A microdroplet mixing and splitting device and method based on an asymmetric offset structure

Abstract

This invention provides a microdroplet mixing and splitting device and method based on an asymmetric offset structure. The device includes: a low-concentration aqueous solution inlet, a high-concentration aqueous solution inlet, an asymmetric offset structure, an oil phase inlet, and a Y-shaped splitting structure. The asymmetric offset structure generates microdroplets for encapsulating the mixed solution. By adjusting the relative angle and relative offset distance between the continuous and dispersed phases, the asymmetric offset structure generates asymmetric eddies in the dispersed phase, enhancing the mixing disturbance within the microdroplets and thus improving mixing efficiency. The initial distribution of the dispersed phase—low concentration on both sides and high concentration in the middle—shortens the mass transfer distance between the high-concentration and low-concentration regions within the microdroplets, further improving mixing efficiency and reducing mixing time. Applying an electric field to the two branch sidewalls of the Y-shaped splitting structure and adjusting the voltage allows for precise splitting of the mixed microdroplets, supporting the rapid development of related biochemical technologies.

Description

Technical Field

[0001] This invention relates to the field of hybrid enhanced microfluidics, and more particularly to a microdroplet mixing and splitting device and method based on an asymmetric offset structure. Background Technology

[0002] In recent years, droplet microfluidics has facilitated the development of microsystems in fields such as chemistry, biology, and medicine, and has become the preferred method for manipulating microscale droplets. Microdroplets prepared using microfluidics are small in size and highly manipulable, and are widely used as microreactors, effectively reducing reagent consumption, accelerating reactions, and improving experimental precision.

[0003] Thorough mixing of multiple components within microdroplets is essential for the efficient operation of microreactors. Existing microdroplet mixing enhancement technologies are divided into active and passive methods. Active methods utilize external forces such as electrodynamics, magnetodynamics, sound waves, and pressure to actively mix fluids, consuming a certain amount of energy. Examples include electroosmotic micromixers and piezoelectric-driven micromixers, which respectively generate electroosmosis and reciprocating continuous vibration to enhance mixing. Passive methods mainly involve interfering with fluid flow through microchannels of various complex shapes, disrupting the flow boundary layer, and increasing the contact area between fluids. Examples include microchannel mixing devices containing multiple obstacles and laminated structure micromixers, both of which exacerbate disturbances and improve mixing efficiency.

[0004] The above solutions can enhance multiphase fluid mixing in most scenarios. However, none of them involve liquid mixing inside the droplets, which cannot meet the requirement of sufficient droplet mixing in microreactor scenarios. Therefore, there is an urgent need to find a new and efficient solution and technology to enhance the mixing inside the droplets. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a microdroplet mixing and splitting device based on an asymmetric offset structure. The invention primarily utilizes the asymmetric offset structure to adjust the relative angle and offset distance between the continuous and dispersed phases. Due to axial asymmetry, asymmetric eddy currents are generated in the dispersed phase, disrupting the stable laminar flow within the microchannel and thus improving mixing efficiency. Furthermore, by altering the initial distribution of the dispersed phase solution—a "low concentration on both sides, high concentration in the middle" initial distribution—the mass transfer distance between the high-concentration and low-concentration regions within the droplet is shortened, further enhancing mixing efficiency. During droplet splitting, there exists a critical ratio of electrocapillary number to critical dielectric constant. When the applied electric field strength and the ratio of the dielectric constant inside and outside the droplet exceed these critical values, the droplet deformation rate oscillation amplitude increases over time, eventually leading to droplet splitting. The inconsistent magnitude of the electric field forces on both sides results in uneven droplet splitting, thus the droplet splitting can be controlled by applying a voltage.

