阅读说明：本技术 一种多频超声换能器及具有其的超声成像系统、方法 (Multi-frequency ultrasonic transducer and ultrasonic imaging system and method with same ) 是由 邱维宝 伍伟昌 张志强 潘东文 郑海荣 于 2021-08-20 设计创作，主要内容包括：本发明提出了一种多频超声换能器及具有其的超声成像系统、方法,多频换能器包括第一换能器组件和第二换能器组件,第二换能器组件的频率低于第一换能器组件的频率,每个第一换能器组件、每个第二换能器组件均包括层叠设置的背衬层、压电层和匹配层,第二换能器组件排列在第一换能器组件的两侧或周围；还包括一体式声透镜,一体式声透镜同时层叠在第一换能器组件的匹配层前侧和第二换能器组件的匹配层前侧；还包括柔性电路板,柔性电路板电性连接压电层；压电层包括地电极面和信号电极面,地电极面和信号电极面分别具有电极,且信号电极面的电极割开使压电层形成多个压电阵元。(The invention provides a multi-frequency ultrasonic transducer, an ultrasonic imaging system with the same and a method for the same, wherein the multi-frequency ultrasonic transducer comprises a first transducer component and a second transducer component, the frequency of the second transducer component is lower than that of the first transducer component, each first transducer component and each second transducer component respectively comprise a backing layer, a piezoelectric layer and a matching layer which are arranged in a stacking mode, and the second transducer components are arranged on two sides or the periphery of the first transducer components; the integrated acoustic lens is simultaneously laminated on the front side of the matching layer of the first transducer assembly and the front side of the matching layer of the second transducer assembly; the flexible circuit board is electrically connected with the piezoelectric layer; the piezoelectric layer comprises a ground electrode surface and a signal electrode surface, the ground electrode surface and the signal electrode surface are respectively provided with an electrode, and the electrodes of the signal electrode surface are cut to enable the piezoelectric layer to form a plurality of piezoelectric array elements.)

1. A multi-frequency ultrasonic transducer comprising a first transducer assembly and a second transducer assembly, the frequency of the second transducer assembly being lower than the frequency of the first transducer assembly, each of the first transducer assembly and the second transducer assembly comprising a backing layer, a piezoelectric layer and a matching layer arranged in a stack, the second transducer assembly being arranged on either side of or around the first transducer assembly;

further comprising a unitary acoustic lens laminated simultaneously to the matching layer front side of the first transducer assembly and the matching layer front side of the second transducer assembly;

the flexible circuit board is electrically connected with the piezoelectric layer;

the piezoelectric layer comprises a ground electrode surface and a signal electrode surface, the ground electrode surface and the signal electrode surface are respectively provided with an electrode, and the electrodes of the signal electrode surface are cut to enable the piezoelectric layer to form a plurality of piezoelectric array elements.

2. The multi-frequency ultrasonic transducer of claim 1, wherein the integral acoustic lens has an ultrasonic focusing characteristic for focusing ultrasonic waves of different frequencies emitted by the first transducer assembly and the second transducer assembly onto a predetermined monolithic target point or a plurality of predetermined target points along a first direction.

3. The multi-frequency ultrasonic transducer of claim 2, wherein the integral acoustic lens has a variable physical parameter, the integral acoustic lens having different physical parameters focusing ultrasonic waves of different frequencies emitted by the first transducer assembly and the second transducer assembly at a same depth in the first direction;

or, the integral acoustic lens with the different physical parameters focuses the ultrasonic waves of different frequencies emitted by the first transducer assembly and the second transducer assembly at different depths in the first direction.

4. The multi-frequency ultrasonic transducer of claim 1, wherein said second transducer assembly is arranged on both left and right sides of said first transducer assembly, said second transducer assembly emitting ultrasonic waves focused in said first direction;

the ultrasonic wave emitted by the second transducer assembly passes through the integrated acoustic lens to form a focus on the central line of the first transducer assembly, or in the ultrasonic left and right areas of the first transducer assembly.

5. The multi-frequency ultrasonic transducer of claim 1, wherein said second transducer assembly is arranged on both left and right sides of said first transducer assembly, said second transducer assembly and said first transducer assembly each emitting ultrasonic waves focused in said first direction;

the ultrasonic wave emitted by the second transducer assembly and the ultrasonic wave emitted by the first transducer assembly pass through the integrated acoustic lens to form a focus, and the focus is superposed in the first direction or at different positions on the central line of the first transducer assembly.

