A switchable dual-function acoustic metasurface device and method based on partitioned electrodes

Abstract

The application discloses a kind of based on partition electrode's switchable dual-function acoustic metasurface device and method.Partition electrode acoustic piezoelectric transducer and flat plate polymer metasurface are included, partition electrode acoustic piezoelectric transducer includes the lower surface partition electrode, lead zirconate titanate piezoelectric ceramic sheet, upper surface non-partition electrode and matching layer sequentially stacked from bottom to top, and flat plate polymer metasurface is arranged on the upper surface of matching layer;Lower surface partition electrode is divided into two partial electrodes of mutually insulated center internal area electrode and peripheral external area electrode, and upper surface non-partition electrode is whole electrode.The structure of the present application only switches the input voltage of the area electrode of partition electrode to realize the dual-function switching of focusing sound field and bottle-shaped sound field, so that it simultaneously has the dual-function demand of acoustic energy focusing and "sound tweezers", and flat plate polymer metasurface is directly imprinted on piezoelectric ceramic transducer, improves sound field coupling efficiency, and the thickness is thinner and the price is good.

Description

Technical Field

[0001] The present invention relates to an acoustic generating device, and more particularly to a switchable dual-function acoustic metasurface device based on partitioned electrodes. Background Technology

[0002] Acoustic metasurfaces are designed analogously to optical metasurfaces. Based on the generalized Snell's law, researchers have proposed designing acoustic metasurfaces with phase gradients. By artificially combining a series of subwavelength-sized artificial microstructures in a specific manner, researchers can achieve special manipulation of transmitted or reflected sound waves, such as anomalous transmission, negative refraction, plane wave focusing, and self-bending sound fields. Compared to acoustic metamaterials, acoustic metasurfaces have a thickness smaller than the wavelength of the operating frequency, achieving large wave fields with small dimensions. They also have advantages such as relatively low fabrication losses, small size, and thinness, demonstrating great research value and broad application prospects in the field of acoustics, thus attracting great attention from the scientific and engineering communities.

[0003] With the miniaturization and precision of machining technology, acoustic metasurfaces are developing towards miniaturization, integration, and multifunctionality. Currently, most designed acoustic metasurfaces are composed of transmissive frequency-selective structural units with similar topologies. These are simply arrayed together from multiple individual metasurface units with different phase modulation sizes. Before practical use, the array structure needs to be pre-arranged and assembled, resulting in low design efficiency. Furthermore, most metasurface units currently used for phase modulation are based on resonant cavity structures or curved structures based on acoustic path differences. Metasurface structures composed of these arrays are relatively thick and difficult to manufacture. Therefore, this invention uses a thin polymer as an acoustic planar metalens. Phase modulation is achieved by changing the unit height of the sound field at each location. This structure can be realized using 3D printing, which is simple and highly precise. Simultaneously, the planar polymer metasurface can achieve a large acoustic transmittance, effectively increasing the energy of the modulated sound field.

[0004] Based on the piezoelectric effect and vibration coupling theory, the most commonly used piezoelectric material on the market is lead zirconate titanate (longitudinal coupling coefficient K). t=0.47, dielectric constant η=900), lead zirconate titanate is a binary piezoelectric ceramic. Polarized lead zirconate titanate exhibits piezoelectricity, enabling sensing and detection through the interconversion of force and electricity. Lead zirconate titanate polarized along its thickness will generate a longitudinal wave acoustic field in the electric field formed by the upper and lower surface electrodes. The input of a sinusoidal electrical signal excites continuous sinusoidal mechanical vibrations, which are coupled into the target medium through a matching layer, generating continuous ultrasonic waves. Based on the three-medium theory, a planar polymer metasurface with acoustic impedance matching can phase-modulate the mechanical vibrations of the probe surface and transmit them into the background domain to achieve a complex target acoustic field. However, currently, most acoustic metasurfaces primarily operate in a single mode of transmission or reflection, used to achieve a single function such as anomalous deflection of the sound field, acoustic cloaking, or focusing of acoustic energy.

[0005] It is evident that currently reported metasurface devices mainly suffer from a single operating mode, require multiple sets of metaunits or multilayer asymmetric structures to achieve different functions, and are rarely directly integrated with conventional commercial probes. Summary of the Invention

[0006] To overcome the shortcomings of the existing technologies, including insufficient coupling and difficult assembly between conventional probes and metasurface lenses, as well as the complex structure, large thickness dimension, and single working mode of existing metasurfaces, this invention provides a switchable dual-function acoustic metasurface device based on partitioned electrodes. This device enables the switching between focused acoustic energy and bottle-shaped sound fields. The planar polymer metasurface is directly deposited on the piezoelectric ceramic transducer of the partitioned electrodes. No additional equipment is required. The dual-function switching between focused sound fields and bottle-shaped sound fields at the same target location can be achieved simply by changing the phase difference of the voltage signals of the two input channels.

[0007] The device of this invention mainly utilizes liquid silver deposited as insulating regional electrodes, called partitioned electrodes, on the lower surface of a lead zirconate titanate piezoelectric ceramic sheet. These electrodes are connected to an external excitation signal source via leads, serving as the positive electrode of the piezoelectric element. Similarly, liquid silver is deposited as a non-partitioned electrode on the upper surface of the lead zirconate titanate piezoelectric ceramic sheet, which is led out via leads and directly grounded, serving as the negative electrode of the piezoelectric element. In actual operation, the dual-function switching between sound energy focusing and bottle-shaped sound field is achieved simply by changing the phase difference of the input voltage between the two regions of the partitioned electrodes.

[0008] The technical solution adopted in this invention is as follows:

[0009] I. A switchable dual-function acoustic metasurface device based on partitioned electrodes:

[0010] The device is placed in a background medium environment. The device includes a partitioned electrode acoustic piezoelectric transducer and a planar polymer metasurface. The partitioned electrode acoustic piezoelectric transducer includes a lower surface partitioned electrode, a lead zirconate titanate piezoelectric ceramic sheet, an upper surface non-partitioned electrode and a matching layer, which are stacked sequentially from bottom to top. The planar polymer metasurface is arranged on the upper surface of the matching layer.

[0011] The lower surface partitioned electrode is divided into two parts: an inner region electrode at the center and an outer region electrode on the periphery. The upper surface non-partitioned electrode is a single electrode.

[0012] The partitioned electrode acoustic piezoelectric transducer further includes a housing and a backing. The upper end of the housing is open, the bottom end of the partitioned electrode on the lower surface is embedded in the opening, and the backing is provided in the cavity formed between the partitioned electrode on the lower surface and the housing.

[0013] The backing is made of sound-absorbing material.

[0014] This invention innovatively sets up a lower surface electrode composed of two partial electrodes, and then applies different phase control to the two partition electrodes of the lower surface electrode to cleverly achieve two sound field effects, i.e. dual-function switching. Moreover, it can conveniently switch between the two sound field functions simultaneously without replacing the flat polymer metasurface.

