Particle movement control method based on phononic crystal plate and phononic crystal plate

Abstract

The application discloses a kind of particle movement control method and phononic crystal plate based on phononic crystal plate, it is related to the technical field of acoustic manipulation particle.Gradient hole two-dimensional phononic crystal plate is constructed, the gradient hole two-dimensional phononic crystal plate is excited using external ultrasonic wave, the resonance mode of the gradient hole two-dimensional phononic crystal plate is excited, and the gradient sound pressure field of the gradient hole two-dimensional phononic crystal plate is obtained;By changing resonance frequency, the position of gradient sound pressure field is changed, and then the acoustic radiation force in gradient sound pressure field is used to control micro-particle movement.The particle movement control method based on phononic crystal plate provided in the application effectively solves the problem that the incident sound wave transducer position needs to be moved or the acoustic radiation force focus needs to be adjusted during the control of particle movement, and realizes that only the resonance frequency during work needs to be changed to accurately capture and control the effect of particle movement.

Description

Technical Field

[0001] This invention relates to the technical field of acoustically manipulated particles, and more particularly to a particle movement control method based on a phonon crystal plate and the phonon crystal plate itself. Background Technology

[0002] Particle manipulation refers to the technology of manipulating and controlling microscopic particles using physical means, and it is very important for applications in physics, biology, biomedicine and medicine.

[0003] From the 1970s to the 1990s, optical manipulation and acoustic manipulation were proposed successively. After years of development, particle manipulation using optical and acoustic radiation forces has received widespread research attention. In the development of optical and acoustic radiation forces, optical tweezers and acoustic tweezers were developed. Compared with optical tweezers, acoustic tweezers have several advantages: lower power consumption, less biological damage, and greater sound wave penetration, thus enabling manipulation of deep samples. Therefore, acoustic manipulation of particles utilizes acoustic radiation force (ARF) to provide a non-contact and harmless method for handling particles suspended in fluids.

[0004] Acoustic particle manipulation refers to the technique of manipulating microscopic particles using the radiation force generated by sound waves. Common techniques include surface acoustic wave manipulation and acoustic laser traps. However, these techniques are quite complex and require complex array transducers or chips, making them difficult to implement.

[0005] Over the past decade, the excitation of phonon crystal plates by sound waves has enabled the generation of localized sound fields, providing new methods for particle manipulation. For example, one-dimensional phonon crystal plates can be used to capture and filter particles, while two-dimensional phonon crystal plates can be used to pattern particles. Phonon crystal plates can be used in various shapes to create diverse sound fields, demonstrating their excellent structural flexibility. However, in the acoustic manipulation of particle movement, current acoustic manipulation techniques lack research on how to utilize the localized sound fields induced by the interaction between the phonon crystal plate and sound waves to achieve particle manipulation. Furthermore, using acoustic manipulation to move particles requires moving the ventilation location or the position of the phonon crystal plate, which increases workload and cost. Summary of the Invention

[0006] This invention addresses the problems of existing acoustic particle movement control technologies, such as high workload, high cost, and low control accuracy. It proposes a particle movement control method and phononic crystal plate based on a phononic crystal plate. By constructing a gradient-hole two-dimensional phononic crystal plate, the acoustic radiation force in the gradient acoustic pressure field of the gradient-hole two-dimensional phononic crystal plate is used to control particle movement, making acoustic particle movement control more convenient.

[0007] To achieve the objectives of this invention, the following technical solution is adopted:

[0008] A particle movement control method based on a phonon crystal plate includes the following steps:

[0009] S1: Construct a gradient-hole two-dimensional phonon crystal plate;

[0010] S2: Obtain the gradient acoustic pressure field of the gradient aperture two-dimensional phonon crystal plate;

[0011] S3: Control particle movement using the gradient acoustic pressure field.

[0012] In the above technical solution, a gradient aperture two-dimensional phononic crystal plate is constructed based on the transmission characteristics of the phononic crystal plate, and the gradient acoustic pressure field of the gradient aperture two-dimensional phononic crystal plate is obtained. Then, the acoustic radiation force in the gradient acoustic pressure field is used to control the movement of particles. This effectively solves the problem that the position of the incident acoustic wave transducer or the focal spot of the acoustic radiation force needs to be adjusted in the process of controlling the movement of particles. It realizes that the effect of controlling the movement of particles can be achieved simply by changing the resonant frequency during operation.

