A non-contact rotating device and a method for preparing a modulation component

Abstract

The present invention discloses a non-contact rotating device and a method for preparing a modulator. The non-contact rotating device of the present invention 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; wherein the modulator can cause the plane wave passing through the modulator to produce a phase difference, so as to form a vortex sound field with multi-order topological charges, and the vortex sound field can drive the target object to rotate. The non-contact rotating device has a relatively simple structure and the overall device cost is relatively low, and can be widely used in experimental systems or industrial manufacturing. It can also generate an acoustic vortex field with multi-order topological charges, and the rotation speed of the object can be controlled by adjusting the distance between the modulator and the target object, which is more conducive to the operator selecting an acoustic vortex field of appropriate order according to needs and applying it to the target object, and is more flexible to operate.

Description

Technical Field

[0001] The present invention relates to the field of acoustics, and in particular to a non-contact rotating device and a method for preparing a modulation component. Background Art

[0002] Most existing rotary drive devices use direct contact, for example, by rotating a rotatable stage to drive the object placed on the stage to rotate, or by connecting the output shaft of a rotary motor to the rotating shaft of the object to be controlled to drive the object to rotate. However, in fields such as biology, medicine, and chemistry that have high requirements for environmental cleanliness, direct contact drive is prone to external contamination, affecting product quality or interfering with experimental results.

[0003] Since sound waves carry momentum and angular momentum, they can transfer momentum or angular momentum to objects in a non-contact manner, enabling operations such as capturing, translating, or rotating objects. Therefore, non-contact manipulation of objects through sound fields has become a hot topic of research both at home and abroad. In traditional technologies, a large number of acoustic transducers are arranged into a ring-shaped sound source array, and by controlling the phase delay of each transducer separately, an acoustic vortex field is formed through the superposition of sound fields. However, the device for generating such an acoustic vortex field requires a relatively complex control system and a large transducer array, which is costly. The debugging process for generating an acoustic vortex field with target parameters is particularly complex. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a non-contact rotating device that can generate an acoustic vortex field with multiple topological charges, has a relatively simple structure, and is relatively inexpensive to manufacture.

[0005] The invention also provides a method for preparing a modulation component.

[0006] A non-contact rotating device according to a first embodiment of the present invention includes:

[0007] an ultrasonic transducer for generating a plane wave;

[0008] a modulator, the modulator being disposed on a propagation path of the plane wave and located between the ultrasonic transducer and the target object;

[0009] The modulator can cause the plane wave passing through the modulator to generate a phase difference, so as to form a vortex sound field with multi-order topological charges, and the vortex sound field can drive the target object to rotate.

[0010] The non-contact rotating device according to the embodiment of the present invention has at least the following beneficial effects: compared with the active phase control technology in the prior art, the non-contact rotating device of this embodiment has a simpler device structure and a relatively cheap overall device cost, and can be widely used in experimental systems or industrial manufacturing. Compared with the existing passive phase modulation technology, the non-contact rotating device of this embodiment can generate an acoustic vortex field with multiple orders of topological charge, and can control the rotation speed of the object by adjusting the distance between the modulator and the target object. It is more conducive to the operator to select an acoustic vortex field of appropriate order to apply to the target object according to needs, and is more flexible to operate. It can effectively reduce the time for the operator to adjust the acoustic structure to obtain the target sound field, thereby improving the efficiency of experimental operations or industrial production.

[0011] According to some embodiments of the present invention, the non-contact rotation device is capable of controlling the rotation of multiple target objects, and each target object is arranged in sequence along the propagation direction of the vortex sound field, and the rotation speed of each target object decreases in sequence in the direction away from the modulator.

[0012] According to some embodiments of the present invention, the modulating member is made of a sound-impermeable material, and the modulating member is provided with a through groove having a spiral structure, wherein the spiral structure satisfies the following formula:

[0013]

[0014] Wherein, r0 is the initial radius of the spiral structure, z is the vertical distance between the target object and the modulator, l is the topological charge of the vortex acoustic field, λ is the wavelength of the acoustic wave, is the polar angle of the spiral structure, and M is a positive integer.

[0015] According to some embodiments of the present invention, the modulating element is made of a sound-transmitting material, the modulating element has a structure with uneven thickness, and the thickness of the modulating element satisfies the following formula:

[0016] ΔT(x,y)=Δφ(x,y) / (k m -k h );

[0017] Wherein, ΔT(x,y) is the thickness of any position of the modulator, Δφ(x,y) is the phase distribution at that position, and k m is the wave number of the sound-transmitting material, k h is the wave number of the propagation medium.