[0015] The internal region electrode, the external region electrode, and the upper surface non-partitioned electrode are each connected to an external two-channel voltage signal generator via their respective wires.

[0016] Both the planar polymer metasurface and the matching layer are made of a mixture of metal powder and polymer, with different proportions of metal powder and polymer. Furthermore, the relative amount of metal powder added in the planar polymer metasurface is less than that in the matching layer.

[0017] The flat polymer metasurface is formed by rotating radial cross-sections with varying thicknesses. Each radial cross-section is divided into multiple sections from the center outwards by a fixed radial length W0. The fixed radial length W0 is significantly smaller than the operating wavelength. The thickness H of each section is... i Adjust the settings according to the modulated phase difference.

[0018] In the aforementioned flat polymer metasurface, the thickness dimensions of each cross-sectional block are set as follows:

[0019] First, obtain the value of each cross-section block as a function of distance x using the following formula. i Phase changes:

[0020] Φ(x i )=k0(mλ+(x i2 +L 2 ) 1 / 2 -L)

[0021] k0=2πf / c1

[0022] In the formula, Φ(x) i () represents the distance x to the center of the flat polymer metasurface. i The phase of the cross-section block, x i The distance from each cross-section to the center of the planar polymer metasurface is represented by i = 1, 2, 3, ..., n, where i represents the ordinal number of the cross-section and n represents the total number of cross-sections; L represents the focal length of the planar polymer metasurface; k0 represents the wavenumber in the background medium, which is the environment in which the probe works; f represents the operating frequency f of the planar polymer metasurface; c1 is the velocity of sound in the background medium; and m is the matching coefficient, which is any positive integer, specifically any integer, and can be directly set to 0.

[0023] Set the thickness dimension H of each cross-section block according to the following formula. i :

[0024] H i =(Φ(x i )c1c2) / (2πf(c1-c2))

[0025] c2=(E(1-σ) / (ρ(1+σ)(1-2σ))) 1 / 2

[0026] In the formula, c2 represents the sound velocity in the flat polymer metasurface material; E is Young's modulus, σ is Poisson's ratio, and ρ is the density of the polymer metasurface.

[0027] II. Sound Field Control Method for Switchable Dual-Function Acoustic Metasurface Devices Based on Partitioned Electrodes:

[0028] The switchable dual-function acoustic metasurface device is placed in a liquid background medium environment. The upper surface non-partitioned electrode is kept grounded. Independent sinusoidal voltage signals are input to the inner and outer region electrodes of the lower surface partitioned electrode. Different sound field controls are achieved by adjusting the two sinusoidal voltage signals input to the inner and outer region electrodes respectively.

[0029] Different sound field controls are achieved by adjusting the phase difference between two sinusoidal voltage signals input to the internal and external region electrodes, respectively.

[0030] When the phase difference between two sinusoidal voltage signals input to the internal and external region electrodes is 0, the lead zirconate titanate piezoelectric ceramic sheet generates sinusoidal mechanical vibration along the thickness direction under the electric field of the lower surface partition electrode and the upper surface non-partition electrode. The sinusoidal mechanical vibration is coupled to the liquid of the background medium through the matching layer and the plate polymer metasurface, and the plate polymer metasurface modulates the phase of the incident sinusoidal mechanical vibration, thereby forming a focusing beam of acoustic energy at the target position.

[0031] When two sinusoidal voltage signals with a phase difference of π are input to the internal and external region electrodes respectively, the lead zirconate titanate piezoelectric ceramic sheet generates the same amplitude along the thickness direction under the electric field of the lower surface partition electrode and the upper surface non-partition electrode, producing sinusoidal mechanical vibration with a phase difference of π. The sinusoidal mechanical vibration is coupled to the liquid of the background medium through the matching layer and the plate polymer metasurface, and the plate polymer metasurface modulates the phase of the incident mechanical vibration, thereby forming a bottle-shaped sound field at the target position.

[0032] The mechanical vibrations in both regions are sinusoidal, and the phase difference pi here refers to pi on the time scale.

[0033] Sound Focusing:

[0034] The two regions of the lower surface partition electrode are connected by leads to input non-zero sinusoidal voltage signals with equal amplitude and phase, while the upper surface non-partition electrode is grounded.

[0035] At this time, the non-zero voltage lower surface partitioned electrode and the zero voltage upper surface non-partitioned electrode together form an electric field along the thickness direction. Since the internal and external regions of the lower surface partitioned electrode have the same phase, at any time, the electric field generated at the corresponding positions of the internal and external regions of the lower surface partitioned electrode has the same direction.

[0036] Based on the inverse piezoelectric effect, at any given time, a uniform electric field along the thickness direction will cause the corresponding positions in the inner and outer regions of the lead zirconate titanate ceramic piezoelectric sheet to generate sinusoidal mechanical vibrations with equal amplitude and the same direction along the thickness direction. These sinusoidal mechanical vibrations are then transmitted to the liquid in the background medium after being coupled and modulated through the matching layer and the flat polymer metasurface, thereby achieving acoustic energy focusing modulation at the target position.

[0037] Bottle-shaped sound field

[0038] The two regions of the lower surface partitioned electrode are connected by leads to input non-zero sinusoidal voltage signals with equal amplitude and a phase difference of π, while the upper surface non-partitioned electrode is grounded.

[0039] At this time, the non-zero voltage lower surface partition electrode and the zero voltage upper surface non-partition electrode together form an electric field along the thickness direction. Since the phase difference between the inner and outer regions in the lower surface partition electrode is π, at any given time, the electric field generated at the corresponding positions in the inner and outer regions of the lower surface partition electrode has opposite directions.

[0040] Based on the inverse piezoelectric effect, under the action of two electric fields in opposite directions, the lead zirconate titanate ceramic piezoelectric sheet is virtually divided into two parts: an inner region and an outer region. At any given time, the lead zirconate titanate ceramic piezoelectric sheets in the inner and outer regions will generate sinusoidal mechanical vibrations with the same amplitude but opposite direction along the thickness direction. These sinusoidal mechanical vibrations, with a phase difference of π between the two regions, are transmitted and modulated through a matching layer and a planar polymer metasurface, and then transmitted to the liquid background medium, thereby achieving bottle-shaped sound field modulation at the target location. A sound hydrazine exists at the lower part of the bottle-shaped sound field, enabling acoustic tweezers particle trapping.

[0041] In practice, by switching the phase difference of the voltage signal of the input partition electrode, dual-function switching between sound energy focusing sound field and bottle-shaped sound field can be achieved without additional active equipment.