[0013] Furthermore, the specific process of constructing the gradient-hole two-dimensional phonon crystal plate in step S11 is as follows:

[0014] S11: Calculate the transmission coefficient of the phononic crystal plate in the liquid;

[0015] S12: Design phononic crystal plates with different aperture radii and determine the variations in transmission coefficient and resonance frequency in phononic crystal plates with different aperture radii;

[0016] S13: Based on the changes in transmission coefficient and resonance frequency, construct a gradient-hole two-dimensional phonon crystal plate with a gradient change in aperture radius.

[0017] The specific process for calculating the transmission coefficient of the phonon crystal plate in the liquid in step S11 is as follows:

[0018] Let the transmission coefficient of the phonon crystal plate be T, the density of the liquid be ρ1, and the velocity of sound in the liquid be c1. Then the expression for the transmission coefficient satisfies:

[0019]

[0020] Where, p ta p represents the transmitted wave sound pressure. ia This represents the sound pressure of the incident wave.

[0021] The specific process for determining the variations in transmission coefficient and resonance frequency in phonon crystal plates with different aperture radii, as described in step S12, is as follows:

[0022] Let the initial aperture radius of the phonon crystal plate be r, and the resonant frequency be f. Keeping the liquid density ρ1 and the liquid sound velocity c1 constant, determine the changes in the transmission coefficient T and the resonant frequency f of the phonon crystal plate as the initial aperture radius r changes. The process satisfies:

[0023] As the initial aperture radius r gradually increases, the peak value of the transmission coefficient T shifts towards the direction of decreasing resonant frequency f;

[0024] As the initial aperture radius r gradually decreases, the peak value of the transmission coefficient T shifts towards the direction of increasing resonant frequency f.

[0025] The specific process of constructing a gradient-hole two-dimensional phonon crystal plate with varying aperture radius as described in step S13 is as follows:

[0026] Based on the changes in transmission coefficient T and resonant frequency f caused by the change in the initial aperture radius r of the phononic crystal plate, a periodic structure with gradient aperture variation is designed on the surface of the phononic crystal plate to obtain a gradient aperture two-dimensional phononic crystal plate.

[0027] According to the above technical solution, by calculating the transmission coefficient T of phononic crystal plates with different aperture radii, the relationship between the transmission coefficient T and the resonant frequency f of phononic crystal plates with different aperture radii can be analyzed and determined. Based on the changes in the transmission coefficient T and the resonant frequency f under different aperture radii, a gradient aperture two-dimensional phononic crystal plate with a gradient aperture is designed. Through the gradient aperture two-dimensional phononic crystal plate, the problem of moving the incident sound wave transducer or adjusting the focal spot of the sound radiation force can be eliminated in the process of controlling particle movement. The effect of controlling particle movement can be achieved by simply changing the resonant frequency f during operation.

[0028] Furthermore, the specific process of obtaining the gradient acoustic pressure field of the gradient-hole two-dimensional phonon crystal plate in step S2 is as follows:

[0029] Let the center point of the gradient aperture surface of the gradient aperture two-dimensional phononic crystal plate be the origin of the coordinate system, and establish a spatial coordinate system xyz;

[0030] Using ultrasound to radiate acoustic waves onto a gradient-hole two-dimensional phononic crystal plate, the process satisfies:

[0031] Based on the periodic structure of the gradient aperture two-dimensional phononic crystal plate, the plate is excited by ultrasonic waves along the z-axis of the spatial coordinate system to obtain a gradient acoustic pressure field with acoustic radiation force and whose position changes with the resonant frequency f; wherein, the excitation means that the resonant mode of the phononic crystal plate is excited.

[0032] According to the above technical solution, by establishing a spatial coordinate system xyz at the center point of the surface of the gradient aperture two-dimensional phononic crystal plate, and using ultrasonic waves to excite the gradient aperture two-dimensional phononic crystal plate along the z-axis of the spatial coordinate system, a gradient acoustic pressure field with acoustic radiation force and whose position changes with the resonant frequency f can be obtained. Constructing the spatial coordinate system xyz can better reflect the directionality.

