] Step 3: Finally, introduce discrete phase 18 into discrete phase inlet 10, and adjust the liquid supply pressure of discrete phase 18 and continuous phase 19 so that discrete phase 18 is sheared at the intersection of discrete phase channel 4 and continuous phase channel 5 to form a stable microdroplet.
[0052] Step 4: If the microdroplets sink due to microgravity, when the auxiliary phase 20 and the continuous phase 19 are miscible solutions, the auxiliary phase 20 is injected upward through the porous outlet 9 to form a reverse viscous flow field relative to the sinking microdroplets, such as... Figure 3 As shown, microdroplets experience viscous lift at the immiscible interface, which is opposite to the direction of microgravity. , , For fluid viscosity, Let V be the velocity gradient, i.e., the rate of change of fluid velocity v in the vertical z direction with spatial position, and A be the area of action. By adjusting the flow rate of auxiliary phase 20, the magnitude of viscous lift can be linearly controlled, achieving dynamic equilibrium of the microdroplet suspension height. The microdroplets are then collected after flowing out of the droplet transport channel outlet 8 along with the continuous phase 19 and auxiliary phase 20. When auxiliary phase 20 and continuous phase 19 are immiscible solutions, the interfacial tension between them... In synergy with the flow rate of auxiliary phase 20, the liquid film thickness can be changed by adjusting the flow rate. , For liquid film thickness, To assist the flow rate of phase 20, the sinking microdroplets are confined within the potential well range of the liquid-liquid interface energy barrier, forming stable two-dimensional suspension transport, such as... Figure 5 As shown, the microdroplets flow out of the droplet transport channel outlet 8 along with the continuous phase 19 and the auxiliary phase 20 and are then collected. If the microdroplets float due to microgravity (the resultant force of gravity and buoyancy), the entire microfluidic chip 13 can be inverted with the porous outlet 9 on the upper side. The microdroplets may not necessarily sink due to microgravity (the resultant force of gravity and buoyancy), but may float, depending on the density of the dispersed phase and the density of the continuous phase. This invention greatly reduces the possibility of the generated microdroplets contacting the inner wall, thereby improving the stability of the droplet preparation process and the reliability of long-term operation.
[0053] Specifically, the microdroplets are water-in-oil microdroplets; the present invention is also applicable to the preparation of micron-sized dual emulsion microspheres, and by changing the channel size and pressure ratio, suspension flow of particles of different sizes at different heights can be achieved.
[0054] The beneficial effects of this invention are as follows: Compared with traditional anti-adhesion schemes that rely on surface modification, this design achieves three major technical advantages through innovative flow channel structure and matching of fluid dynamic parameters: 1. It is compatible with auxiliary phase-continuous phase combinations of arbitrary solubility. When the auxiliary phase and the continuous phase are of the same nature, the introduction of a third phase can be reduced, thereby lowering system complexity and reagent costs; 2. Based on adjustable fluid parameters such as flow rate, viscosity, and interfacial tension, the droplet suspension state is dynamically controlled, avoiding the limitations of working condition adaptability caused by fixed surface treatment; 3. The physical modification design without micro / nano structures or coatings gives the chip excellent mechanical stability and reusability, significantly reducing manufacturing and maintenance costs. This technology is particularly suitable for scenarios such as drug microsphere encapsulation with strict biocompatibility requirements and high-throughput single-cell analysis, and can effectively solve the problems of deformation, contamination, and throughput reduction caused by droplet adhesion in traditional microfluidic chips in inclined flow channels and low-viscosity systems.
[0055] Although the present disclosure has been illustrated and described in detail in the accompanying drawings and the foregoing description, such illustrations and descriptions should be considered illustrative or exemplary rather than limiting.
[0056] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined and / or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.
[0057] Although this disclosure has been shown and described with reference to specific exemplary embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made to this disclosure without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents. Therefore, the scope of this disclosure should not be limited to the above embodiments, but should be defined not only by the appended claims, but also by their equivalents.
Claims
1. A device for generating anti-wall-adhering microdroplets based on multiphase flow synergistic lift regulation, comprising a substrate, characterized in that: The substrate includes an upper substrate (1), a middle substrate (2), and a lower substrate (3). A concave flow channel is provided below the upper substrate (1). The flow channel includes a discrete phase flow channel (4), a continuous phase flow channel (5), and a droplet transport flow channel (7). The three are located at the same horizontal level and are interconnected. The continuous phase flow channel (5) is symmetrically located on both sides of the discrete phase flow channel (4). An auxiliary phase flow channel (6) is provided below the middle substrate. A porous outlet (9) is evenly distributed at the connection between the bottom side of the droplet transport flow channel (7) and the upper side of the auxiliary phase flow channel (6). The porous outlet (9) is connected to the droplet transport flow channel (7). A discrete phase flow channel inlet (1) is provided at one end of each of the discrete phase flow channel (4), the continuous phase flow channel (5), and the auxiliary phase flow channel (6). 0) Continuous phase inlet (11) and auxiliary phase inlet (12), one end of the droplet transport channel (7) is provided with a channel outlet (8); the discrete phase inlet (10) and the continuous phase inlet (11) are through holes in the upper substrate (1) through which the discrete phase (18) and the continuous phase (19) are respectively introduced; the auxiliary phase inlet (12) is a through hole penetrating the upper substrate (1) and the middle substrate (2) through which the auxiliary phase (20) is introduced; the auxiliary phase (20) introduced into the auxiliary phase channel (6) forms a dynamic liquid film layer (21) on the bottom surface of the droplet transport channel (7); the microdroplets formed by the continuous phase (19) shearing the discrete phase (18) are subjected to the upward impact of the auxiliary phase (20) and maintain a certain height and flow out from the droplet transport channel outlet (8).