[0042] For sound focusing, it is only necessary to ensure that the input amplitude and phase are the same as two sinusoidal voltages; for far-field bottle-shaped sound field operation, it is only necessary to ensure that the input amplitude is the same and the phase difference is π sinusoidal voltages; in actual operation, the dual-function sound field can generally be switched by simply switching the phase of any one of the input voltage signals.

[0043] The device of this invention achieves acoustic energy focusing at any frequency and focal length, or acoustic tweezers trapping of a bottle-shaped sound field, by designing a flat polymer metasurface cross-sectional block with an arbitrary size. In particular, when the same switchable dual-function acoustic metasurface device is used to switch between acoustic energy focusing and bottle-shaped sound field functions, the position of acoustic energy focusing and the position of acoustic tweezers trapping are the same.

[0044] This invention achieves integrated encapsulation of metasurface and conventional probe by partitioning the lower surface electrodes, directly depositing an impedance matching layer, and using a planar polymer metasurface. It can also switch the sound field of focusing and bottle beam in real time by directly switching the phase delay of one of the input voltage signals, greatly improving the sound field modulation function of the device. Moreover, it is simple and convenient to operate and inexpensive.

[0045] Specifically, this involves combining a piezoelectric ceramic transducer with partitioned electrodes deposited on its surface with a planar polymer metasurface. By changing the input voltage of the partitioned electrodes, a dual-function switching between focusing and bottle-shaped acoustic fields is achieved. The electrodes deposited on the surface of the ceramic piezoelectric transducer are divided into two regions, each independently connected to two external input voltage signals. Changing the phase difference between the input signals in the two electrode regions alters the vibration of the lead zirconate titanate piezoelectric transducer. The excited mechanical vibration is coupled by the surface-deposited planar polymer metasurface, enabling background acoustic field focusing and bottle-shaped acoustic field switching. Therefore, using this switchable dual-function acoustic metasurface device with partitioned electrodes, inspectors can focus the excitation plane incident wave from a conventional piezoelectric probe at the target location, and also achieve bottle-shaped acoustic field distribution at the target location, thereby enabling acoustic tweezers particle trapping.

[0046] Moreover, the planar polymer metasurface uses polymer materials, which have a better match with the matching layer of conventional probes, resulting in higher acoustic transmission efficiency. This invention maintains the switchable dual-function acoustic metasurface device structure with partitioned electrodes, and can achieve dual-function switching of acoustic energy focusing and acoustic tweezer particle trapping at the same location by simply switching the input voltage.

[0047] Furthermore, both the planar polymer metasurface and the matching layer of the present invention are made of polymer materials. The lower surface of the planar polymer metasurface is flat and is directly imprinted on the matching layer surface of the piezoelectric transducer of the partitioned electrode. The upper surface of the planar polymer metasurface is an array structure with varying concave and convex shapes. The thickness variation units have the same width but different thicknesses. The dual-function acoustic metasurface devices of the partitioned electrodes are all symmetrical with respect to the central axis. The planar polymer metasurface of the dual-function acoustic metasurface device of the partitioned electrodes can perform phase modulation on the mechanical vibration signal excited by the piezoelectric transducer, and then couple it into the background domain to achieve sound field control.

[0048] The device of the present invention has the following beneficial effects:

[0049] (1) The present invention utilizes the piezoelectric transducer with partitioned electrodes and the flat polymer metasurface to achieve dual functions of sound energy focusing and bottle-shaped sound field by simply switching the phase difference of two input voltage signals. First, when two sinusoidal voltage signals with the same amplitude and phase are input, the lead zirconate titanate piezoelectric element will generate sinusoidal mechanical vibration with the same amplitude and phase. After coupling and phase modulation through the matching layer and the flat polymer metasurface, sound energy focusing at the target position can be achieved.

[0050] Meanwhile, when two sinusoidal voltage signals with the same amplitude but a phase difference of π are input, the parts corresponding to the voltage in the internal and external regions of the lead zirconate titanate piezoelectric element will generate sinusoidal mechanical vibrations with the same amplitude but a phase difference of π. Similarly, after coupling and phase modulation through the matching layer and the flat polymer metasurface, a bottle-shaped sound field can be realized at the target position for particle capture.

[0051] (2) The flat polymer metasurface used in this invention is thin and inexpensive. It is integrated with the acoustic transducer by directly imprinting it onto the surface of the matching layer. Due to impedance matching and sufficient coupling, the sound field transmittance is high.

[0052] Meanwhile, since the planar polymer metasurface does not rely on resonance principles for phase modulation, it can achieve broadband acoustic focusing and particle trapping. The assembled dual-function acoustic metasurface device can switch sound fields without additional components; simply changing the phase value of one of the input electric fields is sufficient for real-time sound field switching, making it highly operable. Attached Figure Description

[0053] To more clearly illustrate the embodiments and design schemes of the present invention, the accompanying drawings required for these embodiments will be briefly described below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a partial cross-sectional schematic diagram of the device in Embodiment 1 of the present invention;

[0055] Figure 2 This is a half-sectional view and a dimensioned view of the partitioned electrode acoustic piezoelectric transducer 1 of Embodiment 1 of the present invention;

[0056] Figure 3 and Figure 4 This is a schematic diagram of the piezoelectric element of the switchable dual-function acoustic metasurface device based on partitioned electrodes of the present invention, including a lower surface partitioned electrode 13, a lead zirconate titanate piezoelectric ceramic sheet 14, and an upper surface non-partitioned electrode 15; wherein Figure 3 In the diagram, (a) represents a three-dimensional view of the circular electrode, (b) represents a top surface view of the circular electrode, and (c) represents a bottom surface view of the circular electrode. Figure 4 In the diagram, (a) represents a three-dimensional view of the square electrode, (b) represents a top surface electrode view of the square electrode, and (c) represents a bottom surface electrode view of the square electrode.

[0057] Figure 5 and Figure 6 This is a schematic diagram of the planar polymer metasurface 2 of the present invention; wherein Figure 5Images (a) and (b) in the diagram represent three-dimensional schematic diagrams of circular and square flat polymer metasurfaces. Figure 6 The image shows a cross-sectional view of a planar polymer metasurface.

[0058] Figure 7 This is a schematic diagram showing the mechanical vibration distribution of the lead zirconate titanate piezoelectric ceramic sheet 14 and the sound field distribution in the background water medium under phase modulation without the plate-type polymer metasurface 2 when the phase of the input voltage signal corresponding to the external region electrode 132 is switched in Embodiments 1 and 2 of the present invention. Figure 7 (a) shows the phase distribution of the mechanical vibration of the piezoelectric ceramic sheet and the sound field in the water when the internal and external regions are excited with voltage signals of the same phase. (b) shows the phase distribution of the mechanical vibration of the piezoelectric ceramic sheet and the sound field in the water when the internal and external regions are excited with voltage signals of the same phase but different by π.