[0006] The technical means employed in this invention are as follows:

[0007] A microdroplet mixing and splitting device based on an asymmetric offset structure includes: a low-concentration aqueous solution inlet, a high-concentration aqueous solution inlet, an asymmetric offset structure, two oil phase inlets, and a Y-shaped splitting structure, wherein:

[0008] The asymmetric offset structure includes a first aqueous phase channel, a second aqueous phase channel, a third aqueous phase channel, a microchannel, a necking channel, a first oil phase channel, a second oil phase channel, and a microdroplet generation channel, wherein:

[0009] One end of the first and second aqueous phase channels are both connected to the inlet of the low-concentration aqueous phase solution, and the other end of each is connected to one end of the third aqueous phase channel, and they are distributed on both sides of the inlet of the high-concentration aqueous phase solution; the other end of the third aqueous phase channel is connected to the inlet of the high-concentration aqueous phase solution, and it is distributed in the middle of the first and second aqueous phase channels, forming a sandwich distribution, which shortens the mass transfer distance between the high-concentration region and the low-concentration region inside before the formation of microdroplets, thereby improving the mixing efficiency.

[0010] One end of the microchannel is connected to the third aqueous phase channel, and the other end is connected to one end of the necking channel, the first oil phase channel, and the second oil phase channel, respectively. The other end of the necking channel is connected to the microdroplet generation channel. The first oil phase channel and the second oil phase channel are distributed on both sides of the connection of the microdroplet generation channel and are asymmetrical with respect to the microchannel axis. The other ends of the first oil phase channel and the second oil phase channel are connected to the first oil phase inlet and the second oil phase inlet, respectively.

[0011] A Y-shaped splitting structure is connected to the end of the microdroplet generation channel, including a first microdroplet splitting channel, a second microdroplet splitting channel, a first microdroplet outlet, and a second microdroplet outlet, wherein:

[0012] One end of the first microdroplet splitting channel and the second microdroplet splitting channel are connected at a certain angle to the end of the microdroplet generation channel, and the other end is connected to the first microdroplet outlet and the second microdroplet outlet, respectively.

[0013] Furthermore, the second oil phase channel is offset to the right by a certain distance relative to the first oil phase channel. The flow rates of the first and second oil phase channels are the same. Since the first and second oil phase channels are asymmetrical relative to the microchannel axis, asymmetrical vortices are generated, and the filling time is extended, thereby improving the mixing efficiency.

[0014] Furthermore, the high-concentration aqueous solution flows into the microchannel at twice the inlet velocity of the low-concentration aqueous solution. When passing through the first oil phase channel and the second oil phase channel respectively, it generates asymmetric vortices. The low-concentration solution is distributed on both sides, and the high-concentration solution is distributed in the middle. The mass transfer distance between the high-concentration solution and the low-concentration solution is shortened, which accelerates the mixing of solutions of different concentrations. Microdroplets are formed by encapsulation through the asymmetric offset structure. They are squeezed at the constriction channel, which causes microdroplet deformation, further promoting mixing. They reach the Y-shaped splitting structure through the microdroplet generation channel.

[0015] Furthermore, a first included angle is provided at the connection between the first oil phase channel and the microchannel.

[0016] Furthermore, a second included angle is provided at the connection between the first microdroplet splitting channel and the second microdroplet splitting channel and the microdroplet generation channel.

[0017] Furthermore, an electrically driven splitting unit is connected to the Y-shaped splitting structure. The electrically driven splitting unit includes two electrode pairs and wires, wherein:

[0018] The two electrode pairs are designated as a first electrode, a second electrode, a third electrode, and a fourth electrode. The first electrode is disposed on the outer wall of the first microdroplet splitting channel and is connected to the positive terminal of the power supply via a wire. The second electrode is disposed on the inner wall of the first microdroplet splitting channel and is connected to the negative terminal of the power supply via a wire. The third electrode is disposed on the outer wall of the second microdroplet splitting channel and is connected to the positive terminal of the power supply via a wire. The fourth electrode is disposed on the inner wall of the second microdroplet splitting channel and is connected to the negative terminal of the power supply via a wire.

[0019] Furthermore, after the mixed concentration of microdroplets is generated, it reaches the Y-shaped splitting structure. Since the voltage applied to the first microdroplet splitting channel and the second microdroplet splitting channel is different, the electric field force generated on both sides of the channel is different, thereby achieving precise control over the size of the split microdroplets.

