Acoustic metasurface device for local multi-dimensional manipulation of millimeter-level particles

Abstract

The invention discloses an acoustic metasurface for local non-contact multi-dimensional manipulation of millimeter-level particles. The suspension height and rotation of a single millimeter-level particle are controlled by adjusting a background sound pressure amplitude and an initial phase. The designed acoustic metasurface is composed of N * N units which are arranged in a plane according to a specific rule. The metasurface unit needs to meet the condition that the formed scattering sound field phase delay is distributed in 2n discrete gradients (n is an integer greater than or equal to 1) in one period under the condition that the jet sound waves are applied to the two sides of the metasurface unit. Besides, the configuration of the units needs to meet the requirements of double isotropy and high transmission (the transmissivity is greater than or equal to 95%), so that the acoustic metasurface formed by the units with different phase delays is ensured to form a scattering sound field with low energy loss and left and right mirror symmetry under forward and reverse incidence.

Description

Technical Field

[0001] The present invention relates to the field of acoustic tweezers technology, and in particular to an acoustic metasurface device for local multi-dimensional manipulation of millimeter-level particles. Background Art

[0002] The working principle of acoustic tweezers is to build a specific acoustic field environment based on sound waves. When sound waves propagate in space, their energy distribution forms a specific pattern. By precisely designing and controlling the parameters of sound waves, a specific acoustic field environment can be created around tiny objects, thereby generating an acoustic pressure gradient on the surface of the object. The uneven distribution of sound pressure leads to the generation of force, thereby achieving indirect control of particles.

[0003] In the existing literature on aeroacoustics, the suspension and rotation control of a single particle mainly relies on a phased array composed of a large number of loudspeakers. Although this method can achieve particle manipulation, the system is complex and bulky. Introducing acoustic metasurfaces into acoustic tweezers technology and manufacturing passive acoustic tweezers devices has overcome the complexity and volume problems of active acoustic tweezers devices to a certain extent. However, existing research has mostly focused on the suspension manipulation of particles, and there has been no technology that uses acoustic metasurfaces to simultaneously achieve particle suspension and rotation, which makes it difficult to meet the needs of complexity and functional diversity in practical applications. Summary of the invention

[0004] The present invention provides an acoustic metasurface device for local multi-dimensional manipulation of millimeter-level particles. The present invention can simultaneously realize the suspension and rotation of a single millimeter-level particle at a specific frequency, change the intensity and initial phase of the incident sound wave, and manipulate the suspension and rotation speed of the particle, as described below:

[0005] An acoustic metasurface device for local multi-dimensional manipulation of millimeter-level particles, the device consisting of N×N units, each unit being arranged in a plane according to a preset phase gradient rule;

[0006] Each unit of the acoustic metasurface satisfies the condition that the incident sound wave is applied on both sides, and the phase delay of the scattered sound field formed is 2 in one cycle. n A discrete gradient distribution;

[0007] The acoustic metasurface composed of multiple units with different phase delays forms low energy loss under forward incident plane acoustic waves and reverse incident plane acoustic waves, and the forward scattered acoustic field and the reverse scattered acoustic field are highly symmetrical;

[0008] Both the forward scattered acoustic field and the backscattered acoustic field are vortex acoustic fields, which use their special sound pressure gradient to provide the radiation force and torque required to manipulate particles. The acoustic metasurface controls the suspension height and rotation of a single millimeter-scale particle by adjusting the background sound pressure amplitude and initial phase.

[0009] By placing the acoustic metasurface in the forward and reverse directions, the forward and reverse spin of particles can be achieved.

[0010] The unit size of each acoustic metasurface is determined by the operating frequency, and the unit size is λ / 2×λ / 2×kλ (k∈[0.8,1.3]).

[0011] The calculation formula of phase delay is:

[0012]

[0013] Where ω is the angular frequency, c s is the speed of sound, F0 represents the distance from the origin to the focus, r ij represents the distance from the unit at the (i, j)th position to the focus, l is the vortex topological charge, represents the spiral phase distribution, N x and N y Represents the number of elements in the x and y directions respectively.

[0014] The acoustic metasurface is composed of 16×16 units, each unit has a size of 4.4mm×4.4mm×12mm; and four baffles are arranged inside each unit.