[0059] Figure 8 This is a schematic diagram of the sound field distribution in the background water medium excited by the phase modulation of the plate polymer metasurface 2 when the phase of the input voltage signal corresponding to the external region electrode 132 is switched in Embodiments 1 and 2 of the present invention. Figure 8 (a) shows the sound field distribution in the water when the internal and external regions are excited with voltage signals of the same phase, and (b) shows the sound field distribution in the water when the internal and external regions are excited with voltage signals of the same phase but π out of phase.

[0060] Figure reference numerals: 1. Partitioned electrode acoustic piezoelectric energy generator; 11. Wire; 12. Backing; 13. Lower surface partitioned electrode; 131. Internal region electrode; 132. External region electrode; 14. Lead zirconate titanate piezoelectric ceramic sheet; 15. Upper surface non-partitioned electrode; 16. Matching layer; 17. Shell; 2. Flat polymer metasurface. Detailed Implementation

[0061] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0062] In the description of this invention, it should be understood that the terms "middle," "upper," "lower," "left," "right," "lateral," "longitudinal," "horizontal," "vertical," "axial," "mirror image," "length," "width," and "thickness," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the technical solutions of this invention and simplifying the description, and do not indicate or imply that the device or equipment referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, and will not be elaborated further here.

[0063] like Figure 1 As shown, it includes a partitioned electrode acoustic piezoelectric transducer 1 and a flat polymer metasurface 2, with the flat polymer metasurface 2 covering the partitioned electrode acoustic piezoelectric transducer 1; the partitioned electrode acoustic piezoelectric transducer 1 includes a lower surface partitioned electrode 13, a lead zirconate titanate piezoelectric ceramic sheet 14, an upper surface non-partitioned electrode 15 and a matching layer 16 stacked sequentially from bottom to top, and the flat polymer metasurface 2 is arranged on the upper surface of the matching layer 16;

[0064] The lower surface partitioned electrode 13 is divided into two parts: an inner region electrode 131 at the center and an outer region electrode 132 at the periphery, which are mutually insulated from each other. The upper surface non-partitioned electrode 15 is a whole electrode.

[0065] In a specific implementation, the partitioned electrode acoustic piezoelectric transducer 1 also includes a housing 17 and a backing 12. The upper end of the housing 17 is open, the bottom end of the lower surface partitioned electrode 13 is embedded in the opening, and the backing 12 is provided in the cavity formed between the lower surface partitioned electrode 13 and the housing 17.

[0066] The backing 12 is made of sound-absorbing material to absorb sound waves and prevent them from passing through one side of the outer shell 17. Specifically, silicone can be used. In practice, the backing is made of silicone material. Liquid silicone is poured into the pre-reserved opening in the outer shell and cured at room temperature, which achieves both the effect of absorbing vibration and the function of sealing.

[0067] Specifically, the partitioned electrode 13 and the non-partitioned electrode 15 are obtained by depositing liquid silver on the upper and lower surfaces of the lead zirconate titanate ceramic sheet by cooling, respectively; the backing is deposited on the surface of the partitioned electrode 13 to absorb mechanical vibration; the matching layer 16 is a polymer of tungsten metal and epoxy resin that matches the impedance of the lead zirconate titanate material, used to couple and transmit mechanical vibration; the flat polymer metasurface 2 is directly imprinted on the matching layer 16, and the polymer material used is a metal polymer with an epoxy base that matches the impedance of the matching layer and water.

[0068] The lower surface partitioned electrode 13 and the upper surface non-partitioned electrode 15 are formed by uniformly depositing liquid silver on both sides of the lead zirconate titanate piezoelectric ceramic sheet 14 through direct cooling. The partitioned electrode serves as the positive electrode of the lead zirconate titanate piezoelectric element, and the non-partitioned electrode serves as the negative electrode of the lead zirconate titanate piezoelectric element.

[0069] The internal region electrode 131, the external region electrode 132, and the upper surface non-partitioned electrode 15 are each connected to an external two-channel voltage signal generator via their respective wires 11, which is equivalent to two independent excitation signal sources forming the positive electrode of the piezoelectric transducer device. Specifically, the internal region electrode 131 and the external region electrode 132 are connected to the positive electrode, and the upper surface non-partitioned electrode 15 is connected to the negative electrode.

[0070] The lower surface partitioned electrode 13 is shaped to match the lead zirconate titanate piezoelectric ceramic sheet and serves as the positive electrode of the sheet. The upper surface non-partitioned electrode 15 is a single-region electrode, shaped to match the lead zirconate titanate piezoelectric ceramic sheet but slightly smaller, and serves as the negative electrode.

[0071] For the lower surface partition electrode 13, liquid silver is directly deposited on the lower surface of the lead zirconate titanate piezoelectric ceramic sheet, forming two insulated regions: an inner region and an outer region. The shape of the two region electrodes depends on the lead zirconate titanate piezoelectric sheet and can be circular or square: for a circular cross-section piezoelectric sheet, the two region electrodes are concentric circles and rings; for a square cross-section piezoelectric sheet, the two region electrodes are a square and a square ring region.

[0072] For the unpartitioned electrode 15 on the upper surface, liquid silver is directly deposited onto the upper surface of the lead zirconate titanate piezoelectric ceramic sheet, forming a single connected region. The shape of this electrode region is consistent with the shape of the lead zirconate titanate piezoelectric sheet. To facilitate subsequent deposition of the matching layer and metasurface, the unpartitioned electrode is flipped to the partitioned electrode side of the lead zirconate titanate piezoelectric ceramic element and then led out via a wire and directly grounded as the negative electrode of the piezoelectric transducer device.

[0073] The plate-shaped polymer metasurface 2 with varying thickness, the partitioned electrode 13, and the non-partitioned electrode 15 are all symmetrically distributed relative to the center of the lead zirconate titanate piezoelectric sheet 14. At the same time, the shape of the plate-shaped polymer metasurface with varying thickness is related to the shape of the lead zirconate titanate piezoelectric sheet 14: if the lead zirconate titanate piezoelectric sheet 14 used at this time is circular, then the cross-section of the plate-shaped polymer metasurface 2 is a circular ring structure; if the lead zirconate titanate piezoelectric sheet 14 used at this time is square, then the cross-section of the plate-shaped polymer metasurface 2 is a rectangular ring structure.

[0074] Furthermore, the maximum outer dimensions of both partitioned and unpartitioned electrodes are the same, and the electrode thicknesses are both the same and uniform.

[0075] The thickness H of the lead zirconate titanate piezoelectric ceramic element 14 PZT The thickness is related to the excitation frequency f. The thickness at which the characteristic modes are generated is selected at the excitation frequency f, and the resonance of the characteristic frequency is achieved at that thickness.

[0076] Lead zirconate titanate piezoelectric sheets with partitioned and non-partitioned electrodes deposited and connected to wires are directly assembled into the 3D-printed transducer housing. The transducer housing and the piezoelectric element are in a transition fit. The partitioned electrode side of the piezoelectric element is installed downward and positioned by a limiting platform to ensure that the partitioned electrode side is five times the wavelength away from the bottom of the polymer housing for casting the backing.

