Modular ultrasonic generation device and ultrasonic manipulation method for microparticles

Abstract

A modular ultrasonic generation device and an ultrasonic manipulation method for microparticles. The modular ultrasonic generation device is configured to generate an acoustic field for manipulating the movement of a target object (300). The device comprises an ultrasonic transducer (100) and a modulation member (200); the ultrasonic transducer (100) is configured to generate a planar wave; the modulation member (200) is provided on a propagation path of the planar wave and located between the ultrasonic transducer (100) and the target object (300), and the modulation member (200) can modulate the planar wave into a target acoustic field for manipulating the target object (300) so as to drive the target object (300) to move along a set movement path; and the modulation member (200) comprises a plurality of unit modules (210) capable of modulating corresponding sub-acoustic fields, and the unit modules (210) are spliced to superimpose the sub-acoustic fields to form the target acoustic field. In the modular ultrasonic generation device, diversified acoustic fields for manipulation having different functions are realized by means of the splicing of the plurality of unit modules (210), and dynamic combination can be performed according to manipulation requirements in different application scenarios to form different modulation members (200), so as to modulate microparticle manipulation modes having different functions.

Description

A modular ultrasonic generating device and ultrasonic microparticle manipulation method Technical Field

[0001] The present invention relates to ultrasonic manipulation technology, and in particular to a modular ultrasonic generating device and a method for ultrasonically manipulating particles. Background Art

[0002] With the advancement of microfabrication technology, particle manipulation has found widespread application in fields such as chemical analysis, industrial manufacturing, and biomedicine. Currently, a variety of methods exist for particle manipulation, including magnetic fields, ultrasound, and hydrodynamics. Compared to other methods, ultrasonic actuation offers numerous advantages in biomedical applications due to its label-free, contact-free nature, strong penetration, and excellent biocompatibility.

[0003] Ultrasound-based particle manipulation technology primarily exploits the mechanical effects generated by the interaction between the acoustic field and the particles to drive their directional motion. Therefore, the trajectory of the particles under the influence of acoustic waves depends on the distribution pattern of the acoustic field. Current approaches to acoustic field manipulation are primarily divided into active and passive methods. Active methods, primarily based on ultrasonic phased arrays, enable dynamic configuration of excitation signals in real time, thereby achieving dynamic acoustic field manipulation. However, this technology requires the construction of complex drive circuit modules, making repair and maintenance difficult. Furthermore, due to the size of the transducer, the manipulation accuracy is low, and miniaturization and integration are difficult to achieve. Passive methods, primarily based on various artificial structures, can generate more sophisticated and complex acoustic fields than active manipulation methods. Advances in micro-nanofabrication technology have enabled the fabrication of these artificial structures to be more precise and cost-effective. However, once the structure is set, the resulting acoustic field remains relatively fixed, making it difficult to dynamically manipulate in real time. This requires redesigning the structure to accommodate changing needs, resulting in limited flexibility.

[0004] Summary of the Invention

[0005] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention proposes a modular ultrasonic generating device that can dynamically and on-demand combine multiple unit modules to form different modulation elements, based on the control requirements of different application scenarios. This modulates target sound fields with different functions, thereby achieving diverse particle control modes.

[0006] The present invention also provides a method for ultrasonically manipulating particles using the modular ultrasonic generating device.

[0007] According to the first aspect of the present invention, a modular ultrasonic generating device includes an ultrasonic transducer and a modulator, wherein the ultrasonic transducer is used to generate a plane wave; the modulator is arranged on the propagation path of the plane wave and is located between the ultrasonic transducer and the target object, and the modulator can modulate the plane wave into a target sound field for manipulating the target object to drive the target object to move along a set motion path; wherein the modulator includes a plurality of unit modules, each of the unit modules can modulate a corresponding sub-sound field respectively, and the unit modules are spliced ​​so that the sub-sound fields are superimposed to form the target sound field.

[0008] The modular ultrasound generating device according to the embodiment of the present invention has at least the following beneficial effects:

[0009] The modular ultrasonic generating device in the embodiment of the first aspect of the present application can dynamically and on-demand combine multiple unit modules to form different modulators according to the control requirements in different application scenarios, thereby modulating target sound fields with different functions, thereby realizing diversified control modes. The modular ultrasonic generating device can pre-assemble a module library with commonly used unit modules. When a new target sound field needs to be rebuilt, the unit modules in the original modulator are replaced and rearranged, thereby having high flexibility. And because a unit module can be applied to the assembly of multiple modulators, for this reason, the reuse rate is high and the overall cost is low.