[0015] The beneficial effects of the technical solution provided by the present invention are:

[0016] 1. The present invention systematically evaluates its performance and effect in manipulating single millimeter-sized particles through theoretical analysis, simulation and experimental verification;

[0017] 2. The present invention can achieve high precision and high adaptability in suspension and rotation control, providing an efficient solution for customized applications in complex control scenarios;

[0018] 3. The present invention can simultaneously realize the suspension and rotation control of particles, meet the practical needs of multifunctionality, and provide a new technical approach for the precise control of particles;

[0019] 4. The solution provided by the present invention can expand the practical application areas of acoustic metasurfaces, such as micromanipulation, biomedicine, microfluidics, etc., and lay a certain foundation for future research and development in related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of an acoustic metasurface device for local multi-dimensional manipulation of millimeter-scale particles;

[0021] Figure 2 It is the basic configuration of the metasurface unit;

[0022] Figure 3These are the 16 unit configurations obtained after optimizing the unit configuration parameters;

[0023] Figure 4 It is the acoustic response of 16 units;

[0024] Figure 5 It is a three-dimensional schematic diagram of the arrangement of the super surface units and the composition of all units;

[0025] Figure 6 It is the result of theoretical and simulation calculations of metasurfaces;

[0026] Figure 7 It is the correlation analysis between scattered acoustic field theory and simulation calculation;

[0027] Figure 8 It is the analysis of the super surface scattering acoustic field morphology, fluid intensity distribution and particle force;

[0028] Fig. 9 This is a picture of an acoustic metasurface actually made in China;

[0029] Fig.10 This is the experimental test and simulation comparison of the forward and reverse scattering sound fields at a distance of 5.5 cm from the metasurface.

[0030] Fig.11 It is the measurement result of the forward scattered acoustic field at a height of 3 to 8 cm from the metasurface;

[0031] Fig.12 It is the comparison of the correlation between the experimental test and the theoretical calculation of the sound field;

[0032] Fig.13 This is a screenshot of the particle manipulation video.

[0033] Among them, 1-acoustic metasurface; 2-forward incident plane acoustic wave; 3-forward scattered acoustic field; 4-reverse incident plane acoustic wave; 5-reverse scattered acoustic field; 6-force and torque exerted on the particle. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention are described in further detail below.

[0035] An acoustic metasurface device for local multi-dimensional manipulation of millimeter-level particles, the device is composed of N×N units, each unit is arranged in a plane according to a preset phase gradient law;

[0036] Each unit of the acoustic metasurface 1 needs to satisfy the condition that the incident sound wave is applied on both sides, and the phase delay of the scattered sound field formed is 2 in one cycle. ndiscrete gradient distributions (n ​​is an integer greater than or equal to 1). In addition, the unit configuration of each acoustic metasurface 1 needs to meet the requirements of dual isotropy and high transmission (transmittance greater than or equal to 95%).

[0037] The acoustic metasurface 1 composed of multiple units with different phase delays forms low energy loss and highly symmetric forward scattered acoustic field 3 and reverse scattered acoustic field 5 under forward incident plane acoustic wave 2 and reverse incident plane acoustic wave 4. The size of each metasurface unit is determined by the operating frequency, and the unit size is λ / 2×λ / 2×kλ (k∈[0.8,1.3]).

[0038] Both the forward scattered acoustic field 3 and the reverse scattered acoustic field 5 are vortex acoustic fields, which use their special sound pressure gradient to provide the radiation force and torque required to manipulate particles. The acoustic metasurface 1 can flexibly control the suspension height and rotation of a single millimeter-scale particle by adjusting the background sound pressure amplitude and initial phase.

[0039] By placing the acoustic metasurface 1 in the forward and reverse directions, the forward and reverse spin of particles can be achieved.

[0040] In a preferred embodiment, the acoustic metasurface 1 is composed of 16×16 units, each unit is 4.4mm×4.4mm×12mm in size. Four baffles are designed inside each unit, and their sizes and positions are precisely determined by an optimization algorithm to ensure that the target phase shift error of all units is extremely small and the transmittance is kept greater than 97%; then, these units are combined according to specific rules to form the required acoustic metasurface, and the precise control of single millimeter-level particles is successfully achieved at a working frequency of 40kHz.

[0041] The embodiments of the present invention are arranged in a plane according to a specific spiral arrangement to generate a vortex sound field. By utilizing the pressure gradient and momentum transfer effect in the sound field and adjusting the background sound pressure amplitude of the incident sound wave, the suspension height and rotation of a single millimeter-level particle can be accurately controlled. The arrangement of the units follows the phase delay array design, and the phase delay of each unit is distributed according to a preset rule:

[0042]

[0043] Where ω is the angular frequency, c s is the speed of sound, F0 represents the distance from the origin to the focus, r ij represents the distance from the unit at the (i, j)th position to the focus, l is the vortex topological charge, represents the spiral phase distribution, N x and N y Represents the number of elements in the x and y directions respectively.

