Core-shell polymer droplet generation device based on alternating electric field microfluidic device

Abstract

The invention discloses a core-shell polymer droplet generation device based on an alternating electric field micro-fluidic device, which comprises a micro-fluidic chip, and the micro-fluidic chip comprises a sealing cover layer, a chip layer and a substrate layer which are stacked in sequence; the sealing cover layer is provided with five fluid inlets communicated with the chip layer, and the five fluid inlets are respectively communicated with an injection pump through thin pipes; the chip layer comprises five fluid leading-in channels and a micro-droplet leading-out channel, and ports of the five fluid leading-in channels are communicated with the five fluid inlets; the substrate layer is provided with a micro-droplet collecting outlet communicated with a port of the micro-droplet leading-out channel; the chip layer is provided with a non-contact electrode, and the non-contact electrode is connected with a high-voltage alternating current power supply through a wire; by applying the alternating electric field and actively regulating and controlling the frequency and voltage parameters of the electric field, the shape, the size, the generation frequency and other characteristics of the core-shell polymer liquid drop can be controlled, accurate preparation of the core-shell polymer liquid drop is achieved, and the diversified requirements of different application scenes are met.

Description

Technical Field

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

[0002] In the field of microfluidics, the precise preparation of core-shell polymer droplets is a core requirement in the fields of biomedicine, functional materials, and fine chemicals. However, when traditional passive droplet generation technology achieves droplet control through fixed channel geometry and fluid mechanics, the droplet size and generation frequency are strongly coupled due to the law of conservation of mass, making it difficult to achieve independent regulation of the two. At the same time, traditional technologies face the problem of difficult control of flow behavior in the process of regulating the generation of highly viscoelastic core-shell polymer droplets, which increases the difficulty of achieving droplet size and generation frequency regulation.

[0003] The micro-droplet generating device proposed in the Chinese invention patent with announcement number CN111889156B includes a control module, an air supply module, a chip moving module and an air pressure regulating module, etc. The air supply module has an air cylinder, and the air pressure regulating module has an air cavity. The air cylinder is provided with a first pressure sensor for real-time monitoring of the gas pressure in the air cylinder, and the air cavity is provided with a second pressure sensor for real-time monitoring of the gas pressure therein. The air 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, 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℃ refrigeration system, a micro-droplet preparation system and a collection system. Among them, the liquid outlet pipe and liquid inlet pipe of the -80℃ refrigeration system are respectively inserted into the condensate inlet and condensate outlet of the collection system; the micro-droplet preparation system is composed of a carrier gas device, a three-way pipe fitting and an injection pump; the liquid injected by the injection pump is broken into micro-droplets by the high-pressure carrier gas; the collection system is a U-shaped glass device, which is connected to the left micro-droplet blowing end, the bottom liquid intake port and the right gas outlet; the micro-droplet reaction completes the reaction at the micro-droplet blowing end, and the micro-droplets are condensed in the serpentine condenser of the U-shaped glass device and collected through the bottom liquid intake port, but it does not have the ability to accurately control the micro-droplet generation process.

[0005] In addition, the viscoelasticity of polymer solutions in the existing technology will lead to nonlinear responses of interfacial tension and shear force during the flow process, further exacerbating the uncertainty of the droplet generation process. Therefore, there is an urgent need for a new technology that can actively regulate fluid behavior and break through the limitations of passive control to achieve independent and precise control of the shape, size, generation frequency and other characteristics of high-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 by adopting 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 comprises a microfluidic chip 1, wherein the microfluidic chip 1 comprises a capping layer 4, a chip layer 5 and a base layer 6 which are stacked in sequence; the capping layer 4 is provided with five fluid inlets which are connected to the chip layer 5, and the five fluid inlets are respectively connected to an injection pump 2 through thin tubes; the chip layer 5 comprises five fluid introduction channels and a micro-droplet outlet 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 which is connected to the port of the micro-droplet outlet 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 intermediate phase inlets 8 and two continuous phase inlets 9; the five fluid introduction channels are respectively one dispersed phase introduction channel 10, two polymer intermediate phase introduction channels 11 and two continuous phase introduction channels 12.

[0010] The dispersed phase introduction channel 10 is connected with a polymer intermediate phase introduction channel 11 and a 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; the second flow focusing node 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.

