A method for regulating the droplet migration speed in a microchannel based on nanoparticle surfactant

Abstract

The present application relates to the field of droplet transport speed regulation, and discloses a method for regulating the droplet transport speed in a microchannel based on nanoparticle surfactant, which specifically comprises the reaction of carboxyl-functionalized nanoparticles in an aqueous phase and amino-terminated polydimethylsiloxane in an oil phase at an oil-water interface to generate nanoparticle surfactant. The nanoparticle surfactant can significantly reduce the oil-water interfacial tension, and the interface adsorbed by the nanoparticle also exhibits special mechanical properties such as viscoelasticity and bending resistance, so as to regulate the droplet transport speed in the microchannel.

Description

Technical Field

[0001] This invention belongs to the field of droplet transport velocity control technology in microchannels, and relates to a method for regulating droplet transport velocity in microchannels based on nanoparticle surfactants. Background Technology

[0002] Controlling droplet migration velocity is of significant research importance in numerous fields. For example, in biological sample analysis, droplet migration velocity can be used to regulate the mixing degree and reaction time of biomolecules, thereby improving the accuracy and sensitivity of the analysis. In drug delivery systems, droplets can act as microreactors; by controlling droplet migration velocity, precise drug release and targeted delivery can be achieved. Furthermore, in disease diagnosis, droplet migration velocity can be used to regulate the contact time and reaction degree between biomarkers and detection reagents, thereby improving diagnostic accuracy and reliability. In the field of nano-enhanced oil recovery, studying the migration velocity of water-in-oil emulsion droplets is crucial for improving oil recovery rates. It is evident that droplet migration velocity has a wide range of applications and is of great importance across various fields. Precise control of droplet migration velocity can achieve multiple functions and applications, providing new ideas and methods for development in various fields.

[0003] Chinese patent CN105797792A proposes a "low-voltage dielectric droplet driving method on a digital microfluidic chip," but this method uses a water-based surfactant environment and is not suitable for transporting water-based droplets. Chinese patent CN111255778A proposes a "method for optically controlled droplet movement, optically controlled droplet movement microtube and its fabrication method," which uses light to regulate droplet movement. This method requires high ambient light levels and, due to the insignificant effect of the Laplace force on larger droplets, cannot achieve wide-range control of droplet movement speed. Chinese patent CN107497509A proposes a "microfluidic system and its driving method," which uses applied voltage signals to control droplets. This method is complex and costly to implement. Chinese patent CN115583054A proposes a "droplet movement speed control device and testing method based on viscosity adjustment," which controls droplet speed through temperature and viscosity. However, in actual oil extraction processes, ambient temperature and viscosity cannot be controlled. In summary, existing technologies for controlling the transport speed of microdroplets require changes to the environment and structure, resulting in low operability and flexibility in practical applications. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for regulating the droplet transport velocity in a microchannel based on nanoparticle surfactants, thereby solving the technical problems of poor operability and low flexibility in regulating droplet transport velocity in the prior art.

[0005] This invention is achieved through the following technical solution:

[0006] A method for regulating droplet transport velocity in microchannels based on nanoparticle surfactants involves introducing an aqueous solution of carboxyl-functionalized nanoparticles into the dispersed phase inlet of a microfluidic chip, and introducing an amino-terminated polymer oil solution into both the continuous phase inlet and the accelerating phase inlet; the carboxyl-functionalized nanoparticles react with the amino-terminated polymer to generate water-in-oil droplets with nanoparticle surfactants coated on their surfaces.

[0007] Preferably, the particle size range of the carboxyl functionalized nanoparticles is 10–50 nm.

[0008] Preferably, the concentration of the aqueous solution of the carboxyl-functionalized nanoparticles is 0.001 wt.% to 2.5 wt.%.

[0009] Preferably, the concentration of the amino-terminated polymer oil solution is 0.1 wt.% to 5 wt.%.

[0010] Preferably, the flow rate ratio of the continuous phase inlet amino-terminated polymer oil solution to the dispersed phase inlet carboxyl-functionalized nanoparticle aqueous solution is (1-30):3.

[0011] Preferably, the flow rate of the accelerated phase inlet amino-terminated polymer oil solution is 1–30 μL / min.

[0012] Preferably, the capillary number of the water-in-oil droplet moving in the microchannel is 1*102. -4 ~1*10 -1 .