6. The multi-frequency ultrasonic transducer of claim 1, wherein the flexible circuit board covers an entire surface of the piezoelectric layer;

or, the flexible circuit board is connected with one side or multiple sides of the piezoelectric layer;

preferably, additional connecting areas are reserved on two sides of the piezoelectric layer, and the flexible circuit board covers the surfaces of the connecting areas.

7. A method for manufacturing a multi-frequency ultrasonic transducer, which is used for manufacturing the multi-frequency ultrasonic transducer of any one of claims 1 to 7, wherein the manufacturing of the multi-frequency ultrasonic transducer comprises:

fabricating a piezoelectric layer, comprising: sputtering an electrode on the ground electrode surface of the piezoelectric layer and sputtering an electrode on the signal electrode surface;

electrically connecting the piezoelectric layer with a flexible circuit board, superposing and manufacturing a matching layer on one side of the ground electrode surface of the piezoelectric layer, and superposing and manufacturing a backing layer on one side of the signal electrode surface;

arranging and fixing the second transducer assembly on two sides or the periphery of the first transducer assembly, simultaneously stacking an integrated acoustic lens on the front side of the matching layer of the first transducer assembly and the front side of the matching layer of the second transducer assembly, and attaching and fixing the integrated acoustic lens to the matching layer of the first transducer assembly and the matching layer of the second transducer assembly.

8. The method for manufacturing a multi-frequency ultrasonic transducer according to claim 7, wherein said step of "sputtering electrodes on the ground electrode surface of the piezoelectric layer" further comprises: cutting the ground electrode surface according to the number of array elements of the preset piezoelectric layer and the spacing of the array elements, and filling acoustic decoupling materials into cutting seams formed by cutting;

the following is included after the sputtering electrode on the signal electrode surface: and cutting the electrodes of the signal electrode surface according to the gaps among the array elements of the ground electrode surface.

9. An ultrasound imaging system comprising the multi-frequency ultrasound transducer of any of claims 1-6,

the control unit is used for generating focusing adjusting signals of the first transducer assembly and the second transducer assembly along a second direction so that the multi-frequency ultrasonic transducer can realize focusing with variable focal positions along the second direction;

the unitary acoustic lens enables focusing of the first transducer assembly and the second transducer assembly in a first direction;

wherein the first direction intersects or is perpendicular to the second direction.

10. The ultrasound imaging system of claim 9, wherein the control unit adjusts electronic beam forming of an excitation system of the multi-frequency transducer.

11. An imaging method of the ultrasound imaging system according to claim 9 or 10,

by controlling the focal positions of the first and second transducer assemblies, and controlling the frequencies of the first and second transducer assemblies, at least one of the following imaging modes is achieved:

the first imaging mode: focusing the first transducer assembly and the second transducer assembly along a first direction on a preset monomer target point through the structural characteristics of the integrated acoustic lens, adjusting the focal positions of the first transducer assembly and the second transducer assembly along a second direction to enable the focal positions of the first transducer assembly and the second transducer assembly along the second direction to be the preset monomer target point, controlling the frequency of the first transducer assembly and the frequency of the second transducer assembly, and carrying out multi-frequency synchronous imaging on the monomer target point;

a second imaging mode: and through the structural characteristics of the integrated acoustic lens and the control of the frequency of the first transducer assembly and the frequency of the second transducer assembly, the first transducer assembly and the second transducer assembly are focused on a plurality of target points with different positions and depths on the same section or different sections, and the target points are synchronously imaged.

Technical Field

The invention relates to the technical field of ultrasonic transducers, in particular to a multi-frequency ultrasonic transducer and an ultrasonic imaging system and method with the same.

Background

The ultrasonic imaging is widely applied to the fields of medical diagnosis, industrial detection and the like, and has the advantages of no damage, no radiation, convenience, low cost and the like. The ultrasonic transducer is a device capable of converting an electric excitation signal into an ultrasonic signal and converting a reflected ultrasonic signal into an electric signal, and is a key component of ultrasonic imaging equipment. The performance of an ultrasound transducer directly determines the quality of ultrasound imaging. The ultrasonic transducers are mainly classified into a single-element ultrasonic transducer and an array ultrasonic transducer. Due to the convenience of imaging, the array ultrasonic transducer is mainly used in the ultrasonic imaging apparatus in the medical and industrial fields at present.