[0077] Meanwhile, the non-zoned electrode side of the positioned piezoelectric element is still a certain distance from the upper surface of the transducer housing, which is used to deposit a matching layer. This distance is exactly equal to the thickness of the matching layer. Three wires used to connect the zoned electrode and the non-zoned electrode are led out from the holes reserved at the bottom of the housing to form two voltage signal input interfaces.

[0078] A switchable dual-function acoustic metasurface device emits sound waves when placed in a liquid environment.

[0079] Both the flat polymer metasurface 2 and the matching layer 16 are made of a mixture of metal powder and polymer, with different proportions of metal powder and polymer. The relative amount of metal powder added in the flat polymer metasurface 2 is less than that in the matching layer 16.

[0080] The metal powder is tungsten powder, and the polymer is an epoxy resin polymer.

[0081] In specific implementation, the matching layer 16 is a polymer material in which tungsten powder and epoxy resin polymer are fully mixed in a mass ratio of m:1. It is directly deposited on the surface of the non-partitioned electrode by extrusion or spin coating, and the thickness is about 1 / 4 of the target frequency wavelength.

[0082] The planar polymer metasurface 2 is a polymer material in which tungsten powder and epoxy resin are fully mixed in a mass ratio of n:1, where m>n. It is directly imprinted onto the surface of the matching layer by cooling and demolding, thus completing the assembly between the piezoelectric transducer of the partitioned electrode and the planar polymer metasurface and realizing the integration of the device.

[0083] In specific implementation, the matching layer 16 is made of a mixture of tungsten powder and polymer that matches the impedance of both the lead zirconate titanate piezoelectric ceramic sheet and the water environment within the working wavelength band. It is prepared by direct deposition on the surface of the non-partitioned electrode through extrusion or spin coating, and its shape and size are consistent with those of the lead zirconate titanate piezoelectric ceramic sheet.

[0084] The material of the planar polymer metasurface 2 is a mixture of metal powder and polymer that matches the impedance of the matching layer and the water environment within the working band. It is assembled by directly depositing the mixture onto the surface of the matching layer 16 through imprinting, thereby achieving the integrated sealing of the entire dual-function acoustic metasurface.

[0085] The present invention sets up a planar polymer metasurface 2 and a matching layer 16 with similar materials but different proportions, so that the materials of the planar polymer metasurface 2 and the matching layer 16 are similar, which can better achieve complete matching of acoustic impedance, and can be more convenient to prepare and imprint into one piece.

[0086] The flat polymer metasurface 2 is a rotating component, formed by rotating radial cross-sections with varying thicknesses. Each radial cross-section is divided into multiple sections from the center outwards by a fixed radial length W0. The width of each section is also a fixed radial length W0, which is much smaller than the working wavelength. The thickness H of each section is... i Adjust the settings according to the modulated phase difference.

[0087] The plate-shaped polymer metasurface 2 with varying thickness obtained by imprinting is used to modulate the mechanical vibration excited by the piezoelectric transducer, thereby achieving sound energy focusing or bottle-shaped sound field.

[0088] In the flat polymer metasurface 2, the thickness dimension H of each cross-section is... i At the wavelength level, the phase difference needs to be calculated based on the operating frequency f and the target focusing position L. Then, based on the phase difference and the material properties of the polymer, it is set as follows:

[0089] When focusing at focal length L, first obtain the value of each cross-section as a function of distance x using the following formula. i Phase changes:

[0090] Φ(x i )=k0(mλ+(x i 2 +L 2 ) 1 / 2 -L)

[0091] k0=2πf / c1

[0092] In the formula, Φ(x) i ) represents the distance x to the center of the flat polymer metasurface 2. i The phase of the cross-section block, x iThe distance from each cross-section block to the center of the flat polymer metasurface 2 is represented by i = 1, 2, 3, ..., where i represents the ordinal number of the cross-section block, n represents the total number of cross-section blocks, L represents the focal length of the flat polymer metasurface 2; k0 represents the wave number in the background medium, f represents the operating frequency f of the flat polymer metasurface 2, c1 is the sound velocity of the background medium, specifically the sound velocity of the medium c1 = 1480 m / s; m is the matching coefficient, which is any positive integer, specifically any integer, and can be directly taken as 0.

[0093] In practice, the operating frequency can be selected from 100k-2000 kHz.

[0094] The flat polymer metasurface is an isotropic homogeneous medium, and the thickness H of each cross-section can be varied. i Achieve target phase Φ(x) i Without considering acoustic attenuation in the planar polymer metasurface, the thickness H of each cross-section is set according to the following formula. i :

[0095] H i =(Φ(x i )c1c2) / (2πf(c1-c2))

[0096] c2=(E(1-σ) / (ρ(1+σ)(1-2σ))) 1 / 2

[0097] In the formula, c2 represents the sound velocity in the flat polymer metasurface 2 material, which is calculated based on the material properties of the polymer; E is Young's modulus, σ is Poisson's ratio, and ρ is the material density of the flat polymer metasurface 2.

[0098] After considering the precision of metasurface processing, the operating frequency can be selected from 100k-2000 kHz. When the operating frequency f changes, a lead zirconate titanate ceramic piezoelectric sheet of corresponding thickness is selected according to the operating frequency f to achieve the corresponding resonant frequency. At the same time, the thickness of the matching layer and the lateral and thickness dimensions of the flat polymer metasurface cross-section can be changed proportionally according to the change of the operating frequency f.

[0099] When the focal length L corresponding to the target's focal position changes, the thickness h of each cross-section block... i It needs to be adjusted according to the focal length L at this time, which is convenient, simple and efficient.

[0100] The specific embodiments of the present invention are as follows:

[0101] Both the partitioned electrode acoustic piezoelectric transducer 1 and the planar polymer metasurface 2 are symmetrical with respect to the central axis of the lead zirconate titanate piezoelectric ceramic sheet 14. The direction perpendicular to the upper and lower surfaces of the lead zirconate titanate piezoelectric ceramic sheet 14 is denoted as the z-direction, and the plane parallel to the upper and lower surfaces of the lead zirconate titanate piezoelectric ceramic sheet 14 is denoted as the xoy plane.

[0102] like Figure 1 As shown, the lower surface partitioned electrode 13 and the upper surface non-partitioned electrode 15 are deposited on both sides of the lead zirconate titanate piezoelectric ceramic sheet 14 by cooling liquid silver, serving as the positive and negative electrodes of the piezoelectric element. The partitioned electrode 13 is positioned against the limiting step of the housing 17. The matching layer 16 is directly cured and deposited on the upper surface of the non-partitioned electrode 14. The matching layer 16 is a polymer of tungsten metal and epoxy resin that matches the acoustic impedance of the lead zirconate titanate piezoelectric ceramic sheet 14 and the water medium, used for coupling and transmitting mechanical vibrations. The backing 12 is made of silicone that does not match the acoustic impedance of the lead zirconate titanate piezoelectric ceramic sheet 14, and is cured by pouring liquid silicone into the opening at the bottom of the housing 17, used to absorb mechanical vibrations.

