A core-shell polymer droplet generation device based on an alternating electric field microfluidic device

Abstract

The application discloses a kind of core-shell polymer droplet generation device based on alternating electric field microfluidic device, including microfluidic chip, microfluidic chip includes the cover layer, chip layer and substrate layer sequentially stacked;Cover layer is provided with five fluid inlets with chip layer communication, five fluid inlets are communicated with injection pump by tubule respectively;Chip layer includes five fluid introduction channels and a microdroplet outlet channel, the port of five fluid introduction channels is communicated with five fluid inlets;Substrate layer is provided with the port of microdroplet outlet channel communication microdroplet collection outlet;Chip layer is provided with non-contact electrode, non-contact electrode is connected with high-voltage alternating current power supply by wire;The application can control the shape, size and generation frequency of core-shell polymer droplet and other characteristics by applying alternating electric field, actively regulating electric field frequency and voltage parameters, realize the accurate preparation of core-shell polymer droplet, satisfy the diversified demand of different application scenarios.

Description

Technical Field

[0001] The present invention relates to the field of microfluidic technology, and in particular to a core-shell polymer droplet generating device based on an alternating electric field microfluidic device. Background Art

[0002] In the field of microfluidics, the precise preparation of core-shell polymer droplets is a core requirement in fields such as biomedicine, functional materials, and fine chemicals. However, while traditional passive droplet generation techniques achieve droplet control through fixed channel geometry and fluid dynamics, droplet size and generation frequency are strongly coupled due to the law of conservation of mass, making independent regulation of the two difficult. Furthermore, traditional techniques face the challenge of controlling the flow behavior of highly viscoelastic core-shell polymer droplets during generation, which complicates the control of droplet size and generation frequency.

[0003] The micro-droplet generation device proposed in the Chinese invention patent with announcement number CN111889156B includes a control module, an air supply module, a chip movement module and an air pressure regulation module. The air supply module has a gas cylinder, and the air pressure regulation module has an air cavity. The gas cylinder is provided with a first pressure sensor for real-time monitoring of the gas pressure in the gas cylinder, and the air cavity is provided with a second pressure sensor for real-time monitoring of the gas pressure therein. The gas path output side of the air cavity is provided with an oil phase solenoid valve and a water phase solenoid valve in parallel. The control module is configured to be able to monitor the pressure value in real time based on the first pressure sensor and the second pressure sensor, and when the pressure value exceeds the preset pressure threshold range, control the deflation valve or the oil phase solenoid valve and the water phase solenoid valve to produce a deflation action; however, the device can only prepare droplets of a single size and cannot meet the diverse needs for core-shell polymer droplets of different sizes, which to a certain extent limits its application scope and flexibility.

[0004] The Chinese invention patent application, with publication number CN119319005A, includes a -80°C refrigeration system, a micro-droplet preparation system, and a collection system. The -80°C refrigeration system's liquid outlet and liquid inlet pipes are inserted into the collection system's condensate inlet and outlet, respectively. The micro-droplet preparation system comprises a gas carrier device, a three-way pipe fitting, and a syringe pump. Liquid injected by the syringe pump is broken into micro-droplets by high-pressure carrier gas. The collection system is a U-shaped glass device connected to a micro-droplet injection port on the left, a bottom liquid inlet, and a gas outlet on the right. The micro-droplets react at the micro-droplet injection port, condense in the serpentine condenser tube of the U-shaped glass device, and are collected through the bottom liquid inlet. However, the device lacks precise control over the micro-droplet generation process.

[0005] Furthermore, the viscoelastic nature of existing polymer solutions leads to nonlinear responses in interfacial tension and shear forces during flow, further exacerbating the uncertainty of droplet generation. Therefore, a new technology that can actively regulate fluid behavior, breaking through the limitations of passive control, is urgently needed to achieve independent and precise control of the shape, size, and generation frequency of highly viscoelastic core-shell polymer droplets. Summary of the Invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to propose a core-shell polymer droplet generation device based on an alternating electric field microfluidic device. By actively regulating the generation process of high viscoelastic core-shell polymer droplets using an alternating electric field and adjusting parameters such as the frequency and voltage of the alternating electric field, the precise and controllable preparation of core-shell polymer droplets can be achieved, solving the technical problem that the core-shell polymer droplets are difficult to generate due to their high viscoelasticity and complex rheological properties. The present invention has the characteristics of sensitive parameter response, high control accuracy, and strong process adaptability.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A core-shell polymer droplet generation device based on an alternating electric field microfluidic device includes a microfluidic chip 1, which includes a capping layer 4, a chip layer 5, and a base layer 6 stacked in sequence; the capping layer 4 is provided with five fluid inlets connected to the chip layer 5, and the five fluid inlets are respectively connected to a syringe pump 2 through thin tubes; the chip layer 5 includes five fluid introduction channels and a micro-droplet extraction channel 13, and the ports of the five fluid introduction channels are connected to the five fluid inlets; the base layer 6 is provided with a micro-droplet collection outlet 14 connected to the port of the micro-droplet extraction channel 13; the chip layer 5 is provided with a non-contact electrode 15, and the non-contact electrode 15 is connected to a high-voltage AC power supply 3 through a wire.

