CN116524893A - Switchable dual-function acoustic super-surface device and method based on partition electrode - Google Patents
Switchable dual-function acoustic super-surface device and method based on partition electrode Download PDFInfo
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- 229910052451 lead zirconate titanate Inorganic materials 0.000 claims abstract description 73
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 claims abstract description 66
- 239000000919 ceramic Substances 0.000 claims abstract description 58
- 230000002093 peripheral effect Effects 0.000 claims abstract description 3
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- 229910052751 metal Inorganic materials 0.000 claims description 24
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Classifications
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/36—Devices for manipulating acoustic surface waves
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/18—Methods or devices for transmitting, conducting or directing sound
- G10K11/26—Sound-focusing or directing, e.g. scanning
- G10K11/34—Sound-focusing or directing, e.g. scanning using electrical steering of transducer arrays, e.g. beam steering
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
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- Acoustics & Sound (AREA)
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Abstract
The invention discloses a switchable dual-function acoustic super-surface device and method based on partition electrodes. The piezoelectric transducer comprises a partition electrode acoustic piezoelectric transducer and a planar polymer super-surface, wherein the partition electrode acoustic piezoelectric transducer comprises a lower surface partition electrode, a lead zirconate titanate piezoelectric ceramic sheet, an upper surface non-partition electrode and a matching layer which are sequentially stacked from bottom to top; the lower surface partition electrode is divided into two partial electrodes of a central inner region electrode and a peripheral outer region electrode which are insulated from each other, and the upper surface non-partition electrode is a whole electrode. The invention can realize the dual-function switching of the focusing sound field and the bottle-shaped sound field by switching the input voltage of one area electrode of the partition electrode under the structure, so that the piezoelectric ceramic transducer has the dual-function requirements of sound energy focusing and 'acoustic tweezers', and the flat plate type polymer super surface is directly stamped on the piezoelectric ceramic transducer, thereby improving the coupling efficiency of the sound field, and having thinner thickness and good price realizability.
Description
Technical Field
The invention relates to an acoustic generating device, in particular to a switchable dual-function acoustic super-surface device based on partition electrodes.
Background
The acoustic super surface is designed by analogy to the optical super surface, based on the generalized snell's law, researchers propose to design the acoustic super surface with a phase gradient, and a series of artificial microstructures with sub-wavelength dimensions are combined in a specific manner through artificial design to realize special regulation and control on transmitted or reflected sound waves, such as: abnormal transmission, negative refraction, plane wave focusing, self-bending acoustic field, etc. Compared with the acoustic metamaterial, the thickness of the acoustic metamaterial is smaller than the wavelength of the working frequency, the small-size control of a large wave field is achieved, the advantages of relatively low manufacturing loss, small volume, thin thickness and the like are achieved, and the acoustic metamaterial has great research value and wide application prospect in the field of acoustic research, so that great attention is paid to the scientific community and the engineering community.
Along with miniaturization and precision of mechanical processing technology, the development of miniaturization, integration and multifunction of the acoustic super surface is advanced, most of the acoustic super surfaces designed at present are composed of transmission type frequency selective structural units with similar topological structures, and a plurality of single super surface units with different phase modulation sizes are assembled together through simple arrays, so that the array structures are required to be arranged and assembled into a whole in advance before actual use, and the design efficiency is low. Meanwhile, most of the current ultra-surface units for phase adjustment are cavity structures based on resonance or bending structures based on sound path difference, and the ultra-surface structures formed by the arrays have thicker thickness and are difficult to process. Therefore, the invention uses the polymer with thinner thickness as the acoustic plane superlens, and the phase modulation is realized by changing the unit height of the sound field at each position, and the structure can be realized by using 3D printing, so that the method is simple and has higher precision; meanwhile, the ultra-surface of the flat polymer can realize larger sound transmittance, and can effectively improve the energy of the modulated sound field.
According to the piezoelectric effect and vibration coupling theory, the most piezoelectric materials currently used in the market are lead zirconate titanate materials (longitudinal coupling coefficient K t =0.47, dielectric constant η=900), lead zirconate titanate belongs to a binary piezoelectric ceramic, and the polarized lead zirconate titanate has piezoelectricity, and at this time, a sensing detection function is realized through mutual conversion between force and electricity; lead zirconate titanate polarized along thickness direction is formed in electric field formed by upper and lower surface electrodesThe excitation is used for generating a longitudinal wave sound field, the input excitation of a sinusoidal electric signal is used for generating continuous sinusoidal mechanical vibration, the continuous sinusoidal mechanical vibration is coupled into a target medium through a matching layer, and continuous ultrasonic waves are generated; based on a three-medium theory, the acoustic impedance matching flat polymer super surface can be used for carrying out phase modulation on mechanical vibration of the probe surface and then transmitting the mechanical vibration into a background field to realize a target complex sound field. But currently most acoustic supersurfaces operate primarily in a single mode of transmission or reflection for the single function of abnormal deflection of the sound field, acoustic stealth or focusing of acoustic energy.
Therefore, the currently reported super-surface device mainly has single working mode, needs a plurality of groups of super-unit compound or multilayer asymmetric structures to realize different functions, and is less directly integrated with a conventional commercial probe.
Disclosure of Invention
Aiming at the defects of insufficient coupling and difficult assembly between the conventional probe and the ultrasonic surface lens, complex structure, large size in the thickness direction and single working mode of the conventional ultrasonic surface, the invention provides a partition electrode-based switchable dual-function acoustic ultrasonic surface device for realizing acoustic energy focusing and bottle-shaped acoustic field switching, the planar flat plate type polymer ultrasonic surface is directly deposited on a piezoelectric ceramic transducer of a partition electrode, no additional equipment is needed, and dual-function switching between a focusing acoustic field and a bottle-shaped acoustic field at the same target position can be realized only by changing the phase difference of voltage signals of two input channels.
The device mainly comprises two insulated area electrodes which are formed by cooling and depositing liquid silver on the lower surface of a lead zirconate titanate piezoelectric ceramic plate, wherein the electrodes are called partition electrodes, and an excitation signal source is externally connected through a lead wire to serve as the positive electrode of a piezoelectric element. The upper surface of the lead zirconate titanate piezoelectric ceramic sheet is also cooled and deposited with liquid silver to form an electrode which is not partitioned, and the electrode is directly grounded to serve as a negative electrode of the piezoelectric element after being led out through a lead; under the actual operation condition, the dual-function switching of the sound energy focusing and the bottle-shaped sound field can be realized by only changing the phase difference of the input voltages of the two areas of the partition electrode.
The invention adopts the technical scheme that:
1. switchable dual-function acoustic subsurface device based on segmented electrodes:
the device is placed in a background medium environment, the device comprises a partition electrode acoustic piezoelectric transducer and a planar polymer super surface, the partition electrode acoustic piezoelectric transducer comprises a lower surface partition electrode, a lead zirconate titanate piezoelectric ceramic plate, an upper surface non-partition electrode and a matching layer which are sequentially stacked from bottom to top, and the planar polymer super surface is arranged on the upper surface of the matching layer;
the lower surface partition electrode is divided into two partial electrodes of an inner region electrode in the center and an outer region electrode in the periphery, and the upper surface non-partition electrode is a whole electrode.