[0013] Preferably, the size of the water-in-oil droplets containing nanoparticle surfactants is 10–500 μm.

[0014] Preferably, the viscosity of the oil phase is 10–500 mPa·s.

[0015] Preferably, the channel height on the microfluidic chip is 50–500 μm and the channel width is 50–500 μm.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects:

[0017] This invention discloses a method for regulating the transport velocity of droplets in microchannels based on nanoparticle surfactants. Carboxyl-functionalized nanoparticles are added to an aqueous phase, and an amino-terminated polymer is added to an oil phase. When the aqueous and oil phases come into contact, the carboxyl-functionalized nanoparticles and the amino-terminated polymer undergo a dehydration condensation reaction to generate water-in-oil droplets. The surface of these water-in-oil droplets is coated with nanoparticle surfactants. In this method, the nanoparticle surfactants on the surface of the water-in-oil droplets can effectively regulate the specific mechanical properties of the oil-water interfacial tension, viscoelasticity, and bending resistance, thereby controlling the transport velocity of the water-in-oil droplets in the microchannel.

[0018] Furthermore, the carboxyl-functionalized nanoparticles have a particle size range of 10–50 nm, which allows the nanoparticles to be dispersed in droplets.

[0019] Furthermore, the concentration of the carboxyl-functionalized nanoparticle aqueous solution is 0.001 wt.% to 2.5 wt.%, and the concentration of the amino-terminated polymer oil solution is 0.1 wt.% to 10 wt.%, which allows the formation of nanoparticle surfactants at the oil-water interface.

[0020] Furthermore, the flow rate ratio of the continuous phase inlet amino-terminated polymer oil solution to the dispersed phase inlet carboxyl-functionalized nanoparticle aqueous solution is (1-30):3, which can effectively control the size of the generated droplets.

[0021] Furthermore, the flow rate of the amino-terminated polymer oil solution at the inlet of the accelerating phase is 1–30 μL / min, which allows for control of the capillary number range for different reagent groups to be the same.

[0022] Furthermore, the capillary count of the water-in-oil droplets ranges from 1*10^6. -4 ~1*10 -1 The size of the water-in-oil droplets is 10–500 μm, and the viscosity of the oil phase is 10–500 mPa·s, which can effectively control the droplet migration speed. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram illustrating the reaction principle of the reaction between carboxyl-functionalized nanoparticles and amino-terminated polymers to generate water-in-oil droplets encapsulated by nanoparticle surfactants in this invention.

[0025] Figure 2This is a diagram of a microfluidic pressure control system;

[0026] Figure 3 This is a schematic diagram of the structure of a PDMS chip used to prepare droplets;

[0027] Figure 4 Images of water-in-oil droplets during droplet movement in this invention, wherein (a) is an image of a droplet in a microchannel taken using an inverted microscope in this invention, and (b) and (c) are fluorescence images of water-in-oil droplets at different injection flow rates in this invention;

[0028] Figure 5 The graph shows the test results of the transport velocity of water-in-oil droplets obtained in Comparative Examples 1-3 and Example 1 in this invention.

[0029] Figure 6 The graph shows the test results of the transport velocity of water-in-oil droplets obtained in Examples 1 to 3 of this invention.

[0030] Among them, 21. Air compressor pump, 22. Flow sensor, 23. Flow meter, 24. High-speed camera, 25. Inverted microscope, 26. Microfluidic chip, 27. Computer, 28. Liquid storage tank, 29. Microfluidic pressure pump, 31. Accelerated oil phase injection end, 32. Continuous oil phase injection end, 33. Dispersed aqueous phase injection end, 34. Droplet generation structure, 35. Droplet flow rate control structure, 36. Chip outlet. Detailed Implementation