In conventional ultrasound imaging, ultrasonic acoustic signals are directed to a detection region and corresponding reflected echo signals are detected. The echo signals are analyzed for characteristics such as amplitude, phase shift, doppler shift, power, etc., and quantized into pixel data that are used to create an image of or represent the flow. With conventional single transducer ultrasound imaging, the received ultrasound echo signal is in the same frequency range as the transmitted ultrasound signal.

Another way to perform ultrasound imaging is to apply an ultrasound signal to a region of interest at one frequency and capture and analyze received echo signals at another frequency (e.g., one or more harmonics of the transmitted ultrasound signal). Typically, the harmonics are 3-5 times as frequent as the transmitted signal. One particular use of harmonic imaging is in imaging tissue using contrast agents. The contrast agent is typically a liquid or lipid-encapsulated microbubble of a size that resonates at a particular transmitted ultrasound frequency. Exposure to ultrasound waves in the body at the resonance frequency of the microbubbles causes the bubbles to collapse and produce nonlinear ultrasound echoes at a much higher frequency than the applied ultrasound waves. For example, a non-linear microbubble may be designed to resonate at 1-6MHz, but will produce an echo signal in the 10-30MHz range. The high frequency echo signals allow detailed images of tissue structures, such as the microvasculature surrounding a tumor in a clinical or preclinical setting, to be generated and studied.

The most conventional way to perform dual frequency imaging is to use a mechanically scanned single element transducer with confocal low and high frequency transducer elements. Although such transducers work well, faster scans can be performed using an array of transducers that can be electronically controlled. Such transducers typically have a low frequency transducer array and a high frequency transducer array aligned with each other. One problem with dual frequency transducers is aligning the low and high frequency arrays. In a 30MHz high frequency phased array, the element size (e.g., 1/2 λ or less) is about 25 microns. At 50MHz, the element size was about 15 microns. The process required to align the arrays typically requires fine tuning of the position of the high and low frequency transducers on the damp table and then bonding them together when the best match is found. This is both time consuming and expensive. The technology discussed herein relates to an improved dual frequency transducer that is easier and less costly to manufacture.

Most of the existing manufacturing methods of multi-frequency ultrasonic transducers are that a low-frequency transducer is placed behind a high-frequency transducer to form a superposed structure, and due to the shielding of the high-frequency transducer, sound wave signals emitted by the rear low-frequency transducer are greatly interfered, and the output of acoustic signals is influenced. For the high-frequency transducer at the front end, because the backing layer cannot be added at the back end, redundant acoustic signals cannot be well absorbed, and the single oscillation time of the piezoelectric layer cannot be shortened in time, the bandwidth is seriously reduced, so that the imaging resolution and the bandwidth are influenced. The side-by-side multi-frequency ultrasonic transducers have complicated mechanical structures, so that the processing difficulty is improved, the reliability of equipment is reduced, or the plurality of transducers only have fixed angles, so that the change of a focus needs to depend on the position of the transducer to be manually moved, the operation is complicated, and the accuracy is low.

In summary, most of the existing multi-frequency ultrasonic transducers are dual-frequency confocal transducers with fixed confocal points, and the change operation of the confocal points is complex and the accuracy is low only by manually moving the positions of the transducers, and when the high-frequency transducers are stacked in front of the low-frequency transducers, the high-frequency transducers are shielded, so that the propagation of sound waves emitted by the low-frequency transducers is affected, and the performance of the low-frequency transducers is reduced. In practical applications, the focus of the ultrasound transducer needs to be precisely controlled to meet the use requirements, for example, in the treatment processes of tumor ablation, ultrasound administration and the like, the confocal point needs to be precisely controlled to prevent internal bleeding or other negative symptoms caused by damage to healthy tissue cells. Therefore, the existing ultrasonic transducer has a great limitation in practical application.

Disclosure of Invention

In view of the above, in order to overcome the defects of the prior art, the present invention provides a variable-focus multi-frequency ultrasonic transducer, and an ultrasonic imaging system and method having the same.