[0020] The present invention also provides a microdroplet mixing and splitting method based on the above-mentioned microdroplet mixing and splitting device based on an asymmetric offset structure, comprising the following steps:

[0021] S1. The bonded microdroplet mixing and splitting device based on the asymmetric offset structure is placed in a plasma cleaner for plasma cleaning to improve the hydrophilicity of the channel and facilitate liquid flow.

[0022] S2. Connect the first, second, third, and fourth electrodes of the DC power supply, turn on the DC power supply switch, and adjust the output voltage to power the microdroplet mixing and splitting device based on the asymmetric offset structure.

[0023] S3. Use an injection pump to inject a low-concentration aqueous solution into the low-concentration aqueous solution inlet and a high-concentration aqueous solution into the high-concentration aqueous solution inlet. Use a pressure pump to inject oil into the first oil phase inlet and the second oil phase inlet. The flow rate of the high-concentration aqueous solution inlet is twice that of the low-concentration aqueous solution inlet.

[0024] S4. Observe the microdroplet mixing and microdroplet splitting effects under a microscope. In the Y-shaped splitting structure, adjust the applied voltage to precisely control the size of the splitting microdroplets.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The present invention provides a microdroplet mixing and splitting device based on an asymmetric offset structure. By designing an asymmetric offset structure and changing the initial distribution of solution concentration, the mixing time is reduced to the millisecond level. An electric field is applied to the sidewall of the Y-shaped splitting structure. By changing the magnitude of the electric field force, precise control of microdroplet splitting is achieved, and the same chip can be used multiple times.

[0027] 2. The present invention provides a microdroplet mixing and splitting device based on an asymmetric offset structure. By adjusting the relative angle and offset distance between the continuous phase and the dispersed phase, the asymmetric vortex phenomenon is generated in the dispersed phase due to the axial asymmetry, thereby disrupting the stable laminar flow in the microchannel and improving the mixing efficiency.

[0028] 3. The present invention provides a microdroplet mixing and splitting device based on an asymmetric offset structure. By changing the initial distribution of the dispersed phase solution, the initial distribution of "low concentration on both sides and high concentration in the middle" shortens the mass transfer distance between the high concentration region and the low concentration region inside the droplet, thereby further improving the mixing efficiency.

[0029] 4. The microdroplet mixing and splitting device based on an asymmetric offset structure provided by this invention is low in cost, flexible in design, has a short reaction time, and can be integrated with other functions. It does not require much from the experimenters, who only need to master the correct experimental methods.

[0030] Based on the above reasons, this invention can be widely applied in fields such as single-cell analysis and drug delivery. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the channel structure of the device of the present invention.

[0033] Figure 2 This is a partial schematic diagram of the asymmetric offset structure of the present invention.

[0034] In the diagram: 1. Low-concentration aqueous solution inlet; 2. High-concentration aqueous solution inlet; 3. First aqueous phase channel; 4. Second aqueous phase channel; 5. Third aqueous phase channel; 6. First included angle; 7. Microchannel; 8. Necked channel; 9. First oil phase channel; 10. Second oil phase channel; 11. Microdroplet generation channel; 12. First oil phase inlet; 13. Second oil phase inlet; 14. First electrode; 15. Second electrode; 16. First microdroplet outlet; 17. Third electrode; 18. Fourth electrode; 19. Second microdroplet outlet; 20. Second included angle; 21. First microdroplet splitting channel; 22. Second microdroplet splitting channel; 23. Y-shaped splitting structure. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] like Figure 1 As shown, this invention provides a microdroplet mixing and splitting device based on an asymmetric offset structure, comprising: a low-concentration aqueous solution inlet 1, a high-concentration aqueous solution inlet 2, an asymmetric offset structure, two oil phase inlets, and a Y-shaped splitting structure 23, wherein:

[0038] like Figure 2As shown, the asymmetric offset structure includes a first aqueous phase channel 3, a second aqueous phase channel 4, a third aqueous phase channel 5, a microchannel 7, a necking channel 8, a first oil phase channel 9, a second oil phase channel 10, and a microdroplet generation channel 11, wherein:

[0039] One end of the first aqueous phase channel 3 and the second aqueous phase channel 4 are both connected to the inlet 1 of the low-concentration aqueous phase solution, and the other end of both are connected to one end of the third aqueous phase channel 5, and are distributed on both sides of the inlet 2 of the high-concentration aqueous phase solution; the other end of the third aqueous phase channel 5 is connected to the inlet 2 of the high-concentration aqueous phase solution, and is distributed in the middle of the first aqueous phase channel 3 and the second aqueous phase channel 4, forming a sandwich distribution state, which shortens the mass transfer distance between the high-concentration region and the low-concentration region inside before the generation of microdroplets, thereby improving the mixing efficiency;

[0040] One end of the microchannel 7 is connected to the third aqueous phase channel 5, and the other end is connected to one end of the necking channel 8, the first oil phase channel 9, and the second oil phase channel 10, respectively. The other end of the necking channel 8 is connected to the microdroplet generation channel 11. The first oil phase channel 9 and the second oil phase channel 10 are distributed on both sides of the connection of the microdroplet generation channel 11 and are asymmetrical with respect to the axis of the microchannel 7. The other ends of the first oil phase channel 9 and the second oil phase channel 10 are connected to the first oil phase inlet 12 and the second oil phase inlet 13, respectively.

[0041] Y-shaped splitting structure 23, connected to the end of microdroplet generation channel 11, includes a first microdroplet splitting channel 21, a second microdroplet splitting channel 22, a first microdroplet outlet 16, and a second microdroplet outlet 19, wherein:

[0042] One end of the first microdroplet splitting channel 21 and the second microdroplet splitting channel 22 are connected at a certain angle to the end of the microdroplet generation channel 11, and the other end is connected to the first microdroplet outlet 16 and the second microdroplet outlet 19, respectively.

[0043] In a specific implementation, as a preferred embodiment of the present invention, the second oil phase channel 10 is offset to the right by a certain distance relative to the first oil phase channel 9. The flow rates of the first oil phase channel 9 and the second oil phase channel 10 are the same. Since the first oil phase channel 9 and the second oil phase channel 10 are asymmetrical relative to the microchannel 7 axis, asymmetrical vortices are generated, and the filling time is extended, thereby improving the mixing efficiency.

[0044] In a specific implementation, as a preferred embodiment of the present invention, the high-concentration aqueous solution inlet 2 flows into the microchannel 7 at twice the flow rate of the low-concentration aqueous solution inlet 1. When passing through the first oil phase channel 9 and the second oil phase channel 10 respectively, an asymmetric vortex is generated, with the low-concentration solution distributed on both sides and the high-concentration solution distributed in the middle. The mass transfer distance between the high-concentration solution and the low-concentration solution is shortened, accelerating the mixing of solutions of different concentrations. Microdroplets are formed by encapsulation through the asymmetric offset structure and are squeezed at the necking channel 8, causing microdroplet deformation, which further promotes mixing. The microdroplets then reach the Y-shaped splitting structure 23 through the microdroplet generation channel 11.

[0045] In a specific implementation, as a preferred embodiment of the present invention, a first included angle 6 is provided at the connection between the first oil phase channel 9 and the microchannel 7, and the preferred first included angle 6 is 45°.

[0046] In a specific implementation, as a preferred embodiment of the present invention, a second included angle 20 is provided at the connection between the first microdroplet splitting channel 21 and the second microdroplet splitting channel 22 and the microdroplet generation channel 11, and the preferred second included angle 20 is 60°.