[0031] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0032] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0033] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0034] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0035] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0036] like Figure 1 As shown, the present invention provides a method for regulating the droplet transport velocity in a microchannel based on nanoparticle surfactants. Specifically, an aqueous solution of carboxyl-functionalized nanoparticles is introduced into the dispersed phase inlet of a microfluidic chip, and an amino-terminated polymer oil solution is introduced into both the continuous phase inlet and the accelerating phase inlet. The carboxyl-functionalized nanoparticles react with the amino-terminated polymer to generate water-in-oil droplets encapsulated by nanoparticle surfactants. Figure 1 Chinese V m The theoretical velocity, i.e., the total input flow rate converted to velocity, is the ratio of the overall flow rate of the mixed carboxyl-functionalized nanoparticle aqueous solution and the amino-terminated polymer oil solution introduced through the continuous phase inlet and the accelerating phase inlet to the cross-sectional area of ​​the channel after mixing. Here, V m The velocity V is obtained through the above calculation method; V is the actual measured velocity, that is, the actual flow velocity of the water-in-oil droplet in the microchannel. Here, V is calculated based on the actual distance and time of movement after being captured by a high-speed camera. In this invention, an inverted microscope is used to magnify and observe the droplet movement behavior in the microchannel, and high-speed photography is used to quickly observe and record the droplet movement process. The shooting frequency is 250 frames / second to 16000 frames / second, and the preferred shooting frequency range is 1000 frames / second to 8000 frames / second.

[0037] During this regulation process, the channel height of the microfluidic chip is 50–500 μm, with a preferred channel height of 100 μm; the channel width is 50–500 μm, with a preferred channel width of 100 μm, i.e., the channel has a square tube structure.

[0038] Furthermore, the particle size range of the carboxyl-functionalized nanoparticles is 10–50 nm, with a preferred particle size of 30 nm. These carboxyl-functionalized nanoparticles are carboxyl-functionalized polystyrene nanoparticles or carboxyl-functionalized silica nanoparticles. In a preferred embodiment, the concentration of the aqueous solution containing the carboxyl-functionalized nanoparticles is 0.001 wt.% to 2.5 wt.%, and a more preferred concentration is 0.001 wt.% to 1 wt.%.

[0039] Furthermore, the concentration of the amino-terminated polymer oil solution is 0.1 wt.% to 10 wt.%, and more preferably, the concentration of the amino-terminated polymer oil solution is 0.1 wt.% to 5 wt.%. The amino-terminated polymer is a mono-amino-terminated polydimethylsiloxane or a di-amino-terminated polydimethylsiloxane.

[0040] The carboxyl-functionalized polystyrene nanoparticles, carboxyl-functionalized silica nanoparticles, mono-amino-terminated polydimethylsiloxane, and di-amino-terminated polydimethylsiloxane used in this invention were all purchased from Sigma Reagents website.

[0041] In this invention, during the reaction process, the flow ratio of the amino-terminated polymer oil solution at the continuous phase inlet to the carboxyl-functionalized nanoparticle aqueous solution at the dispersed phase inlet is controlled at (1-30):3. The flow rate of the amino-terminated polymer oil solution at the accelerating phase inlet is 1-30 μL / min. The capillary number of the water-in-oil droplets is 1*10^6. -4 ~1*10 -1 .

[0042] In this invention, the aqueous phase liquid can be deionized water, the oil phase can be dimethyl silicone oil, and the viscosity of the oil phase is 10-500 mPa·s, preferably 10-50 mPa·s.

[0043] In this invention, when a simple aqueous phase comes into contact with an oil phase, the resulting water droplets have a size of 100–1000 μm. However, when carboxyl-functionalized nanoparticles are added to the aqueous phase and an amino-terminated polymer is added to the oil phase, the carboxyl-functionalized nanoparticles react with the amino-terminated polymer to generate water-in-oil droplets with a surface coated with nanoparticle surfactants. These nanoparticle surfactants can significantly reduce the interfacial tension between the oil and water, thereby effectively reducing the droplet size. In this invention, microcapsules are obtained by constructing nanoparticle surfactants on the droplet surface. The size of these microcapsules is 10–500 μm, with a more preferred size of 20–200 μm.

[0044] The microfluidic pressure control system used in this invention is shown in the figure below. Figure 2 The system includes a microfluidic experimental setup and a microscope observation setup. The microfluidic experimental setup includes an air compressor pump 21, which is connected to a microfluidic pressure pump 29 to provide pressure to the microfluidic pressure pump 29. A computer 27 controls the output pressure of the microfluidic pressure pump 29 to inject the continuous phase, dispersed phase, and accelerating phase in the reservoir 28 into the microfluidic chip 26 through a flow meter 23. The flow rate data measured by the flow meter 23 is transmitted to the computer 27 through a flow sensor 22. The microscope observation setup mainly consists of an inverted microscope 25 and a high-speed camera 24.