[0010] According to some embodiments of the present invention, each of the unit modules modulates at least one of the following sub-sound fields:

[0011] a first sub-sound field for driving the target object to move in a straight line;

[0012] A second sub-sound field is used to drive the target object to change its moving direction.

[0013] According to some embodiments of the present invention, the modulator further includes a base, one side of the base is connected to the ultrasonic transducer, and the other side of the base is provided with a groove, and each of the unit modules is arranged in the groove.

[0014] According to some embodiments of the present invention, the modular ultrasonic generating device further includes a transducer moving mechanism and a loading mechanism, wherein the loading mechanism is used to place the target object, and the transducer moving mechanism is used to drive the ultrasonic transducer to move closer to or away from the loading mechanism so that the target object is located in the target sound field.

[0015] According to some embodiments of the present invention, the loading mechanism includes a container containing a sound propagation medium, and the target object floats in the container due to the buoyancy of the sound propagation medium.

[0016] According to some embodiments of the present invention, the modular ultrasonic generating device is provided with a plurality of ultrasonic transducers, and each of the ultrasonic transducers is provided corresponding to one of the unit modules.

[0017] According to some embodiments of the present invention, a plurality of microstructures are provided on the unit module, and each of the microstructures has a different height, or each of the microstructures has a different cross-sectional area.

[0018] According to some embodiments of the present invention, the arrangement and / or quantity of the microstructures on each unit module are different.

[0019] According to some embodiments of the present invention, the unit module is provided with a plurality of adjustment parts, each of the adjustment parts is made of a combination of at least two materials capable of modulating the sound field, and the proportion of the materials in each of the adjustment parts is different.

[0020] According to the second embodiment of the present invention, the method for ultrasonic manipulation of microparticles comprises the following steps:

[0021] Determine a set motion path of a target object;

[0022] Dividing the set motion path into a plurality of sub-paths;

[0023] Selecting a corresponding unit module according to the subpath;

[0024] splicing the unit modules to form a modulation component;

[0025] A target sound field is formed by the modulation element to drive the target object to move along the set motion path.

[0026] According to some embodiments of the present invention, the step of dividing the set motion path into a plurality of sub-paths includes:

[0027] determining the number of unit modules according to the control accuracy, the size of the set motion path, or the complexity of the set motion path;

[0028] The sub-paths are divided according to the number of the unit modules.

[0029] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0031] FIG1 is a schematic structural diagram of a modular ultrasound generating device according to an embodiment of the present invention;

[0032] FIG2 is a schematic diagram of a modulation component formed by splicing unit modules according to an embodiment of the present invention;

[0033] FIG3 is a schematic diagram of an implementation of a debugging component according to an embodiment of the present invention;

[0034] FIG4 is a set of test data diagrams of a modular ultrasonic generating device according to an embodiment of the present invention;

[0035] FIG5 is another set of test data diagrams of the modular ultrasonic generating device according to an embodiment of the present invention;

[0036] FIG6 is a schematic flow chart of a method for ultrasonic manipulation of microparticles according to an embodiment of the present invention;

[0037] FIG. 7 is another schematic flow chart of the method for ultrasonic manipulation of microparticles according to an embodiment of the present invention.

[0038] Reference numerals: ultrasonic transducer 100 ; modulation element 200 ; unit module 210 ; linear unit module 211 ; curved unit module 212 ; target object 300 ; container 400 ; sound propagation medium 410 . DETAILED DESCRIPTION

[0039] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0040] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0041] In the description of the present invention, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0042] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0043] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0044] When particles are exposed to an ultrasonic sound field, they are subject to the acoustic radiation force, which drives their motion. This force is the force exerted on an object by the energy and momentum generated by sound waves propagating through a medium. When sound waves pass through matter, they cause the medium to vibrate and deform, which in turn generates momentum in the particles, which in turn is subject to a radiation force. This radiation force, also known as an interaction force, is typically a non-contact force that is related to the distance between the particles. Therefore, acoustically driven microparticle manipulation enables non-contact, directional manipulation.