2. The anti-wall-adhering microdroplet generation device based on multiphase flow synergistic lift regulation method according to claim 1, characterized in that: The cross-section of the porous outlet (9) is circular or rectangular, and it has at least two rows that communicate with the droplet transport channel (7).
3. The anti-wall-adhering microdroplet generation device based on multiphase flow synergistic lift regulation method according to claim 1, characterized in that: The solution introduced into the discrete phase channel (4) is immiscible with the solution in the continuous phase channel (5), the solution introduced into the auxiliary phase channel (6) is immiscible with the discrete phase (18), and the solution introduced into the continuous phase channel (5) is either a soluble solution or an immiscible solution with the solution in the auxiliary phase channel (6).
4. The anti-wall-adhering microdroplet generation device based on multiphase flow synergistic lift regulation method according to claim 3, characterized in that: When the solution introduced into the continuous phase channel (5) and the solution introduced into the auxiliary phase channel (6) are miscible solutions, the solution introduced into the discrete phase channel (4) is sodium alginate solution, the solution introduced into the continuous phase channel (5) is liquid paraffin or dimethyl silicone oil, and the solution introduced into the auxiliary phase channel (6) is liquid paraffin or dimethyl silicone oil. When the solution introduced into the continuous phase channel (5) and the solution introduced into the auxiliary phase channel (6) are immiscible solutions, the solution introduced into the discrete phase channel (4) is pure water, the solution introduced into the continuous phase channel (5) is fluorinated oil, and the solution introduced into the auxiliary phase channel (6) is dimethyl silicone oil.
5. The anti-wall-adhering microdroplet generation device based on multiphase flow synergistic lift regulation method according to claim 1, characterized in that: The flow cross-sectional shape of the discrete phase flow channel (4), the continuous phase flow channel (5), and the auxiliary phase flow channel (6) can be circular or rectangular.
6. The anti-wall-adhering microdroplet generation device based on multiphase flow synergistic lift regulation method according to claim 1, characterized in that: The upper substrate (1), middle substrate (2) and lower substrate (3) are photosensitive resin or plexiglass with light transmittance.
7. The anti-wall-adhering microdroplet generation device based on multiphase flow synergistic lift regulation method according to claim 1, characterized in that: It also includes a microfluidic chip (13), a liquid supply bottle (14), a pressure pump (15), a beaker (16), and a microscope imaging device (17): The microfluidic chip (13) is located below the microscope imaging device (17). The discrete phase flow channel inlet (10), the continuous phase flow channel inlet (11), and the auxiliary phase flow channel inlet (12) are respectively connected to the solution supply bottle (14) through hoses and are located below the liquid surface. The solution supply bottle (14) is sealed. Another hose is provided on the liquid surface of the solution supply bottle (14) and is located above the liquid surface. The other end is connected to the pressure pump (15). The droplet transport channel outlet (8) is connected to the collecting beaker (16) through a hose.
8. A method for using the anti-wall-adhering microdroplet generation device based on multiphase flow synergistic lift control method as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Introduce an auxiliary phase (20) that is insoluble in or soluble in the continuous phase (19) into the auxiliary phase inlet (12), and let it flow out from the porous outlet (9) to pre-fill the droplet transport channel (7) and form a dynamic liquid film; Step 2: Next, drive the pressure pump to inject the continuous phase (19) into the inlet (11) of the continuous phase channel, adjust the flow rate ratio of the continuous phase (19) and the auxiliary phase (20) to form a stable interface channel, and form a dynamic liquid film layer (21) at the bottom of the droplet transport channel (7). Step 3: Finally, introduce discrete phase (18) into the discrete phase inlet (10), and adjust the liquid supply pressure of discrete phase (18) and continuous phase (19) so that discrete phase (18) is sheared at the junction of discrete phase channel (4) and continuous phase channel (5) to form a stable microdroplet. Step 4: If the microdroplets sink due to microgravity, when the auxiliary phase (20) and the continuous phase (19) are miscible solutions, the auxiliary phase (20) is injected upward through the porous outlet (9) to form a viscous flow field opposite to that of the sinking microdroplets. The microdroplets are subjected to viscous lift force opposite to the direction of microgravity at the immiscible interface. , , For fluid viscosity, Let v be the velocity gradient, i.e., the rate of change of fluid velocity v in the vertical z direction with spatial position, and A be the area of action. By adjusting the flow rate of the auxiliary phase (20), the magnitude of the viscous lift can be linearly controlled to achieve dynamic equilibrium of the microdroplet suspension height. The microdroplets are collected after flowing out of the droplet transport channel outlet (8) together with the continuous phase (19) and the auxiliary phase (20). When the auxiliary phase (20) and the continuous phase (19) are immiscible solutions, the interfacial tension between the two is... In synergy with the flow rate of the auxiliary phase (20), the liquid film thickness is changed by adjusting the flow rate. , For liquid film thickness, The auxiliary phase (20) flow rate is used to confine the sinking microdroplets within the potential well range of the liquid-liquid interface energy barrier, forming a stable two-dimensional suspension transport, and they are collected after flowing out of the droplet transport channel outlet (8) together with the continuous phase (19) and the auxiliary phase (20); If the microdroplets float due to microgravity, simply invert the entire microfluidic chip (13) and position the porous outlet (9) on the top.
9. The method for the anti-wall-adhering microdroplet generation device based on multiphase flow synergistic lift regulation according to claim 8, characterized in that: The microdroplets are water-in-oil microdroplets.