[0011] The thickness of the capping layer 4, the chip layer 5 and the 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 intermediate phase 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 micro-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 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.

[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 source 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 source 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 sets a microfluidic chip with a dual-flow focusing microchannel structure, applies an alternating electric field near the continuous phase introduction channel of the microfluidic chip, actively regulates the electric field frequency and voltage parameters, and can control the shape, size, generation frequency and other characteristics of the core-shell polymer droplets, thereby achieving the precise preparation of core-shell polymer droplets to meet the diverse needs of different application scenarios. Compared with the complex high-pressure carrier gas technology, the generation device of the present invention is simpler, has a lower manufacturing cost, 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 It is a schematic structural diagram of a core-shell polymer droplet generating device based on an alternating electric field microfluidic device of the present invention.

[0017] Figure 2 It is a three-dimensional exploded schematic diagram of the microfluidic chip of the present invention.

[0018] Figure 3 The schematic diagram of the structure of the chip layer of the microfluidic chip under the application of an alternating electric field of 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 diameter and generation frequency of the core-shell polymer droplets generated under different electric field frequencies provided in Example 2 is shown in FIG. Figure 5 a is the diameter, Figure 5 b is the generation frequency.

[0021] Figure 6 The graph of the change of the diameter and generation frequency of the core-shell polymer droplets generated under different electric field voltages provided in Example 3, wherein: 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 scheme of the present invention, the technical scheme 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 embodiments of a part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention. The present invention is 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, which are respectively 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 capillaries; 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 intermediate phase introduction channel 11 is connected to the polymer intermediate phase 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 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 intermediate phase introduction channels 12 are connected. 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, 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 micro-droplet extraction 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, and the frequency of the alternating electric field is within 50Hz and the voltage is within 2kV; Figure 3 As shown in a, when the alternating electric field is tangential to the fluid flow direction, spherical droplets can be generated; Figure 3 As shown in Fig. b, when the alternating electric field is normal to the fluid flow direction, the formation of droplets is affected by the electric field lines of the alternating electric field, generating flat droplets. The non-contact electrode 15 is arranged near the continuous phase introduction channel 12, which not only directly avoids direct contact with the sample, thereby overcoming the challenges of sample contamination and Joule heating, but also accelerates the continuous phase to cut off the encapsulation fluid formed by the polymer intermediate phase encapsulating the dispersed phase, forming core-shell polymer droplets.

[0029] The size of the microfluidic chip 1 is (100-200mm)×(50-100mm), preferably 100mm×75mm. The thickness of the capping layer 4, the chip layer 5 and the base layer 6 are all 2-4mm, preferably 2mm; in the chip layer 5, the size of the dispersed phase introduction channel 10 is (10-20mm)×(0.1-1mm), the size of the two polymer intermediate phase introduction channels 11 is (10-20mm)×(0.1-1mm), the size of the two continuous phase introduction channels 12 is (10-20mm)×(0.05-1mm), and the size of the micro droplet extraction channel 13 is (10-40mm)×(0.1-1mm); the diameters of the dispersed phase fluid inlet 7, the polymer intermediate phase inlet 8 and the continuous phase inlet 9 are the same as the widths 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. The ratio of the dispersed phase flow rate, the polymer intermediate phase flow rate and the continuous phase flow rate is 1:5:10, and the total flow rate is between 10 and 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 precisely controlled by the injection pump 2 to ensure 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 at the first flow focusing node to form an encapsulated fluid, and the continuous phase cuts off the encapsulated fluid at the second flow focusing node. At the same time, the alternating electric field provided by the high-voltage AC power supply 3 acts at the second flow focusing node, accelerating the cutting process to form core-shell polymer droplets, such as Figure 4 As shown. By adjusting the output voltage and frequency, when the alternating electric field is tangential to the fluid flow direction, uniform spherical droplets are formed, and when the alternating electric field is normal to the fluid flow direction, the droplet morphology becomes flat. This adjustment method can flexibly control the size and shape of core-shell polymer droplets to meet different experimental needs, thus showing wide application potential in fields such as materials science and biomedicine. The alternating electric field provided by the high-voltage AC power supply provides the necessary driving force and control means for the formation process of core-shell polymer droplets.