[0018] According to some embodiments of the present invention, the non-contact rotating device further includes a container for accommodating a propagation medium, and the target object is disposed in the container and floats on the propagation medium.

[0019] According to some embodiments of the present invention, the modulator is made of a metasurface, micropillars are arranged at different positions on the metasurface, and the metasurface is divided into a plurality of metasurface units. The volume fraction of the micropillars arranged on each metasurface unit satisfies the following formula:

[0020]

[0021] in, represents the phase, c m The speed of sound in the medium in which the sound propagates, c unit is the equivalent sound velocity of the metasurface unit composed of micropillars and medium, where c unit =(B unit / ρ unit ) 1 / , B unit is the equivalent bulk modulus of the metasurface unit, ρ unit is the equivalent density of metasurface units, and f is the plane wave frequency.

[0022] According to some embodiments of the present invention, the target object, the modulator and the ultrasonic transducer are arranged in sequence from top to bottom. When the non-contact rotating device is in a working state, it can drive the target object to float above the modulator and perform rotational motion.

[0023] According to some embodiments of the present invention, the non-contact rotation device further includes a connector connected to the target object, and when the vortex sound field drives the target object to rotate, the axial direction of the connector is coaxially arranged with the rotation axis of the target object.

[0024] According to some embodiments of the present invention, the ultrasonic transducer is connected to the modulator, and the non-contact rotating device further includes a position adjustment mechanism, which is capable of adjusting the distance between the ultrasonic transducer and the modulator and the target object to adjust the topological charge of the vortex sound field at the location of the target object.

[0025] The method for preparing a modulation element according to the second embodiment of the present invention comprises the following steps:

[0026] S100 models a modulator in simulation software, defines parameters of the modulator, sets a target plane and an emission plane, the distance between the target plane and the emission plane is z, and the modulator is located on the emission plane;

[0027] S200 constructs a plane wave sound field that propagates along a first direction and passes through the modulator, and an iterative sound field that propagates along a second direction, the first direction and the second direction being opposite, the plane wave sound field forming a vortex sound field after passing through the modulator;

[0028] S300 propagates the iterative sound field along the second direction to the emission plane of the modulator;

[0029] S400 extracts the amplitude and phase information on the emission plane, adjusts the amplitude of the vortex sound field to the amplitude on the emission plane, and keeps the phase of the plane wave sound field unchanged;

[0030] S500 propagates the vortex acoustic field along the first direction to the target plane;

[0031] S600 extracts amplitude and phase information on the target plane, adjusts the amplitude of the iterative sound field to the amplitude on the target plane, and keeps the phase of the iterative sound field unchanged;

[0032] S700 repeats steps S200 to S600 until the iterative sound field converges;

[0033] S800 extracts phase distribution information of the iterative sound field propagating to the emission plane in a converged state;

[0034] S900 calculates thickness distribution information of the modulator according to the phase distribution information;

[0035] S1000: manufacturing the modulation component.

[0036] According to some embodiments of the present invention, in step S1000 , the modulation element is manufactured by a 3D printing process or an etching process.

[0037] 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

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0039] Figure 1 Schematic diagram of vortex acoustic field with different orders of topological charge;

[0040] Figure 2 Schematic diagram of the structure of a non-contact rotating device according to an embodiment of the present invention;

[0041] Figure 3 This is a schematic structural diagram of a first embodiment of a modulation element according to an embodiment of the present invention;

[0042] Figure 4 for Figure 3 Another structural diagram of the middle modulation component;

[0043] Figure 5 Schematic diagram of the generation principle of vortex sound field;

[0044] Figure 6 Graph showing theoretical calculations of the sound intensity field and phase field of the vortex sound field according to an embodiment of the present invention;

[0045] Figure 7 Graphs showing experimental measurements of the sound intensity field and phase field of the vortex sound field according to an embodiment of the present invention;

[0046] Figure 8 A schematic diagram showing the time required for a target object to rotate one circle in acoustic fields with different topological charges according to an embodiment of the present invention;

[0047] Figure 9 A schematic structural diagram of a second embodiment of a modulation element according to an embodiment of the present invention;

[0048] Figure 10 Schematic diagram of the microstructure of the metasurface in the third embodiment of the modulation element according to an embodiment of the present invention;

[0049] Figure 11 Schematic diagram of the arrangement of micropillars with different volume fractions in each metasurface unit in the third embodiment of the modulation element according to an embodiment of the present invention;

[0050] Figure 12 Flow chart of the preparation of the modulation component according to an embodiment of the present invention.