Specifically, the multi-frequency ultrasonic transducer comprises a first transducer assembly and a second transducer assembly, the frequency of the second transducer assembly is lower than that of the first transducer assembly, each first transducer assembly and each second transducer assembly comprise a backing layer, a piezoelectric layer and a matching layer which are arranged in a stacked mode, and the second transducer assemblies are arranged on two sides or on the periphery of the first transducer assembly; further comprising a unitary acoustic lens laminated simultaneously to the matching layer front side of the first transducer assembly and the matching layer front side of the second transducer assembly; the multiple transducers are arranged side by side or in a surrounding mode, a superposition structure is avoided, the influence between the first transducer assembly and the second transducer assembly is eliminated, and a multi-mode imaging mode of multi-band high-quality ultrasonic imaging, ultraharmonic imaging and elastography can be simultaneously carried out.

The flexible circuit board is electrically connected with the piezoelectric layer; the piezoelectric layer comprises a ground electrode surface and a signal electrode surface, the ground electrode surface and the signal electrode surface are respectively provided with an electrode, and the electrodes of the signal electrode surface are cut to enable the piezoelectric layer to form a plurality of piezoelectric array elements. The integrated structural design of the acoustic lens simplifies the preparation process and difficulty of the equipment and improves the integration and consistency of the equipment. The array design of the piezoelectric layers provides the transducer with the capability of electronic focusing, so that the focal positions of the transducer in two dimensions are variable, and the focusing efficiency and the focusing range of the transducer are greatly improved.

Specifically, the array elements of the ground electrode surface are arranged in a one-dimensional linear array; or the array elements of the ground electrode surface are arrayed in a two-dimensional area array.

The integrated acoustic lens has an ultrasonic focusing characteristic and is used for focusing ultrasonic waves with different frequencies, emitted by the first transducer assembly and the second transducer assembly, on a preset single target point or a plurality of preset target points along a first direction. Further, the physical parameters of the integral acoustic lens are variable, and the integral acoustic lens with different physical parameters focuses the ultrasonic waves with different frequencies emitted by the first transducer assembly and the second transducer assembly at the same depth in the first direction; or, the integral acoustic lens with the different physical parameters focuses the ultrasonic waves of different frequencies emitted by the first transducer assembly and the second transducer assembly at different depths in the first direction.

The shape of the integrated acoustic lens is concave or convex. The array design of the piezoelectric layer and the existence of the integrated acoustic lens simultaneously enable the first transducer component and the second transducer component to achieve focusing functions in two directions of variable electronic focusing and physical focusing of the acoustic lens, and accuracy of target point positions and resolution of images are greatly improved.

In some embodiments, the second transducer assembly is arranged on the left and right sides of the first transducer assembly, the second transducer assembly emitting ultrasonic waves focused in the first direction; the ultrasonic wave emitted by the second transducer assembly passes through the integrated acoustic lens to form a focus on the central line of the first transducer assembly, or in the ultrasonic left and right areas of the first transducer assembly.

Or the second transducer assemblies are arranged at the left and right sides of the first transducer assembly, and the second transducer assembly and the first transducer assembly emit ultrasonic waves to be focused along the first direction; the ultrasonic wave emitted by the second transducer assembly and the ultrasonic wave emitted by the first transducer assembly pass through the integrated acoustic lens to form a focus, and the focus is superposed in the first direction or at different positions on the central line of the first transducer assembly.

The flexible circuit board covers the entire surface of the piezoelectric layer; or, reserving additional connecting areas on two sides of the piezoelectric layer, and covering the surface of the connecting areas by the flexible circuit board. Preferably, the flexible circuit board covers the surface of the connection area, and the piezoelectric layer is in direct contact with the backing layer, so that a better sound absorption effect can be achieved. The flexible circuit board connects one or more sides of the piezoelectric layer.

The invention also provides a manufacturing method of the multi-frequency ultrasonic transducer, which is used for manufacturing the multi-frequency ultrasonic transducer, and the manufacturing method of the multi-frequency ultrasonic transducer comprises the following steps:

fabricating a piezoelectric layer, comprising: sputtering an electrode on the ground electrode surface of the piezoelectric layer and sputtering an electrode on the signal electrode surface;

electrically connecting the piezoelectric layer with a flexible circuit board, superposing and manufacturing a matching layer on one side of the ground electrode surface of the piezoelectric layer, and superposing and manufacturing a backing layer on one side of the signal electrode surface;

arranging and fixing the second transducer assembly on two sides or the periphery of the first transducer assembly, simultaneously stacking an integrated acoustic lens on the front side of the matching layer of the first transducer assembly and the front side of the matching layer of the second transducer assembly, and attaching and fixing the integrated acoustic lens to the matching layer of the first transducer assembly and the matching layer of the second transducer assembly.