[0009] The five fluid inlets are respectively one dispersed phase inlet 7, two polymer mesophase inlets 8 and two continuous phase inlets 9; the five fluid introduction channels are respectively one dispersed phase introduction channel 10, two polymer mesophase introduction channels 11 and two continuous phase introduction channels 12.

[0010] The dispersed phase introduction channel 10 is connected to the polymer intermediate phase introduction channel 11 and the continuous phase introduction channel 12 in sequence according to the fluid flow direction, and the two polymer intermediate phase introduction channels 11 and the two continuous phase introduction channels 12 are arranged axially symmetrically about the dispersed phase introduction channel 10; the second flow focusing junction formed at the connection point between the dispersed phase introduction channel 10 and the continuous phase introduction channel 12 is connected to the micro-droplet outlet channel 13.

[0011] The thickness of the capping layer 4, chip layer 5 and base layer 6 are all 2 to 4 mm; in the chip layer 5, the size of the dispersed phase introduction channel 10 is (10 to 20 mm) × (0.1 to 1 mm), the size of the polymer interphase introduction channel 11 is (10 to 20 mm) × (0.1 to 1 mm), the size of the continuous phase introduction channel 12 is (10 to 20 mm) × (0.05 to 1 mm), and the size of the droplet extraction channel 13 is (10 to 40 mm) × (0.1 to 1 mm); the diameters of the dispersed phase fluid inlet 7, the polymer interphase inlet 8 and the continuous phase inlet 9 are the same as the widths of the corresponding dispersed phase introduction channel 10, the polymer interphase introduction channel 11 and the continuous phase introduction channel 12.

[0012] The chip layer 5 is embedded with two groups of non-contact electrodes 15 near the continuous phase introduction channel 12. Each group of non-contact electrodes 15 is connected to the high-voltage AC power supply 3 through a wire, and the direction of the alternating electric field generated is tangential to the fluid flow direction or normal to the fluid flow direction.

[0013] The frequency of the alternating electric field of the high-voltage AC power supply 3 is within 50 Hz, and the voltage is within 2 kV.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects:

[0015] The present invention provides a microfluidic chip with a dual-flow focusing microchannel structure, and applies an alternating electric field near the continuous phase introduction channel of the microfluidic chip, actively regulating the electric field frequency and voltage parameters, thereby controlling the shape, size, and generation frequency of core-shell polymer droplets and other characteristics, thereby achieving precise preparation of core-shell polymer droplets to meet the diverse needs of different application scenarios. Compared with complex high-pressure carrier gas technology, the generation device of the present invention is simpler, has lower manufacturing costs, and has stronger process adaptability. At the same time, the device of the present invention is small in size and easy to integrate with other devices to achieve more and more complex functions; the core-shell polymer droplets prepared by the present invention can be widely used in the fields of drug carriers, microreactors, and functional microcapsule preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the core-shell polymer droplet generation device based on the alternating electric field microfluidic device of the present invention.

[0017] Figure 2 3D exploded schematic diagram of the microfluidic chip of the present invention.

[0018] Figure 3 This is a schematic structural diagram of the chip layer of the microfluidic chip under the application of an alternating electric field according to the present invention, wherein: Figure 3 a is the tangential direction, Figure 3 b is the normal direction.

[0019] Figure 4 Schematic diagram of the generation of core-shell polymer droplets of the present invention.

[0020] Figure 5 The graph of the change in diameter and generation frequency of core-shell polymer droplets generated at different electric field frequencies provided in Example 2, wherein: Figure 5 a is the diameter, Figure 5 b is the generation frequency.

[0021] Figure 6 The graph of the change in diameter and generation frequency of core-shell polymer droplets generated under different electric field voltages provided in Example 3 is shown in FIG. Figure 6 a is the diameter, Figure 6 b is the generation frequency.

