A device and method for controlling the size of microspheres / droplets based on surface acoustic wave technology.

Abstract

The present invention discloses a device and method for regulating the size of microspheres / droplets based on surface acoustic wave technology. A transducer group is attached to the upper surface of a piezoelectric substrate, which is bonded to a microchannel. A sample flows within the microchannel, and the transducer group generates an acoustic field, which acts as a driving force to manipulate the sample in the main channel to cause a lateral displacement across the oil-water interface between the reaction liquid and the sample solution, thereby controlling the sample's path within the reaction liquid. The lateral displacement distance of the sample in the flow channel can be controlled by controlling focusing interdigital electrodes. Then, under the action of parallel interdigital transducers, the sample is controlled to cross the oil-water interface and return to the sample solution, thereby controlling the reaction time between the reaction liquid and the sample, thereby achieving control of the sample size. The present invention can control the contact time between the sample and the reaction liquid with the assistance of the acoustic field, achieving varying degrees of sample refinement, and is applicable to a variety of sample materials.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano technology, specifically relating to a device and method for controlling the size of microspheres / droplets based on surface acoustic wave technology. Background Technology

[0002] In the field of microfluidic microsphere fabrication, precise control of microspheres is crucial for realizing many applications, with broad prospects in biomedicine, drug delivery, materials science, and defense. By precisely controlling the size, shape, and surface properties of microspheres, material properties can be tuned; for example, refined energetic materials release energy at a faster rate. However, traditional microsphere fabrication techniques primarily synthesize microspheres on a macroscopic scale, requiring researchers to use equipment such as ultrasound and magnetic stirring, which is time-consuming and labor-intensive, limiting the widespread application of microspheres in biomedicine, nanomaterials, and chemical reactions.

[0003] Surface Acoustic Wave (SAW) technology is an advanced technique that utilizes the propagation of sound waves on a crystal surface. In microfluidic systems, it is commonly used to manipulate fluids or particles within channels. By exciting SAW waves on the surface of microfluidic channels, fluid separation, manipulation, and transmission can be achieved, while also allowing for precise control of the movement of microscale particles. SAW technology features high frequency, high precision, and non-contact operation, and has wide applications in fields such as biosensing, microfluidic manipulation, and particle control.

[0004] Currently, existing microsphere preparation technologies include solvent evaporation, gelation, and emulsification. These methods are often limited by preparation conditions, making it difficult to achieve precise control over microsphere size. In recent years, electrospray scattering and microfluidic preparation methods have made significant progress in microsphere size control and functionality, but they still have certain limitations, such as uneven size distribution of microspheres obtained by electrospray scattering and high equipment requirements for microfluidic preparation methods.

[0005] The above method obtains microsphere structures through direct preparation. In addition, the size of microspheres can also be controlled by etching the surface structure of microspheres, thereby obtaining microsphere structures with smaller sizes. The morphology and size of microspheres will be affected by many factors in the etching process, such as parameters such as etchant concentration, contact area and etching time. At the same time, waste liquid and harmful gases may be generated during the etching preparation process.

[0006] Therefore, it is urgent to seek a new microsphere preparation technology to overcome the limitations of existing technologies. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a device and method for controlling the size of microspheres / droplets based on surface acoustic wave technology, which addresses the shortcomings of the prior art and solves the technical problem that the samples obtained by the current microsphere preparation method have large particle size and poor uniformity.

[0008] The present invention adopts the following technical solution:

[0009] A device for controlling the size of microspheres / droplets based on surface acoustic wave technology includes a piezoelectric substrate. A transducer array and microchannels are disposed on the upper surface of the piezoelectric substrate. The microchannels include a main channel, a buffer solution channel and a reaction solution channel connected to the inlet end of the main channel, and a waste liquid channel and a collection channel connected to the outlet end of the main channel. The sample flows in the microchannels. The sample is a microsphere or a droplet. The other end of the buffer solution channel is connected to the sample inlet channel and a first buffer solution inlet channel and a second buffer solution inlet channel that do not contain the sample.

[0010] The transducer array generates an acoustic field to manipulate the sample in the main channel to shift laterally across the oil-water interface between the reaction liquid and the sample solution. It then uses the difference in solubility of the sample between the buffer solution and the reaction liquid to control the degree of corrosion of the sample surface structure by the reaction liquid, thereby controlling the sample size. The transducer array controls the lateral shift distance of the sample in the channel, and then controls the sample to pass through the oil-water interface and return to the sample solution. The sample is then collected through the collection channel.

[0011] Preferably, the transducer group is a surface acoustic wave interdigital transducer.

[0012] More preferably, the transducer assembly includes a focusing interdigitated electrode and a parallel interdigitated electrode. The focusing interdigitated electrode is located below the main channel and near the buffer channel. The parallel interdigitated electrode is located on the axis of the main channel and at an angle of 0 to 60° to the main channel and near the collection channel. The focusing interdigitated electrode and the parallel interdigitated electrode are used to generate a focused sound field and a standing wave sound field, respectively.