[0045] Based on the above principles, the first embodiment of the present application proposes a modular ultrasonic generating device, as shown in Figure 1, the modular ultrasonic generating device includes an ultrasonic transducer 100 and a modulator 200, which can be used to manipulate the movement of a target object 300. It should be explained that the target object 300 can be a macroscopic object or a microscopic object such as particles and cells. By changing the ultrasonic frequency, ultrasonic energy, ultrasonic pulse length, ultrasonic pulse repetition frequency and other parameters of the ultrasonic transducer 100, objects of different sizes can be driven to move. Specifically, the ultrasonic transducer 100 can be a piezoelectric ultrasonic transducer 100, or a capacitive micromachined ultrasonic transducer 100, a piezoelectric micromachined ultrasonic transducer 100 or other types of ultrasonic transducers 100. The ultrasonic transducer 100 can emit a plane wave, and the wavefront phase distribution of the plane wave is relatively uniform, which is conducive to the modulation of the modulator 200. The modulator 200 is disposed on the propagation path of the plane wave. In some embodiments, as shown in FIG. 1 , the modulator 200 is embedded in the ultrasonic transducer 100 . In other embodiments, the modulator 200 may be spaced apart from the ultrasonic transducer 100 .

[0046] It is understood that the modulator 200 is located between the ultrasonic transducer 100 and the target object 300. The plane wave emitted by the ultrasonic transducer 100 passes through the modulator 200 and reaches the plane of the target object 300. Due to the interaction between the structure of the modulator 200 and the acoustic wave, the wavefront phase of the acoustic wave changes, thereby forming a target sound field for manipulating the movement of the target object 300. The manipulated sound field produces a specific distribution pattern on the plane of the target object 300, enabling the target object 300 to move along a predetermined motion path.

[0047] It is understandable that the shape of the modulator 200 includes but is not limited to circular, square, etc., the materials used to manufacture the modulator 200 include but are not limited to resin, silicone, rubber, etc., and the manufacturing process includes but is not limited to laser etching, 3D printing, infusion molding, etc. In the prior art, in order to generate a controllable sound field through an ultrasonic phased array, it is necessary to build a complex drive circuit module, which is difficult to repair and maintain, and is limited by the size of the vibrator, the control accuracy is low, and it is difficult to achieve a miniaturized integrated design. The modular ultrasonic generating device in the embodiment of the present application uses the modulator 200 to construct the target sound field. Since the manufacturing accuracy of the modulator 200 is high, the modular ultrasonic generating device in the embodiment of the present application can achieve fine trajectory control of particles of smaller size. In addition, the material used to make the modulator 200 is cheap and the manufacturing process is simple, which reduces the cost of using the device.

[0048] It is understood that the modular ultrasonic generating device also includes an ultrasonic excitation mechanism (not shown in the figure), which includes an ultrasonic signal generator and a signal amplifier. When the modular ultrasonic generating device is in operation, the ultrasonic signal generator generates a continuous electrical excitation signal, which is amplified by the signal amplifier and transmitted to the ultrasonic transducer 100, and the electrical signal is converted into a mechanical vibration signal to generate sound waves. The modular ultrasonic generating device also includes a cooling mechanism (not shown in the figure). The cooling mechanism is attached to the ultrasonic transducer 100 and can enhance the heat dissipation performance of the ultrasonic transducer 100 to prevent the ultrasonic transducer 100 from overheating and causing failure when operating for a long time.

[0049] In existing technology, the modulator 200 is often manufactured in one piece using processes such as 3D printing. This modulator 200 has a fixed structure, and each modulator 200 can only produce one target sound field. Without replacing the modulator 200, the target object 300 can only move along a fixed path. If usage requirements change and the target object 300's set motion path changes, adaptive adjustments to the sound field are required, requiring the modulator 200 to be remade. Ultrasonic control debugging can only be performed after the modulator 200 is completed, which takes a long time.

[0050] When the target object 300 needs to be manipulated along multiple paths, multiple modulation elements 200 must be prepared for replacement. This makes it difficult to dynamically adjust the target object 300's path according to demand, requiring only the selection of the corresponding modulation element 200 from a specific set of paths. This results in limited flexibility. Furthermore, when the target object 300 has a wide variety of movement paths, the same number of modulation elements 200 must be prepared, each corresponding to each path. Consequently, a large number of modulation elements 200 must be manufactured for use, resulting in high costs.

[0051] To solve the above problems, as shown in Figures 2 to 5, the modulator 200 in the embodiment of the first aspect of the present application includes a plurality of unit modules 210, each of which is capable of modulating a plane wave into a corresponding sub-sound field. The unit modules 210 include a linear unit module 211, a curved unit module 212, a composite unit module, and the like. For example, as shown in Figure 5, the linear unit module 211 is capable of modulating a first sub-sound field. When the target object 300 is located in the first sub-sound field, the target object 300 is able to move linearly along a set direction under the action of the acoustic radiation force. As shown in Figure 4, the curved unit module 212 is capable of modulating a second sub-sound field. When the target object 300 is located in the second sub-sound field, the target object 300 is able to change its direction of movement under the action of the acoustic radiation force. Alternatively, the composite unit module is capable of modulating the first sub-sound field and the second sub-sound field so that the target object 300, when located in the sound field of the composite unit module, can sequentially perform linear and curved motions.