The partition electrode acoustic piezoelectric transducer also comprises a shell and a backing, wherein the upper end of the shell is provided with an opening, the bottom end of the partition electrode on the lower surface is embedded in the opening, and the backing is arranged in an inner cavity formed between the partition electrode on the lower surface and the shell.
The back lining adopts sound absorbing material.
The invention innovatively sets the lower surface electrode formed by the two partial electrodes, further applies different phase control on the two partial electrodes of the lower surface electrode, further skillfully realizes two sound field effects, namely, dual-function switching, and can realize the switching of two sound field functions simultaneously without replacing the super surface of the flat polymer.
The inner area electrode, the outer area electrode and the upper surface non-partition electrode are respectively connected to an external two-channel voltage signal generator through respective leads.
The material of the flat polymer super surface and the material of the matching layer are mixed materials composed of metal powder and polymer, the proportion of the metal powder and the polymer is different, and the relative addition amount of the metal powder in the flat polymer super surface is smaller than that of the metal powder in the matching layer.
The planar polymer super surface is formed by rotating radial cross sections with different thickness distributionsFormed by rotation, the radial section is fixed to a radial length W from the center outwards 0 Divided into a plurality of section blocks, the fixed radial length W 0 All are far smaller than the working wavelength, and the thickness dimension H of each section block i And adjusting and setting according to the modulated phase difference.
In the flat polymer super surface, the thickness dimension of each section block is set as follows:
the distance x of each section block is obtained according to the following formula i Phase of change:
Φ(x i )＝k 0 (mλ+(x i 2 +L 2 ) 1/2 -L)
k 0 ＝2πf/c 1
in which phi (x i ) Representing a distance x from the center of the planar polymer supersurface i Phase of cross-sectional block x i Representing the distance of each section block from the center of the planar polymer supersurface, i=1, 2,3, … n, i representing the ordinal number of the section blocks, n representing the total number of section blocks, L representing the focal length of the planar polymer supersurface; k (k) 0 Representing wave number in background medium, i.e. the working environment of the probe, f represents working frequency f, c of the super surface of the flat polymer 1 Sound velocity for background medium; m is a matching coefficient, is any positive integer, specifically any integer, and can be directly taken as 0;
the thickness dimension H of each section block is set according to the following formula i ：
H i ＝(Φ(x i )c 1 c 2 )/(2πf(c 1 -c 2 ))
c 2 ＝(E(1-σ)/(ρ(1+σ)(1-2σ))) 1/2
Wherein, c 2 Representing the speed of sound in a planar polymeric subsurface material; e is Young's modulus, σ is Poisson's ratio, ρ is the density of the polymer supersurface.
2. The sound field control method of the switchable dual-function acoustic super-surface device based on the partition electrode comprises the following steps:
the switchable dual-function acoustic super-surface device is placed in a liquid background medium environment, the upper surface non-partition electrode is kept grounded, independent sinusoidal voltage signals are respectively input to the inner area electrode and the outer area electrode of the lower surface partition electrode, and two paths of sinusoidal voltage signals respectively input to the inner area electrode and the outer area electrode are adjusted to realize different sound field control.
Different sound field control is realized by adjusting the phase difference of two paths of sine voltage signals respectively input to the inner area electrode and the outer area electrode:
when the phase difference of two paths of sinusoidal voltage signals respectively input to the inner area electrode and the outer area electrode is 0, the lead zirconate titanate piezoelectric ceramic sheet integrally generates sinusoidal mechanical vibration along the thickness direction under the action of electric fields of the lower surface partition electrode and the upper surface non-partition electrode, the sinusoidal mechanical vibration is coupled into liquid of a background medium through the matching layer and the planar polymer super surface, and the planar polymer super surface carries out phase modulation on the incident sinusoidal mechanical vibration, so that acoustic energy Focusing beam is formed at a target position;
when the phase difference of two paths of sine voltage signals respectively input to the inner area electrode and the outer area electrode is pi, the lead zirconate titanate piezoelectric ceramic sheet integrally generates the same amplitude along the thickness direction under the action of the electric fields of the lower surface partition electrode and the upper surface non-partition electrode, sinusoidal mechanical vibration with pi phase difference is generated, the sinusoidal mechanical vibration is coupled into liquid of a background medium through the matching layer and the planar polymer super surface, and the planar polymer super surface carries out phase modulation on the incident mechanical vibration, so that a bottle-shaped sound field foam beam is formed at a target position.
The mechanical vibrations of both regions are sinusoidal, where the phase difference pi refers to pi on a time scale.
Focusing of acoustic energy:
the two area electrodes of the partitioned electrode on the lower surface are input with sine voltage signals with non-zero amplitude and phase equal through leads, and the non-partitioned electrode on the upper surface is grounded.
At this time, the non-zero voltage lower surface partition electrode and the zero voltage upper surface non-partition electrode form an electric field along the thickness direction together, and the inner area and the outer area in the lower surface partition electrode have the same phase, so that the directions of the electric fields generated at the positions corresponding to the inner area and the outer area in the lower surface partition electrode are the same at any time.
Based on the inverse piezoelectric effect, the uniform electric field along the thickness direction can lead the positions corresponding to the inner area and the outer area of the lead zirconate titanate ceramic piezoelectric sheet to generate the same amplitude along the thickness direction, and the same mechanical displacement forms sinusoidal mechanical vibration, so that the sinusoidal mechanical vibration is transmitted to the liquid of the background medium after being coupled and modulated through the matching layer and the planar polymer super surface, and further the focusing modulation of the acoustic energy at the target position is realized.
Bottle-shaped sound field
The two area electrodes of the partitioned electrode on the lower surface are input with non-zero sine voltage signals with equal amplitude and phase difference through leads, and the non-partitioned electrode on the upper surface is grounded.
At this time, the non-zero voltage lower surface partition electrode and the zero voltage upper surface non-partition electrode form an electric field along the thickness direction together, and the directions of the electric fields generated at the positions corresponding to the inner area and the outer area in the lower surface partition electrode are opposite at any moment because the phase difference pi between the inner area and the outer area in the lower surface partition electrode.
Based on the inverse piezoelectric effect, under the action of electric fields with opposite directions, the lead zirconate titanate ceramic piezoelectric sheet is virtually divided into two parts: an inner ring region and an outer ring region; at any moment, the lead zirconate titanate ceramic piezoelectric plates in the inner ring area and the outer ring area generate the same amplitude along the thickness direction, and the mechanical displacement in opposite directions forms sinusoidal mechanical vibration, so that the sinusoidal mechanical vibration with the phase difference pi in the two areas is transmitted to liquid of a background medium after being transmitted and modulated by the matching layer and the planar polymer super surface, and bottle-shaped sound field modulation at a target position is realized. And an acoustic hydrazine is arranged at the lower part of the bottle-shaped sound field to capture the particles of the acoustic tweezers.