[0013] More preferably, the focused interdigitated electrode includes 10 to 50 pairs of interdigitated fingers, the width of which is 5 to 50 micrometers arc-shaped, and the angle of which is 30 to 120°.

[0014] More preferably, the parallel interdigitated electrode includes 10 to 100 pairs of parallel interdigitated fingers, the width of which is 5 to 50 micrometers and the length of which is 2 to 5 millimeters, located below the main channel (3-3) and at an angle of 0 to 60° with the main channel (3-3).

[0015] Preferably, the buffer solution channel is connected to the inlet and outlet ends of the main channel, and is arranged parallel to the collection channel and the main channel;

[0016] The reaction liquid flow channel forms an angle of 15° with the buffer solution flow channel and is located diagonally above the buffer solution flow channel;

[0017] The waste liquid flow channel forms an angle of 15~60° with the collection flow channel and is located diagonally above the collection flow channel;

[0018] The inlet end of the buffer channel is connected to the sample inlet channel, the first buffer inlet channel and the second buffer inlet channel. The sample inlet channel is parallel to the buffer channel. The first buffer inlet channel and the second buffer inlet channel are symmetrically designed at 120~180° on both sides of the sample inlet channel.

[0019] More preferably, the height of the microchannels is 50~120 micrometers, and all of them are direct current channels, with different widths at different locations of the microchannels;

[0020] The width of the main flow channel is 100-500 micrometers, the width of the buffer solution flow channel and the collection flow channel is 50-150 micrometers, and the width of the reaction solution flow channel and the waste solution flow channel is 100-400 micrometers.

[0021] More preferably, during the droplet size control process, the widths of the sample inlet channel, the first buffer inlet channel, and the second buffer inlet channel are all 50 to 150 micrometers.

[0022] During the microsphere size control process, the width of the sample inlet channel is 50 micrometers, and the widths of the first buffer inlet channel and the second buffer inlet channel are both 50~150 micrometers.

[0023] Preferably, the sample material includes ester droplets, CL-20 microspheres, and / or metal microspheres.

[0024] Another technical solution of the present invention is a method for controlling the size of microspheres / droplets based on surface acoustic wave technology, comprising the following steps:

[0025] S1. Fix the device for controlling the size of microspheres / droplets based on surface acoustic wave technology on the stage, and observe through the objective lens to ensure that the main channel is parallel to the lower boundary of the viewing window and is located in the center of the microscope viewing window;

[0026] S2, the first buffer inlet channel interface and the second buffer inlet channel interface are connected to the buffer syringe on the injection pump through PTFE tubes respectively; the sample inlet channel interface is connected to the sample syringe on the injection pump through PTFE tubes; the reaction liquid channel interface is connected to the reaction liquid syringe through PTFE tubes; the waste liquid channel interface and the collection channel interface are connected to the waste liquid collection container and the microsphere / droplet collection container through PTFE tubes respectively.

[0027] S3. Connect the two poles of the focusing interdigital electrode and the parallel interdigital electrode of the transducer group to the positive and negative poles of the output signal of the two signal generators respectively, and adjust the output signal of the signal generator to be a continuous sinusoidal output.

[0028] S4. Turn on the syringe pump and adjust the flow rates of the buffer solution and reaction solution channels to form a stable two-phase fluid. After a stable oil-water interface is formed in the main flow channel, an acoustic field is constructed within the channel. Under the influence of the acoustic field, the sample moves from the buffer solution to the reaction solution and back to the buffer solution.

[0029] By increasing or decreasing the voltage amplitude of the focusing interdigital transducer, the lateral offset distance of the sample in the main channel can be adjusted, thereby controlling the trajectory of the sample in the main channel, controlling the reaction time between the sample and the reaction solution, and finally controlling the sample size.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] A device for controlling the size of microspheres / droplets based on surface acoustic wave (SAW) technology combines SAW technology with a microsphere etching preparation method, enabling the preparation of smaller microspheres using microfluidic chips. By manipulating the microspheres through an acoustic field, the surface of the microspheres can be made into full contact with the reaction liquid, resulting in a microsphere structure with a superior surface structure compared to traditional etching methods.

[0032] Furthermore, surface acoustic waves are excited on a piezoelectric substrate using interdigital transducers, and the sample is manipulated using acoustic radiation force. This method offers high manipulation precision and a wide range of applications. Non-contact manipulation avoids damage or contamination to the sample surface, resulting in microsphere structures with superior surface structures.

[0033] Furthermore, by manipulating the sample using focused interdigitated electrodes, rapid displacement of the sample in the vertical flow direction can be achieved within a short acoustic field range. Combined with the wide acoustic field of parallel interdigitated electrodes, the sample is slowly pushed into the collection channel with an approximately arc-shaped trajectory. By controlling the acoustic energy density of the focused acoustic field, the lateral displacement distance of the sample can be controlled, allowing the sample to have different arc-shaped trajectories in the reaction solution. This, in turn, controls the reaction time between the sample and the reaction solution, resulting in microspheres of different sizes when they return to the collection solution. This enables the fabrication of microspheres of different sizes on the same chip.