[0033] Example 1

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

[0035] Prepare dispersed phase solution: Use an electromagnetic stirrer to stir surfactant Span85 and mineral oil at a mass ratio of 1:300 for 5 minutes until fully mixed to obtain a dispersed phase solution;

[0036] Preparation of polymer mesophase solution: Use an electromagnetic stirrer to stir Carbomer 940 powder and deionized water at a mass ratio of 1:1000 for 5 hours until fully swollen and uniform without agglomeration; Add NaOH solution dropwise for neutralization, and stir evenly with a stirrer until a gel network is formed in the solution and it becomes transparent, and the pH meter shows that the pH of the solution is 6-7;

[0037] Prepare the continuous phase solution: Use an electromagnetic stirrer to stir the surfactant Span85 and mineral oil at a mass ratio of 1:20 for 5 minutes until they are fully mixed to obtain a continuous phase solution.

[0038] A microfluidic chip 1 with a dual-flow focusing microchannel is prepared by a photolithography process. The sizes of the capping layer 5, the chip layer 6 and the base layer 7 are all 100 mm×50 mm×2 mm, and the diameters of the dispersed phase inlet 7, the polymer intermediate phase fluid inlet, the continuous phase inlet 9 and the microdroplet collection outlet 14 are all 0.1 mm; the sizes of the dispersed phase introduction channel 10 and the polymer intermediate phase introduction channel 11 are both 30 mm×0.1 mm, the size of the continuous phase introduction channel 12 is 40 mm×0.05 mm, and the size of the microdroplet outlet channel 13 is 0.1 mm×40 mm.

[0039] according to Figure 1 The microfluidic chip 1 is connected to the syringe pump 2 and the high-voltage AC power supply 3, and a high-precision pulse-free syringe pump system is used to transport the fluid. 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 500μL / min. Chemically resistant polytetrafluoroethylene microtubes are used to connect the syringe and the microchannel to complete the fluid system. An alternating electric field is applied, and the shape, size, generation frequency and other characteristics of the droplets are precisely controlled by adjusting the frequency and voltage of the alternating electric field to generate core-shell polymer droplets.

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

[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 by photolithography process according to the same size 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, and the diameter thereof 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 4.9 Hz and 34.30 Hz, as shown in Figure 5 As shown in b, it shows that the size and generation frequency of polymer core-shell droplets can be effectively controlled by changing the frequency of the alternating electric field.

[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 by photolithography according to the same size as in Example 1; when the direction of the applied alternating electric field was tangential to the direction of fluid flow, the frequency was 34.30 Hz, and the voltage varied between 0.5 kV and 2 kV, spherical core-shell polymer droplets were obtained, and the diameter varied from 80 μm to 5 μm, as shown in FIG. Figure 6 a; at the same time, the droplet generation frequency is stabilized at 34.3 Hz, as shown in Figure 6 As shown in b, it shows that the size and generation frequency of polymer core-shell droplets can be effectively controlled by changing the voltage of the alternating electric field.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant 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 within 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 in that: The microfluidic chip (1) comprises a cover layer (4), a chip layer (5) and a base layer (6) stacked in sequence; the cover 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 source (3) through a wire.

2. According to claim 1, a core-shell polymer droplet generation device based on an alternating electric field microfluidic device is characterized in that: The five fluid inlets are respectively one dispersed phase inlet (7), two polymer intermediate phase inlets (8) and two continuous phase inlets (9); the five fluid introduction channels are respectively one dispersed phase introduction channel (10), two polymer intermediate phase introduction channels (11) and two continuous phase introduction channels (12).

3. According to claim 2, a core-shell polymer droplet generation device based on an alternating electric field microfluidic device is characterized in that: The dispersed phase introduction channel (10) is connected with a polymer intermediate phase introduction channel (11) and a 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) axis; and 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 with the micro-droplet extraction channel (13).

4. According to claim 1, a core-shell polymer droplet generation device based on an alternating electric field microfluidic device is characterized in that: The thickness of the capping layer (4), the chip layer (5) and the 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 intermediate phase 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 micro-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 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).

5. According to claim 2, a core-shell polymer droplet generation device based on an alternating electric field microfluidic device is characterized in that: Two groups of non-contact electrodes (15) are embedded in the chip layer (5) near the continuous phase introduction channel (12), and 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.

6. 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 source (3) is within 50 Hz, and the voltage is within 2 kV.

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