In the implementation, the dual-function switching of the sound energy focusing sound field or the bottle-shaped sound field can be realized without additional active equipment by switching the phase difference of the voltage signals input to the partition electrodes.
For the operation of focusing the acoustic energy, only two sinusoidal voltages with the same input amplitude and the same phase are required to be ensured; for the operation of far-field bottle-shaped sound field, the input amplitude is only required to be ensured to be the same, and the phase difference pi sinusoidal voltage is required; in actual operation, the switching of the dual-function sound field can be realized by simply switching the phase of any input voltage signal.
The device realizes the focusing of acoustic energy of any focal length or the capture of the particles of the acoustic tweezers of a bottle-shaped sound field under any frequency by designing the size of the super-surface section block of the flat polymer. In particular, if the same switchable dual-function acoustic super-surface device is used to switch to achieve dual functions of focusing acoustic energy or bottle-shaped acoustic field, the focusing position of acoustic energy is the same as the capturing position of particles of the acoustic tweezers.
According to the invention, the integrated packaging of the ultrasonic surface and the conventional probe is realized by the partition arrangement of the lower surface electrode and the direct deposition of the impedance matching layer and the planar polymer ultrasonic surface, and meanwhile, the sound field switching of the Focusing and the lattice beam is realized in real time by directly switching the phase delay of one path of voltage signal, so that the sound field modulation function of the device is greatly improved, and the operation is simple and convenient, and the cost is low.
The piezoelectric ceramic transducer with the surface deposited as the partition electrode and the planar polymer super surface are combined together, and the dual-function switching of focusing and bottle-shaped sound field is realized by changing the input voltage of the partition electrode. The electrode deposited on the upper surface of the ceramic piezoelectric sheet is divided into two areas, and two input voltage signals are mutually and independently connected, when the phase difference of the input signals of the two electrode areas is changed, the vibration condition of the lead zirconate titanate piezoelectric sheet can be changed, and after excited mechanical vibration is coupled by the super surface of the flat polymer deposited on the surface, the sound field focusing and bottle-shaped sound field switching of a background area can be realized; therefore, through the switchable dual-function acoustic ultrasonic surface device with the partition electrodes, a detector can realize the focusing of acoustic energy on the target position of the excitation plane incident wave of the conventional piezoelectric probe, and can also realize the distribution of bottle-shaped acoustic fields through the bottle-shaped acoustic fields on the target position, so that the particle capture of the acoustic forceps is realized.
The flat plate type polymer super surface is made of polymer materials, acoustic impedance of the flat plate type polymer super surface is matched with that of a matching layer of a conventional probe, and sound transmission efficiency is high; under the condition that the structure of the switchable dual-function acoustic super-surface device of the partition electrode is kept unchanged, the dual-function switching of the functions of acoustic energy focusing and acoustic forceps particle capturing can be realized at the same position through simple switching of input voltage.
In addition, the upper surface of the flat polymer super surface is of an array structure with concave-convex change, and the thickness change units have the same width and different thicknesses; the dual-function acoustic super-surface devices of the partitioned electrodes are symmetrical with respect to the central axis; the planar polymer super surface of the dual-function acoustic super surface device of the partition electrode can carry out phase modulation on a mechanical vibration signal excited by the piezoelectric transducer, and is further coupled to a background field to realize sound field regulation.
The device has the following beneficial effects:
(1) The invention can realize the dual functions of sound energy focusing and bottle-shaped sound field by simply switching the phase difference of two paths of input voltage signals by utilizing the piezoelectric transducer of the partition electrode and the planar polymer ultrasonic surface, firstly, when two paths of sine voltage signals with the same amplitude and the same phase are input, the lead zirconate titanate piezoelectric element generates sine mechanical vibration with the same amplitude and the same phase, and can realize the sound energy focusing at the target position after being coupled and phase modulated by the matching layer and the planar polymer ultrasonic surface.
Meanwhile, when two paths of sine voltage signals with the same amplitude and pi phase difference are input, the corresponding parts of the voltages of the inner area and the outer area of the lead zirconate titanate piezoelectric element generate sine mechanical vibration with the same amplitude and pi phase difference, and after the matching layer and the planar polymer super-surface are coupled and phase modulated, a bottle-shaped sound field at a target position can be realized for particle capture.
(2) The flat polymer super surface used in the invention has the advantages of thinner thickness and low price, and realizes the integration with the acoustic transducer by directly imprinting on the surface of the matching layer, and the acoustic field transmittance is high because of the impedance matching and the full coupling.
Meanwhile, the planar polymer super surface does not carry out phase modulation based on the resonance principle, so that broadband acoustic focusing and particle capturing can be realized. The assembled and integrated dual-function acoustic ultrasonic surface device can realize sound field switching without additional accessories, and can realize sound field real-time switching by only changing the phase value of one path of input electric field, thereby having high operability.
Drawings
In order to more clearly illustrate the embodiments of the present invention and the design thereof, the drawings required for the embodiments will be briefly described below. The drawings in the following description are only some of the embodiments of the present invention and other drawings may be made by those skilled in the art without the exercise of inventive faculty.
FIG. 1 is a schematic partial cross-sectional view of a device according to example 1 of the present invention;
FIG. 2 is a semi-sectional view and a size representation of a segmented electrode acoustic piezoelectric transducer 1 of embodiment 1 of the present invention;
FIGS. 3 and 4 are schematic views of piezoelectric elements of the switchable dual function acoustic super surface device of the present invention based on segmented electrodes, comprising a lower surface segmented electrode 13, a lead zirconate titanate piezoelectric ceramic sheet 14, and an upper surface non-segmented electrode 15; wherein fig. 3 (a) shows a three-dimensional view of a circular electrode, (b) shows an upper surface electrode view of a circular electrode, (c) shows a lower surface electrode view of a circular electrode, fig. 4 (a) shows a three-dimensional view of a square electrode, (b) shows an upper surface electrode view of a square electrode, and (c) shows a lower surface electrode view of a square electrode;
FIGS. 5 and 6 are schematic views of a planar polymer supersurface 2 of the present invention; wherein (a) and (b) represent three-dimensional schematic views of circular and square planar polymer supersurfaces and (b) represents a cross-sectional view of the planar polymer supersurface
Fig. 7 is a schematic diagram showing the mechanical vibration distribution of the lead zirconate titanate piezoelectric ceramic sheet 14 and the distribution of sound field in the background aqueous medium excited without the phase modulation of the planar polymer supersurface 2 when the phase of the input voltage signal corresponding to the external region electrode 132 is switched in examples 1 and 2 of the present invention; wherein (a) represents the mechanical vibration of the piezoelectric ceramic plate and the phase distribution diagram of the sound field in the water area when the voltage signals with the same phase are excited by the inner area and the outer area, and (b) represents the mechanical vibration of the piezoelectric ceramic plate and the phase distribution diagram of the sound field in the water area when the voltage signals with the same phase difference pi are excited by the inner area and the outer area;
FIG. 8 is a schematic diagram showing the distribution of sound field in the background aqueous medium excited by the phase modulation of the planar polymer supersurface 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; wherein (a) the distribution diagram of the sound field in the water area when the internal area and the external area excite the voltage signals with the same phase, and (b) the distribution diagram of the sound field in the water area when the internal area and the external area excite the voltage signals with the same phase different from pi.