[0033] Furthermore, the specific process of controlling particle movement using the gradient acoustic pressure field described in step S3 is as follows:

[0034] The movement of particles is controlled by the acoustic radiation force in the gradient acoustic pressure field, and the process satisfies:

[0035] Decrease the resonant frequency f to control the position of the gradient sound pressure field to move along the negative y-axis, and use the radiation force in the gradient sound pressure field to control the particle to move along the negative y-axis.

[0036] Increase the resonant frequency f to control the position of the gradient sound pressure field to move along the positive y-axis, and use the radiation force in the gradient sound pressure field to control the particle to move along the positive y-axis.

[0037] The particle experiences a radiation force in the gradient acoustic pressure field of a gradient-aperture two-dimensional phonon crystal plate, and the calculation process of the acoustic radiation force satisfies:

[0038] Let F be the acoustic radiation force experienced by a particle in a gradient acoustic pressure field, and let its expression satisfy:

[0039] F=∮ T >·dA;

[0040]

[0041] Where d represents the outer integral pointing towards the particle surface. T > represents the time-averaged Bloch radiation stress tensor, I represents the unit tensor, ρ0 represents the density of water, C0 represents the speed of sound in water, u represents the first-order flow velocity, and p represents the sound pressure.

[0042] The process of calculating the acoustic radiation force on a particle with a diameter much smaller than the wavelength of a sound wave satisfies:

[0043]

[0044]

[0045]

[0046]

[0047] Where, p in V represents the first-order incident sound pressure. in ​​This represents the speed of sound of the particle. t c represents the transverse wave velocity of a particle. l This represents the longitudinal wave velocity of a particle.

[0048] According to the above technical solution, by changing the resonant frequency f during operation, the position of the gradient sound pressure field changes, and the sound radiation force in the gradient sound pressure field also changes accordingly. Then, the sound radiation force in the gradient sound pressure field is used to control the movement of particles along the y-axis of the spatial coordinate system, and the magnitude of the sound radiation force experienced by the particles during the movement is calculated.

[0049] A phonon crystal plate is provided, wherein the phonon crystal plate has a plurality of holes, the radii of the plurality of holes are distributed in an arithmetic gradient, and the depth of the plurality of holes is less than the thickness of the phonon crystal plate, and the phonon crystal plate is used in the above-mentioned particle movement control method.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] By constructing a gradient-aperture two-dimensional phonon crystal plate, the plate can be excited by external ultrasonic waves to elicit its resonant modes and obtain its gradient acoustic pressure field. During particle movement control, the position of the gradient acoustic pressure field is changed by altering the resonant frequency, thereby changing the position of the acoustic radiation force within the field. The particle movement is controlled by this acoustic radiation force. This invention, based on a phonon crystal plate, effectively solves the problem of needing to move the incident acoustic transducer or adjust the focal spot of the acoustic radiation force during particle movement control. It achieves accurate particle capture and control simply by changing the resonant frequency. Attached Figure Description

[0052] Figure 1 A flowchart illustrating a particle movement control method based on a phonon crystal plate, provided for an embodiment of this application;

[0053] Figure 2 A schematic diagram of a periodic phonon crystal plate provided in an embodiment of this application;

[0054] Figure 3 Normalized transmission spectra of phononic crystal plates with three different aperture radii provided in the embodiments of this application;

[0055] Figure 4 A graph showing the relationship between transmission coefficient and resonant frequency in a gradient-hole two-dimensional phononic crystal plate provided in an embodiment of this application;

[0056] Figure 5 Numerical distribution diagram of the yz plane of a gradient-hole two-dimensional phononic crystal plate provided in an embodiment of this application;

[0057] Figure 6 This is a schematic diagram illustrating particle movement controlled by acoustic radiation force in a gradient acoustic pressure field, provided in an embodiment of this application.

[0058] Figure 7 A top view of a phononic crystal plate with holes of different radii at the bottom, provided in an embodiment of this application. Detailed Implementation

[0059] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0061] Example 1:

[0062] This embodiment provides a particle movement control method based on a phonon crystal plate. See [link to relevant documentation]. Figure 1 This includes the following steps:

[0063] S1: Construct a gradient-hole two-dimensional phonon crystal plate;

[0064] S2: Obtain the gradient acoustic pressure field of the gradient aperture two-dimensional phonon crystal plate;

[0065] S3: Control particle movement using the gradient acoustic pressure field.