[0103] like Figure 2 The image shown is a half-sectional view of the partitioned electrode acoustic piezoelectric transducer 1 provided by the present invention. The thickness H of the backing 12, the lead zirconate titanate piezoelectric ceramic sheet 14, and the matching layer 17 is also shown. b H PZT and H c The thickness H of the lead zirconate titanate piezoelectric ceramic sheet 14 is determined by the target frequency f. PZT H represents the value of H when thickness-direction resonance is achieved at excitation frequency f. b and H c These are 10 times and 1 / 4 times the wavelength at the target excitation frequency f, respectively.

[0104] like Figure 3 The diagram shows a three-dimensional view and a two-dimensional dimensional view of the lower surface partitioned electrode 13, the lead zirconate titanate piezoelectric ceramic sheet 14, and the upper surface non-partitioned electrode 15 provided by the present invention. The lower surface partitioned electrode 13 and the upper surface non-partitioned electrode 15 have the same and uniform thickness. The lower surface partitioned electrode 13 consists of two completely insulated regions: an inner region 131 and an outer region 132. The two regions are led out by wires and connected to two signal input terminals. The upper surface non-partitioned electrode 15 is a single electrode. To facilitate the subsequent deposition of the matching layer 16, one side of the upper surface non-partitioned electrode 15 is deposited on one side of the lower surface partitioned electrode 13, bypassing the lead zirconate titanate piezoelectric ceramic sheet 14, for direct grounding by lead-out wires.

[0105] The shapes of the lower surface partitioned electrode 13 and the upper surface non-partitioned electrode 15 are both related to the lead zirconate titanate piezoelectric ceramic sheet 14. When the lead zirconate titanate piezoelectric ceramic sheet 14 is cylindrical, the inner region electrode 131 and the outer region electrode 132 of the lower surface partitioned electrode 13 are circular and annular structures, respectively, and the upper surface non-partitioned electrode 15 is circular. When the lead zirconate titanate piezoelectric ceramic sheet 14 is cuboid, the inner region electrode 131 and the outer region electrode 132 of the lower surface partitioned electrode 13 are square and square annular structures, respectively, and the upper surface non-partitioned electrode 15 is square. Both the lower surface partitioned electrode 13 and the upper surface non-partitioned electrode 15 are symmetrical about the z-axis, and their maximum width D is... d3 and D u3 Equal to, and slightly smaller than, the width W of the lead zirconate titanate piezoelectric ceramic sheet 14. PZT Meanwhile, for ease of design, the width D of the inner region electrode 131 of the lower surface partition electrode 13 along the x and y axes is... d1 Half of the entire area: D d1 ≈2D d3 Furthermore, the inner and outer electrodes differ in size by 4mm: D d2 -D d1 =4mm.

[0106] like Figure 4 The three-dimensional structural diagram and two-dimensional cross-sectional diagram of the planar polymer metasurface 2 provided by the present invention include a unit array with varying thickness. The material of the planar polymer metasurface 2 is an epoxy-based metal polymer material selected to match the impedance of the matching layer 16 and water. Specifically, both the planar polymer metasurface 2 and the matching layer 16 use a mixture of tungsten powder and epoxy resin, with a mass ratio of tungsten powder to epoxy resin of n:1 and m:1, respectively, where m>n>1.

[0107] Combination Figure 4 (c) The width W of the flat polymer metasurface ms =W PZT The width W0 of the thickness variation element along the x or y direction. The thickness H of each cross-section block. i The thickness calculation differs; it is designed based on the phase difference calculated using the generalized Snell's law, taking into account the operating frequency used in actual engineering and the target acoustic energy focusing position. Simultaneously, the structure of the planar polymer metasurface 2 provided by this invention can be designed based on the structure of the lead zirconate titanate piezoelectric ceramic sheet 14; such as... Figure 3 (a) If the lead zirconate titanate piezoelectric ceramic sheet 14 is cylindrical at this time, then the planar polymer metasurface 2 is also selected as a cylindrical structure, and the cross-sectional blocks are a circular array structure; such as Figure 3 (b) If the lead zirconate titanate piezoelectric ceramic sheet 14 is a cuboid, then the flat polymer metasurface 2 is also selected as a cuboid structure with a square ring array structure for the cross-section blocks.

[0108] Specifically, in this embodiment, the switchable dual-function acoustic metasurface device based on partitioned electrodes is implemented underwater, with an operating frequency of 100k-5000 kHz. Taking an operating frequency of f=2000 kHz as an example, the wavelength λ=0.75mm. The thickness H of the lead zirconate titanate piezoelectric ceramic sheet 14 is... PZT =1 mm, width W PZT =50 mm, thickness H of matching layer 16 c =0.2 mm, width W c =50 mm, backing thickness H 12 b =7.5 mm, width W b =47 mm. The mass ratio of tungsten powder to epoxy resin in the epoxy metal mixture used for matching layer 16 is 3:1.

[0109] The width of the internal region of the lower surface partition electrode 13 is D d1 =20 mm, the width of the outer region is D d3 =46 mm, the interval between the inner and outer regions is D. d2 -D d1 =4 mm;

[0110] The width dimension of the non-partitioned electrode 15 on the upper surface is D. u =46 mm;

[0111] The width dimension of the flat polymer metasurface 2 is W. ms =50 mm, and the width of each cross-section is W0=1 mm. With a target acoustic energy focusing focal length L=120 mm, and since all cross-sections are symmetrical about the axis, the thickness H of the cross-sections on the right side of the axis from the inside out is... i The thicknesses are as follows: 2.30mm, 2.33mm, 2.37mm, 2.47mm, 2.53mm, 4.61mm, 2.77mm, 2.92mm, 1.12mm, 1.32mm, 1.54mm, 1.78mm, 2.04mm, 4.30mm, 2.63mm, 2.96mm, 1.33mm, 3.67mm, 4.06mm, 2.50mm, 4.91mm, 1.41mm, 1.89mm, 4.36mm, and 2.90mm. The mass ratio of tungsten powder to epoxy resin in the epoxy-metal mixture used in the planar polymer metasurface 2 is 2.1:1.

[0112] It should be noted that the structural parameters of the above-mentioned planar polymer metasurface 2 are designed based on the incident frequency, the sound velocity of the polymer material, and the target sound energy focusing focal length. When the metasurface structure is made of other polymer materials for arbitrary frequencies and focusing, the sound energy focusing and bottle-shaped sound field can be reproduced under any circumstances simply by redesigning the thickness and width dimensions of each cross-section.