[0047] In a specific implementation, as a preferred embodiment of the present invention, an electrically driven splitting unit is connected to the Y-shaped splitting structure 23. The electrically driven splitting unit includes two electrode pairs and wires, wherein:

[0048] The two electrode pairs are designated as first electrode 14, second electrode 15, third electrode 17, and fourth electrode 18. First electrode 14 is disposed on the outer wall of the first microdroplet splitting channel 21 and connected to the positive terminal of the power supply via a wire. Second electrode 15 is disposed on the inner wall of the first microdroplet splitting channel 21 and connected to the negative terminal of the power supply via a wire. Third electrode 17 is disposed on the outer wall of the second microdroplet splitting channel 22 and connected to the positive terminal of the power supply via a wire. Fourth electrode 18 is disposed on the inner wall of the second microdroplet splitting channel 22 and connected to the negative terminal of the power supply via a wire.

[0049] In a specific implementation, as a preferred embodiment of the present invention, after the microdroplets of mixed concentration are generated, they reach the Y-shaped splitting structure 23. Since the voltages applied to the first microdroplet splitting channel 21 and the second microdroplet splitting channel 22 are different, the electric field forces generated on both sides of the channel are different, thereby achieving precise control over the size of the split microdroplets.

[0050] In this embodiment, the chip substrate of the microdroplet mixing and splitting device based on the asymmetric offset structure is a silicon wafer, and its fabrication process includes the following steps:

[0051] Cleaning: Rinse the glass slide with acetone and deionized water, and dry it with nitrogen to remove surface impurities.

[0052] Photoresist coating: Place the glass slide in the center of the spin coater, then pour an appropriate amount of photoresist into the center of the glass slide. Finally, set the rotation speed and time according to the required height of the chip to make the photoresist evenly cover the surface of the glass slide.

[0053] Pre-baking: Place the glass slide coated with photoresist on a heater and heat it. After heating, cool it to allow the photoresist to heat and solidify.

[0054] Exposure: After cooling, place the glass slide under the exposure machine, place the mask film on the glass slide, and set the exposure time.

[0055] Post-baking: The exposed glass slide is placed on a heater and heated. After heating, it is cooled to improve the toughness of the photoresist and make it less prone to breakage.

[0056] Development: After post-baking, the glass slide is immersed in the developer. At this time, the photoresist in the unexposed areas will be washed away by the developer, leaving the pattern in the exposed areas.

[0057] In this embodiment, the microchannels 7 are all made of PDMS material and fabricated using a photolithography casting process. The fabrication process includes the following steps:

[0058] Vacuuming: Pour liquid PDMS and curing agent into a clean glass in a 10:1 ratio, stir evenly with a stirring rod, and then place it in a vacuum chamber to remove the air from the glass to prevent air bubbles from forming after the PDMS has cured.

[0059] Casting and curing: After vacuuming, pour PDMS onto the substrate of the device's discrete chip, then place it in an oven to stand and wait for the PDMS to cure.

[0060] Cleaning: Trim the cured PDMS chip according to the graphic size, drill holes in the chip's inlet and outlet with a hole punch, and then place the chip and glass slide in a plasma cleaner for cleaning.

[0061] Bonding: The glass slide and PDMS chip are taken out of the plasma cleaner one after the other, and the two are quickly bonded together.

[0062] This invention also provides a microdroplet mixing and splitting method based on the above-described microdroplet mixing and splitting device with an asymmetric offset structure, comprising the following steps:

[0063] S1. The bonded microdroplet mixing and splitting device based on the asymmetric offset structure is placed in a plasma cleaner for plasma cleaning to improve the hydrophilicity of the channel and facilitate liquid flow.

[0064] S2. Connect the first electrode 14, the second electrode 15, the third electrode 17 and the fourth electrode 18 of the DC power supply, turn on the DC power supply switch, adjust the output voltage, and supply power to the microdroplet mixing and splitting device based on the asymmetric offset structure.

[0065] S3. Use an injection pump to inject a low-concentration aqueous solution into the low-concentration aqueous solution inlet 1 and a high-concentration aqueous solution into the high-concentration aqueous solution inlet 2. Use a pressure pump to inject oil into the first oil phase inlet 12 and the second oil phase inlet 13. The flow rate of the high-concentration aqueous solution inlet 2 is twice that of the low-concentration aqueous solution inlet 1.