[0051] Reference numerals:

[0052] Ultrasonic transducer 100 , modulation element 200 , helical structure 210 , target object 300 , container 400 . DETAILED DESCRIPTION

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] The embodiment of the first aspect of the present application proposes a non-contact rotation device that can manipulate the rotation of a target object 300 through sound waves. Specifically, the non-contact rotation device includes an ultrasonic transducer 100 and a modulator 200. The ultrasonic transducer 100 is used to generate a plane wave. The modulator 200 is arranged on the propagation path of the plane wave and is located between the ultrasonic transducer 100 and the target object 300. The plane wave is emitted by the ultrasonic transducer 100, converted into a vortex sound wave after being processed by the modulator 200, and transmitted to the target object 300. The modulator 200 can cause a phase difference in the plane wave passing through the modulator 200 to form a vortex sound field with a multi-order topological charge, which can drive the target object 300 to rotate.

[0059] It needs to be explained that if Figure 1As shown in the figure, the topological charge is the number of times the wavefront twists within the propagation distance of one wavelength. When the topological charge is 0, the sound wave propagates in the form of a plane wave. When the topological charge is 1, the sound wave is a vortex wave, and the wavefront of the vortex wave beam is a continuous spiral surface that extends infinitely along the propagation direction. When the topological charge is greater than or equal to 2, the wavefront of the vortex wave beam will be composed of multiple intertwined spiral surfaces. As shown in the figure, the topological charge is always an integer and can be positive or negative, depending on the direction of the twist. The larger the topological charge, the faster the wavefront rotates along the central axis. Vortex sound waves with non-zero topological charge carry non-zero orbital angular momentum. When the vortex sound wave interacts with an object that can absorb sound energy, the orbital angular momentum it carries can be transferred to the object, thereby exerting a certain amount of torque on it to cause its target object to rotate 300. The rotation speed of the target object 300 is proportional to the magnitude of the topological charge, that is, the larger the topological charge, the faster the rotation speed of the target object 300.

[0060] Current methods for generating acoustic vortices mainly fall into two categories: active phase control technology and passive phase modulation technology. Active phase control methods primarily utilize transducer arrays, individually adjusting the initial phase of each transducer to construct an acoustic vortex with any topological charge. Active phase control technology offers the advantage of high flexibility in acoustic field control, but its circuits are complex and expensive, limiting its practical application in experimental system construction. Passive phase modulation technology, on the other hand, primarily utilizes acoustic structures, utilizing special structures or metasurface materials to phase-modulate the wavefront of the incident acoustic wave, generating an acoustic vortex with a fixed topological charge. While this passive phase control method overcomes the limitations of complex circuit drive systems, it lacks flexibility because the topological charge of the generated vortex acoustic field is fixed, making it impossible to adjust the rotational speed and position of the target object 300.

[0061] To this end, the non-contact rotating device of the present application can generate a vortex sound field with multi-order topological charges. More specifically, on the propagation path of the vortex sound wave, there are multiple positions with relatively stable acoustic vortex fields, and the topological charges of the acoustic vortex fields at different positions are different. It should be explained that along the propagation direction of the vortex sound wave, the value of the topological charge gradually decreases. Therefore, after the acoustic vortex field is generated, the operator will select the more stable position with an integer-order topological charge to perform non-contact manipulation of the target object 300. The operator can adjust the distance between the modulator 200 and the target object 300 as needed, thereby switching the target object 300 from a vortex sound field of a certain order to a vortex sound field of another order, so as to flexibly control the rotation speed of the target object 300.

[0062] In some embodiments, the non-contact rotation device can simultaneously manipulate the rotation of multiple target objects 300, such as Figure 2In the embodiment shown, the non-contact rotating device drives three target objects 300 to rotate above the ultrasonic transducer 100 simultaneously and non-contactly. Furthermore, the rotation speed of each target object 300 decreases in sequence as it moves away from the modulating element 200. Figure 2 As shown in the example, three target objects 300 are coaxially arranged from bottom to top, and the rotation speeds of the target objects 300 after being driven by the vortex sound field gradually slow down from bottom to top, that is, the rotation speed of the target object 300 closest to the modulator 200 is the fastest, and the rotation speed of the target object 300 farthest from the modulator 200 is the slowest.