[0113] A planar polymer metasurface 2 is directly deposited onto the matching layer 16 of the partitioned electrode acoustic piezoelectric transducer 1 via imprinting, achieving device integration and phase modulation of the piezoelectrically excited mechanical vibration. The partitioned electrode 13 on the lower surface of the partitioned electrode acoustic piezoelectric transducer 1 can easily achieve dual functions of acoustic energy focusing and bottle-shaped sound field without additional active equipment or complex operation. The dual functions of acoustic energy focusing and bottle-shaped sound field can be switched simply by switching the phase of the input voltage signal of one of the channels.

[0114] Below, in conjunction with Figures 1-6 The dual-function implementation of the switchable dual-function acoustic metasurface device based on partitioned electrodes in the embodiments of the present invention will be described in detail.

[0115] Acoustic focusing: When a switchable dual-function acoustic metasurface device based on partitioned electrodes is used for acoustic focusing, the following steps are included:

[0116] S1: Based on Figures 1-3 First, two sinusoidal voltage signals with equal amplitude and same phase are input from the signal generator through wire 17 to the inner region electrode 131 and outer region electrode 132 of the lower surface partition electrode 13, serving as the positive terminal of the piezoelectric element. Interfaces 1 and 2 both input sinusoidal voltage signals with an amplitude of 50V and a phase of 0. The upper surface non-partition electrode 15 is directly grounded through the ground wire in wire 17, serving as the negative terminal of the piezoelectric element.

[0117] like Figure 4 As shown, based on the inverse piezoelectric effect, at any given time, the lead zirconate titanate piezoelectric ceramic sheet 14, polarized along the thickness direction, will generate a mechanical displacement along the thickness direction z under the action of the electric field generated by the partitioned electrode 13 and the non-partitioned electrode 15, which is consistent with the direction of the electric field. The sinusoidal mechanical vibration along the thickness direction is then coupled to the background medium water through the impedance matching layer 16 to generate a plane sound wave propagating along the z direction. Without phase modulation by the flat polymer metasurface 2 structure, a plane wave propagating along the z direction will be generated in the background water, and the sound pressure magnitude and phase are equal in the xoy plane at any z distance.

[0118] S2: Based on such Figure 1 , Figure 4 and Figure 6The planar polymer metasurface 2, directly deposited on the surface of the matching layer 16, modulates the phase of the mechanical vibrations coupled from the matching layer 16 based on impedance matching. This ensures that the phase at the surface of the planar polymer metasurface 2 in contact with the background medium is equal to the phase value Φ(x) designed according to the target acoustic energy focusing. i Therefore, the phase-modulated mechanical vibration excites a sound field from the interface position of the flat polymer metasurface 2, and the sound beams scattered by each cross-section block will be superimposed at the target position L=200 mm to achieve sound energy focusing.

[0119] Bottle-shaped sound field: When a switchable dual-function acoustic metasurface device based on partitioned electrodes is used for bottle-shaped sound field modulation, the following steps are included:

[0120] S1: Based on Figures 1-3 First, two sinusoidal voltage signals with equal amplitude and a phase difference of π are input from the signal generator via wire 17 to the inner region 131 and outer region 132 of the lower surface partition electrode 13 as the positive terminals of the piezoelectric element: interface 1 still inputs a sinusoidal voltage signal with an amplitude of 50V and a phase of 0, and interface 2 inputs a sinusoidal voltage signal with an amplitude of 50V and a phase of π. The upper surface non-partition electrode 15 is directly grounded through the ground wire in wire 17, serving as the negative terminal of the piezoelectric element. At this time, swapping the inputs of interfaces 1 and 2 does not affect the excitation sound field effect.

[0121] like Figure 5 As shown, when the voltage amplitudes input to the inner region electrode 131 and the outer region electrode 132 of the lower surface partitioned electrode 13 are the same, and their phases differ by π, based on the inverse piezoelectric effect, at any given moment, the inner region 131, the outer region 132, and the upper surface non-partitioned electrode 15 will generate two sinusoidal electric fields with a phase difference of π in the thickness direction. Under the excitation of these two electric fields, the lead zirconate titanate piezoelectric ceramic sheet 14 is also virtually divided into an inner piezoelectric region and an outer piezoelectric region. The piezoelectric sheets in the two regions will exhibit sinusoidal mechanical vibrations with a phase difference of π in the time dimension. Due to impedance matching, the sinusoidal mechanical vibration displacement will be coupled to the matching layer 16 and transmitted to the background medium, thereby exciting a sound field. In the time dimension, the matched layer 16 is also virtually divided into an inner region and an outer region, and the sinusoidal mechanical vibrations of the two regions also exhibit the same amplitude and a phase difference of π. In the absence of phase modulation by the non-planar polymer metasurface 2, the mechanical vibration coupled from the matching layer 16 to the background water will excite a plane sine wave propagating along the z direction, and the plane waves corresponding to the inner and outer regions on the xoy plane at any z distance will always maintain equal amplitude and phase difference of π.

[0122] S2: Based on such Figure 1 , Figure 4 and Figure 6Taking advantage of the impedance matching of the flat polymer metasurface 2 of the matching layer 16, the sinusoidal mechanical vibration transmitted from the matching layer 16 will be phase modulated. Each unit of the thickness change will produce a different phase delay for the sinusoidal mechanical vibration incident at each position, so that the phase in the interface region above the electrode 131 of the internal region of the partition electrode 13 on the interface between the flat polymer metasurface 2 and the background medium is still equal to the phase value φ designed according to the target acoustic energy focusing. i The phase within the interface region corresponding to the external region electrode 132 is equal to Φ(x). i Therefore, the phase-modulated mechanical vibration excites a sound beam from the interface between the flat polymer metasurface 2 and the background medium. Considered as a point sound source, the scattered sound beams at each cross-section can realize a bottle-shaped wave field at the target sound energy focusing position.

[0123] like Figure 5 As shown, when the mechanical vibration excited by the partitioned electrode acoustic piezoelectric transducer 1 is coupled from the matching layer 16 into the planar polymer metasurface 2, due to the different thicknesses of each unit of the planar polymer metasurface 2, the phases of each unit are different at the interface with water. Furthermore, the phase on the plane corresponding to the outer region electrode at the interface between the planar polymer metasurface 2 and water is equal to the phase value Φ(x) designed according to the target acoustic energy focusing. i Adding π, after being modulated by two cross-sectional blocks of a flat polymer metasurface, the incident sound from each cross-sectional block at the interface can be regarded as the scattering of a point sound source. At this time, the scattered sound beam realizes the cavity capture region of the bottle-shaped sound field at the focal length L=200 mm where the target sound energy is focused.