[0045] Furthermore, the microfluidic chip 26 used in this invention is a PDMS chip, the schematic diagram of which is shown below. Figure 3 The working principle is as follows: a continuous oil phase is injected at the continuous oil phase injection end 32, and a dispersed aqueous phase is injected at the dispersed aqueous phase injection end 33. The continuous oil phase and the dispersed aqueous phase are sheared at the droplet generation structure 34 to generate oil-in-water droplets. The accelerated oil phase injected at the accelerated oil phase injection end 31 controls the capillary number at the droplet flow rate control structure 35, and the generated oil-in-water droplets flow out from the chip outlet 36.

[0046] Capillary number (Ca) is the most commonly used and most important dimensionless parameter in droplet microfluidic analysis. When the capillary number is less than 0.1, surface tension has a more significant effect, and the droplet interface will shrink into a spherical shape under the stress caused by surface tension. At high capillary numbers, viscous forces play a dominant role, and the droplet interface will be affected by the viscous drag force of the fluid, causing the droplet to deform or even break up.

[0047] The capillary number Ca = μv / σ, where μ is the viscosity of the continuous phase, σ is the interfacial tension, and v is the Darcy velocity, which is obtained by dividing the flow rate by the cross-sectional area of ​​the microchannel.

[0048] This invention generates nanoparticle surfactants through a dehydration condensation reaction at the oil-water interface between surface-functionalized nanoparticles in the aqueous phase and functionalized polymer groups in the oil phase. These nanoparticle surfactants significantly reduce the interfacial tension between the oil and water, and the interface to which the nanoparticles are adsorbed also exhibits unique mechanical properties such as viscoelasticity and bending resistance, thereby influencing the droplet transport velocity in microchannels. Specifically, nanoparticle surfactants are generated by a dehydration condensation reaction between surface-functionalized nanoparticles added to the aqueous phase and functionalized polymer groups added to the oil phase at the oil-water interface. Using a microfluidic chip, an amino-terminated polymer oil solution serves as the continuous phase, while a carboxyl-functionalized nanoparticle aqueous solution serves as the dispersed phase. By controlling the oil-water flow ratio and channel structure dimensions, monodisperse water-in-oil droplets with controllable particle size ranges are generated within the chip.

[0049] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0050] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0051] Example 1

[0052] In a microfluidic PDMS chip, a 10 mPa·s dimethyl silicone oil containing 1 wt.% diamino-terminated polydimethylsiloxane (NH2-PDMS-NH2) is introduced into the continuous phase inlet, a 0.5 wt.% aqueous solution of carboxyl-functionalized polystyrene nanoparticles (NPS-COOH) is introduced into the dispersed phase inlet, and a 10 mPa·s dimethyl silicone oil containing 1 wt.% NH2-PDMS-NH2 is introduced into the accelerating phase inlet. By controlling the oil-to-water flow ratio at droplet generation to 4:3, water-in-oil droplets with a length of 300 μm can be generated. By controlling the flow rate of the accelerating oil phase, the capillary number range can be controlled to be 5.417*10. -3 .

[0053] Example 2

[0054] In a microfluidic PDMS chip, a continuous phase inlet containing 1 wt.% NH2-PDMS-NH2 at 10 mPa·s dimethyl silicone oil is introduced, a dispersed phase inlet containing 0.05 wt.% NPS-COOH aqueous solution is introduced, and an accelerating phase inlet containing 1 wt.% NH2-PDMS-NH2 at 10 mPa·s dimethyl silicone oil is introduced. By controlling the oil-to-water flow ratio at droplet formation to 5:3, water-in-oil droplets with a length of 300 μm can be generated. Controlling the flow rate of the accelerating oil phase allows for control of the capillary number range to be maintained at 6.875 × 10⁻⁶. -3 .

[0055] Example 3

[0056] In a microfluidic PDMS chip, a continuous phase inlet containing 1 wt.% NH2-PDMS-NH2 at 10 mPa·s dimethyl silicone oil is introduced, the dispersed phase inlet containing 0.005 wt.% NPS-COOH aqueous solution is introduced, and the accelerating phase inlet containing 1 wt.% NH2-PDMS-NH2 at 10 mPa·s dimethyl silicone oil is introduced. By controlling the oil-to-water flow ratio at droplet formation to 6:3, water-in-oil droplets with a length of 300 μm can be generated. Controlling the flow rate of the accelerating oil phase allows for control of the capillary number range to be maintained at 2.75 × 10⁻⁶. -2 .