[0063] In some embodiments, as Figures 2 to 4 As shown, the modulator 200 is made of a sound-impermeable material such as a metal plate or a brick wall. When the sound wave is transmitted to the sound-impermeable material, the sound wave will be reflected back. The modulator 200 is provided with a through groove of a spiral structure 210, so that the plane wave emitted by the ultrasonic transducer 100 can pass through the through groove of the spiral structure 210 through the modulator 200, thereby forming a vortex sound field with a multi-order topological charge. The spiral structure 210 satisfies the following formula:

[0064]

[0065] Among them, r α is the radial coordinate of the helical structure 210, r0 is the initial radius of the helical structure 210, z is the vertical distance between the target object 300 and the modulator 200, l is the topological charge of the vortex acoustic field, λ is the wavelength of the acoustic wave, α is the angular coordinate of the helical structure 210, and M is a positive integer. According to this formula, it can be concluded that, given the parameters of the helical structure 210 and the sound source, the topological charge l is related to the distance z. Figure 3 and Figure 4 As shown, Figure 3 The spiral structure 210 is r0=3mm, z=90mm, l=1mm, λ=0.75mm, and M=4. Figure 4 The spiral structure 210 is shown when r0=3 mm, z=10 mm, l=2 mm, λ=1.5 mm, and M=1. As shown in the figure, M is an integer and determines the number of turns of the spiral structure 210 .

[0066] Based on the principle of sound wave diffraction, the sound wave forms a vortex sound field after passing through the spiral structure 210. The shape of the spiral structure 210 determines the phase change between the transmitted waves, and thus determines the topological charge of the vortex sound field to be generated. The target sound field in this application is an acoustic vortex field of different orders at different positions in space. The characteristics of the vortex field are that the central sound intensity is 0, this point is a phase singularity, the phase is distributed in a spiral along the azimuth angle θ, and the sound field has a phase change of 2πl around the phase singularity. In the process of designing the sound field, the acoustic vortex field is realized by adjusting the phase change 2πl.

[0067] Next, the generation principle of the multi-order vortex sound field in this application is further explained. Figure 5 As shown, Figure 5 The spiral structure 210 located on the z=0 plane is drawn in FIG. α is from point (r α ,α,0) to the center of the observation plane (0,0,z). If a plane wave is incident on the spiral slit, the distance from the two near points (r α ,α) and (r α+Δα ,α+Δα) along the small slit with an angle of Δα, the sound wave propagates through different paths and reaches the center of the observation plane (0, 0, z). The phase difference at (0, 0, z) is Δθ = 2πΔρ / λ, and since Δρ = lλΔα / 2π, then:

[0068]

[0069] Where l is a constant. This means that the phase difference of the acoustic beam around the rotation center on the observation plane is 2πl, that is, there will be an acoustic vortex at the center of the observation plane, and its topological charge is l. α is r α and the function of distance z, that is Thus, the spiral structure 210r can be designed α The expression of φ(λ) indicates that the vortex acoustic field formed by the spiral structure 210 has topological charges of different orders at different positions in space.

[0070] Based on the above-mentioned spiral structure 210 and its design principle, the feasibility of the non-contact rotating device is demonstrated through numerical simulation and experimental verification. In this embodiment, three groups of control groups are set up, and the spiral structure with an ultrasonic frequency of 2MHz and M=4 is taken as an example during the implementation process. The target object 300 of the first group is set at a position 26mm away from the modulator, and the topological charge of the sound field at this position is 3; the target object 300 of the second group is set at a position 40mm away from the modulator, and the topological charge of the sound field at this position is 2; the target object 300 of the third group is set at a position 80mm away from the modulator, and the topological charge of the sound field at this position is 1; it can be understood that the position where the target object 300 should be placed can also be calculated by first determining the value of the required topological charge and then using the above formula (1).

[0071] like Figure 6 and Figure 7 Shown are schematic diagrams of the sound intensity and phase of the vortex sound field at z = 80 mm, z = 40 mm and z = 26 mm, respectively. Figure 6 is the theoretical calculation result of computer simulation. Figure 7 The experimental measurement results. Figure 6and Figure 7 The white area in the medium sound intensity field represents the maximum sound intensity, and the black area represents the minimum sound intensity. The higher the grayscale, the greater the sound intensity. Figure 6 The black area of ​​the phase field is the maximum absolute value of the phase, and the white area is the minimum absolute value of the phase. The higher the grayscale, the larger the phase.