[0034] Furthermore, by adjusting the voltage amplitude of the focused interdigitated electrode, the offset distance of the microsphere in the main channel can be controlled, thereby controlling the contact time between the microsphere and the reaction solution to meet the requirements for different sizes of microspheres; by selecting a suitable reaction solution and adjusting the reaction rate between the microsphere and the reaction solution, a wider range of microsphere sizes can be controlled.

[0035] Furthermore, the parallel design of the buffer solution channel, main channel, and collection channel reduces energy loss during sample movement and avoids problems such as sample adhesion and blockage caused by channel bends. The design of the reaction liquid channel and waste liquid channel facilitates laminar flow of the reaction liquid and buffer solution within the channels. To avoid differences in lateral displacement distance of samples due to different positions within the main channel, the first and second buffer solution inlet channels are symmetrically distributed on both sides of the buffer solution channel, arranging the samples in the center of the channel for precise control of each sample.

[0036] Furthermore, to reduce the impact of flow resistance on sample manipulation, both the height and width of the microchannels are designed to be relatively large. By widening the main channel and the reaction liquid channel, and combining this with a focused acoustic field, droplets / particles can be deflected over greater distances in the main channel, thereby increasing the range of corresponding trajectory changes and expanding the size range of the prepared microspheres. The wider waste liquid channel design is to prevent the reaction liquid from contaminating the sample.

[0037] Furthermore, sound fields can be used to manipulate microparticles of various materials, including but not limited to ester droplets, CL-20 microspheres, and some metal microspheres, enabling the size control of microspheres made of various materials.

[0038] A method for controlling the size of microspheres / droplets based on surface acoustic wave (SAW) technology is presented. This method generates an acoustic field within a microchannel using a transducer array, manipulating the trajectory of the sample within the flow channel. Different arc-shaped trajectories correspond to different reaction times of the droplets / microspheres in the reaction solution, resulting in different sizes upon returning to the collection solution. This method allows for real-time control of the microsphere size by adjusting the voltage amplitude of the signal generator during the experiment. Furthermore, logical control of the voltage amplitude enables the mixing and preparation of microspheres with varying sizes in a specific proportion. Moreover, this microfluidic device reduces material waste during the process, improving experimental efficiency and microsphere quality.

[0039] In summary, this invention has advantages such as adjustable size, high preparation efficiency, and safe preparation process, and is suitable for the preparation of various microsphere materials.

[0040] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0041] Figure 1 It is a schematic diagram of the structure of the present invention;

[0042] Figure 2 This is a schematic diagram of the microfluidic system structure for droplet size control according to the present invention;

[0043] Figure 3This is a schematic diagram of the microchannel system structure for microsphere size control according to the present invention;

[0044] Figure 4 This is a schematic diagram of laminar flow in the two-phase solution of the present invention;

[0045] Figure 5 This is a schematic diagram illustrating the principle of microsphere / droplet size control in this invention.

[0046] The components are: 1. Piezoelectric substrate; 2. Transducer assembly; 2-1. Focused interdigitated electrode; 2-2. Parallel interdigitated electrode; 3. Microchannel; 3-1. Buffer solution channel; 3-2. Reaction solution microchannel; 3-3. Main channel; 3-4. Waste liquid channel; 3-5. Collection channel; 3-6. Sample inlet channel; 3-7. First buffer solution inlet channel; 3-8. Second buffer solution inlet channel; 4. Acoustic field; 5. Sample; 6. Microchannel interface; 6-1. Sample inlet channel interface; 6-2. Reaction solution microchannel interface; 6-3. Waste liquid channel interface; 6-4. Collection channel interface; 6-5. First buffer solution inlet channel interface; 6-6. Second buffer solution inlet channel interface; 7. Oil-water interface; 8. Trajectory; 9. Solution system; 9-1. Reaction solution; 9-2. Buffer solution. Detailed Implementation

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "one side," "one end," and "one side," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0051] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0052] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0053] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0054] This invention provides a device and method for controlling the size of microspheres / droplets based on surface acoustic wave (SAW) technology. A transducer assembly is attached to the upper surface of a piezoelectric substrate, and microchannels are bonded to the upper surface of the substrate. The microchannels include a main channel, buffer solution channels and reaction solution channels connected to the inlet of the main channel, and waste liquid channels and collection channels on the outlet side of the main channel. The sample flows within the microchannels. The transducer assembly generates an acoustic field, which acts as a driving force to manipulate the sample in the main channel to laterally deflect across the oil-water interface between the reaction solution and the sample solution, thereby controlling the sample's path within the reaction solution. By controlling a focusing interdigitated electrode, the lateral deflection distance of the sample in the channel can be controlled. Then, under the action of parallel interdigitated transducers, the sample is controlled to cross the oil-water interface and return to the sample solution, thereby controlling the reaction time between the reaction solution and the sample, and achieving control over the sample size. This invention can control the contact time between the sample and the reaction solution with the assistance of an acoustic field, allowing for different degrees of sample refinement, and is applicable to various sample materials.