[0066] For example, the acoustic field of a structure is modulated based on the interaction between a phononic crystal plate and sound waves. Specifically, the gradient sound pressure field generated by the inherent antisymmetric resonant mode of the excited uniform phononic crystal plate is used to manipulate the acoustic radiation force. Generally, the resonant modes of a phononic crystal plate with uniform thickness cannot be excited. However, by designing a periodic structure on the surface of the phononic crystal plate, the missed antisymmetric modes can be effectively excited. Based on this theory, a two-dimensional phononic crystal plate with a gradient of periodic aperture radius is designed. The radii of three different apertures are 0.5 mm, 0.55 mm, and 0.60 mm, and the aperture depth is 0.3 mm (the aperture does not penetrate the metal plate). Under the excitation of external ultrasonic waves, the periodic grid structure plate exhibits high transmittance in the subwavelength range, and a strong localized sound field appears near the surface of the two-dimensional phononic crystal plate at the resonant frequency corresponding to the transmission peak. Changing the aperture radius changes the resonant frequency. Based on this characteristic of phononic crystal plates, a gradient-aperture two-dimensional phononic crystal plate with varying aperture radius is designed to obtain a local sound pressure field whose position changes with the resonant frequency, i.e., a gradient sound pressure field. Using the gradient sound field constructed by this gradient-aperture two-dimensional phononic crystal plate, the reciprocating motion of a single particle is realized by changing the operating frequency. The phononic crystal plate is a metal plate.

[0067] In this embodiment, a gradient aperture two-dimensional phononic crystal plate is constructed based on the transmission characteristics of the phononic crystal plate, and the gradient acoustic pressure field of the gradient aperture two-dimensional phononic crystal plate is obtained. Then, the acoustic radiation force in the gradient acoustic pressure field is used to control the movement of particles. This effectively solves the problem that the position of the incident acoustic wave transducer or the focal spot of the acoustic radiation force needs to be adjusted during the control of particle movement. It achieves the effect of accurately capturing and controlling particle movement simply by changing the resonant frequency during operation.

[0068] Example 2:

[0069] In this embodiment, steps S1 to S3 in Embodiment 1 will be further explained.

[0070] The specific process of constructing the gradient-hole two-dimensional phonon crystal plate in step S11 is as follows:

[0071] S11: Calculate the transmission coefficient of the phononic crystal plate in the liquid;

[0072] S12: Design phononic crystal plates with different aperture radii and determine the variations in transmission coefficient and resonance frequency in phononic crystal plates with different aperture radii;

[0073] S13: Based on the changes in transmission coefficient and resonance frequency, construct a gradient-hole two-dimensional phonon crystal plate with a gradient change in aperture radius.

[0074] The specific process for calculating the transmission coefficient of the phonon crystal plate in the liquid in step S11 is as follows:

[0075] Let the transmission coefficient of the phonon crystal plate be T, the density of the liquid be ρ1, and the velocity of sound in the liquid be c1. Then the expression for the transmission coefficient satisfies:

[0076]

[0077] Where, p ta p represents the transmitted wave sound pressure. ia This represents the sound pressure of the incident wave.

[0078] The specific process for determining the variations in transmission coefficient and resonance frequency in phonon crystal plates with different aperture radii, as described in step S12, is as follows:

[0079] Let the initial aperture radius of the phonon crystal plate be r, and the resonant frequency be f. Keeping the liquid density ρ1 and the liquid sound velocity c1 constant, determine the changes in the transmission coefficient T and the resonant frequency f of the phonon crystal plate as the initial aperture radius r changes. The process satisfies:

[0080] As the initial aperture radius r gradually increases, the peak value of the transmission coefficient T shifts towards the direction of decreasing resonant frequency f;

[0081] As the initial aperture radius r gradually decreases, the peak value of the transmission coefficient T shifts towards the direction of increasing resonant frequency f.