[0072] like Figure 6 As shown, near the position of z = 26 mm, the phase of the vortex sound field changes three times around the center of the singularity, indicating that its topological charge is 3; at the position of z = 40 mm, the phase of the vortex sound field changes two times around the center of the singularity, indicating that its topological charge is 2; at the position of z = 80 mm, the phase of the vortex sound field changes once around the center of the singularity, indicating that its topological charge is 1; the above results verify the theoretical feasibility of the spiral structure 210 to form a multi-order vortex sound field.

[0073] Figure 6 The graphical results of theoretical calculations are shown in Figure 2. Figure 7 The experimental measurement results are basically consistent with the illustrated results, and the experimental measurement results are almost the same as the theoretical calculation results. The experiment verifies the feasibility of the spiral structure 210 to form a multi-order vortex sound field.

[0074] On the other hand, the relationship between topological charge and object rotation speed was further verified through experiments. In the experiment, a polydimethylsiloxane (PDMS) disk was used as the target object to be manipulated 300. Figure 8 The figure shows the rotation states of the target object 300 at z = 26 mm, z = 40 mm, and z = 80 mm, respectively, in the third-order vortex field, the second-order vortex field, and the first-order vortex field. The horizontal axis of the figure represents the voltage of the power amplifier in the ultrasonic excitation module, and the vertical axis represents the time it takes for the target object to complete one rotation. The figure shows, from top to bottom, the time it takes for the target object 300 to complete one rotation in the first-order acoustic vortex field, the second-order acoustic vortex field, and the third-order acoustic vortex field in the non-contact rotation device. Experimental results show that the target object rotates fastest and in the shortest time in the third-order vortex field; the second-order vortex field takes the second longest time to complete one rotation, and the first-order vortex field takes the longest time to complete one rotation. It can be concluded that, under the same excitation conditions, the higher the order of the vortex field, the faster the target object 300 rotates in the field.

[0075] In other embodiments, acoustic vortex fields of different orders at different positions in space are realized by using acoustic holography. The basis of holography is to spatially store the phase or amplitude of the desired / preset wavefront so that the target wavefront can be reconstructed when an appropriate coherent wave is irradiated. In this embodiment, acoustic holography is used to design the acoustic vortex fields at different positions in space, calculate the thickness of the modulator 200, and thus manufacture the modulator 200. When a plane wave passes through the modulator 200, acoustic vortex fields of different orders at different positions in space can be reconstructed. Specifically, as Figure 9 As shown, the modulator 200 is made of a sound-transparent material. Sound-transparent materials refer to materials through which most sound waves can pass without being absorbed or reflected by the material. Common sound-transparent materials include rubber and resin. The modulator 200 has a structure with uneven thickness. This uneven thickness structure is used to control the phase of the plane wave to form a vortex sound field. The thickness of the modulator 200 satisfies the following formula:

[0076] ΔT(x,y)=Δφ(x,y) / (k m -k h ) (3);

[0077] Wherein, ΔT(x,y) is the thickness of any position of the modulator 200, Δφ(x,y) is the phase distribution at that position, and k m is the wave number of the sound-transmitting material, k h The modulator 200 of this structure can be simulated by iterative angular spectrum method to obtain the thickness at each position, and then manufactured by 3D printing and other technologies.

[0078] In other embodiments, Figure 10 and Figure 11 As shown, the modulator is made of a metasurface. The metasurface is composed of a series of functional elements distributed on a plane or a curved surface. By artificially constructing a subwavelength microstructure on the metasurface, it has a better ability to adjust the wavefront. Specifically, in this embodiment, micropillars are arranged at different positions on the metasurface, and the metasurface is divided into a plurality of metasurface units. The volume fraction of the micropillars in each metasurface unit is not the same, thereby changing the equivalent sound velocity of the metasurface unit. After passing through the metasurface unit, the plane sound wave can produce a phase difference, thereby generating a vortex sound field on the other side of the modulator. Among them, the volume fraction of the micropillars satisfies the following formula:

[0079]

[0080] in, represents the phase, c m The speed of sound in the medium in which the sound propagates, c unit is the equivalent sound velocity of the metasurface unit composed of micropillars and medium, where cunit =(B unit / ρ unit ) 1 / , B unit is the equivalent bulk modulus of the metasurface unit, ρ unit is the equivalent density of metasurface units, and f is the plane wave frequency. Figure 10 This is a schematic diagram of a metasurface modulator. The metasurface modulator in the figure contains 9 metasurface units. The volume fraction of micropillars in each metasurface unit is different, thereby changing the phase of the sound wave. Figure 11 Schematic diagram of micropillar arrangement with different volume fractions in the metasurface unit is shown.