[0052] The curve unit module 212 can be further divided into a steering unit module and a reverse unit module. For example, when the target object 300 is in the sub-sound field of the steering unit module, the target object 300 moves along a quarter-circular path or an L-shaped straight curved path, adjusting the target object 300 from moving in a first direction to moving in a second direction perpendicular to the first direction. When the target object 300 is in the sound field of the reverse unit module, the target object 300 moves along a semi-circular path, adjusting the target object 300 from moving in the first direction to moving in the opposite direction of the first direction. Depending on the design requirements of the steering unit module 210, the movement path of the target object 300 in the second sub-sound field can also be other forms of arc segments, straight curved segments, etc.

[0053] It is understandable that the movement and steering of the target object 300 can be completed in the sound field of a single curve unit module 212, and can also be realized by the combination of the sound field of multiple curve unit modules 212. For example, in the embodiment as shown in Figure 3, it is set that the target object 300 needs to do a single or cyclic movement along the perimeter direction of the square. For this reason, multiple unit modules 210 are selected to be arranged in sequence along the moving path of the target object 300, forming a square ring pattern as shown in Figure 3. It should be explained that in the embodiment as shown in Figure 3, four types of unit modules 210 are provided, and the lower right corners of each unit module 210 in the figure are marked with ①, ②, ③, ④ for distinguishing. Wherein, the first, second and fourth unit modules are curve unit modules 212, and the second unit module and the fourth unit module are respectively arranged on the adjacent two sides of the first unit module. The target object 300 enters the sound field of the first unit module from the sound field of the fourth unit module, and then moves out from the sound field of the second unit module, thereby completing the transition from the first direction (or second direction) to the second direction (or first direction).

[0054] The second and fourth unit modules on the same side of the square path are connected by a third unit module. The third unit module is a linear unit module 211, which can drive the target object 300 to move from the second unit module to the fourth unit module. It can be understood that the target object 300 needs to undergo four changes of direction each time it moves one circle. To this end, the first, second, and fourth unit modules are arranged at the four corners of the square path to form a second sub-sound field that can drive the target object 300 to move and turn. The third unit module is arranged on the four sides of the square path to form a first sub-sound field that can drive the target object 300 to move in a straight line.

[0055] It should be noted that during the assembly of the unit modules 210, there are areas not involved in the manipulation of the target object 300, such as the nine square areas in the middle of the ring modulator 200 in FIG3 . In these areas, blocks of acoustically transparent material as large as the unit modules 210 can be placed to securely abut the surrounding unit modules 210. Alternatively, these areas can be left vacant.

[0056] The individual unit modules 210 are spliced ​​together to form a modulator 200, so that when the plane wave emitted by the ultrasonic transducer 100 is modulated by the individual unit modules 210 on the modulator 200, a target sound field is formed. In the embodiment shown in Figure 4, the feasibility of the modulator 200 formed by splicing for regulating the sound field was verified by experiments. It should be explained that Figure 4 (a) is a schematic diagram of the target trajectory, Figure 4 (b) is a phase distribution diagram on the modulator 200, Figure 4 (c) is a schematic diagram of the target sound field, and Figure 4 (d) is a schematic diagram of the movement trajectory of the target object 300 simulated by a computer. It can be seen that the simulated movement trajectory is basically consistent with the set trajectory. Another embodiment is also proposed in Figure 5. It should be explained that Figure 5 (a) is a schematic diagram of the target trajectory, Figure 5 (b) is a phase distribution diagram on the modulator 200, Figure 5 (c) is a schematic diagram of the target sound field, and Figure 5 (d) is a schematic diagram of the movement trajectory of the target object 300 simulated by a computer.

[0057] In this embodiment, as shown in FIG5(a), it is necessary to manipulate multiple target objects 300 to move from the left to the right at the same time. According to this set motion path, the unit modules 210 are reselected and a new modulator 200 is formed as shown in FIG5(b). Since three target objects 300 need to be manipulated to move in a straight line in this application scenario, three rows of linear unit module groups are provided. Each row of linear unit module groups includes five linear unit modules 211, and each linear unit module 211 is arranged in sequence along the same direction. The distribution pattern of the sound field of the modulator 200 is shown in FIG5(c), and the simulated movement trajectory of the target object 300 under the action of the sound field is shown in FIG5(d).