[0082] The specific process of constructing a gradient-hole two-dimensional phonon crystal plate with varying aperture radius as described in step S13 is as follows:

[0083] Based on the changes in transmission coefficient T and resonant frequency f caused by the change in the initial aperture radius r of the phononic crystal plate, a periodic structure with gradient aperture variation is designed on the surface of the phononic crystal plate to obtain a gradient aperture two-dimensional phononic crystal plate.

[0084] For example, see Figure 2 The transmission characteristics of the phonon crystal plates were analyzed. The thickness of each of the three phonon crystal plates was t = 0.4 mm, the hole depth was h = 0.3 mm, the period constant was a = 1.5 mm, the length was x = 67.5 mm, and the width was y = 7.5 mm. The material parameters required for transmission were as follows: the density of the copper plate was ρ = 8600 mg / m³. 3 Longitudinal wave velocity c l = 4400m / s, shear wave velocity c t =2100m / s; the density of the liquid ρ0 =1000kg / m³ 3 Let the radii of the three apertures be r1 = 0.50 mm, r2 = 0.55 mm, and r3 = 0.60 mm, respectively. Calculate the transmission coefficient T for each aperture type. (See [reference needed]) Figure 3As shown in the figure, there are obvious transmission peaks at frequencies of 0.33MHz, 0.37MHz, and 0.42MHz. With the increase of the aperture radius, the resonant frequency f corresponding to the transmission peak exhibits a redshift, meaning the resonant frequency f shifts to lower frequencies as the aperture radius increases, but the resonant transmission intensity also increases. Therefore, the transmission of the phonon crystal plate originates from the resonance of the grating structure between the two apertures. Different aperture radii result in different grating thicknesses, and consequently, different resonant frequencies f. Based on this theory, the sound field distribution of the phonon crystal plate can be adjusted by designing the aperture size.

[0085] Based on the above, a gradient-aperture two-dimensional phononic crystal plate with varying aperture gradients is designed. (See [reference needed]). Figure 4 The curve in the figure represents the relationship between the transmission coefficient T and the resonance frequency f in a gradient aperture two-dimensional phononic crystal plate.

[0086] Understandably, by calculating the transmission coefficient T of phononic crystal plates with different aperture radii, the relationship between the transmission coefficient T and the resonant frequency f of phononic crystal plates with different aperture radii can be analyzed and determined. Based on the changes in the transmission coefficient T and the resonant frequency f under different aperture radii, a gradient aperture two-dimensional phononic crystal plate with a gradient aperture is designed. Through the gradient aperture two-dimensional phononic crystal plate, it is possible to eliminate the problem of moving the incident sound wave transducer or adjusting the focal spot of the sound radiation force during the control of particle movement. This achieves the effect of controlling particle movement simply by changing the resonant frequency f during operation.

[0087] The specific process for obtaining the gradient acoustic pressure field of the gradient-aperture two-dimensional phonon crystal plate in step S2 is as follows:

[0088] Let the center point of the gradient aperture surface of the gradient aperture two-dimensional phononic crystal plate be the origin of the coordinate system, and establish a spatial coordinate system xyz;

[0089] Using ultrasound to radiate acoustic waves onto a gradient-hole two-dimensional phononic crystal plate, the process satisfies:

[0090] Based on the periodic structure of the gradient aperture two-dimensional phononic crystal plate, the plate is excited by ultrasonic waves along the z-axis of the spatial coordinate system to obtain a gradient acoustic pressure field with acoustic radiation force and whose position changes with the resonant frequency f; wherein, the excitation means that the resonant mode of the phononic crystal plate is excited.