[0081] In some embodiments, the acoustic wave propagation medium is a liquid, and the non-contact rotation device includes a container 400 for containing the propagation medium. The target object 300 is disposed in the container 400 and floats on the propagation medium, thereby offsetting the gravity of the target object 300 with buoyancy, thereby maintaining the target object 300 in a vertically balanced state. This type of non-contact rotation device, without having to consider the influence of the gravity of the target object 300, can achieve rotational drive of larger target objects 300. The ultrasonic transducer 100 and the modulating element 200 can be disposed submerged in the liquid, emitting acoustic waves from bottom to top; they can also be disposed above the container 400, emitting acoustic waves from top to bottom; or they can be disposed below the container 400, with the acoustic waves first passing through the container 400 and then propagating through the liquid to the target object 300.

[0082] In some embodiments, the acoustic wave propagation medium is a gas, and the target object 300, the modulating element 200, and the ultrasonic transducer 100 are sequentially arranged from top to bottom. When the non-contact rotation device is in operation, the target object 300 can be driven to levitate above the modulating element 200 and rotate. It will be appreciated that the acoustic waves carry vertical momentum during their upward transmission, which can drive the target object 300 to levitate on a vertical plane. Furthermore, because the acoustic waves also carry angular momentum, they can drive the target object 300 to rotate on a horizontal plane. During the rotation of the target object 300, the non-contact rotation device of this embodiment maintains a suspended and rotating state, eliminating the need for buoyancy provided by a liquid acoustic wave propagation medium and the need for a connector to lift the target object 300. This reduces the possibility of contact between the target object 300 and other components, further reducing the probability of contact between the target object 300 and contaminants. It is understandable that in other embodiments of the present application, the ultrasonic transducer 100, the modulator 200 and the target object 300 can also be arranged in sequence on any straight line in the horizontal direction or other directions, and when the non-contact rotating device is in working state, it can drive the target object 300 to rotate.

[0083] In some embodiments, the non-contact rotation device further includes a connector, one end of which is connected to the target object 300 at the target object's rotation center, and the other end is fixedly connected to an external structure, such as a frame. The connector is capable of lifting the target object 300, placing the target object 300 in a suspended state. This connector can apply an upward pulling force to the target object 300 to offset gravity, while also preventing the target object 300 from drifting out of the sound field during rotation. When the target object 300 is rotating, the connector's axial direction is coaxial with the target object's 300 rotation axis.

[0084] In some embodiments, the ultrasonic transducer 100 is connected to the modulator 200, and the non-contact rotating device further includes a position adjustment mechanism. The position adjustment mechanism can adjust the distance between the ultrasonic transducer 100 and the modulator 200 and the target object 300 to adjust the topological charge of the vortex acoustic field at the location of the target object 300. For example, in an embodiment where the propagation medium is a liquid and the target object 300 floats on the liquid, the position adjustment mechanism can change the vortex acoustic field at the location of the target object 300 by changing the position of the modulator 200. In other embodiments, the distance between the modulator 200 and the target object 300 can also be adjusted by adjusting the position of the target object 300. For example, in a structure provided with a connector, the vertical height of the target object 300 can be changed by changing the length of the connector or the height of the external structure.

[0085] In some embodiments, the target object 300 can absorb angular momentum in the sound field to achieve rotational drive of the target object 300 by the sound field. In some related technologies, a spiral electrode is coupled to a piezoelectric substrate, and the electrode is connected to an ultrasonic excitation device to excite a vortex sound field. Such electrodes are often small in size due to reasons such as arrangement spacing and production process. The output power of the ultrasonic transducer 100 is limited by the rated power of the electrode. The intensity of the vortex sound field generated by such a device is often small and can only be used for the manipulation of microparticles (size order of magnitude in the micrometer level). In the embodiment of the present application, since the ultrasonic transducer 100 functions to emit a plane wave, the plane wave is converted into a vortex sound field after passing through the modulator 200. Compared with directly generating a vortex sound field, the emission and generation of the plane wave are easier. The output power of the ultrasonic transducer 100 in the embodiment of the present application is not limited by the size of the electrode, thereby enabling the manipulation of target objects 300 of larger sizes and specifications. For example, in this embodiment, the diameter of the target object 300 can reach 5 mm and above.