[0124] It should be noted that the present invention provides a switchable dual-function acoustic metasurface device based on partitioned electrodes for achieving both acoustic energy focusing and bottle-shaped sound field functionality. This device allows for easy switching between acoustic energy focusing and bottle-shaped sound fields without the need for external active equipment, simply by switching the phase of one of the input voltage interfaces. Furthermore, the focal point of the acoustic energy focusing and the cavity location for particle trapping in the bottle-shaped sound field are the same before and after the switching, both occurring at the designed target focal point L.

[0125] As can be seen from this implementation, the present invention combines a partitioned electrode piezoelectric transducer and a planar polymer metasurface. By simply switching the input voltage of one of the partitioned electrode regions, the mechanical vibration of the piezoelectric acoustic transducer can be changed. In turn, the planar metasurface enables dual-function switching between a focused sound field and a bottle-shaped sound field, thus fulfilling the dual functions of sound energy focusing and "acoustic tweezers".

[0126] Meanwhile, this invention can directly imprint a flat polymer metasurface onto a piezoelectric ceramic transducer, improving acoustic field coupling efficiency, with a thinner thickness and good feasibility.

[0127] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0128] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0129] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The switchable dual-function acoustic metasurface device based on partitioned electrodes proposed in the present invention for realizing sound energy focusing and bottle-shaped sound field can not only be used in the flat polymer metasurface of tungsten metal and epoxy resin mixture described in the present invention, but can also be replaced with any metasurface for focusing, so as to realize the dual function of sound energy focusing and bottle-shaped sound field in a single device.

Claims

1. A switchable dual-function acoustic metasurface device based on partitioned electrodes, characterized in that: The device is placed in a background medium environment. The device includes a partitioned electrode acoustic piezoelectric transducer (1) and a flat polymer metasurface (2). The partitioned electrode acoustic piezoelectric transducer (1) includes a lower surface partitioned electrode (13), a lead zirconate titanate piezoelectric ceramic sheet (14), an upper surface non-partitioned electrode (15), and a matching layer (16) stacked sequentially from bottom to top. The flat polymer metasurface (2) is arranged on the upper surface of the matching layer (16). The lower surface partitioned electrode (13) is divided into two parts: a central internal region electrode (131) and a peripheral external region electrode (132). The upper surface non-partitioned electrode (15) is a single electrode. The flat polymer metasurface (2) is formed by rotating radial cross-sections with different thicknesses. The radial cross-sections are divided into multiple cross-sectional blocks from the center outward with a fixed radial length W0. The fixed radial length W0 is much smaller than the working wavelength. The thickness H of each cross-sectional block is... i Adjust the settings according to the modulated phase difference; In the flat polymer metasurface (2), the thickness dimensions of each cross-sectional block are set as follows: First, obtain the value of each cross-section block as a function of distance x using the following formula. i Phase changes: Φ(x i )=k0(mλ+(x i 2 +L 2 ) 1 / 2 -L) k0=2πf / c1 In the formula, Φ(x) i ) represents the distance x to the center of the flat polymer metasurface (2). i The phase of the cross-section block, x i Let i = 1, 2, 3, ..., n, where i represents the ordinal number of the cross-section and n represents the total number of cross-sections; L represents the focal length of the flat polymer metasurface (2); k0 represents the wave number in the background medium; f represents the operating frequency f of the flat polymer metasurface (2); c1 represents the sound velocity in the background medium; m is the matching coefficient; and λ is the wavelength. Set the thickness dimension H of each cross-section block according to the following formula. i : H i =(Φ(x i )c1c2) / (2πf(c1-c2)) c2=(E(1-σ) / (ρ(1+σ)(1-2σ))) 1 / 2 In the formula, c2 represents the sound velocity in the flat polymer metasurface (2) material; E is Young's modulus, σ is Poisson's ratio, and ρ is the density of the polymer metasurface.

2. The switchable dual-function acoustic metasurface device based on partitioned electrodes according to claim 1, characterized in that: The partitioned electrode acoustic piezoelectric transducer (1) further includes a housing (17) and a backing (12). The upper end of the housing (17) is open, the bottom end of the lower surface partitioned electrode (13) is embedded in the opening, and the backing (12) is provided in the cavity formed between the lower surface partitioned electrode (13) and the housing (17).

3. The switchable dual-function acoustic metasurface device based on partitioned electrodes according to claim 2, characterized in that: The backing (12) is made of sound-absorbing material.

4. The switchable dual-function acoustic metasurface device based on partitioned electrodes according to claim 1, characterized in that: The internal region electrode (131), the external region electrode (132), and the upper surface non-partitioned electrode (15) are respectively connected to the external two-channel voltage signal generator via their respective wires (11).

5. The switchable dual-function acoustic metasurface device based on partitioned electrodes according to claim 1, characterized in that: The materials of the flat polymer metasurface (2) and the matching layer (16) are both mixed materials composed of metal powder and polymer. The proportions of metal powder and polymer are different between the two, and the relative amount of metal powder added in the flat polymer metasurface (2) is less than the relative amount of metal powder added in the matching layer (16).

6. A sound field control method applied to the switchable dual-function acoustic metasurface device according to any one of claims 1-5, characterized in that: The switchable dual-function acoustic metasurface device is placed in a liquid background medium environment. Independent sinusoidal voltage signals are input to the inner region electrode (131) and outer region electrode (132) of the lower surface partition electrode (13). Different sound field controls are achieved by adjusting the two sinusoidal voltage signals input to the inner region electrode (131) and outer region electrode (132).

7. The sound field control method according to claim 6, characterized in that: Different sound field controls are achieved by adjusting the phase difference of two sinusoidal voltage signals input to the internal region electrode (131) and the external region electrode (132), respectively. When the phase difference between the two sinusoidal voltage signals input to the inner region electrode (131) and the outer region electrode (132) is 0, the lead zirconate titanate piezoelectric ceramic sheet (14) generates sinusoidal mechanical vibration along the thickness direction under the electric field of the lower surface partition electrode (13) and the upper surface non-partition electrode (15). The sinusoidal mechanical vibration is coupled into the liquid through the matching layer (16) and the flat polymer metasurface (2), and the flat polymer metasurface (2) modulates the phase of the incident sinusoidal mechanical vibration, thereby forming acoustic energy focusing at the target position. When the phase difference of two sinusoidal voltage signals is π when the inner region electrode (131) and the outer region electrode (132) are respectively input, the lead zirconate titanate piezoelectric ceramic sheet (14) generates sinusoidal mechanical vibration with the same amplitude and a phase difference of π along the thickness direction under the electric field action of the lower surface partition electrode (13) and the upper surface non-partition electrode (15). The sinusoidal mechanical vibration is coupled into the liquid through the matching layer (16) and the flat polymer metasurface (2), and the flat polymer metasurface (2) modulates the phase of the incident mechanical vibration, thereby forming a bottle-shaped sound field at the target position.

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