[0091] For example, let the center point of the gradient aperture surface of the gradient aperture two-dimensional phonon crystal plate be the origin, and establish a spatial coordinate system xyz; plane wave radiation is set above and below the gradient aperture two-dimensional phonon crystal plate, and external ultrasonic waves are used to radiate sound waves onto the gradient aperture two-dimensional phonon crystal plate from below upwards, that is, from the positive direction of the z-axis. Periodic boundaries are set around the gradient aperture two-dimensional phonon crystal plate, see [reference]. Figure 5 , Figure 5 (a) indicates that there is a local acoustic pressure field, i.e., a gradient acoustic pressure field, on the surface of a gradient-hole two-dimensional phononic crystal plate with a hole radius r3 = 0.60 mm. Figure 5 In section (b), it is indicated that when the resonant frequency f is changed to 0.37 MHz, the distribution position of the local sound pressure field changes, and it moves to the right to the surface of the gradient aperture two-dimensional phononic crystal plate with aperture radius r2 = 0.55 mm. Figure 5 In section (c), it is indicated that by continuously changing the resonant frequency f to 0.42 NHz, the local acoustic pressure field continues to move to the right to the surface of the gradient-hole two-dimensional phononic crystal plate with a aperture radius r1 = 0.50 mm. The results show that by changing the resonant frequency f during operation, a local acoustic pressure field can be excited at different positions on the gradient-hole two-dimensional phononic crystal plate.

[0092] Understandably, by establishing a spatial coordinate system xyz at the center point of the surface of a gradient-aperture two-dimensional phononic crystal plate, and by using ultrasound to excite the gradient-aperture two-dimensional phononic crystal plate along the z-axis of the spatial coordinate system, a gradient sound pressure field with acoustic radiation force and whose position changes with the resonant frequency f can be obtained. Constructing a spatial coordinate system xyz can better reflect the directionality.

[0093] The specific process of controlling particle movement using the gradient acoustic pressure field described in step S3 is as follows:

[0094] The movement of particles is controlled by the acoustic radiation force in the gradient acoustic pressure field, and the process satisfies:

[0095] Decrease the resonant frequency f to control the position of the gradient sound pressure field to move along the negative y-axis, and use the radiation force in the gradient sound pressure field to control the particle to move along the negative y-axis.

[0096] Increase the resonant frequency f to control the position of the gradient sound pressure field to move along the positive y-axis, and use the radiation force in the gradient sound pressure field to control the particle to move along the positive y-axis.

[0097] The particle experiences a radiation force in the gradient acoustic pressure field of a gradient-aperture two-dimensional phonon crystal plate, and the calculation process of the acoustic radiation force satisfies:

[0098] Let F be the acoustic radiation force experienced by a particle in a gradient acoustic pressure field, and let its expression satisfy:

[0099] F=∮ T >·dA;

[0100]

[0101] Where d represents the outer integral pointing towards the particle surface. T ​​> represents the time-averaged Bloch radiation stress tensor, I represents the unit tensor, ρ0 represents the density of water, C0 represents the speed of sound in water, u represents the first-order flow velocity, and p represents the sound pressure.

[0102] The process of calculating the acoustic radiation force on a particle with a diameter much smaller than the wavelength of a sound wave satisfies:

[0103]

[0104]

[0105]

[0106]

[0107] Where, p in V represents the first-order incident sound pressure. in This represents the speed of sound of the particle. t c represents the transverse wave velocity of a particle. l This represents the longitudinal wave velocity of a particle.

[0108] For example, based on the characteristic that the gradient sound pressure field distribution shifts along the Y-axis with the resonant frequency, we analyze the force on a glass sphere with a radius of 0.2 mm placed on the surface of a two-dimensional phonon crystal plate with a gradient aperture. The material parameters of the glass sphere are: density ρ = 2600 kg / m³. 3 Longitudinal wave velocity c l = 5840 m / s, shear wave velocity c t = 3370 m / s. In the numerical calculation, the distance between the bottom of the glass sphere and the surface of the copper plate is 0.1 mm. According to the formula for acoustic radiation force:

[0109] F=∮ T >·dA;

[0110] Here, the differential region dA points towards the outer integral that tends toward the particle surface. T >Represents the time-averaged Bloch radiation stress tensor:

[0111]

[0112] Where I represents the unit tensor, ρ0 and C0 represent the density of water and the speed of sound in water, respectively, and u and p represent the first-order flow velocity and sound pressure, respectively. For objects much smaller than the wavelength of sound waves, the acoustic radiation force can be approximated by the Gor'kov formula, a simple way to determine the force on particles in a sound field:

[0113]

[0114] In the formula, U can be represented as follows:​​

[0115]

[0116]

[0117] Here p in and v in c represents the first-order incident sound pressure and the particle sound velocity, respectively. t and c l These represent the transverse wave velocity and longitudinal wave velocity of the particle, respectively.