[0055] See also Figure 1 This invention discloses a device for controlling the size of microspheres / droplets based on surface acoustic wave (SAW) technology. The device includes a piezoelectric substrate 1, a transducer assembly 2 attached to the upper surface of the substrate 1, and microchannels 3 bonded to the upper surface of the substrate 1. The microchannels 3 include a main channel 3-3, a buffer solution channel 3-1 and a reaction solution channel 3-2 connected to the inlet of the main channel 3-3, a waste liquid channel 3-4 and a collection channel 3-5 on one side of the outlet of the main channel 3-3, and a sample 5 flowing within the microchannels 3. The buffer solution channel 3-1 is connected on its left side to a sample inlet channel 3-6 and two buffer solution inlets 3-7 and 3-8 (both without sample). The transducer assembly... 2. A sound field 4 is generated, which acts as a driving force to manipulate the sample 5 in the main channel 3-3 to pass through the oil-water interface 7 between the reaction liquid and the sample solution and cause lateral displacement. Then, by utilizing the difference in solubility of the sample 5 in the buffer solution 9-2 and the reaction liquid 9-1, the degree of corrosion of the sample 5 surface structure by the reaction liquid 9-1 is controlled, or the size of the sample 5 is controlled by controlling the solubility of the sample 5 surface by the reaction liquid 9-1. The lateral displacement distance of the sample 5 in the channel is controlled by controlling the energy density of the focused sound field. Then, under the action of the parallel interdigitated electrode 2-2, the sample 5 is controlled to pass through the oil-water interface 7 and return to the sample solution. The sample 5 is collected through the collection channel 3-5.

[0056] Transducer group 2 is a surface acoustic wave interdigital transducer. Transducer group 2 includes a focusing interdigital electrode 2-1 and a parallel interdigital electrode 2-2. The focusing interdigital electrode 2-1 and the parallel interdigital electrode 2-2 are turned on or off respectively, which can turn on or off the focused sound field with a large energy density and the standing wave sound field with a large effective area respectively. The focusing interdigital electrode 2-1 is located below the main channel 3-3 and close to the buffer solution channel 3-1. It uses its focused sound field to quickly deflect the sample 5 into the reaction solution 9-1. The parallel interdigital electrode 2-2 is located on the axis of the main channel 3-3 and is at an angle of 0~60° to the main channel 3-3 and close to the collection channel 3-5. It uses its parallel standing wave field to make the sample 5 enter the buffer solution with an approximately arc-shaped motion trajectory.

[0057] The focused interdigitated electrode 2-1 includes 10 to 50 pairs of interdigitated fingers with a width of 5 to 50 micrometers and an angle of 30 to 120°. Under the drive of a sinusoidal AC voltage, it can focus surface acoustic waves on the surface of the piezoelectric substrate 1. The focused surface acoustic waves mainly act on sample 5 in the buffer solution 9-2.

[0058] The parallel interdigitated electrode 2-2 includes 10 to 100 pairs of parallel interdigitates, with a width of 5 to 50 micrometers and a length of 2 to 5 millimeters. It is located below the main channel 3-3 and forms an angle of 0 to 60° with the main channel 3-3. Under the drive of a sinusoidal AC voltage, it can generate surface acoustic waves with a frequency of 50 MHz and a longer operating window on the surface of the piezoelectric substrate 1. The parallel surface acoustic waves mainly act on the sample 5 in the reaction solution 9-1.

[0059] See also Figure 2 and Figure 3 The microchannel 3 includes a main channel 3-3, the inlet of which is connected to the buffer channel 3-1 and the reaction liquid channel 3-2, and the outlet of which is connected to the waste liquid channel 3-4 and the collection channel 3-5. The left side of the buffer channel 3-1 is connected to a sample-providing cross channel, including a sample inlet channel 3-6, a first buffer inlet channel 3-7, and a second buffer inlet channel 3-8. The buffer channel 3-1 is parallel to the collection channel 3-5 and the main channel 3-3, and is connected to the inlet and outlet of the main channel 3-3, respectively. The reaction liquid channel 3-2 is connected to the buffer... The liquid flow channel 3-1 is at an angle of 15~60° and is located diagonally above the buffer solution flow channel 3-1. The waste liquid flow channel 3-4 is at an angle of 15~60° and is located diagonally above the collection flow channel 3-5. The inlet end of the buffer solution flow channel 3-1 is connected to the sample inlet flow channel 3-6, the first buffer solution inlet flow channel 3-7, and the second buffer solution inlet flow channel 3-8. The sample inlet flow channel 3-6 is parallel to the buffer solution flow channel 3-1. The first buffer solution inlet flow channel 3-7 and the second buffer solution inlet flow channel 3-8 are symmetrically designed on both sides of the sample inlet flow channel 3-6 at an angle of 120~180°.