[0022] In the figure: 1-microfluidic chip; 2-syringe pump; 3-high-voltage AC power supply; 4-capping layer; 5-chip layer; 6-base layer; 7-dispersed phase inlet; 8-polymer intermediate phase inlet; 9-continuous phase inlet; 10-dispersed phase introduction channel; 11-polymer intermediate phase introduction channel; 12-continuous phase introduction channel; 13-microdroplet extraction channel; 14-microdroplet collection outlet; 15-non-contact electrode. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention. The present invention will be further described in detail below in conjunction with the drawings.

[0024] like Figure 1 As shown, a core-shell polymer droplet generation device based on an alternating electric field microfluidic device mainly includes a microfluidic chip 1, a syringe pump 2 and a high-voltage AC power supply 3;

[0025] like Figure 2 As shown, the microfluidic chip 1 includes a capping layer 4, a chip layer 5 and a base layer 6 stacked in sequence; the capping layer 4 is provided with five fluid inlets connected to the chip layer 5, namely, a dispersed phase inlet 7, two polymer intermediate phase inlets 8 and two continuous phase inlets 9, and the five fluid inlets are connected to the injection pump 2 through thin tubes; the base layer 6 is provided with a micro-droplet collection outlet 14 connected to the chip layer 5.

[0026] The chip layer 5 is a dual-flow focusing microchannel structure, including a dispersed phase introduction channel 10, two polymer intermediate phase introduction channels 11, two continuous phase introduction channels 12 and a micro-droplet extraction channel 13;

[0027] The dispersed phase introduction channel 10 is arranged in the middle of the chip layer 5, the port of the dispersed phase introduction channel 10 is connected to the inlet 7 of the dispersed phase fluid, the port of the polymer interphase introduction channel 11 is connected to the polymer interphase inlet 8, the port of the continuous phase introduction channel 12 is connected to the continuous phase inlet 9, and the port of the micro-droplet extraction channel 13 is connected to the micro-droplet collection outlet 14; the dispersed phase introduction channel 10 is connected to the polymer interphase introduction channel 11 and the continuous phase introduction channel 12 in sequence according to the fluid flow direction, and the two polymer interphase introduction channels 11 and the two The continuous phase introduction channel 12 is arranged axially symmetrically with respect to the dispersed phase introduction channel 10; the dispersed phase introduction channel 10 is connected to the polymer intermediate phase introduction channel 11 at an angle of preferably 45°; the dispersed phase introduction channel 10 is connected to the continuous phase introduction channel 12 at an angle of preferably 90°; the connection between the dispersed phase introduction channel 10 and the polymer intermediate phase introduction channel 11 forms a first flow focusing node, and the connection between the dispersed phase introduction channel 10 and the continuous phase introduction channel 12 forms a second flow focusing node, and the second flow focusing node is connected to the droplet outlet channel 13.

[0028] The chip layer 5 is embedded with two groups of non-contact electrodes 15 near the continuous phase introduction channel 12, and each group of non-contact electrodes 15 includes a positive electrode and a negative electrode; the non-contact electrodes 15 are connected to the high-voltage AC power supply 3 through a wire, and the high-voltage AC power supply 3 applies an alternating electric field through the two groups of non-contact electrodes 15 to provide a stable alternating electric field to the microfluidic chip 1, wherein the frequency of the alternating electric field is within 50 Hz and the voltage is within 2 kV; Figure 3 As shown in a, when the direction of the alternating electric field is tangential to the direction of fluid flow, spherical droplets can be generated; Figure 3 As shown in Figure 2b, when the alternating electric field is oriented normal to the fluid flow direction, droplet formation is influenced by the electric field's lines of force, resulting in flat droplets. The non-contact electrode 15 is positioned near the continuous phase introduction channel 12. This not only avoids direct contact with the sample, thus overcoming the challenges of sample contamination and Joule heating, but also accelerates the shearing of the continuous phase from the polymer mesophase encapsulating the dispersed phase, forming core-shell polymer droplets.

[0029] The size of the microfluidic chip 1 is (100-200 mm) x (50-100 mm), preferably 100 mm x 75 mm. The thickness of the cover layer 4, the chip layer 5 and the base layer 6 is 2-4 mm, preferably 2 mm; in the chip layer 5, the size of the dispersed phase introduction channel 10 is (10-20 mm) x (0.1-1 mm), the size of the two polymer intermediate phase introduction channels 11 is (10-20 mm) x (0.1-1 mm), the size of the two continuous phase introduction channels 12 is (10-20 mm) x (0.05-1 mm), and the size of the microdroplet introduction channel 13 is (10-40 mm) x (0.1-1 mm); the diameter of the dispersed phase fluid inlet 7, the polymer intermediate phase inlet 8 and the continuous phase inlet 9 is the same as the width of the dispersed phase introduction channel 10, the polymer intermediate phase introduction channel 11 and the continuous phase introduction channel 12.