Reference numerals illustrate: the piezoelectric acoustic transducer comprises a partition electrode acoustic piezoelectric transducer 1, a lead 11, a backing 12, a lower surface partition electrode 13, an inner area electrode 131, an outer area electrode 132, a lead zirconate titanate piezoelectric ceramic sheet 14, an upper surface non-partition electrode 15, a matching layer 16, a shell 17 and a flat plate type polymer super surface 2.
Detailed Description
In order that those skilled in the art will better understand the technical solution of the present invention and will be able to implement it, the following detailed description of the present invention will be made with reference to the accompanying drawings and specific embodiments. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be understood that the terms "middle," "upper," "lower," "left," "right," "transverse," "longitudinal," "horizontal," "vertical," "axial," "mirror," "length," "width," "thickness," etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the technical solutions of the present invention and to simplify the description, and do not indicate or imply that the apparatus or device in question must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. In the description of the present invention, the meaning of "a plurality" is two or more unless otherwise indicated, and will not be described in detail herein.
As shown in fig. 1, the piezoelectric transducer comprises a partition electrode acoustic piezoelectric transducer 1 and a flat polymer super surface 2, wherein the flat polymer super surface 2 is covered on the partition electrode acoustic piezoelectric transducer 1; the partition electrode acoustic piezoelectric transducer 1 comprises a lower surface partition electrode 13, a lead zirconate titanate piezoelectric ceramic plate 14, an upper surface non-partition electrode 15 and a matching layer 16 which are sequentially stacked from bottom to top, wherein a flat plate type polymer super surface 2 is arranged on the upper surface of the matching layer 16;
The lower surface partition electrode 13 is divided into two partial electrodes of a central inner region electrode 131 and a peripheral outer region electrode 132 insulated from each other, and the upper surface non-partition electrode 15 is a monolithic electrode.
In specific implementation, the partition 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 partition electrode 13 is embedded in the opening, and the backing 12 is disposed in an inner cavity formed between the lower surface partition electrode 13 and the housing 17.
The backing 12 is made of an acoustic absorbing material for absorbing acoustic waves to prevent the acoustic waves from passing through the side of the housing 17, and may be made of silica gel. In the concrete implementation, the back lining is made of a silica gel material, and liquid silica gel is filled from the reserved opening of the shell and cured at room temperature, so that the effect of absorbing vibration of the back lining is realized, and the sealing effect is realized.
Specifically, the partition electrode 13 and the non-partition electrode 15 are obtained by respectively depositing liquid silver on the upper and lower surfaces of a lead zirconate titanate ceramic sheet by cooling; the backing is deposited on the surface of the partition electrode 13 for absorbing mechanical vibration, and the matching layer 16 selects a polymer mixed with tungsten metal and epoxy resin which are matched with lead zirconate titanate material in impedance for coupling and transmitting the mechanical vibration; the planar polymeric supersurface 2 is directly imprinted on the matching layer 16 using a polymeric material that is a metal polymer of an epoxy substrate that is impedance matched to the matching layer and water.
The lower surface partition electrode 13 and the upper surface non-partition electrode 15 are formed by uniformly depositing liquid silver on both side surfaces of the lead zirconate titanate piezoelectric ceramic sheet 14 by direct cooling. The partition electrode is used as a positive electrode of the lead zirconate titanate piezoelectric element, and the non-partition electrode is used as a negative electrode of the lead zirconate titanate piezoelectric element.
The inner area electrode 131, the outer area electrode 132 and the upper surface non-partitioned electrode 15 are respectively connected to an external two-channel voltage signal generator through respective leads 11, and correspond to two independent excitation signal sources to jointly form the positive electrode of the piezoelectric transducer device. Specifically, the inner region electrode 131 and the outer region electrode 132 are connected to the positive electrode, and the upper surface non-partitioned electrode 15 is connected to the negative electrode.
The whole lower surface partition electrode 13 is consistent with the shape of the lead zirconate titanate piezoelectric ceramic sheet and serves as the positive electrode of the lead zirconate titanate piezoelectric ceramic sheet. The upper surface non-partitioned electrode 15 is a single-area electrode, the shape of which is consistent with the shape of the lead zirconate titanate piezoelectric ceramic sheet and slightly smaller than the size thereof, and is used as the negative electrode of the lead zirconate titanate piezoelectric ceramic sheet.
For the lower surface-divided electrode 13, it is deposited directly on the lower surface of the lead zirconate titanate piezoelectric ceramic sheet by means of cooling the liquid silver, as two areas insulated from each other: an inner region and an outer region. The shape of the two-region electrode is related to the lead zirconate titanate piezoelectric sheet, and can be round or square: for the piezoelectric sheet with a circular section, the shape of the two-area electrode is concentric circular and annular; for a piezoelectric sheet of square cross section, the shape of the two-region electrode is one square and one square annular region.
For the upper surface non-partition electrode 15, the electrode is directly deposited on the upper surface of the lead zirconate titanate piezoelectric ceramic sheet by cooling liquid silver, and is directly deposited into a single communication area, and the shape of the electrode area is consistent with that of the lead zirconate titanate piezoelectric sheet. In order to facilitate the deposition of a subsequent matching layer and a super surface, the non-partitioned electrode is turned over to one side of the partitioned electrode of the lead zirconate titanate piezoelectric ceramic element, and is directly grounded as a negative electrode of the piezoelectric transducer device after being led out through a lead.
The flat polymer super surface 2, the partition electrode 13 and the non-partition electrode 15 with the thickness being changed are symmetrically distributed at the center of the lead zirconate titanate piezoelectric sheet 14; meanwhile, the shape of the planar polymer supersurface of varying thickness is related to the shape of the lead zirconate titanate piezoelectric sheet 14: if the lead zirconate titanate piezoelectric sheet 14 is round, the cross section block of the flat polymer super surface 2 is a circular ring structure; if the lead zirconate titanate piezoelectric sheet 14 used at this time is square, the cross-sectional block of the flat polymer supersurface 2 at this time has a rectangular annular structure.
And the maximum sizes of the outer edges of the partitioned electrode and the non-partitioned electrode are the same, and the thicknesses of the electrodes are the same and uniform.
Thickness H of lead zirconate titanate piezoelectric ceramic element 14 PZT In relation to the excitation frequency f, the thickness at which the characteristic mode is generated is selected for achieving resonance at the characteristic frequency at this thickness.