[0058] Thus, the modular ultrasonic generating device in the embodiment of the first aspect of the present application achieves a variety of control modes by splicing multiple unit modules 210. The modular ultrasonic generating device can dynamically and on-demand combine to form different modulators 200 according to the control requirements in different application scenarios, thereby modulating target sound fields with different functions. The modular ultrasonic generating device can pre-assemble a module library with commonly used unit modules 210. When a new target sound field needs to be rebuilt, the unit modules 210 in the original modulator 200 are replaced and rearranged, thereby having high flexibility. And because one unit module 210 can be used for the assembly of multiple modulators 200, the reuse rate is high and the overall cost is low. The module library configured by the modular ultrasonic generating device is provided with multiple unit modules 210, and when it is necessary to construct a sound field model, the appropriate unit module 210 is selected from them for splicing. It is understandable that the same unit module 210 can be provided with only one or multiple, and the unit module 210 can be square, rectangular or other shapes that are easy to splice. For example, in the embodiment shown in FIG. 5 , each linear unit module group includes five 4 mm×4 mm square linear unit modules 211 , and the same function can also be achieved by a 12 mm×4 mm rectangular linear unit module 211 .

[0059] Taking the commonly used L-shaped straight bending unit module as an example, the design principle of each unit module is as follows:

[0060] Assuming that the sound field at z = 0 (i.e., the output sound field of the ultrasonic transducer 100) is p = (x, y, 0), then the sound field at z > 0 p = (x, y, z) can be calculated using the angular spectrum method. The angular spectrum in the plane of constant z is expressed as the Fourier transform of the plane sound field:

[0061] According to the above formula, we can get the angular spectrum P(k x ,k y ,0). The angular spectrum of any plane can be calculated by multiplying the angular spectrum by the propagation function: P(k x ,k y ,z)=P(k x ,k y ,0)H(k x ,k y ,z) (2)

[0062] Here, k = ω / c is the wave number in the medium, ω and c are the angular frequency and the speed of sound in the liquid medium, respectively.

[0063] flatz The sound pressure field in can be substituted into the angular spectrum P(k x ,k y ,z) and calculated by inverse Fourier transform, the sound pressure field of any plane is expressed as:

[0064] Assume that the modulator 200 is located at the initial plane z = 0. First, the modulator 200 is initialized to a random phase distribution is the phase change introduced by the modulation element 200. Assuming that the incident source is uniformly distributed, the amplitude distribution is a constant amplitude, recorded as A0. At this time, the sound pressure field on the upper surface of the modulation element 200 is The forward propagation of the sound pressure field p0, that is, after Fourier transform, multiplying it by the corresponding angular spectrum propagation operator, and then performing inverse Fourier transform, the sound pressure on the imaging plane can be obtained, which is expressed as At this time, the phase and amplitude of the sound field on the imaging plane are modulated simultaneously, the phase at the target pattern is directly replaced with the ideal phase, and the amplitude at the target pattern is changed to the target amplitude. The changed phase is recorded as The changed amplitude is recorded as A T , then the sound field on the imaging plane becomes The sound pressure field p1 is propagated in reverse, that is, after Fourier transformation, it is multiplied by the corresponding inverse angular spectrum propagation operator, and then the inverse Fourier transformation is performed to obtain the sound pressure at the initial plane. The optimized results Assign to And replace A2 with A0. After that, the process of forward propagation, phase amplitude modulation, and reverse propagation is repeated, and the phase distribution of the optimized modulator 200 is finally obtained.

[0065] Taking the thickness-modulated modulator 200 as an example, the following relationship exists between the phase distribution and the thickness distribution: T=T0-ΔT(x,y)

[0066] Where T0 represents the customized initial thickness, ΔT represents the relative thickness change, and k m and k h They respectively represent the wave vectors of the medium and the material used to make the modulation element 200. According to the thickness distribution T finally obtained, the holographic structure of the required unit module can be prepared by applying 3D printing or laser etching.

[0067] The simulation calculation process of the particle motion trajectory in the spliced ​​holographic sound field is as follows:

[0068] To verify whether the particle can move along the preset trajectory, the first step is to calculate the acoustic radiation force on the particle:

[0069] First, assume that the incident sound field at z = 0 is known, and let the complex pressure amplitude be a known function: i | z＝0 =p i (x,y,0) (1)

[0070] Then, through Fourier transform, the angular spectrum of the incident complex sound field is specifically expressed as:

[0071] By multiplying the angular spectrum of the incident complex sound field by the angular spectrum propagation operator and then performing an inverse Fourier transform, we can obtain the complex sound field of any two-dimensional plane parallel to the incident plane in the entire space:

[0072] Where z is the propagation distance. Since plane waves are axisymmetric, the incident sound field can be rewritten using spherical harmonics and the Legendre-Galvans theorem as:

[0073] Where, j n (·) is the nth order spherical Bessel function, is a spherical harmonic function, and the superscript asterisk "*" represents the conjugate of the complex number. For the above incident sound field, the scattered sound field of the particle can be expressed as:

[0074] Where, is the nth order spherical Hankel function of the first kind, c n is the scattering coefficient of the particles. At this time, the total sound field in the whole space is:

[0075] in,

[0076] The acoustic radiation force acting on the particle can be expressed as:

[0077] Where dS=ndS is the unit area element with the normal pointing outward, n is the normal direction pointing outward from the surface of the Mie particle, S is the surface area of ​​the object, and <Π> is the time-averaged momentum current density tensor, which can be expressed as:

[0078] Where ρ and c are the density and speed of sound of the surrounding fluid, respectively, and p and v r are the total sound pressure field and total velocity field of the first-order sound pressure, respectively; <·> represents the time average of a certain physical quantity within a unit period.

[0079] Substitute the total sound field in the entire space into the first-order velocity field equation Get the first-order velocity field:

[0080] Substitute the total sound pressure field and velocity field into formula (7) and formula (8), and transform the spherical Bessel function j into n (·) and the spherical Hankel function of the first kind Assuming the far-field approximation, the normalized acoustic radiation force components in the x, y, and z directions are obtained:

[0081] in,

[0082] The second step is to obtain the motion trajectory of the particles in the sound field based on the acoustic radiation force and other external forces.

[0083] The particles are mainly affected by the acoustic radiation force and the fluid drag force. According to Newton's second law, the motion equation of Mie particles in a static fluid is:

[0084] Where m and v are the mass and velocity of Mie particles, respectively, and F rad is the acoustic radiation force, F drag is the fluid drag force caused by the flow. Due to the large size of Mie particles, the influence of acoustic streaming on the motion of Mie particles is negligible. Therefore, the fluid drag force can be expressed as: F drag =-6πμav (14)

[0085] In the formula, μ is the dynamic viscosity coefficient of the fluid, and a is the radius of the Mie particle.

[0086] Given the initial position and velocity of a Mie particle, a piecewise approximation is used to calculate the particle's trajectory. That is, within a small time interval, the particle is assumed to be in uniformly accelerated linear motion. The sum of all time intervals is the total duration of the particle's motion, and the sum of the particle's displacement within that time interval is the particle's total trajectory.

[0087] Based on the above steps, a unit module 210 capable of modulating a target sub-sound field can be designed and can be simulated and verified.

[0088] In some embodiments, the individual unit modules 210 are spliced ​​together to form the modulation element 200. Alternatively, the modulation element 200 may further include a base, the base generally being made of the same material as the unit modules 210. The modulation element 200 can be connected to the base and spliced ​​together on the base to form the modulation element 200. It is understood that the modulation element 200 and the base may be connected by plugging, snapping, gluing, etc., or the modulation element 200 may be directly placed on the base without providing a connecting structure.

[0089] For example, in the embodiment shown in FIG1 , the ultrasonic transducer 100, the modulator 200, and the target object 300 are arranged in sequence from bottom to top. The lower side of the base (not shown) is connected to the ultrasonic transducer 100, and a groove is provided on the upper side, in which each unit module 210 is arranged. Furthermore, the size of the groove can be exactly equal to the outer diameter of the multiple unit modules 210 after splicing. For example, in the embodiment shown in FIG4 , the size of the groove can be set to 40 mm × 40 mm. Thus, when each unit module 210 is installed in the groove, adjacent unit modules 210 abut against each other, and the unit modules 210 at the edges abut against the groove wall, thereby limiting the horizontal displacement of each unit module 210.

[0090] In some embodiments, the modular ultrasonic generating device further includes a transducer movement mechanism and a loading mechanism. The loading mechanism is used to place the target object 300. It is understood that the loading mechanism can be a platform that is permeable to sound waves. The target object 300 is supported by the platform and can rest on the platform. Furthermore, the target object 300 can move along the surface of the platform due to the acoustic radiation force. The loading mechanism can also be loaded with a sound propagation medium 410, such as gas or liquid. The target object 300 is positioned within the sound propagation medium 410 and rests within the sound propagation medium 410 due to the buoyancy of the sound propagation medium 410. Furthermore, the target object 300 can move within the sound propagation medium 410 due to the acoustic radiation force. The transducer movement mechanism is connected to the ultrasonic transducer 100 to drive the ultrasonic transducer 100 toward or away from the loading mechanism. Thus, the transducer movement mechanism can adjust the position of the ultrasonic transducer 100 based on factors such as the intensity of the sound field and the distance between the target object 300 and the ultrasonic transducer 100, so that the target object 300 is positioned within the target sound field.