[0060] The height of microchannel 3 is 50-120 micrometers, and all are direct-flow channels. The width of the microchannels varies at different locations: the width of the main flow channel 3-3 is 100-500 micrometers; the width of the buffer solution channel 3-1 and the collection channel 3-5 is 50-150 micrometers; and the width of the reaction solution channel 3-2 and the waste solution channel 3-4 is 100-300 micrometers. Depending on the sample properties, the channel width should be adjusted accordingly. During droplet size control, the width of the sample inlet channel 3-6, the first buffer solution inlet channel 3-7, and the second buffer solution inlet channel 3-8 are all 50-150 micrometers. However, during microsphere size control, the position of the sample 5 needs to be controlled by the sheath flow, so the width of channel 3-6 is set to 30-150 micrometers, and the widths of the first buffer solution inlet channel 3-7 and the second buffer solution inlet channel 3-8 are both 50-150 micrometers.

[0061] Please see Figure 2 In the process of controlling the droplet size, the solution containing the material is introduced into the sample inlet channel 3-6 through the sample inlet channel interface 6-1. The buffer solution 9-2 is introduced into the first buffer solution inlet channel 3-7 and the second buffer solution inlet channel 3-8 through the first buffer solution inlet channel interface 6-5 and the second buffer solution inlet channel interface 6-6. By adjusting the flow rate of the buffer solution 9-2 and the solution containing the material, the shear force of the buffer solution 9-2 on the solution in the sample inlet channel 3-6 is used to prepare droplets of 20~100 micrometers. Then, the droplets are prepared into microspheres with a particle size of less than 10 micrometers through the main channel 3-3.

[0062] Please see Figure 3 For the process of controlling the size of microspheres, the microspheres are dispersed in buffer solution 9-2 by ultrasound, and then the microspheres are introduced into sample inlet channel 3-6 through sample inlet channel interface 6-1. The flow rate of buffer solution 9-2 in the first buffer solution inlet channel 3-7 and the second buffer solution inlet channel 3-8 is adjusted to constrain the movement of microspheres in the transverse direction of the channel, and control the microspheres to move in the main channel 3-3 in an approximately linear manner. Then, microspheres with a particle size of less than 10 micrometers or even nanometers are prepared through the main channel 3-3.

[0063] Buffer 9-2 flows in through the first buffer inlet channel 3-7 and the second buffer inlet channel 3-8. Liquid containing the sample flows in through the sample inlet channel 3-6. Reaction solution 9-1 flows in through the reaction solution channel 3-2. In the main channel 3-3, buffer 9-2 and reaction solution 9-1 flow forward in a laminar flow and separate from the outlet end of the main channel 3-3. Reaction solution 9-1 flows out through the waste liquid channel 3-4, and buffer 9-2 flows out through the collection channel 3-5.

[0064] Please see Figure 4In the experiment, reaction solution 9-1 and buffer solution 9-2 flow in laminar flow within microchannel 3. Reaction solution 9-1 dissolves droplet-type samples or corrodes the surface of solid samples. Sample 5 does not react with buffer solution 9-2 and is insoluble in buffer solution 9-2. Sample 5 enters the main channel 3-3 with buffer solution 9-2. Under the action of transducer assembly 2, the size of sample 5 is controlled by dissolving or reacting with reaction solution 9-1. By controlling the working voltage of the focusing interdigital electrode 2-1, the offset distance of sample 5 under the action of the focused acoustic field is controlled, thereby controlling the contact time between sample 5 and reaction solution 9-1, and thus achieving size control of sample 5.

[0065] The reaction solution reduces the size of sample 5 by dissolving or corroding it. By changing the reaction solution, the reaction rate between sample 5 and the reaction solution can be controlled, thereby expanding the adjustable range of sample 5 size while keeping the transducer operating parameters unchanged.

[0066] Sample 5 flows in through sample inlet channel 3-6. The buffer solution 9-2 in the first buffer solution inlet channel 3-7 and the second buffer solution inlet channel 3-8 controls the formation of droplet samples or the lateral position of microsphere samples. It moves in a straight line in buffer solution channel 3-1 towards the main channel 3-3. The focusing interdigital electrode 2-1 in transducer group 2 controls the lateral displacement of sample 5, which passes through the oil-water interface 7 between buffer solution 9-2 and reaction solution 9-1 and enters the reaction solution 9-1. The reaction solution 9-1 reacts with sample 5, and the size of sample 5 gradually decreases. Then, under the action of parallel interdigital electrode 2-2, sample 5 is pushed into buffer solution 9-2, terminating the size reduction process of sample 5 by reaction solution 9-1. Finally, sample 5 flows out with buffer solution 9-2 through collection channel 3-5 for sample collection. The reaction solution 9-2 is discharged through waste liquid channel 3-4.

[0067] Sample 5 is not limited to liquid droplets or solid particles. By adjusting the parameters of transducer 2 and the solution system of reaction liquid and buffer, the size control of different materials can be achieved.

[0068] The materials of sample 5 include, but are not limited to, ester droplets, CL-20 microspheres, and metal microspheres. Ethyl acetate droplets, which are poorly soluble in water, are selected as sample 5. Deionized water is used as the buffer solution, and silicone oil is used as the reaction solution. Under the action of transducer 5, the droplet sample 5 is controlled to enter the silicone oil. The size of the droplet sample 5 is reduced by the dissolution of the droplet by the silicone oil. Then, the droplet is collected through collection channels 4-5. CL-20 microspheres, which are insoluble in water, are selected as sample 5. A certain concentration of aqueous solution is used as the buffer solution, and a diluted ethyl acetate oil solution is used as the reaction solution. Under the action of transducer 2, the time of solid sample 5 in the reaction solution is controlled, thereby achieving the refinement of CL-20.