[0057] Comparative Example 1

[0058] The difference between this comparative example and Example 1 is that NPS-COOH was not added to the aqueous phase, NH2-PDMS-NH2 was not added to the oil phase, and NH2-PDMS-NH2 was not added to the accelerated phase.

[0059] Comparative Example 2

[0060] The difference between this comparative example and Example 1 is that NH2-PDMS-NH2 was not added to the oil phase.

[0061] Comparative Example 3

[0062] The difference between this comparative example and Example 1 is that NPS-COOH was not added to the aqueous phase.

[0063] Example 4

[0064] A method for controlling droplet transport velocity in microchannels based on nanoparticle surfactants involves introducing an aqueous solution of carboxyl-functionalized polystyrene nanoparticles with a particle size range of 16.5 nm and a concentration of 2.5 wt.% into the dispersed phase inlet of a microfluidic chip with a channel height of 50 μm and a channel width of 50 μm. An oil solution of mono-amino-terminated polydimethylsiloxane with a concentration of 10 wt.% is introduced into both the continuous phase inlet and the accelerating phase inlet. The oil phase is dimethyl silicone oil with a viscosity of 10 mPa·s. The carboxyl-functionalized polystyrene nanoparticles react with the mono-amino-terminated polydimethylsiloxane to generate water-in-oil droplets coated with nanoparticle surfactants. The flow rate ratio of the amino-terminated polymer oil solution at the continuous phase inlet to the carboxyl-functionalized nanoparticle aqueous solution at the dispersed phase inlet is 1:3, and the capillary number of the water-in-oil droplets is 1*10^6. -4 The resulting water-in-oil droplets with surface-coated nanoparticle surfactants had a size of 500 μm.

[0065] Example 5

[0066] A method for regulating droplet transport velocity in microchannels based on nanoparticle surfactants involves introducing an aqueous solution of carboxyl-functionalized silica nanoparticles with a particle size range of 30 nm and a concentration of 1.5 wt.% into the dispersed phase inlet of a microfluidic chip with a channel height and width of 100 μm. An oil solution of diamino-terminated polydimethylsiloxane with a concentration of 5 wt.% is introduced into both the continuous phase inlet and the accelerating phase inlet. The oil phase is dimethyl silicone oil with a viscosity of 50 mPa·s. The carboxyl-functionalized silica nanoparticles react with the diamino-terminated polydimethylsiloxane to generate water-in-oil droplets coated with nanoparticle surfactants. The flow rate ratio of the amino-terminated polymer oil solution at the continuous phase inlet to the carboxyl-functionalized nanoparticle aqueous solution at the dispersed phase inlet is 10:1, and the capillary number of the water-in-oil droplets is 5*10^6. -2The resulting water-in-oil droplets with surface-coated nanoparticle surfactants had a size of 10 μm.

[0067] Example 6

[0068] A method for controlling droplet transport velocity in microchannels based on nanoparticle surfactants involves introducing an aqueous solution of carboxyl-functionalized polystyrene nanoparticles with a particle size range of 50 nm and a concentration of 0.001 wt.% into the dispersed phase inlet of a microfluidic chip with a channel height and width of 500 μm. An oil solution of diamino-terminated polydimethylsiloxane with a concentration of 0.1 wt.% is introduced into both the continuous phase inlet and the accelerating phase inlet. The oil phase is dimethyl silicone oil with a viscosity of 500 mPa·s. The carboxyl-functionalized polystyrene nanoparticles react with the diamino-terminated polydimethylsiloxane to generate water-in-oil droplets coated with nanoparticle surfactants. The flow rate ratio of the amino-terminated polymer oil solution at the continuous phase inlet to the carboxyl-functionalized nanoparticle aqueous solution at the dispersed phase inlet is 2:1, and the capillary number of the water-in-oil droplets is 1*10⁻⁶. -1 The resulting water-in-oil droplets with surface-coated nanoparticle surfactants had a size of 300 μm.