[0091] Further, referring to FIG1 , the loading mechanism includes a container 400 containing an acoustic propagation medium 410. The acoustic propagation medium 410 can be either a liquid or a gas. Due to the buoyancy of the acoustic propagation medium 410, the target object 300 floats within the container 400. It is understood that the density of the target object 300 can be the same as that of the acoustic propagation medium 410, thereby floating within the acoustic propagation medium 410, or its density can be less than that of the acoustic propagation medium 410, thereby floating on the upper surface of the acoustic propagation medium 410. The gravity of the target object 300 and the buoyancy exerted by the acoustic propagation medium 410 offset each other, maintaining the target object 300 in a vertically balanced state. In the embodiment shown in FIG1 , the acoustic propagation medium 410 is a liquid, and the target object 300 floats on the liquid surface. The transducer movement mechanism is capable of moving the ultrasonic transducer 100 to a corresponding position so that the target acoustic field generated by the modulation element 200 acts precisely on the liquid surface, facilitating manipulation of the target object 300.

[0092] It is understandable that the ultrasonic transducer 100 and the modulator 200 can be arranged above the container 400 to emit sound waves from top to bottom, or the ultrasonic transducer 100 and the modulator 200 can be arranged below the container 400, and the sound waves pass through the container 400 and are then propagated by the sound propagation medium 410 to the plane where the target object 300 is located.

[0093] In some embodiments, if the individual unit modules 210 of the modulator 200 are small and the number of unit modules 210 is small, the entire modulator 200 is not large, and the sound waves generated by a single ultrasonic transducer 100 can fully cover all the unit modules 210, then a single ultrasonic transducer 100 can generate the desired target sound field. In other embodiments, if the unit modules 210 in the modulator 200 are large or the number of unit modules 210 is large, multiple ultrasonic transducers 100 can be combined to emit plane waves. Furthermore, the number of ultrasonic transducers 100 is consistent with the number of unit modules 210, so that each ultrasonic transducer 100 is provided corresponding to a unit module 210. Thus, through the coordinated operation of multiple ultrasonic transducers 100, they can operate at the same frequency or at multiple frequencies. By providing artificial microstructures on the unit modules 210, different phase delays can be achieved through different microstructures. It is understood that the micropillars can be prisms, cylinders, or other shapes. In some embodiments, as shown in Figure 2, a unit module 210 is provided with multiple micropillars, each with the same cross-sectional area but varying heights. Micropillars of varying heights can produce different phase delays. Through the orderly combination of multiple microstructures, sound waves experience varying delays as they pass through unit module 210, forming a new phase distribution and propagating forward. In other embodiments, micropillars of the same height but varying cross-sectional areas can also produce varying delay effects.

[0094] It should be explained that FIG2 is a schematic diagram of the microstructure on the unit module 210 , and the number and arrangement of the micropillars on the unit module 210 do not represent the number and arrangement of the micropillars on the unit module 210 in a real state.

[0095] In other embodiments, a plurality of adjustment parts are provided on the unit module 210, and each adjustment part can be composed of a combination of at least two materials capable of modulating the sound field. The proportion of materials in each adjustment part is different, thereby being able to produce different delay effects on the sound waves.

[0096] Based on the modular ultrasonic generating device mentioned in any of the above embodiments, as shown in FIG6 , the second embodiment of the present application further proposes a method for ultrasonic manipulation of particles, which includes the following steps:

[0097] S100, determining a set motion path of a target object;

[0098] S200, dividing the set motion path into multiple sub-paths;

[0099] In the process of dividing the sub-paths, generally, the curve segments and the straight line segments are divided into different sub-paths first, and then implemented by the curve unit module 212 and the straight line unit module 211 respectively.

[0100] S300, selecting a corresponding unit module according to the sub-path;

[0101] As shown in FIG. 3 , different types of unit modules 210 have significantly different appearances, and different types of unit modules 210 can be easily distinguished when selecting a unit module 210 .

[0102] S400, splicing the unit modules to form a modulation component;

[0103] S500: forming a target sound field through a modulation element to drive a target object to move along a set motion path.

[0104] Specifically, the ultrasonic excitation mechanism can be used to adjust parameters such as ultrasonic frequency and ultrasonic energy to generate a suitable plane wave for the ultrasonic transducer 100. The transducer movement mechanism can also be used to adjust the distance between the ultrasonic transducer 100 and the target object 300 to ensure that the target object 300 is within the target sound field.