Lead zirconate titanate piezoelectric sheets for completing the deposition of the partition electrodes and the non-partition electrodes and connecting wires are directly assembled in a transducer shell for 3D printing, the transducer shell and a piezoelectric element are in transition fit, one side of the partition electrode of the piezoelectric element is downwards installed and positioned through a limiting platform, and the distance between one side of the partition electrode and the bottom of the polymer shell is ensured to be kept at a distance of five times of wavelength for pouring backing.
Meanwhile, one side of the non-partition electrode of the piezoelectric element after positioning is still a certain distance from the upper surface of the transducer shell, the distance is just equal to the thickness of the matching layer, and three wires for connecting the partition electrode and the non-partition electrode are led out from a hole reserved at the bottom of the shell to form two voltage signal input interfaces.
The switchable dual-function acoustic ultra-surface device emits sound waves when placed in a liquid environment.
The materials of the flat polymer super surface 2 and the matching layer 16 are mixed materials mainly composed of metal powder and polymer, the proportion of the metal powder and the polymer is different, and the relative addition amount of the metal powder in the flat polymer super surface 2 is smaller than that of the metal powder in the matching layer 16.
The metal powder is tungsten powder and the polymer is epoxy resin polymer.
In a specific implementation, the matching layer 16 is made of a polymer material formed by fully mixing tungsten powder and epoxy resin polymer according to the mass ratio m 1, and is directly deposited on the surface of the non-partitioned electrode in a manner of extrusion or spin coating, and the thickness of the matching layer is about 1/4 of the wavelength of the target frequency.
The flat polymer super surface 2 is a polymer material prepared by fully mixing tungsten powder and epoxy resin material according to the mass ratio n:1, wherein m is more than n, and the flat polymer super surface is directly stamped on the surface of the matching layer in a cooling and demoulding mode, so that the assembly between the piezoelectric transducer of the partition electrode and the flat polymer super surface is completed, and the integration of the device is realized.
In specific implementation, the preparation material of the matching layer 16 is a mixed material of metal tungsten powder and polymer, which are matched with the impedance of the lead zirconate titanate piezoelectric ceramic sheet and the water environment in the working wave band, and the matching layer is prepared by directly depositing the material on the surface of a non-partitioned electrode through extrusion or spin coating, wherein the shape and the size of the material are consistent with those of the lead zirconate titanate piezoelectric ceramic sheet.
The flat plate type polymer super surface 2 is made of metal powder and polymer mixed materials which are matched with the matching layer and the water environment impedance in the working wave band, and is directly deposited on the surface of the matching layer 16 for assembly in an embossing mode, so that the integral sealing of the whole dual-function acoustic super surface is realized.
The invention sets the materials of the flat polymer super surface 2 and the matching layer 16 which are similar in substances but only different in proportion, so that the materials of the flat polymer super surface 2 and the matching layer 16 are close to each other, the complete matching of acoustic impedance can be better realized, the preparation can be more convenient, and the imprinting is convenient to integrate.
The flat polymer super surface 2 is a rotating member and is formed by rotating radial sections with different thickness distribution, wherein the radial sections are outward from the center to fix the radial length W 0 Divided into a plurality of section blocks, each section block having a width of a fixed radial length W 0 Fixed radial length W 0 All are far smaller than the working wavelength, and the thickness dimension H of each section block i And adjusting and setting according to the modulated phase difference.
The flat polymer super surface 2 with the thickness changed by embossing is used for modulating the mechanical vibration excited by the piezoelectric transducer, so that the focusing of sound energy or a bottle-shaped sound field is realized.
Thickness dimension H of each section block in planar polymer supersurface 2 i For the wavelength level, after calculating the phase difference according to the working frequency f and the target focusing position L, the phase difference and the material property of the polymer are set according to the following modes, specifically:
When focusing is realized at the focal length L, the distance x of each section block along with the distance x is obtained according to the following formula i Phase of change:
Φ(x i )＝k 0 (mλ+(x i 2 +L 2 ) 1/2 -L)
k 0 ＝2πf/c 1
in which phi (x i ) Indicating a distance x from the center of the planar polymer supersurface 2 i Phase of cross-sectional block x i Representing the distance of each section block from the center of the planar polymer supersurface 2, i=1, 2,3, …, i representing the ordinal number of the section blocks, n representing the total number of section blocks, L representing the focal length of the planar polymer supersurface 2; k (k) 0 Representing wavenumber in background medium, f represents operating frequency f, c of planar polymer supersurface 2 1 Sound velocity of background medium, sound velocity c of specific medium 1 =1480 m/s; m is a matching coefficient, is any positive integer, specifically any integer, and can be directly taken as 0.
In practice, the operating frequency may be selected to be 100k-2000kHz.
The super surface of the flat plate type polymer is isotropic uniform medium, and the thickness H of each section block is changed i Achieving a target phase phi (x i ) The thickness dimension H of each section block is set according to the following formula without considering the acoustic attenuation of acoustic waves in the planar polymer supersurface i ：
H i ＝(Φ(x i )c 1 c 2 )/(2πf(c 1 -c 2 ))
c 2 ＝(E(1-σ)/(ρ(1+σ)(1-2σ))) 1/2
Wherein, c 2 Represents the sound velocity, c, in the planar polymer supersurface 2 material 2 According to the material properties of the polymer; e is Young's modulus, σ is Poisson's ratio, ρ is the material density of the planar polymer supersurface 2.
The operating frequency may be selected to be 100k-2000kHz after considering the accuracy of the machining of the super surface. When the working frequency f changes, the lead zirconate titanate ceramic piezoelectric plate with corresponding thickness is newly selected according to the working frequency f to realize corresponding resonance frequency, and meanwhile, according to the change of the working frequency f, the thickness of the matching layer and the transverse and thickness dimensions of the planar polymer super-surface section block can be changed in equal proportion.
And when the focal length L corresponding to the target focusing position is changed, the thickness dimension h of each section block i The focal length L is modulated at the moment, so that the adjustment is convenient, simple and efficient.
The embodiment of the invention is specifically as follows:
the partition electrode acoustic piezoelectric transducer 1 and the planar polymer super surface 2 of the partition electrode are symmetrical 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.
As shown in fig. 1, the lower surface-divided electrode 13 and the upper surface-non-divided electrode 15 are respectively deposited on both side surfaces of the lead zirconate titanate piezoelectric ceramic sheet 14 by cooling liquid silver as positive and negative stages of the piezoelectric element. The partition electrode 13 is abutted against a limit step of the shell 17 to realize positioning, the matching layer 16 is directly solidified and deposited on the upper surface of the non-partition electrode 14, and the matching layer 16 selects a polymer mixed with the lead zirconate titanate piezoelectric ceramic sheet 14 and the metal tungsten and epoxy resin matched with the acoustic impedance of the aqueous medium for coupling and transmitting mechanical vibration. The backing 12 is made of silica gel with unmatched acoustic impedance to the lead zirconate titanate piezoelectric ceramic sheet 14 by pouring liquid silica gel into an opening in the bottom of the housing 17 for curing, and is used for absorbing mechanical vibration.