[0030] The injection pump 2 is used to accurately deliver each phase solution. In actual operation, the injection pump 2 can finely adjust the delivery state of the solution in the fluid introduction channel according to the preset fluid flow rate, thereby ensuring the continuity and stability of the liquid supply, and the ratio of the dispersed phase flow, the polymer intermediate phase flow and the continuous phase flow is 1:5:10, and the total flow is between 10-1000 μL / min.

[0031] The working principle of the core-shell polymer droplet generation device based on the alternating electric field microfluidic device is as follows:

[0032] The flow rate of each phase solution is accurately controlled by the injection pump 2, so that the dispersed phase, the polymer intermediate phase and the continuous phase flow into the corresponding fluid introduction channel according to the preset ratio, the polymer intermediate phase wraps the dispersed phase to form a wrapped fluid at the first flow focusing junction, and the continuous phase cuts off the wrapped fluid at the second flow focusing junction; at the same time, the alternating electric field provided by the high-voltage alternating current power supply 3 acts at the second flow focusing junction, accelerating the cutting-off process, and forming a core-shell polymer droplet, as shown in Figure 4 By adjusting the output voltage and frequency, when the direction of the alternating electric field is tangential to the direction of the fluid flow, uniform spherical droplets are formed, and when the direction of the alternating electric field is normal to the direction of the fluid flow, the droplet shape becomes flat. This adjustment method can flexibly control the size and shape of the core-shell polymer droplet to meet different experimental requirements, thereby showing wide application potential in the fields of material science and biomedical science. The alternating electric field provided by the high-voltage alternating current power supply provides the necessary driving force and control means for the formation process of the core-shell polymer droplet.

[0033] Example 1

[0034] The configurations of the dispersed phase solution, the polymer intermediate phase solution and the continuous phase solution used in the embodiments of the present application are as follows:

[0035] Preparation of the dispersed phase solution: the surfactant Span 85 and mineral oil were mixed with a mass ratio of 1:300 using an electromagnetic stirrer for 5 min until fully mixed to obtain the dispersed phase solution;

[0036] Preparation of the polymer middle phase solution: the carbomer 940 powder and deionized water were mixed with a mass ratio of 1:1000 using an electromagnetic stirrer for 5 h until fully swelled and uniform without caking. The NaOH solution was added dropwise and stirred uniformly using a stirrer until a gel network was formed in the solution, which was transparent, and the pH meter showed that the solution had a pH of 6-7.

[0037] Preparation of the continuous phase solution: the surfactant Span 85 and mineral oil were mixed with a mass ratio of 1:20 using an electromagnetic stirrer for 5 min until fully mixed to obtain the continuous phase solution.

[0038] The microfluidic chip 1 with double-flow focusing microchannels was prepared using a photolithography process. The sizes of the cover layer 5, the chip layer 6, and the substrate layer 7 were all 100 mm x 50 mm x 2 mm. The diameters of the dispersed phase inlet 7, the polymer middle phase fluid inlet, the continuous phase inlet 9, and the microdroplet collection outlet 14 were all 0.1 mm. The sizes of the dispersed phase introduction channel 10 and the polymer middle phase introduction channel 11 were both 30 mm x 0.1 mm. The size of the continuous phase introduction channel 12 was 40 mm x 0.05 mm. The size of the microdroplet introduction channel 13 was 0.1 mm x 40 mm.

[0039] According to the above-mentioned method, the dispersed phase solution, the polymer middle phase solution, and the continuous phase solution were prepared. Figure 1 The microfluidic chip 1 was connected with the syringe pump 2 and the high-voltage alternating current power supply 3. A high-precision pulse-free syringe pump system was used to transport the fluid. The ratio of the dispersed phase flow rate, the polymer middle phase flow rate, and the continuous phase flow rate was 1:5:10, and the total flow rate was 500 μL / min. A chemical-resistant polytetrafluoroethylene microtube was used to connect the syringe and the microchannel to complete the fluid system. An alternating electric field was applied. By adjusting the frequency and voltage of the alternating electric field, the shape, size, generation frequency, and other characteristics of the droplets were precisely controlled to generate core-shell polymer droplets.

[0040] Specifically, when the direction of the applied alternating electric field was normal to the direction of the fluid flow, the voltage was 1.1 kV, and the frequency was 27.27 Hz, flat core-shell polymer droplets with a diameter of 30 μm were obtained.