[0066] S4. Observe the microdroplet mixing and microdroplet splitting effects under a microscope. In the Y-shaped splitting structure 23, adjust the applied voltage to precisely control the size of the splitting microdroplets.

[0067] Example

[0068] In this embodiment, red and blue inks are used instead of high-concentration and low-concentration solutions to perform microdroplet mixing and splitting based on an asymmetric offset structure. Specifically: First, three customized injection pumps are used to push the oil through the first oil phase inlet 12 and the second oil-oil phase inlet 13. Blue ink enters the first aqueous phase channel 3 and the second aqueous phase channel 4 through the low-concentration aqueous phase solution inlet 1, and red ink enters the third aqueous phase channel 5 through the high-concentration aqueous phase solution inlet 2. Through the asymmetric offset structure, the mixed ink is encapsulated to form microdroplets, which then enter the microdroplet generation channel and reach the Y-shaped splitting structure 23. Because the voltages applied to the first microdroplet splitting channel 21 and the second microdroplet splitting channel 22 are different, electric field forces of different magnitudes are generated. This allows the splitting to form microdroplets of different / identical sizes. The split microdroplets flow out through the first microdroplet splitting channel and the second microdroplet splitting channel to the first microdroplet outlet 16 and the second microdroplet outlet 19, respectively.

[0069] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microdroplet mixing and splitting device based on an asymmetric offset structure, characterized in that, include: Low-concentration aqueous solution inlet (1), high-concentration aqueous solution inlet (2), asymmetric offset structure, two oil phase inlets, Y-type split structure (23), wherein: The asymmetric offset structure includes a first aqueous phase channel (3), a second aqueous phase channel (4), a third aqueous phase channel (5), a microchannel (7), a necking channel (8), a first oil phase channel (9), a second oil phase channel (10), and a microdroplet generation channel (11), wherein: One end of the first aqueous phase channel (3) and the second aqueous phase channel (4) are both connected to the low-concentration aqueous phase solution inlet (1), and the other end of each is connected to one end of the third aqueous phase channel (5), and they are distributed on both sides of the high-concentration aqueous phase solution inlet (2); the other end of the third aqueous phase channel (5) is connected to the high-concentration aqueous phase solution inlet (2), and it is distributed in the middle of the first aqueous phase channel (3) and the second aqueous phase channel (4), forming a sandwich distribution state, which shortens the mass transfer distance between the high-concentration region and the low-concentration region inside before the generation of microdroplets, thereby improving the mixing efficiency; One end of the microchannel (7) is connected to the third aqueous phase channel (5), and the other end is connected to one end of the necking channel (8), the first oil phase channel (9), and the second oil phase channel (10), respectively. The other end of the necking channel (8) is connected to the microdroplet generation channel (11). The first oil phase channel (9) and the second oil phase channel (10) are distributed on both sides connected to the microdroplet generation channel (11) and are asymmetrical with respect to the axis of the microchannel (7). The other ends of the first oil phase channel (9) and the second oil phase channel (10) are connected to the first oil phase inlet (12) and the second oil phase inlet (13), respectively. A Y-shaped splitting structure (23) is connected to the end of the microdroplet generation channel (11), including a first microdroplet splitting channel (21), a second microdroplet splitting channel (22), a first microdroplet outlet (16), and a second microdroplet outlet (19), wherein: One end of the first microdroplet splitting channel (21) and the second microdroplet splitting channel (22) are connected at a certain angle to the end of the microdroplet generation channel (11), and the other end is connected to the first microdroplet outlet (16) and the second microdroplet outlet (19), respectively.

2. The microdroplet mixing and splitting device based on an asymmetric offset structure according to claim 1, characterized in that, The second oil phase channel (10) is offset to the right by a certain distance relative to the first oil phase channel (9). The flow rates of the first oil phase channel (9) and the second oil phase channel (10) are the same. Since the first oil phase channel (9) and the second oil phase channel (10) are asymmetrical relative to the microchannel (7) axis, asymmetrical vortices are generated, and the filling time is extended, thereby improving the mixing efficiency.