Fig. 2 is a semi-sectional view of a zoned electrode acoustic piezoelectric transducer 1 of the zoned electrode provided by the present invention. Thickness H of backing 12, lead zirconate titanate piezoelectric ceramic sheet 14 and matching layer 17 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 To achieve the value of thickness direction resonance at the excitation frequency f, H b And H c 10 times and 1/4 times the wavelength at the target excitation frequency f, respectively.
Fig. 3 shows a three-dimensional view and a two-dimensional size view of the lower surface partition electrode 13, the lead zirconate titanate piezoelectric ceramic sheet 14 and the upper surface non-partition electrode 15 provided by the invention. The thickness of the lower surface partition electrode 13 and the upper surface non-partition electrode 15 is the same and uniform; the lower surface-divided electrode 13 is a completely insulated two-area electrode: an inner region 131 and an outer region 132, which are led out by wires and then circumscribe two signal input ends. The upper surface non-partition electrode 15 is a monolithic electrode, and for facilitating the subsequent deposition of the matching layer 16, one side electrode area of the upper surface non-partition electrode 15 bypasses the lead zirconate titanate piezoelectric ceramic sheet 14 and is deposited on one side of the lower surface partition electrode 13, and is used for leading out a lead to be directly grounded.
The shape of the lower surface partition electrode 13 and the upper surface non-partition electrode 15 are both related to the lead zirconate titanate piezoelectric ceramic sheet 14, when the lead zirconate titanate piezoelectric ceramic sheet 14 is a cylinder, the inner area electrode 131 and the outer area electrode 132 of the lower surface partition electrode 13 are respectively circular and annular structures, the upper surface non-partition electrode 15 is a circular structure, when the lead zirconate titanate piezoelectric ceramic sheet 14 is a cuboid, the inner area electrode 131 and the outer area electrode 132 of the lower surface partition electrode 13 are respectively square and square annular structures, and the upper surface is provided with The surface non-partitioned electrode 15 has a square structure. The lower surface segmented electrode 13 and the upper surface non-segmented electrode 15 are both symmetric about the z-axis and have a maximum width D d3 And D u3 Equal to, is slightly smaller than the width W of the lead zirconate titanate piezoelectric ceramic sheet 14 PZT . Meanwhile, for convenience in design, the width D of the inner region electrode 131 of the lower surface partition electrode 13 along the x and y axes d1 Half of the total area: d (D) d1 ≈2D d3 . And the difference between the inner ring electrode and the outer ring electrode is 4mm: d (D) d2 -D d1 ＝4mm。
As shown in fig. 4, the three-dimensional structure and two-dimensional cross-section of the planar polymer supersurface 2 provided by the invention comprise an array of cells of varying thickness. The material of the planar polymeric supersurface 2 is selected to be an epoxy-based metal polymer material that matches the impedance of the matching layer 16 and water. Specifically, the flat polymer supersurface 2 and the matching layer 16 are made of a mixture of metal tungsten powder and epoxy resin, wherein the mass ratio of the metal tungsten powder to the epoxy resin is n:1 and m:1 respectively, and m > n >1.
In connection with FIG. 4 (c), the planar polymer has a supersurface width W ms ＝W PZT . Width W of the thickness variation unit in x or y direction 0 . Thickness H of each section block i The thickness calculation is designed based on the phase difference calculated by the generalized Snell's law according to the working frequency used in the actual engineering and the focusing position of the target acoustic energy. Meanwhile, the structure of the flat polymer super surface 2 provided by the invention can be designed according to the structure of the lead zirconate titanate piezoelectric ceramic sheet 14; if the lead zirconate titanate piezoelectric ceramic sheet 14 is cylindrical, the flat polymer super surface 2 is also selected to be cylindrical, and the cross-section blocks are circular array structures, as shown in fig. 3 (a); if the lead zirconate titanate piezoelectric ceramic sheet 14 is rectangular, the flat polymer super surface 2 is also rectangular, and the cross-sectional blocks are square annular array structures, as shown in fig. 3 (b).
Specifically, in this embodiment, the switchable dual-function acoustic super-surface device based on the partition electrode is implemented underwater, and the working frequency is 100k-5000kHz, taking the working frequency f=2000 kHz as an exampleAt this time, wavelength λ=0.75 mm, thickness H of the lead zirconate titanate piezoelectric ceramic sheet 14 PZT =1 mm, width W PZT Thickness H of matching layer 16 =50 mm c =0.2 mm, width W c Thickness H of backing 12 =50 mm b =7.5 mm, width W b =47 mm. The mass ratio of the tungsten powder and the epoxy resin of the epoxy-based metal mixture used for the matching layer 16 is 3:1.
the inner region of the lower surface-divided electrode 13 has a width D d1 =20mm, width of outer zone D d3 =46 mm, the interval between the inner and outer regions is D d2 -D d1 ＝4mm；
The upper surface non-partitioned electrode 15 has a width dimension D u ＝46mm；
The planar polymer supersurface 2 has a width dimension W ms =50mm, width of each section block is W 0 =1mm. Focusing focal length l=120 mm with the target acoustic energy, the thickness dimension H of the section block from inside to outside on the right side of the axis is due to the symmetry of the section block with respect to the axis i The method comprises the following steps of: 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,2.90mm. The mass ratio of the tungsten powder and the epoxy resin of the epoxy-based metal mixture used for the flat polymer super surface 2 is as follows: 2.1:1.
It should be noted that the structural parameters of the planar polymer super-surface 2 are designed based on the incident frequency, the sound velocity of the polymer material and the target focusing focal length of the sound energy, and when the super-surface structure is prepared from other polymer materials for any frequency and focusing, the sound energy focusing and the bottle-shaped sound field under any condition can be reproducibly realized by only redesigning the thickness and width dimensions of each section block.
The flat polymer super surface 2 is directly deposited on the surface of the matching layer 16 of the partition electrode acoustic piezoelectric transducer 1 of the partition electrode in an imprinting mode to realize the integration of the device, and the phase modulation is carried out on the mechanical vibration excited by piezoelectricity. The partition electrode 13 on the lower surface of the partition electrode acoustic piezoelectric transducer 1 can conveniently realize the dual functions of sound energy focusing and bottle-shaped sound field, and can realize the dual functions of sound energy focusing and bottle-shaped sound field switching only by switching the phase of the input voltage signal of one channel without additional active equipment and complex operation.
Hereinafter, a dual-function implementation of the switchable dual-function acoustic super-surface device based on the segmented electrodes in an embodiment of the present invention will be described in detail with reference to fig. 1 to 6,
Focusing of acoustic energy: when a switchable dual function acoustic subsurface device based on segmented electrodes is used as acoustic energy focusing, comprising the steps of:
s1: referring to fig. 1 to 3, first, two sinusoidal voltage signals having equal amplitude and equal phase are inputted from a signal generator through a wire 17 to an inner area electrode 131 and an outer area electrode 132 of a lower surface partition electrode 13 as positive electrodes of a piezoelectric element: interfaces 1 and 2 both input a sinusoidal voltage signal with amplitude of 50V and phase of 0. The upper surface non-partitioned electrode 15 is directly grounded through a ground wire in the lead 17 as a negative electrode of the piezoelectric element.