[0105] Furthermore, as shown in FIG7 , the above step S200 can be further refined into the following steps:

[0106] S210, determining the number of unit modules according to the control accuracy, the size of the set motion path, or the complexity of the set motion path;

[0107] For example, when the motion path is set to a longer straight path, multiple straight unit modules 211 can be selected and spliced ​​to modulate the corresponding target sound field. When the motion path is set to an arc with a larger radius, multiple curved unit modules 212 can be selected and spliced ​​to modulate the corresponding target sound field. Alternatively, when the design path is S-shaped, a combination of multiple curved unit modules 212 and straight unit modules 211 is required to modulate the corresponding target sound field. Alternatively, when the control accuracy requirement is high, more precise control can be achieved by reducing the size of each unit module 210 and increasing the number of unit modules 210.

[0108] S220: Divide the sub-paths according to the number of unit modules.

[0109] It is understandable that the number of sub-paths should be consistent with the number of unit modules 210, and each sub-path corresponds to a unit module 210 that can realize the corresponding sound field.

[0110] Based on the above-mentioned ultrasonic manipulation method of particles, the flexibility of the modular ultrasonic generating device in the embodiment of the first aspect of the present application is fully demonstrated. The set motion path can be dynamically adjusted according to needs, and the sound field can be reconstructed by replacing the unit module 210 or changing the arrangement order of the unit module 210, which is relatively convenient and quick.

[0111] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A modular ultrasonic generating device for generating a sound field for manipulating the movement of a target object, characterized in that: include: An ultrasonic transducer, the ultrasonic transducer being used to generate a plane wave; A modulator, the modulator is disposed on the propagation path of the plane wave and is located between the ultrasonic transducer and the target object, the modulator is capable of modulating the plane wave into a target sound field for manipulating the target object, so as to drive the target object to move along a set motion path; The modulator includes a plurality of unit modules, each of which can modulate a corresponding sub-sound field, and each of the unit modules is spliced ​​so that each of the sub-sound fields is superimposed to form the target sound field.

2. The modular ultrasonic generating device according to claim 1, characterized in that: Each of the unit modules modulates at least one of the following sub-sound fields: A first sub-sound field for driving the target object to move in a straight line; A second sub-sound field is used to drive the target object to change its moving direction.

3. The modular ultrasonic generating device according to claim 1, characterized in that: The modulation element also includes a base, one side of the base is connected to the ultrasonic transducer, and the other side of the base is provided with a groove, and each of the unit modules is arranged in the groove.

4. The modular ultrasonic generating device according to claim 1, characterized in that: The modular ultrasonic generating device also includes a transducer moving mechanism and a loading mechanism, wherein the loading mechanism is used to place the target object, and the transducer moving mechanism is used to drive the ultrasonic transducer to move closer to or away from the loading mechanism so that the target object is located in the target sound field.

5. The modular ultrasonic generating device according to claim 4, characterized in that: The loading mechanism comprises a container, in which a sound propagation medium is contained. Under the buoyancy of the sound propagation medium, the target object floats in the container.

6. The modular ultrasonic generating device according to claim 1, characterized in that: The modular ultrasonic generating device is provided with a plurality of ultrasonic transducers, and each of the ultrasonic transducers is respectively provided corresponding to one of the unit modules.

7. The modular ultrasonic generating device according to claim 1, characterized in that: A plurality of microstructures are arranged on the unit module, and each of the microstructures has a different height, or each of the microstructures has a different cross-sectional area.

8. The modular ultrasound generating device according to claim 7, characterized in that: The arrangement and / or quantity of the microstructures on each of the unit modules are different.

9. The modular ultrasonic generating device according to claim 1, characterized in that: The unit module is provided with a plurality of adjustment parts, each of which is made of a combination of at least two materials capable of modulating the sound field, and the proportion of the materials in each of the adjustment parts is different.

10. A method for ultrasonic manipulation of particles, applied to the modular ultrasonic generating device according to any one of claims 1 to 9, characterized in that: The following steps are involved: Determine a set motion path of a target object; Dividing the set motion path into a plurality of sub-paths; Selecting a corresponding unit module according to the subpath; splicing the unit modules to form a modulation piece; A target sound field is formed by the modulation element to drive the target object to move along the set motion path.

11. The method for ultrasonic manipulation of microparticles according to claim 10, characterized in that: The step of dividing the set motion path into a plurality of sub-paths includes: Determining the number of unit modules according to the control accuracy, the size of the set motion path, or the complexity of the set motion path; The sub-paths are divided according to the number of the unit modules.

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