[0069] This invention discloses a method for controlling the size of microspheres / droplets based on surface acoustic wave (SAW) technology. By precisely manipulating microspheres in a microfluidic system using SAW technology, the corrosion process between the microspheres and the reaction solution is controlled, resulting in smaller microsphere structures. Leveraging the high precision and non-contact nature of SAW technology, precise control of the microsphere corrosion process is achieved, primarily by controlling the contact time between the microspheres and the corrosive solution. This method can also be used to control the process of preparing microspheres via droplet microfluidics. By using a solvent instead of a corrosive agent to dissolve the reagent on the droplet surface, the microsphere size is controlled by controlling the droplet size. The specific steps include:

[0070] S1. Fix a device for controlling the size of microspheres / droplets based on surface acoustic wave technology on the stage, and observe through the objective lens to ensure that the main channel 3-3 is parallel to the lower boundary of the viewing window and is located in the center of the microscope viewing window;

[0071] S2, the first buffer inlet channel interface 6-5 and the second buffer inlet channel interface 6-6 are connected to the buffer syringe on the injection pump through PTFE tubes respectively; the interface of the sample inlet channel 3-6 is connected to the sample syringe on the injection pump through PTFE tubes; the interface of the reaction liquid channel 3-2 is connected to the reaction liquid syringe through PTFE tubes; the interfaces of the waste liquid channel 3-4 and the collection channel 3-5 are connected to the waste liquid collection container and the microsphere collection container respectively through PTFE tubes.

[0072] S3. Connect the two poles of the focused interdigital electrode 2-1 and the parallel interdigital electrode 2-2 to the positive and negative poles of the output signals of the two signal generators respectively, and adjust the output signal of the signal generator to be a continuous sinusoidal output with a frequency of 37.5MHz and a voltage amplitude of 10~40Vpp.

[0073] S4. Turn on the injection pump and adjust the flow rate of the buffer solution channel 3-1 and the reaction solution channel 3-2 to make the buffer solution and the reaction solution of the suspended particles form a stable laminar flow. After the two-phase fluid forms a stable oil-water interface 7 in the main flow channel 3-3, turn on the signal generator to construct the sound field 4 in the flow channel. Under the action of the sound field 4, the sample 5 moves from the buffer solution to the reaction solution and back to the buffer solution.

[0074] S5. By increasing or decreasing the voltage amplitude of the focusing interdigital transducer 2-1, the lateral offset distance of sample 5 in the main channel 3-3 is adjusted, the reaction time between sample 5 and the reaction solution is controlled, thereby achieving control of the size of sample 5.

[0075] See also Figure 5The process of controlling the size of microspheres using surface acoustic wave (SAW) technology is as follows: Buffer solution and reaction solution are simultaneously introduced into buffer channel 3-1 and reaction solution channel 3-2, respectively. The flow rates of the buffer solution and reaction solution are adjusted using a syringe pump, causing them to fill the main channel 3-3 in a laminar flow manner, forming a... Figure 5 The stable oil-water interface 7 is shown by the dashed line. When a sinusoidal AC voltage is input to the transducer, a converging surface acoustic wave with a converging energy beam is generated. Under the action of acoustic radiation force, the sample 5 in the main channel 3-3 is rapidly deflected laterally, passes through the oil-water interface and enters the reaction solution. The surface structure of the sample reacts with the reaction solution, and the size of the sample 5 decreases. Then, the sample 5 in the reaction solution is deflected by the action of the parallel interdigital transducer, passes through the oil-water interface 7 and enters the buffer solution. After the reaction is completed, the sample 5 enters the collection channel 3-5 with the buffer solution for collection.

[0076] The focused interdigitated electrode 2-1 controls the offset distance of sample 5 by adjusting the voltage amplitude of the control signal generator, thereby controlling the contact time between sample 5 and the reaction solution. Figure 5 The trajectory of sample 5 is shown in 8. As the voltage amplitude of the control signal generator increases, the acoustic radiation force acting on the sample surface increases, the lateral offset distance of the sample increases, and the contact time between the sample and the reaction solution also prolongs. For example, when the voltage amplitude of the signal generator is 15Vpp, sample 5 is laterally offset in the main channel 3-3, and then quickly separates from the reaction solution and enters the buffer solution after entering the working window of the parallel interdigital transducer 2-2, as shown in the shortest movement path in trajectory 8. When the voltage amplitude of the signal generator is 40Vpp, the lateral offset distance of sample 5 increases, and after entering the working window of the parallel interdigital transducer 2-2, sample 5 enters the buffer solution after a longer contact time with the reaction solution, as shown in the longest movement path in trajectory 8.