As shown in fig. 4, the lead zirconate titanate piezoelectric ceramic sheet 14 polarized in the thickness direction is mechanically displaced in the thickness direction z by the electric field in the thickness direction generated by the divided electrodes 13 and the non-divided electrodes 15 at any time based on the inverse piezoelectric effect, and is aligned with the electric field direction. Sinusoidal mechanical vibrations in the thickness direction are in turn coupled into the background medium water through the impedance matching layer 16 creating a plane acoustic wave propagating in the z-direction. In the case of phase modulation without the planar polymer supersurface 2 structure, plane waves propagating along the z direction will be generated in the background water area, and the sound pressure and the phase are equal in the xoy plane at any z distance.
S2: based on the planar polymer supersurface 2 being deposited directly on the surface of the matching layer 16 as in fig. 1, 4 and 6, based on impedance matching, individual elements of varying thickness will phase modulate the mechanical vibrations coupled in from the matching layer 16 such that the planar polymer supersurface 2 is in phase with the surface of the background medium, etcAt a phase value phi (x) designed in accordance with the focus of the target acoustic energy i ). Therefore, the mechanical vibration after phase modulation excites a sound field from the planar polymer ultrasonic surface 2 from the interface position, and the sound beams scattered by each section block are overlapped at the target position l=200mm, so that the focusing of sound energy is realized.
Bottle-shaped sound field: when a switchable bi-functional acoustic ultrasound surface device based on segmented electrodes is used as a bottle-shaped acoustic field modulation, comprising the steps of:
s1: based on fig. 1 to 3, first, two paths of sinusoidal voltage signals having equal amplitude and phase difference pi are inputted from a signal generator through a wire 17 to an inner region 131 and an outer region 132 of the lower surface partition electrode 13 as positive electrodes of the piezoelectric element: the interface 1 still inputs a sinusoidal voltage signal with amplitude of 50V and phase of 0, and the interface 2 inputs a sinusoidal voltage signal with amplitude of 50V and phase of pi. The upper surface non-partitioned electrode 15 is directly grounded through a ground wire in the lead 17 as a negative electrode of the piezoelectric element. The inputs of the transposed interfaces 1 and 2 at this time do not affect the sound field effect of the excitation.
As shown in fig. 5, when the voltages input to the inner area electrode 131 and the outer area electrode 132 of the lower surface-divided electrode 13 are the same in magnitude and are out of phase by pi. Based on the inverse piezoelectric effect, at any time, since the inner region 131 and the outer region 132 and the upper surface non-partitioned electrode 15 will generate two sinusoidal electric fields with a phase difference pi in the thickness direction, and the lead zirconate titanate piezoelectric ceramic sheet 14 is virtually divided into an inner piezoelectric region and an outer piezoelectric region under the excitation of the two electric fields, the piezoelectric sheets of the two regions will exhibit sinusoidal mechanical vibration with a phase difference pi in the time dimension. Due to the impedance matching, the sinusoidal mechanical vibration displacement will couple into the matching layer 16 and pass into the background medium, thereby exciting the acoustic field. In the time dimension, the matched 16 is also virtually divided into an inner region and an outer region, and the sinusoidal mechanical vibrations of the two regions are also represented by the same amplitude and phase difference pi. In the absence of phase modulation of the planar polymer supersurface 2, mechanical vibrations coupled from the matching layer 16 to the background waters will excite planar sine waves propagating in the z direction, and the planar waves corresponding to the inner and outer regions on the xoy plane at any z distance remain equal in amplitude and out of phase by pi at all times.
S2: based on the planar polymer supersurface 2 as shown in fig. 1, 4 and 6, the sinusoidal mechanical vibration transmitted by the matching layer 16 will be phase modulated due to impedance matching directly on the planar polymer supersurface 2 of the matching layer 16, each unit of thickness conversion will generate different phase delays for the sinusoidal mechanical vibration incident at each position, so that the phase in the corresponding interface area above the inner area electrode 131 of the partition electrode 13 on the interface where the planar polymer supersurface 2 is coupled with the background medium is still equal to the designed phase value under the focus of the target acoustic energyWhile the phase in the interface region corresponding to the outer region electrode 132 is equal to phi (x i ) +pi. Thus, the phase modulated mechanical vibrations excite the acoustic beam from the interface of the planar polymer subsurface 2 and the background medium, which acts as a point source, where the scattered acoustic beam at each cross-sectional block can achieve a bottle-shaped wavefield at the target acoustic energy focus location.
As shown in FIG. 5, when the mechanical vibration excited by the segmented electrode acoustic piezoelectric transducer 1 is coupled from the matching layer 16 into the planar polymer subsurface 2, the phases of the respective units are different when reaching the interface with water due to the different thicknesses of the respective units of the planar polymer subsurface 2, and the phase on the electrode-corresponding plane of the outer region of the interface where the planar polymer subsurface 2 is coupled with water is equal to the phase value Φ (x i ) Plus pi. After being modulated by the cross-sectional blocks of the planar polymer ultrasound surface 2, the incidence of each cross-sectional block at the interface can be regarded as scattering of a point sound source, and the scattered sound beam realizes a cavity capturing area of the bottle-shaped sound field at the focal length l=200mm of the target sound energy focusing.
The invention is used for realizing the dual-function switchable dual-function acoustic ultrasonic surface device based on the partition electrode for realizing the dual-function of the acoustic energy focusing and the bottle-shaped sound field, and can realize the conversion of the two sound fields of the acoustic energy focusing and the bottle-shaped sound field by only switching the phase of one input voltage interface under the condition that active equipment is not externally added. And the focusing point position of the acoustic energy before and after switching and the cavity position of the bottle-shaped sound field for particle capture are the same position, and both appear at the designed target focal point L.
Therefore, the piezoelectric transducer with the partition electrodes and the ultrasonic surface of the flat polymer are combined, the mechanical vibration condition of the piezoelectric acoustic transducer can be changed by simply switching the input voltage of one of the area electrodes of the partition electrodes, and further the dual-function switching of a focusing sound field and a bottle-shaped sound field is realized through the ultrasonic surface of the flat polymer, so that the piezoelectric transducer has the dual-function requirements of sound energy focusing and 'acoustic tweezers'.
Meanwhile, the flat polymer super surface can be directly stamped on the piezoelectric ceramic transducer, so that the sound field coupling efficiency is improved, the thickness is thinner, and the price realizability is good.
In the foregoing embodiments, the descriptions of the embodiments are focused on, and for those portions of one embodiment that are not described in detail, reference may be made to the related descriptions of other embodiments.