Before the step of sputtering the electrode on the ground electrode surface of the piezoelectric layer, the method further comprises the following steps: cutting the ground electrode surface according to the number of array elements of the preset piezoelectric layer and the spacing of the array elements, and filling acoustic decoupling materials into cutting seams formed by cutting;

the following is included after the sputtering electrode on the signal electrode surface: and cutting the electrodes of the signal electrode surface according to the gaps among the array elements of the ground electrode surface.

The invention also provides an ultrasonic imaging system, the ultrasonic imaging system adopts the multi-frequency ultrasonic transducer,

the control unit is used for generating focusing adjusting signals of the first transducer assembly and the second transducer assembly along a second direction so that the multi-frequency ultrasonic transducer can realize focusing with variable focal positions along the second direction;

the unitary acoustic lens enables focusing of the first transducer assembly and the second transducer assembly in a first direction;

wherein the first direction intersects or is perpendicular to the second direction.

In particular, the control unit regulates electronic beam forming of an excitation system of the multi-frequency transducer.

An imaging method of the ultrasonic imaging system comprises the following steps:

by controlling the focal positions of the first and second transducer assemblies, and controlling the frequencies of the first and second transducer assemblies, at least one of the following imaging modes is achieved:

the first imaging mode: focusing the first transducer assembly and the second transducer assembly along a first direction on a preset monomer target point through the structural characteristics of the integrated acoustic lens, adjusting the focal positions of the first transducer assembly and the second transducer assembly along a second direction to enable the focal positions of the first transducer assembly and the second transducer assembly along the second direction to be the preset monomer target point, controlling the frequency of the first transducer assembly and the frequency of the second transducer assembly, and carrying out multi-frequency synchronous imaging on the monomer target point;

a second imaging mode: and through the structural characteristics of the integrated acoustic lens and the control of the frequency of the first transducer assembly and the frequency of the second transducer assembly, the first transducer assembly and the second transducer assembly are focused on a plurality of target points with different positions and depths on the same section or different sections, and the target points are synchronously imaged.

In summary, the multi-frequency ultrasonic transducer of the present invention has the following beneficial effects: the multiple transducers are arranged side by side or in a surrounding mode, a superposition structure is avoided, the influence between the first transducer assembly and the second transducer assembly is eliminated, and a multi-mode imaging mode of multi-band high-quality ultrasonic imaging, ultraharmonic imaging and elastography can be simultaneously carried out. The array design of the piezoelectric layers provides the transducer with the capability of electronic focusing, so that the focal positions of the transducer in two dimensions are variable, and the focusing efficiency and the focusing range of the transducer are greatly improved. Furthermore, due to the array design of the piezoelectric layer and the existence of the acoustic lens, the electronic focusing and the physical focusing can be simultaneously realized by the first transducer assembly and the second transducer assembly, and the accuracy of the target position and the resolution of an image are greatly improved. The multi-frequency ultrasonic transducer can be suitable for array ultrasonic transducers in all working frequency ranges, has no built-in mechanical structure, simple process, high reliability and strong operability, and the integrated structural design of the acoustic lens simplifies the preparation process and difficulty of equipment and improves the integration and consistency of the equipment. An ultrasonic imaging system using the multi-frequency transducer can realize a plurality of imaging modes through controlling the first transducer assembly and the second transducer assembly.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a multi-frequency ultrasonic transducer of the present invention;

fig. 2 is a schematic diagram of the overall structure of the multi-frequency ultrasonic transducer of the present invention;

FIG. 3a is a schematic diagram of the longitudinally variable electronic focusing of the multi-frequency ultrasonic transducer of the present invention;

fig. 3b is a schematic diagram of the lateral physical focusing of the multi-frequency ultrasound transducer of the present invention;

FIG. 4a is a schematic diagram of a multi-frequency simultaneous imaging mode of the multi-frequency ultrasound transducer of the present invention;

FIG. 4b is a schematic diagram of the simultaneous imaging of different depth targets by the multi-frequency ultrasound transducer of the present invention;

fig. 5a is a schematic diagram of a low frequency excitation high frequency reception mode of the multi-frequency ultrasonic transducer of the present invention;

FIG. 5b is a schematic diagram of the multi-frequency ultrasonic transducer of the present invention performing ultrasonic wave forming and elastography on target spots at different depths;

fig. 6 is another schematic structural diagram of the multi-frequency ultrasonic transducer of the present invention.