[0077] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0078] Example 1

[0079] The process of controlling droplet size using surface acoustic wave technology is as follows:

[0080] In the process of preparing microspheres by droplet microfluidic control, the size of the solidified microspheres is controlled by adjusting the size of the droplets. Ethyl acetate is a commonly used solvent in the field of materials science, used to dissolve a variety of pyrotechnic agents such as CL-20. As an ester reagent, ethyl acetate is insoluble in some aqueous solvents such as saturated sodium carbonate solution, but soluble in silicone oil.

[0081] In a reaction solution channel 3-3, ethyl acetate droplets are prepared using an aqueous phase as the continuous phase and ethyl acetate as the dispersed phase. Silicone oil, as the solvent, is introduced into the reaction solution channel. The flow rate of the silicone oil is adjusted using a syringe pump, ensuring that the oil-phase solvent and the aqueous solution fill the main channel 3-3 in a laminar flow, forming a... Figure 5 The stable oil-water interface 7 is shown by the dashed line. When a sinusoidal AC voltage is input to the transducer 2, the ethyl acetate droplets (sample 5) in the main channel 3-3 are rapidly deflected laterally under the action of acoustic radiation force, pass through the oil-water interface 7 and enter the silicone oil solution. The ethyl acetate slowly dissolves in the silicone oil, and the size of the ethyl acetate droplets decreases. Under the action of the parallel interdigital transducer, the ethyl acetate droplets are deflected, pass through the oil-water interface 7 and enter the aqueous solution. After the reaction is completed, the ethyl acetate droplets enter the collection channel 3-5 with the aqueous solution for collection, and then the droplets are solidified by heating and stirring.

[0082] Example 2

[0083] The process of controlling the size of microspheres using surface acoustic wave technology is as follows:

[0084] Microspheres of CL-20 material were ultrasonically dispersed in deionized water and introduced into the main channel 3-3 through buffer channel 3-1. A low-concentration ethyl acetate chloroform solution was prepared and introduced into the main channel 3-3 through reaction channel 3-2. The flow rates of the aqueous and oil phase solvents were adjusted using a syringe pump to ensure that the oil and aqueous solutions filled the main channel 3-3 in a laminar flow manner, forming a... Figure 5 The stable oil-water interface is shown by the dashed line 7;

[0085] When a sinusoidal AC voltage is input to transducer 2, the CL-20 microspheres (sample 5) in the main channel 3-3 are rapidly deflected laterally under the action of acoustic radiation force, pass through the oil-water interface 7 and enter the oil phase solution. The ethyl acetate in the oil phase reagent corrodes the surface structure of the CL-20 microspheres. As the reaction proceeds, the size of the CL-20 microspheres gradually decreases. Under the action of the parallel interdigital transducer, the CL-20 microspheres deflect, pass through the oil-water interface 7 and enter the aqueous phase solution. The microspheres enter the collection channel 3-5 with the aqueous solution for collection.

[0086] In summary, the present invention provides a device and method for controlling the size of microspheres / droplets based on surface acoustic wave technology. This device and method can control the contact time between the sample and the reaction solution under the assistance of an acoustic field, thereby refining the sample to different degrees and is applicable to a variety of sample materials.

[0087] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A device for controlling the size of microspheres / droplets based on surface acoustic wave technology, characterized in that, The device includes a piezoelectric substrate (1), on the upper surface of which a transducer assembly (2) and a microchannel (3) are provided. The microchannel (3) includes a main channel (3-3), a buffer solution channel (3-1) and a reaction liquid channel (3-2) connected to the inlet end of the main channel (3-3), and a waste liquid channel (3-4) and a collection channel (3-5) connected to the outlet end of the main channel (3-3). The sample (5) flows in the microchannel (3). The sample (5) is a microsphere or a droplet. The other end of the buffer solution channel (3-1) is connected to the sample inlet channel (3-6), the first buffer solution inlet channel (3-7) which does not contain the sample, and the second buffer solution inlet channel (3-8) which does not contain the sample. The transducer group (2) manipulates the sample (5) in the main channel (3-3) to pass through the oil-water interface (7) of the reaction liquid (9-1) and the sample solution by generating a sound field (4). Then, the difference in solubility of the sample (5) in the buffer solution (9-2) and the reaction liquid (9-1) is used to control the degree of corrosion of the surface structure of the sample (5) by the reaction liquid (9-1), thereby controlling the size of the sample (5). The transducer group (2) controls the lateral displacement distance of the sample (5) in the channel, and then controls the sample (5) to pass through the oil-water interface (7) and return to the sample solution. The sample (5) is collected by the collection channel (3-5).

2. The device for controlling the size of microspheres / droplets based on surface acoustic wave technology according to claim 1, characterized in that, The transducer group (2) is a surface acoustic wave interdigital transducer.

3. The device for controlling the size of microspheres / droplets based on surface acoustic wave technology according to claim 2, characterized in that, The transducer assembly (2) includes a focusing interdigital electrode (2-1) and a parallel interdigital electrode (2-2). The focusing interdigital electrode (2-1) is located below the main channel (3-3) and close to the buffer channel (3-1). The parallel interdigital electrode (2-2) is located on the axis of the main channel (3-3) and is at an angle of 0~60° to the main channel (3-3) and close to the collection channel (3-5). The focusing interdigital electrode (2-1) and the parallel interdigital electrode (2-2) are used to generate a focused sound field and a standing wave sound field, respectively.