The foregoing has described in detail the examples of the present application, wherein specific examples are employed to illustrate the principles and embodiments of the present invention, and the above examples are provided to assist in understanding the methods and core ideas of the present invention; meanwhile, as a person skilled in the art will have variations in the specific implementation method and application scope according to the idea of the present invention, the present disclosure should not be construed as limiting the present invention.
It should be noted that the above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above description, and the dual-functional acoustic ultrasonic surface device based on the partition electrode provided by the present invention can be used for not only the planar polymer ultrasonic surface mixed by metal tungsten and epoxy resin described in the present invention, but also any ultrasonic surface used for focusing, so as to realize dual functions of acoustic focusing and bottle-shaped acoustic field by a single device.
Claims (9)
1. A switchable dual-function acoustic subsurface device based on segmented electrodes, characterized by:
the device is placed in a background medium environment, the device comprises a partition electrode acoustic piezoelectric transducer (1) and a flat polymer super surface (2), the partition electrode acoustic piezoelectric transducer (1) comprises a lower surface partition electrode (13), a lead zirconate titanate piezoelectric ceramic plate (14), an upper surface non-partition electrode (15) and a matching layer (16) which are sequentially stacked from bottom to top, and the flat polymer super surface (2) is arranged on the upper surface of the matching layer (16); the lower surface partition electrode (13) is divided into two partial electrodes of a central inner region electrode (131) and a peripheral outer region electrode (132), and the upper surface non-partition electrode (15) is a whole electrode.
2. A switchable dual function acoustic subsurface device based on segmented electrodes as claimed in claim 1 wherein: the partition electrode acoustic piezoelectric transducer (1) further comprises a shell (17) and a back lining (12), the upper end of the shell (17) is opened, the bottom end of the lower surface partition electrode (13) is embedded in the opening, and the back lining (12) is arranged in an inner cavity formed between the lower surface partition electrode (13) and the shell (17).
3. A switchable dual function acoustic subsurface device based on segmented electrodes as claimed in claim 1 wherein: the backing (12) is made of an acoustic absorbing material.
4. A switchable dual function acoustic subsurface device based on segmented electrodes as claimed in claim 1 wherein: the inner area electrode (131), the outer area electrode (132) and the upper surface non-partition electrode (15) are respectively connected to an external two-channel voltage signal generator through respective leads (11).
5. A switchable dual function acoustic subsurface device based on segmented electrodes as claimed in claim 1 wherein: the flat polymer super surface (2) and the matching layer (16) are made of mixed materials composed of metal powder and polymer, the ratio of the metal powder to the polymer is different, and the relative addition amount of the metal powder in the flat polymer super surface (2) is smaller than that of the metal powder in the matching layer (16).
6. A switchable dual function acoustic subsurface device based on segmented electrodes as claimed in claim 1 wherein: the flat polymer supersurface (2) is formed by rotating radial sections of different thickness distribution, the radial sections are fixed with radial length W from the center outwards 0 Divided into a plurality of section blocks, the fixed radial length W 0 All are far smaller than the working wavelength, and the thickness dimension H of each section block i And adjusting and setting according to the modulated phase difference.
7. A switchable dual function acoustic subsurface device based on segmented electrodes as claimed in claim 1 wherein: in the flat polymer super surface (2), the thickness dimension of each section block is set as follows:
the distance x of each section block is obtained according to the following formula i Phase of change:
Φ(x i )＝k 0 (mλ+(x i 2 +L 2 ) 1/2 -L)
k 0 ＝2πf/c 1
in which phi (x i ) Representing a distance x from the centre of the planar polymer supersurface (2) i Phase of cross-sectional block x i Representing the distance of each section block from the center of the planar polymer supersurface (2), i=1, 2,3, … n, i representing the ordinal number of the section blocks, n representing the total number of section blocks, L representing the focal length of the planar polymer supersurface (2); k (k) 0 Representing the wavenumber in the background medium, f representing the operating frequency f, c of the planar polymer supersurface (2) 1 Sound velocity for background medium; m is a matching coefficient;
the thickness dimension H of each section block is set according to the following formula i ：
H i ＝(Φ(x i )c 1 c 2 )/(2πf(c 1 -c 2 ))
c 2 ＝(E(1-σ)/(ρ(1+σ)(1-2σ))) 1/2
Wherein, c 2 Representing the speed of sound in the planar polymeric supersurface (2) material; e is Young's modulus, σ is Poisson's ratio, ρ is the density of the polymer supersurface.
8. A sound field control method applied to a switchable dual-function acoustic super-surface device as claimed in any one of claims 1 to 7, characterized by: the switchable dual-function acoustic super-surface device is placed in a liquid background medium environment, independent sinusoidal voltage signals are respectively input to an inner area electrode (131) and an outer area electrode (132) of a lower surface partition electrode (13), and two paths of sinusoidal voltage signals respectively input to the inner area electrode (131) and the outer area electrode (132) are adjusted to realize different sound field control.
9. The sound field control method according to claim 8, wherein:
different sound field control is realized by adjusting the phase difference of two paths of sine voltage signals respectively input to the inner area electrode (131) and the outer area electrode (132):
when the phase difference of two paths of sinusoidal voltage signals respectively input to the inner area electrode (131) and the outer area electrode (132) is 0, the lead zirconate titanate piezoelectric ceramic sheet (14) integrally generates sinusoidal mechanical vibration along the thickness direction under the action of the electric fields of the lower surface partition electrode (13) and the upper surface non-partition electrode (15), the sinusoidal mechanical vibration is coupled into liquid through the matching layer (16) and the flat polymer super surface (2), and the flat polymer super surface (2) carries out phase modulation on the incident sinusoidal mechanical vibration so as to form acoustic energy focusing at a target position;
when the phase difference of two paths of sine voltage signals is pi, which is input to the inner area electrode (131) and the outer area electrode (132), the lead zirconate titanate piezoelectric ceramic sheet (14) integrally generates the same amplitude along the thickness direction under the action of the electric field of the lower surface partition electrode (13) and the upper surface non-partition electrode (15), sinusoidal mechanical vibration with pi phase difference is generated, the sinusoidal mechanical vibration is coupled into liquid through the matching layer (16) and the flat polymer super surface (2), and the flat polymer super surface (2) carries out phase modulation on the incident mechanical vibration, so that a bottle-shaped sound field is formed at a target position.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310453372.9A CN116524893A (en) | 2023-04-25 | 2023-04-25 | Switchable dual-function acoustic super-surface device and method based on partition electrode |
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| CN117598728A (en) * | 2024-01-23 | 2024-02-27 | 浙江大学 | Planar multi-focus acoustic lens and acoustic lens device for medical diagnosis and treatment |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117598728A (en) * | 2024-01-23 | 2024-02-27 | 浙江大学 | Planar multi-focus acoustic lens and acoustic lens device for medical diagnosis and treatment |
| CN117598728B (en) * | 2024-01-23 | 2024-05-03 | 浙江大学 | Planar multi-focus acoustic lens and acoustic lens device for medical diagnosis and treatment |
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