[0069] Figure 4 Images of water-in-oil droplets during droplet movement in this invention are shown, where (a) is an image of the droplet in the microchannel taken using an inverted microscope, and (b) and (c) are fluorescence images of water-in-oil droplets at different injection flow rates. The fluorescence images in (b) and (c) clearly show that the nanoparticle surfactant adheres to the surface of the droplet, forming microcapsules. The adhesion of the nanoparticle surfactant effectively reduces the oil-water interfacial tension and regulates the liquid's transport velocity. Furthermore, the nanoparticle surfactant is formed by bonding between additives in the aqueous and oil phases; therefore, the adsorption of nanoparticles at the oil-water interface is more stable and will not detach due to liquid movement, resulting in a more durable and long-lasting effect on droplet transport velocity regulation.

[0070] Figure 5 The figure shows the test results of the transport velocity of water-in-oil droplets obtained by Comparative Examples 1-3 and Example 1 in this invention. As can be seen from the figure, the nanoparticle surfactant significantly reduces the transport velocity of droplets when the droplet transport velocity is calculated by high-speed photography using data processing software. The transport velocity of microdroplets can be controlled by constructing nanoparticle surfactants on the surface of microdroplets.

[0071] Figure 6The figures show the test results of the transport velocity of water-in-oil droplets obtained in Examples 1-3 of this invention. As can be seen from the figures, the droplet transport velocity further decreases with increasing concentration of nanoparticles adsorbed at the oil-water interface. Therefore, the transport velocity of microdroplets can be controlled by adjusting process parameters, including the concentration of carboxyl-functionalized nanoparticles added to the aqueous phase, the concentration of amino-terminated polymer added to the oil phase, the nanoparticle size, the viscosity of the oil phase, the size of the microchannel, the flow ratio of the amino-terminated polymer oil solution at the continuous phase inlet to the carboxyl-functionalized nanoparticle aqueous solution at the dispersed phase inlet, the flow rate of the amino-terminated polymer oil solution at the accelerating phase inlet, the capillary number of the water-in-oil droplets during transport, and the size of the water-in-oil droplets coated with nanoparticle surfactants. In this control process, adjusting the flow ratio of the amino-terminated polymer oil solution at the continuous phase inlet to the carboxyl-functionalized nanoparticle aqueous solution at the dispersed phase inlet controls the size of the generated water-in-oil droplets coated with nanoparticle surfactants, and adjusting the flow rate of the amino-terminated polymer oil solution at the accelerating phase inlet controls the capillary number of the water-in-oil droplets.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for regulating droplet transport velocity in microchannels based on nanoparticle surfactants, characterized in that, An aqueous solution of carboxyl-functionalized nanoparticles is introduced into the dispersed phase inlet of the microfluidic chip, while an amino-terminated polymer oil solution is introduced into both the continuous phase inlet and the accelerating phase inlet. The carboxyl-functionalized nanoparticles react with the amino-terminated polymer oil solution introduced into the continuous phase inlet at the droplet generation structure to generate water-in-oil droplets with nanoparticle surfactants coated on their surface. The amino-terminated polymer oil solution introduced into the accelerating phase inlet controls the capillary number of the water-in-oil droplets at the droplet flow rate control structure, and the generated water-in-oil droplets flow out from the microfluidic chip outlet. The size of the water-in-oil droplets containing nanoparticle surfactants is 10~500μm; The flow rate ratio of the amino-terminated polymer oil solution introduced through the continuous phase inlet to the carboxyl-functionalized nanoparticle aqueous solution introduced through the dispersed phase inlet is (1~30):

3. The flow rate of the amino-terminated polymer oil solution introduced into the accelerating phase inlet is 1~30 μL / min; The concentration of the aqueous solution containing the carboxyl-functionalized nanoparticles is 0.001 wt% to 2.5 wt%. The concentration of the amino-terminated polymer oil solution is 0.1 wt% to 5 wt%. The capillary number of the water-in-oil droplet moving in the microchannel is: ; The viscosity of the oil phase is ; The carboxyl-functionalized nanoparticles are carboxyl-functionalized polystyrene nanoparticles or carboxyl-functionalized silica nanoparticles. The amino-terminated polymer is a mono-amino-terminated polydimethylsiloxane or a di-amino-terminated polydimethylsiloxane.

2. The method for regulating droplet transport velocity in microchannels based on nanoparticle surfactants according to claim 1, characterized in that, The particle size range of the carboxyl functionalized nanoparticles is 10~50 nm.

3. The method for regulating droplet transport velocity in microchannels based on nanoparticle surfactants according to claim 1, characterized in that, The channel height on the microfluidic chip is 50~500μm, and the channel width is 50~500μm.

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