Reference numerals:

1-a first transducer assembly; 2-a second transducer assembly; 3-backing layer; 4-a flexible circuit board; 5-a piezoelectric layer; 6-matching layer; 7-integral acoustic lens.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a variable-focus multi-frequency ultrasonic transducer, an ultrasonic imaging system with the same and a method. The multi-frequency ultrasonic transducer comprises a first transducer assembly and a second transducer assembly, wherein the second transducer assembly comprises two or more transducers, and the number of the transducers can be two, three, four or more. The first transducer assembly is centered and the second transducer assembly is arranged on two sides or around the first transducer assembly, specifically the second transducer assembly is arranged on two sides or three sides of the first transducer assembly or arranged around the first transducer assembly. Wherein the frequency of the second transducer assembly is lower than the frequency of the first transducer assembly. The frequency of the second transducer assembly may be 1-5 MHz; the frequency of the first transducer assembly is 5-30 MHz. Thus, in the present invention, the transducers of the first transducer assembly form high frequency elements of the multi-frequency ultrasonic transducer having relatively high frequencies, and the transducers of the second transducer assembly form low frequency elements of the multi-frequency ultrasonic transducer having relatively low frequencies.

Each first transducer assembly and each second transducer assembly includes a backing layer, a piezoelectric layer, and a matching layer in a stacked arrangement. The multi-frequency ultrasonic transducer further comprises an integral acoustic lens which is simultaneously laminated on the front side of the matching layer of the first transducer assembly and the front side of the matching layer of the second transducer assembly. The second transducer assembly is used for outputting acoustic signals, and the first transducer assembly is used for receiving acoustic signals. A plurality of transducers are integrated by adopting a non-overlapping structure, so that mutual interference among the transducers is avoided.

Example 1

The present embodiment provides a specific structure of a dual-frequency transducer. Referring to fig. 1 and 2, the first transducer assembly 1 of the dual frequency transducer comprises one high frequency unit and the second transducer assembly 2 comprises two low frequency units; the type of the first transducer assembly 1 may be a linear array or an area array transducer, either a phased array or a non-phased array transducer. Each transducer comprises a backing layer 3, a flexible circuit board 4, a piezoelectric layer 5 and a matching layer 6, wherein the backing layer 3, the piezoelectric layer 5 and the matching layer 6 are arranged in a stack in sequence. The two low-frequency units of the second transducer assembly 2 are arranged in parallel and side by side at two sides close to the first transducer assembly 1, the matching layers 6 of the first transducer assembly 1 and the second transducer assembly 2 of the double-frequency transducer are on the same plane, all the transducers are connected by an integral acoustic lens 7, and the integral acoustic lens 7 is simultaneously laminated at the front side of the matching layer 6 of the first transducer assembly 1 and at the front sides of the matching layers 6 of the two second transducer assemblies 2. The surface dimensions of the integral acoustic lens 7 are consistent with the size of the matching layer 6 formed after the arrangement of the dual frequency transducers.

A direction perpendicular to the surface of the piezoelectric layer 5 is defined as a first direction, and the integrated acoustic lens 7 has a focusing characteristic for focusing ultrasonic waves of different frequencies emitted by the first transducer assembly 1 and the second transducer assembly 2 to a single target point or a plurality of preset target points along the first direction. The physical parameters of the integrated acoustic lens 7 are variable, and the integrated acoustic lens 7 with different physical parameters enables the ultrasonic waves emitted by the multi-frequency transducer to be focused at the same depth in the first direction or enables the ultrasonic waves emitted by the multi-frequency transducer to be focused at different depths in the first direction. The shape of the integrated acoustic lens 7 can be concave or convex, the number of the matching layers 6 is one or more, and the preparation processes of the matching layers 6 and the backing layer 3 comprise methods of direct bonding, casting, centrifugation, vapor deposition and the like. The integrated structural design of the acoustic lens simplifies the preparation process and difficulty of the equipment and improves the integration and consistency of the equipment. The plurality of transducers are arranged in a side-by-side or surrounding type without a stacked structure, eliminating the influence between the first transducer assembly 1 and the second transducer assembly 2.