[0041] Example 2

[0042] The dispersed phase solution, polymer intermediate phase solution and continuous phase solution in Example 1 were used, and a microfluidic chip 1 with a dual-flow focusing microchannel was prepared using a photolithography process with the same dimensions as in Example 1; when the direction of the applied alternating electric field was tangential to the direction of fluid flow, the voltage was 1.1 kV, and the frequency varied from 4.9 Hz to 34.30 Hz, spherical core-shell polymer droplets were obtained, whose diameter varied from 90 μm to 10 μm, as shown in FIG. Figure 5 At the same time, the frequency of droplet generation is the same as the frequency of the alternating electric field, both between 4.9Hz and 34.30Hz, as shown in Figure 5 As shown in b, it shows that by changing the frequency of the alternating electric field, the size and generation frequency of the polymer core-shell droplets can be effectively controlled.

[0043] Example 3

[0044] The dispersed phase solution, polymer intermediate phase solution and continuous phase solution in Example 1 were used, and a microfluidic chip 1 with a dual-flow focusing microchannel was prepared using a photolithography process with the same dimensions as in Example 1; when the alternating electric field was applied in a direction tangential to the fluid flow direction, the frequency was 34.30 Hz, and the voltage was varied between 0.5 kV and 2 kV, spherical core-shell polymer droplets were obtained, with a diameter varying from 80 μm to 5 μm, as shown in FIG. Figure 6 As shown in a; at the same time, the droplet generation frequency is stable at 34.3 Hz, as shown in Figure 6 As shown in b, it shows that by changing the voltage of the alternating electric field, the size and generation frequency of the polymer core-shell droplets can be effectively controlled.

[0045] 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, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A core-shell polymer droplet generation device based on an alternating electric field microfluidic device, characterized by: The microfluidic chip (1) comprises a capping layer (4), a chip layer (5) and a base layer (6) stacked in sequence; the capping layer (4) is provided with five fluid inlets connected to the chip layer (5), and the five fluid inlets are respectively connected to the injection pump (2) through thin tubes; the chip layer (5) comprises five fluid introduction channels and a micro-droplet extraction channel (13), and the ports of the five fluid introduction channels are connected to the five fluid inlets; the base layer (6) is provided with a micro-droplet collection outlet (14) connected to the port of the micro-droplet extraction channel (13); the chip layer (5) is provided with a non-contact electrode (15), and the non-contact electrode (15) is connected to a high-voltage AC power supply (3) through a wire; The five fluid inlets are respectively one dispersed phase inlet (7), two polymer mesophase inlets (8) and two continuous phase inlets (9); the five fluid introduction channels are respectively one dispersed phase introduction channel (10), two polymer mesophase introduction channels (11) and two continuous phase introduction channels (12); The dispersed phase introduction channel (10) is connected to the polymer intermediate phase introduction channel (11) and the continuous phase introduction channel (12) in sequence according to the fluid flow direction, and the two polymer intermediate phase introduction channels (11) and the two continuous phase introduction channels (12) are arranged symmetrically about the dispersed phase introduction channel (10); a second flow focusing junction formed at the connection point between the dispersed phase introduction channel (10) and the continuous phase introduction channel (12) is connected to the micro-droplet extraction channel (13); Two groups of non-contact electrodes (15) are embedded in the chip layer (5) near the continuous phase introduction channel (12). Each group of non-contact electrodes (15) is connected to a high-voltage AC power source (3) via a wire, and the direction of the alternating electric field generated is tangential to the fluid flow direction or normal to the fluid flow direction.

2. The core-shell polymer droplet generation device based on an alternating electric field microfluidic device according to claim 1, characterized in that: The thickness of the capping layer (4), the chip layer (5) and the base layer (6) are all 2-4 mm; in the chip layer (5), the size of the dispersed phase introduction channel (10) is (10-20 mm) × (0.1-1 mm), the size of the polymer intermediate phase introduction channel (11) is (10-20 mm) × (0.1-1 mm), the size of the continuous phase introduction channel (12) is (10-20 mm) × (0.05-1 mm), and the size of the micro-droplet extraction channel (13) is (10-40 mm) × (0.1-1 mm); the diameters of the dispersed phase inlet (7), the polymer intermediate phase inlet (8) and the continuous phase inlet (9) are the same as the widths of the corresponding dispersed phase introduction channel (10), the polymer intermediate phase introduction channel (11) and the continuous phase introduction channel (12).

3. The core-shell polymer droplet generation device based on an alternating electric field microfluidic device according to claim 1, characterized in that: The frequency of the alternating electric field of the high-voltage AC power supply (3) is within 50 Hz, and the voltage is within 2 kV.

Images