[0118] See Figure 6 , represents the XY plane 0.2 mm from the surface of the two-dimensional phonon crystal plate with gradient aperture, and the red arrow represents the magnitude and direction of the acoustic radiation force. Figure 6 The aperture radius in region 1 is r3 = 0.6 mm, in region 2 it is r2 = 0.55 mm, and in region 3 it is r1 = 0.5 mm. As shown in the figure, at a resonant frequency f of 0.33 MHz, the acoustic radiation is mainly concentrated in region 1. Changing the resonant frequency f to 0.37 MHz shifts the acoustic radiation along the Y-axis to region 2. Further changing the resonant frequency f to 0.42 MHz causes the acoustic radiation to continue shifting along the Y-axis to region 3. Continuing to change the resonant frequency f to 0.33 MHz further shifts the acoustic radiation distribution along the positive Y-axis to... Figure 7 In region 1' shown; Figure 7 In the diagram, x = 7.5 mm, y = 67.5 mm, and regions 1, 2, and 3 each contain 5x5 holes of the same radius. The remaining regions of the board are arrays of regions 1, 2, and 3. Specifically, the hole radius in region 1 is r3 = 0.6 mm, in region 2 it is r2 = 0.55 mm, and in region 3 it is r1 = 0.50 mm. Furthermore, the acoustic radiation is concentrated above the holes. Figure 6 As indicated by (d), the acoustic radiation force arrow points to the center point, meaning the particles on the gradient-aperture 2D phonon crystal plate will also converge towards the center. Therefore, by changing the resonant frequency f from 0.33MHz→0.37MHz→0.42MHz→0.33MHz repeatedly, the particles will move along the positive Y-axis of the gradient-aperture 2D phonon crystal plate surface under the influence of the acoustic radiation force. Conversely, if the resonant frequency f is changed from 0.42MHz→0.37MHz→0.33MHz→0.42MHz repeatedly, the particles will move along the negative Y-axis of the gradient-aperture 2D phonon crystal plate surface.

[0119] Understandably, by changing the resonant frequency f during operation, the position of the gradient sound pressure field changes, and the sound radiation force in the gradient sound pressure field also changes accordingly. Then, the sound radiation force in the gradient sound pressure field is used to control the movement of particles along the y-axis of the spatial coordinate system, and the magnitude of the sound radiation force experienced by the particles during the movement is calculated.

[0120] In this embodiment, by constructing a gradient-aperture two-dimensional phonon crystal plate, the plate can be excited by external ultrasonic waves to elicit its resonant mode and obtain its gradient acoustic pressure field. During particle movement control, the position of the gradient acoustic pressure field is changed by altering the resonant frequency, thereby changing the position of the acoustic radiation force within the field. The particle movement is controlled by utilizing the acoustic radiation force within the acoustic pressure field. The particle movement control method based on a phonon crystal plate proposed in this invention effectively solves the problem of needing to move the incident acoustic transducer or adjust the focal spot of the acoustic radiation force during particle movement control. It achieves accurate particle capture and control simply by changing the resonant frequency during operation.

[0121] Example 3:

[0122] This embodiment provides a phonon crystal plate, including:

[0123] The phonon crystal plate is made of copper plate. The phonon crystal plate has a plurality of holes with the radii of the holes distributed in an arithmetic gradient. The depth of the holes is less than the thickness of the phonon crystal plate. The phonon crystal plate is used to implement the particle movement control methods described in Embodiments 1 and 2 above.