3. The microdroplet mixing and splitting device based on an asymmetric offset structure according to claim 1, characterized in that, The high-concentration aqueous solution inlet (2) flows into the microchannel (7) at twice the flow rate of the low-concentration aqueous solution inlet (1). When passing through the first oil phase channel (9) and the second oil phase channel (10), asymmetric vortices are generated. The low-concentration solution is distributed on both sides and the high-concentration solution is distributed in the middle. The mass transfer distance between the high-concentration solution and the low-concentration solution is shortened, which accelerates the mixing of solutions of different concentrations. Microdroplets are formed by encapsulation through the asymmetric offset structure. They are squeezed at the constriction channel (8) and microdroplet deformation is generated, which further promotes mixing. They reach the Y-shaped split structure (23) through the microdroplet generation channel (11).

4. The microdroplet mixing and splitting device based on an asymmetric offset structure according to claim 1, characterized in that, A first included angle (6) is provided at the connection between the first oil phase channel (9) and the micro channel (7).

5. The microdroplet mixing and splitting device based on an asymmetric offset structure according to claim 1, characterized in that, A second included angle (20) is provided at the connection between the first microdroplet splitting channel (21) and the second microdroplet splitting channel (22) and the microdroplet generation channel (11).

6. The microdroplet mixing and splitting device based on an asymmetric offset structure according to claim 1, characterized in that, An electrically driven splitting unit is connected to the Y-shaped splitting structure (23). The electrically driven splitting unit includes two electrode pairs and wires, wherein: The two electrode pairs are the first electrode (14), the second electrode (15), the third electrode (17), and the fourth electrode (18), respectively. The first electrode (14) is disposed on the outer wall of the first microdroplet splitting channel (21) and is connected to the positive terminal of the power supply through a wire. The second electrode (15) is disposed on the inner wall of the first microdroplet splitting channel (21) and is connected to the negative terminal of the power supply through a wire. The third electrode (17) is disposed on the outer wall of the second microdroplet splitting channel (22) and is connected to the positive terminal of the power supply through a wire. The fourth electrode (18) is disposed on the inner wall of the second microdroplet splitting channel (22) and is connected to the negative terminal of the power supply through a wire.

7. The microdroplet mixing and splitting device based on an asymmetric offset structure according to claim 1, characterized in that, After the mixed concentration of microdroplets is generated, it reaches the Y-shaped splitting structure (23). Due to the different voltages applied to the first microdroplet splitting channel (21) and the second microdroplet splitting channel (22), the electric field forces generated on both sides of the channel are different, thereby achieving precise control over the size of the split microdroplets.

8. A method for microdroplet mixing and splitting based on the microdroplet mixing and splitting device based on an asymmetric offset structure as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. The bonded microdroplet mixing and splitting device based on the asymmetric offset structure is placed in a plasma cleaner for plasma cleaning to improve the hydrophilicity of the channel and facilitate liquid flow. S2. Connect the first electrode (14), second electrode (15), third electrode (17) and fourth electrode (18) of the DC power supply, turn on the DC power supply switch, adjust the output voltage, and power the microdroplet mixing and splitting device based on the asymmetric offset structure. S3. Use an injection pump to inject a low-concentration aqueous solution into the low-concentration aqueous solution inlet (1) and a high-concentration aqueous solution into the high-concentration aqueous solution inlet (2). Inject oil into the first oil phase inlet (12) and the second oil phase inlet (13) by pressure pump. The flow rate of the high-concentration aqueous solution inlet (2) is twice that of the low-concentration aqueous solution inlet (1). S4. Observe the microdroplet mixing and microdroplet splitting effect under a microscope. In the Y-shaped splitting structure (23), adjust the applied voltage to precisely control the size of the splitting microdroplets.

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