[0086] like Figure 12 As shown, the present application also proposes a method for preparing a modulation element 200, which specifically includes the following steps:

[0087] S100 models a modulator in simulation software, defines parameters of the modulator, sets a target plane and an emission plane, the distance between the target plane and the emission plane is z, and the modulator is located on the emission plane;

[0088] The physical parameters such as the speed of sound propagation in the modulator, the density of the material, the attenuation coefficient, etc. are defined in the simulation software so that the simulation results are closer to the experimental results. In addition, a unit grid is generated on the modulator according to factors such as the shape and size of the modulator, and a plurality of unit primitives are divided. In the subsequent simulation process, the software performs calculations and extracts data based on each unit primitive. The size of the unit primitive can be adjusted according to the experimental accuracy. The smaller the unit primitive, the more detailed the result can be obtained by the computer simulation, which is reflected on the modulator 200. The sound field after the sound wave passes through the modulator 200 can be closer to the target vortex sound field. When the unit primitive is larger, the computing load of the computer will be greatly reduced, but the simulated result may be distorted, resulting in the failure of the final vortex sound field to form.

[0089] S200 constructs a plane wave sound field that propagates along a first direction and passes through the modulator, and an iterative sound field that propagates along a second direction, the first direction and the second direction being opposite, the plane wave sound field forming a vortex sound field after passing through the modulator;

[0090] The propagation process can be defined by the following formula:

[0091]

[0092] P(k x , k y , 0) = P(k x , k y ,z)H(k x , k y ,-z) (6);

[0093] Among them, P(k x , k y , 0 is the sound pressure field of the emission plane, P(k x , k y , z is the angular spectrum of the plane (target plane) at a distance of z from the emission plane, H(k x , k y ,-z) is the propagation function, k x 、k y are the components of the wave vector in the fluid medium in the x and y directions.

[0094] S300 propagates the iterative sound field along the second direction to the emission plane of the modulator;

[0095] The propagation process can be defined by the following formula:

[0096]

[0097] S400 extracts the amplitude and phase information on the emission plane, adjusts the amplitude of the vortex sound field to the amplitude on the emission plane, and keeps the phase of the plane wave sound field unchanged;

[0098] S500 propagates the vortex acoustic field along the first direction to the target plane;

[0099] S600 extracts amplitude and phase information on the target plane, adjusts the amplitude of the iterative sound field to the amplitude on the target plane, and keeps the phase of the iterative sound field unchanged;

[0100] S700 repeats steps S200 to S600 until the iterative sound field converges;

[0101] S800 extracts phase distribution information of the iterative sound field propagating to the emission plane in a converged state;

[0102] S900 calculates thickness distribution information of the modulator according to the phase distribution information;

[0103] According to the formula ΔT(x,y)=Δφ(x,y) / (k m -k h ), where k m is the wave number in the fluid medium, k h is the wave number in the phase plate. It can be seen that in a homogeneous medium, the acoustic path of an acoustic wave propagating through a uniform solid material is related to the change in the phase of the acoustic wave front. Therefore, the phase distribution information of the emitting plane can be equivalent to the thickness distribution of the material required to construct the sound field modulation structure.

[0104] S1000: manufacturing the modulation component.

[0105] The modulated element 200 can be manufactured using methods such as injection molding, 3D printing, and laser etching. For experimental modulated element 200, local thickness adjustments may be necessary as the experiment progresses. 3D printing is particularly suitable for producing the modulated element 200, as it offers relatively low production costs and eases the adjustment of production parameters. For large-scale, systematic production, injection molding using a mold is more efficient.

[0106] In summary, compared with the active phase control technology in the prior art, the non-contact rotating device of the present application has a simpler device structure and a relatively cheap overall device cost, and can be widely used in experimental systems or industrial manufacturing. Compared with the existing passive phase modulation technology, the non-contact rotating device of this embodiment can generate an acoustic vortex field with multiple orders of topological charge, and can control the rotation speed of the object by adjusting the distance between the modulating element 200 and the target object 300. It is more conducive to the operator to select an acoustic vortex field of appropriate order according to needs and apply it to the target object 300. It is more flexible to operate and can effectively reduce the time for the operator to adjust the acoustic structure to obtain the target sound field, thereby improving the efficiency of experimental operation or industrial production.