4. The device for controlling the size of microspheres / droplets based on surface acoustic wave technology according to claim 3, characterized in that, The focused interdigital electrode (2-1) includes 10 to 50 pairs of interdigits, with the width of the interdigits being 5 to 50 micrometers in an arc shape and the angle of the interdigits being 30 to 120°.

5. The device for controlling the size of microspheres / droplets based on surface acoustic wave technology according to claim 3, characterized in that, The parallel interdigitated electrode (2-2) includes 10 to 100 pairs of parallel interdigitated fingers with a width of 5 to 50 micrometers and a length of 2 to 5 millimeters. It is located below the main channel (3-3) and forms an angle of 0 to 60° with the main channel (3-3).

6. The device for controlling the size of microspheres / droplets based on surface acoustic wave technology according to claim 1, characterized in that, The buffer solution channel (3-1) is connected to the inlet and outlet ends of the main channel (3-3) respectively, and is arranged in parallel with the collection channel (3-5) and the main channel (3-3); The reaction liquid channel (3-2) forms an angle of 15-60° with the buffer solution channel (3-1) and is located diagonally above the buffer solution channel (3-1); The waste liquid flow channel (3-4) forms an angle of 15~60° with the collection flow channel (3-5) and is located diagonally above the collection flow channel (3-5); The inlet end of the buffer channel (3-1) is connected to the sample inlet channel (3-6), the first buffer inlet channel (3-7) and the second buffer inlet channel (3-8). The sample inlet channel (3-6) is parallel to the buffer channel (3-1). The first buffer inlet channel (3-7) and the second buffer inlet channel (3-8) are symmetrically designed at 120~180° on both sides of the sample inlet channel (3-6).

7. The device for controlling the size of microspheres / droplets based on surface acoustic wave technology according to claim 6, characterized in that, The height of the microchannels (3) is 50~120 micrometers, and they are all direct current channels. The width of the microchannels varies at different locations. The width of the main channel (3-3) is 100~500 micrometers, the width of the buffer solution channel (3-1) and the collection channel (3-5) is 50~150 micrometers, and the width of the reaction liquid channel (3-2) and the waste liquid channel (3-4) is 100~400 micrometers.

8. The device for controlling the size of microspheres / droplets based on surface acoustic wave technology according to claim 7, characterized in that, During the droplet size control process, the widths of the sample inlet channel (3-6), the first buffer inlet channel (3-7), and the second buffer inlet channel (3-8) are all 50~150 micrometers; During the microsphere size control process, the width of the sample inlet channel (3-6) is 50 micrometers, and the widths of the first buffer inlet channel (3-7) and the second buffer inlet channel (3-8) are both 50~150 micrometers.

9. The device for controlling the size of microspheres / droplets based on surface acoustic wave technology according to claim 1, characterized in that, The materials of sample (5) include ester droplets, CL-20 microspheres and / or metal microspheres.

10. A method for controlling the size of microspheres / droplets based on surface acoustic wave technology, characterized in that, Includes the following steps: S1. Fix the device for controlling the size of microspheres / droplets based on surface acoustic wave technology as described in any one of claims 1 to 9 on the stage, and observe through the objective lens to ensure that the main channel (3-3) is parallel to the lower boundary of the viewing window and is located at the center of the microscope viewing window; S2, the first buffer inlet channel interface (6-5) and the second buffer inlet channel interface (6-6) are connected to the buffer syringe on the injection pump through PTFE tubes respectively. The interface of the sample inlet channel (3-6) is connected to the sample syringe on the injection pump through PTFE tubes. The interface of the reaction liquid channel (3-2) is connected to the reaction liquid syringe through PTFE tubes. The interface of the waste liquid channel (3-4) and the interface of the collection channel (3-5) are connected to the waste liquid collection container and the microsphere / droplet collection container respectively through PTFE tubes. S3. Connect the two poles of the focusing interdigital electrode (2-1) and the parallel interdigital electrode (2-2) of the transducer group (2) to the positive and negative poles of the output signals of the two signal generators respectively, and adjust the output signal of the signal generator to be a continuous sinusoidal output. S4. Turn on each injection pump and adjust the flow rate of the buffer solution channel (3-1) and the reaction solution channel (3-2) to form a stable two-phase fluid between the sample solution and the reaction solution. After the two-phase fluid forms a stable oil-water interface (7) in the main channel (3-3), a sound field (4) is constructed in the channel. Under the action of the sound field (4), the sample (5) moves from the buffer solution to the reaction solution and back to the buffer solution. By increasing or decreasing the voltage amplitude of the focused interdigital transducer (2-1), the lateral offset distance of the sample (5) in the main channel (3-3) can be adjusted, thereby controlling the trajectory of the sample (5) in the main channel (3-3), thus controlling the reaction time of the sample (5) with the reaction liquid, and finally controlling the size of the sample (5).

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