[0044] Furthermore, the Huygens-Fresnel principle and the surface integration method are used to calculate the acoustic radiation force and acoustic radiation torque 6 of the target particles, thereby more accurately controlling the suspension and rotation states of the particles.

[0045] Furthermore, the unit size of the acoustic metasurface 1 needs to be determined based on multiple factors, including: the operating frequency of the sound wave, the acoustic properties of the selected material (for example: acoustic impedance, density, elastic modulus, etc.), and the phase delay gradient and scattering effect required for the sound field design.

[0046] Furthermore, the unit of the acoustic metasurface 1 must satisfy the dual isotropy, that is, when the same incident wave is applied on both sides, the phase shift and transmission amplitude are the same, and the phase delay of the scattered sound field formed is 2 in one cycle. n discrete gradient distributions (n ​​is an integer greater than or equal to 1), and the phase delay between adjacent units is π / 2 n-1 ; It is worth noting that, in the application process, there must be at least two or more unit structures; the more unit resolutions, the more perfect the reproduced sound field.

[0047] Furthermore, the units of the acoustic metasurface 1 need to meet high transmission requirements (transmittance greater than or equal to 95%), thereby ensuring that the acoustic metasurface 1 composed of multiple units with different phase delays has low energy loss under forward and reverse incidence and the forward scattered sound field 3 is highly symmetrical with the reverse scattered sound field 5.

[0048] In an illustrative embodiment, the acoustic metasurface (1) is composed of 16×16 units, the operating frequency is positioned at 40 kHz, and the size of the unit is 4.4 mm×4.4 mm×12 mm.

[0049] In an exemplary embodiment, in order to suspend a particle with a diameter of 2 mm and a density of 20-25 kg / m at a distance of 5.5 cm from the acoustic metasurface 1, 3 The present invention adopts the surface integration method to test the acoustic radiation force and torque 6 of the particle at a height of 5.5 cm under different F0 conditions at l = 1. Finally, F0 = 9.43 cm was selected, and the background sound pressure amplitude was set to 196.47 Pa.

[0050] In an illustrative embodiment, four baffles are arranged inside the unit of the acoustic metasurface 1, and the position and size of the baffles are determined by multiple parameters. Through parameter optimization, the unit of the acoustic metasurface 1 can form a scattered sound field with a phase delay of 16 discrete gradient distributions (n ​​is 4) within one cycle under the condition that incident sound waves are applied on both sides, and the phase delay difference between adjacent units is π / 8, which meets the dual isotropic requirements; in addition, the transmittance of the unit is greater than 97%, which meets the high transmittance requirements.

[0051] In an illustrative embodiment, the units of the acoustic metasurface 1) are arranged according to a phase array (needs to be divided into 16 discrete values) calculated under F0=9.43cm, l=1.

[0052] In an illustrative embodiment, the Pearson correlation coefficient is used to quantitatively analyze the errors among theory, simulation and experiment.

[0053] Figure 1 It is a schematic diagram of a method for simultaneously controlling particle suspension and rotation in the field of aeroacoustics provided by an embodiment of the present invention.

[0054] Figure 2 It is the basic unit configuration of the super surface 1 in the exemplary embodiment of the present invention. Four baffles are arranged inside the unit, and the positions and sizes of the baffles are determined by 12 parameters.

[0055] like Figure 3 is based on Figure 2 16 cell configurations optimized from the basic configuration in the exemplary embodiment. The phase delay between adjacent cells is π / 8.

[0056] Figure 4 yes Figure 3 The acoustic responses of the 16 units in the exemplary embodiment can be seen from the phase and projection rate curves. The scattered sound fields formed by the positive and negative incidence of the 16 units have extremely small phase delay errors with the target, and the transmittances are all greater than 97%.

[0057] Figure 5 is based on Figure 3 Schematic diagram of the acoustic metasurface 1 composed of 16 types of units in a predetermined distribution pattern in an exemplary embodiment.

[0058] Figure 6 is the theoretical calculation result of the sound field in the exemplary embodiment of the present invention and Figure 5 Simulation calculation results of the acoustic metasurface 1 of the exemplary embodiment. Figure 7 It is the correlation curve of the acoustic field amplitude and phase between the theoretical and simulation results. It can be seen from the figure that the theoretical calculation results are highly consistent with the simulation data, especially at a distance of 5.5 cm from the acoustic metasurface 1, the overall similarity of the amplitude field and phase field can reach more than 98.7% and 98.1% respectively.