[0107] 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 non-contact rotation device for controlling the rotation of a target object, characterized in that: include: an ultrasonic transducer for generating a plane wave; a modulator, the modulator being disposed on a propagation path of the plane wave and located between the ultrasonic transducer and the target object; The modulator can cause the plane wave passing through the modulator to generate a phase difference, so as to form a vortex acoustic field with multi-order topological charges, and the vortex acoustic field can drive the target object to rotate; The non-contact rotation device is capable of manipulating the rotation of a plurality of target objects, wherein the target objects are arranged sequentially along the propagation direction of the vortex acoustic field, and the rotation speed of each target object decreases sequentially in the direction away from the modulating element; The larger the topological charge is, the faster the target object rotates, and the value of the topological charge gradually decreases along the propagation direction of the vortex sound wave.

2. The non-contact rotating device according to claim 1, characterized in that: The modulating member is made of a sound-impermeable material and is provided with a through groove having a spiral structure. The spiral structure satisfies the following formula: ； in, is the initial radius of the spiral structure, z is the vertical distance between the target object and the modulator, l is the topological charge of the vortex acoustic field, λ is the wavelength of the sound wave, φ is the polar angle of the spiral structure, and M is a positive integer.

3. The non-contact rotating device according to claim 1, characterized in that: The modulating element is made of a sound-transmitting material and has a structure with uneven thickness. The thickness of the modulating element satisfies the following formula: ； in, is the thickness of the modulated element at any position, is the phase distribution at that position, is the wave number of the sound-transmitting material, is the wave number of the propagation medium.

4. The non-contact rotating device according to claim 1, characterized in that: The modulator is made of a metasurface, micropillars are arranged at different positions of the metasurface, and the metasurface is divided into a plurality of metasurface units. The volume fraction of the micropillars arranged on each metasurface unit satisfies the following formula: ； in, Indicates the phase, The speed of sound in the medium in which sound propagates, is the equivalent sound velocity of the metasurface unit composed of micropillars and medium, where , is the equivalent bulk modulus of the metasurface unit, is the equivalent density of the metasurface unit, is the plane wave frequency.

5. The non-contact rotating device according to claim 1, characterized in that: The non-contact rotating device further includes a container for accommodating a propagation medium. The target object is disposed in the container and floats on the propagation medium.

6. The non-contact rotating device according to claim 1, characterized in that: The target object, the modulation element and the ultrasonic transducer are arranged in sequence from top to bottom. When the non-contact rotation device is in a working state, it can drive the target object to float above the modulation element and perform rotational motion.

7. The non-contact rotating device according to claim 6, characterized in that: The non-contact rotation device further includes a connecting member connected to the target object. When the vortex acoustic field drives the target object to rotate, the axial direction of the connecting member is coaxially arranged with the rotation axis of the target object.

8. The non-contact rotating device according to claim 1, characterized in that: The ultrasonic transducer is connected to the modulator, and the non-contact rotating device also includes a position adjustment mechanism, which can adjust the distance between the ultrasonic transducer and the modulator and the target object to adjust the topological charge of the vortex sound field at the position of the target object.

9. A method for preparing a modulated component, for preparing the modulated component according to claim 3, characterized in that: The following steps are involved: S100 models a modulator in simulation software, defines parameters of the modulator, sets a target plane and an emission plane, the distance between the target plane and the emission plane is z, and the modulator is located on the emission plane; S200 constructs a plane wave sound field that propagates along a first direction and passes through the modulator, and an iterative sound field that propagates along a second direction, the first direction and the second direction being opposite, the plane wave sound field forming a vortex sound field after passing through the modulator; S300 propagates the iterative sound field along the second direction to the emission plane of the modulator; S400 extracts the amplitude and phase information on the emission plane, adjusts the amplitude of the vortex sound field to the amplitude on the emission plane, and keeps the phase of the plane wave sound field unchanged; S500 propagates the vortex acoustic field along the first direction to the target plane; S600 extracts amplitude and phase information on the target plane, adjusts the amplitude of the iterative sound field to the amplitude on the target plane, and keeps the phase of the iterative sound field unchanged; S700 repeats steps S200 to S600 until the iterative sound field converges; S800 extracts phase distribution information of the iterative sound field propagating to the emission plane in a converged state; S900 calculates thickness distribution information of the modulator according to the phase distribution information; S1000: manufacturing the modulation component.

10. The method for preparing a modulated component according to claim 9, wherein: In step S1000 , the modulation element is manufactured by a 3D printing process or an etching process.

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