[0124] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A particle movement control method based on a phonon crystal plate, characterized in that, Includes the following steps: S1: Construct a gradient-hole two-dimensional phonon crystal plate; S2: Obtain the gradient acoustic pressure field of the gradient aperture two-dimensional phonon crystal plate; S3: Controlling particle movement using the gradient acoustic pressure field; The specific process of constructing the gradient-hole two-dimensional phonon crystal plate described in step S1 is as follows: S11: Calculate the transmission coefficient of the phononic crystal plate in the liquid; S12: Design phononic crystal plates with different aperture radii and determine the variations in transmission coefficient and resonance frequency in phononic crystal plates with different aperture radii; S13: Based on the changes in transmission coefficient and resonant frequency, construct a gradient-hole two-dimensional phononic crystal plate with a gradient change in aperture radius; The specific process for calculating the transmission coefficient of the phonon crystal plate in the liquid in step S11 is as follows: Let the transmission coefficient of the phonon crystal plate be... The density of the liquid is The speed of sound in a liquid is Then the expression for the transmission coefficient satisfies: ； in, Indicates the sound pressure of the transmitted wave. Indicates the incident wave sound pressure; The specific process for determining the variations in transmission coefficient and resonance frequency in phonon crystal plates with different aperture radii, as described in step S12, is as follows: Let the initial aperture radius of the phonon crystal plate be r, and the resonant frequency be f; maintain the liquid density... With the speed of sound in liquid With the initial aperture radius r varying, determine the transmission coefficient of the phonon crystal plate. The process of changing the resonant frequency f satisfies: As the initial aperture radius r gradually increases, the transmission coefficient The peak value shifts towards the direction where the resonant frequency f decreases; As the initial aperture radius r gradually decreases, the transmission coefficient The peak value shifts towards the direction of increasing resonant frequency f; The specific process of constructing a gradient-hole two-dimensional phonon crystal plate with varying aperture radius as described in step S13 is as follows: Transmission coefficient caused by the change in the initial aperture radius r of the phonon crystal plate Based on the variation of the resonant frequency f, a periodic structure with gradient hole radius variation is designed on the surface of the phononic crystal plate to obtain a gradient hole two-dimensional phononic crystal plate. The specific process for obtaining the gradient acoustic pressure field of the gradient-aperture two-dimensional phonon crystal plate in step S2 is as follows: Let the center point of the gradient aperture surface of the gradient aperture two-dimensional phononic crystal plate be the origin of the coordinate system, and establish a spatial coordinate system xyz; Using ultrasound to radiate acoustic waves onto a gradient-hole two-dimensional phononic crystal plate, the process satisfies: Based on the periodic structure of the gradient aperture two-dimensional phononic crystal plate, the gradient aperture two-dimensional phononic crystal plate is excited by ultrasonic waves along the z-axis of the spatial coordinate system to obtain a gradient acoustic pressure field with acoustic radiation force and whose position changes with the resonant frequency f; wherein, the excitation means that the resonant mode of the phononic crystal plate is excited. The specific process of controlling particle movement using the gradient acoustic pressure field described in step S3 is as follows: The movement of particles is controlled by the acoustic radiation force in the gradient acoustic pressure field, and the process satisfies: Decrease the resonant frequency f to control the position of the gradient sound pressure field to move along the negative y-axis, and use the radiation force in the gradient sound pressure field to control the particle to move along the negative y-axis. Increase the resonant frequency f to control the position of the gradient sound pressure field to move along the positive y-axis, and use the radiation force in the gradient sound pressure field to control the particle to move along the positive y-axis.

2. The particle movement control method based on a phonon crystal plate according to claim 1, characterized in that, The particle experiences a radiation force in the gradient acoustic pressure field of a gradient-aperture two-dimensional phonon crystal plate, and the calculation process of the acoustic radiation force satisfies: Let the acoustic radiation force experienced by the particle in the gradient acoustic pressure field be... The expression satisfies: ； ； in, This represents the external integral pointing towards the particle surface. I represents the time-averaged Bloch radiation stress tensor, where I denotes the unit tensor. This indicates the density of water. Let u represent the speed of sound in water, u represent the first-order flow velocity, and p represent the sound pressure.

3. The particle movement control method based on a phonon crystal plate according to claim 2, characterized in that, The process of calculating the acoustic radiation force on a particle with a diameter much smaller than the wavelength of a sound wave satisfies: ； ； ； ； in, This represents the first-order incident sound pressure. ct represents the sound speed of the particle, ct represents the transverse wave speed of the particle, and cl represents the longitudinal wave speed of the particle.

4. A phonon crystal plate, characterized in that, The phonon crystal plate has a plurality of holes, the radii of which are distributed in an arithmetic gradient, and the depth of which is less than the thickness of the phonon crystal plate. The phonon crystal plate is used to implement the particle movement control method as described in any one of claims 1 to 3.

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