[0059] Figure 8 yes Figure 5 Figure 3 shows the shape of the forward scattered acoustic field 3, fluid strength and force analysis of the acoustic metasurface 1 in the exemplary embodiment. As can be seen from the figure, the force and torque calculated by theory and simulation are consistent.

[0060] Fig. 9 yes Figure 5The actual printing effect diagram of the exemplary embodiment of the acoustic metasurface 1. The test piece was prepared using the MCF microArch S240 ultra-high precision 3D printing system (processing accuracy up to 0.1 mm) and HTL resin material.

[0061] Fig.10 yes Fig. 9 Experimental test results of applying plane acoustic waves to the printed acoustic metasurface 1 in the exemplary embodiment in the forward direction 2 and the reverse direction 4. At a distance of 5.5 cm from the metasurface, the forward scattered acoustic field 3 and the reverse scattered acoustic field 4 show extremely high symmetry, which is the same as the theoretical and simulation cases.

[0062] Fig.11 yes Fig. 9 Detailed experimental test results of acoustic metasurface 1 forward scattering acoustic field 3 of exemplary embodiments. Compared with theoretical and simulation calculation results ( Figure 6 ), the experimental data show an excellent agreement with the simulation results, verifying the accuracy and reliability of the metasurface design.

[0063] Fig.12 yes Fig. 9 Correlation curve between the experimental test of the forward scattered sound field 3 of the acoustic metasurface 1 in the exemplary embodiment and the theoretical sound field. At a height of 5.5 cm from the metasurface, the sound field amplitude can reach more than 75%, and the phase can reach 21%, at the center. The sound field amplitude can reach more than 59%, and the phase can reach 78%, which is enough to prove that the present invention has high accuracy.

[0064] Fig.13 yes Fig. 9 Video screenshot of the acoustic metasurface 1 of the exemplary embodiment actually manipulating particles. In the first 6.5 seconds, the particles can be suspended and rotated at the same time. After 6.5 seconds, the particles fall due to the increasing rotation speed and other uncontrollable factors. The error between the suspension height and the expected value is about 10%.

[0065] Unless otherwise specified, the models of the components in the embodiments of the present invention are not limited, and any device that can perform the above functions may be used.

[0066] Those skilled in the art will appreciate that the accompanying drawing is only a schematic diagram of a preferred embodiment, and the serial numbers of the embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An acoustic metasurface device for local multi-dimensional manipulation of millimeter-level particles, characterized in that: The device is composed of N×N units, each of which is arranged in a plane according to a preset phase gradient rule; Each unit of the acoustic metasurface satisfies the condition that the incident sound wave is applied on both sides, and the phase delay of the scattered sound field formed is 2 in one cycle. n A discrete gradient distribution; The acoustic metasurface composed of multiple units with different phase delays forms low energy loss under forward incident plane acoustic waves and reverse incident plane acoustic waves, and the forward scattered acoustic field and the reverse scattered acoustic field are highly symmetrical; Both the forward scattered acoustic field and the backscattered acoustic field are vortex acoustic fields, which use their special sound pressure gradient to provide the radiation force and torque required to manipulate particles. The acoustic metasurface controls the suspension height and rotation of a single millimeter-scale particle by adjusting the background sound pressure amplitude and initial phase. By placing the acoustic metasurface in the forward and reverse directions, the forward and reverse spin of particles can be achieved.

2. The acoustic metasurface device for local multi-dimensional manipulation of millimeter-level particles according to claim 1, characterized in that: The unit size of each acoustic metasurface is determined by the operating frequency, and the unit size is λ / 2×λ / 2×kλ (k∈[0.8,1.3]).

3. The acoustic metasurface device for local multi-dimensional manipulation of millimeter-level particles according to claim 1, characterized in that: The calculation formula for phase delay is: Where ω is the angular frequency, c s is the speed of sound, F0 represents the distance from the origin to the focus, r ij represents the distance from the unit at the (i, j)th position to the focus, l is the vortex topological charge, represents the spiral phase distribution, N x and N y Represents the number of elements in the x and y directions respectively.

4. The acoustic metasurface device for local multi-dimensional manipulation of millimeter-level particles according to claim 1, characterized in that: The acoustic metasurface is composed of 16×16 units, each unit has a size of 4.4 mm×4.4 mm×12 mm; and four baffles are arranged inside each unit.

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