A direction perpendicular to a cross section of the multi-frequency ultrasonic transducer shown in fig. 1 is defined as a second direction, the first direction intersects or is perpendicular to the second direction, and a focal position of the multi-frequency ultrasonic transducer is variable in the second direction. Defining the direction parallel to the surface of the piezoelectric layer 5 as the third direction, the variable physical parameters of the integral acoustic lens 7 may also enable the multi-frequency transducer to be focused at different positions in the third direction.

The piezoelectric layer 5 comprises a ground electrode surface arranged on one side surface and a signal electrode surface arranged on the other side surface, the ground electrode surface and the signal electrode surface are respectively provided with electrodes, and the electrodes of the signal electrode surface are cut to enable the piezoelectric layer to form a plurality of piezoelectric array elements. Specifically, the ground electrode surface is formed by array elements arranged in an array structure, and acoustic decoupling materials are filled in gaps of the array elements, specifically, the array elements can be a one-dimensional linear array or a two-dimensional planar array; the electrodes on the surface of the signal electrode surface are cut according to the array element gaps of the ground electrode surface, so that electric signals between the array elements are independent. The arrayed design of the piezoelectric layer 5 provides the transducer with the capability of electronic focusing, so that the focal position of the transducer in two dimensions is variable, and the focusing efficiency and the focusing range of the transducer are greatly improved. Further, due to the array design of the piezoelectric layer 5 and the existence of the integrated acoustic lens 7, the first transducer assembly 1 and the second transducer assembly 2 can simultaneously realize the focusing functions in two directions of variable electronic focusing shown in fig. 3a and physical focusing of the acoustic lens shown in fig. 3b, and the accuracy of the target position and the resolution of the image are greatly improved. Alternatively, the material of the piezoelectric layer 5 may be a conventional piezoelectric material, or may be a 1-3 composite piezoelectric material or a 2-2 composite piezoelectric material.

The flexible circuit board 4 is used for realizing the electrical interconnection of the piezoelectric layer 5 and an external circuit, and comprises a plurality of electrode leads and 2 ground wires, wherein the leads in the flexible circuit board 4 are correspondingly attached to each array element of the piezoelectric layer 5 one by one, and the width of each lead is smaller than that of the array element. When the array elements of the piezoelectric layer 5 are in a one-dimensional array structure, the flexible circuit board 4 can lead out the array element lead from a single side or can lead out the array element lead from two sides through lead wires. The first transducer assembly 1 has too small array element spacing and too large single-side lead density, and preferably adopts a mode of two-side cross-insertion leads, which is embodied in that leads are conducted once every other array element on a single side. The leads of two adjacent array elements are respectively led out from two sides, and the two leads mutually differ by the position of an array element interval in the direction vertical to the array element leads. If the array elements of the piezoelectric layer 5 are in a two-dimensional array structure, the flexible circuit board 4 may be formed by leading out the array element leads from one side, two sides or four sides.

The flexible circuit board 4 can be connected to the piezoelectric layer 5 by directly covering the entire surface of the piezoelectric layer 5, and is located between the piezoelectric layer 5 and the backing layer 3; or reserve the additional connection area of segment in array element both sides, cut out the fretwork area on a flexible circuit board 4 for be connected array element electrical signal and flexible circuit board 4, make flexible circuit board 4 only cover the connection area surface on piezoelectric layer 5, piezoelectric layer 5 can direct contact backing layer 3 in order to obtain better sound absorption effect. In some embodiments, a plurality of flexible circuit boards 4 may be respectively used on two sides of the piezoelectric layer 5 to electrically connect the flexible circuit boards 4 with the array element through a small extra connection area reserved on two sides of the array element, so that the piezoelectric layer 5 can be in direct contact with the backing layer 3. Since the first transducer assembly 1 is sensitive to signal interference and attenuation, it is preferable to use a form of hollowing out the center of the flexible circuit board 4 or two flexible circuit boards 4 connected with the piezoelectric layer 5 to obtain better sound absorption effect. In this embodiment, the flexible circuit board 4 covers the surface of the signal electrode surface, and is bonded to the signal electrode surface with epoxy resin according to the one-to-one correspondence relationship between the wires and the array elements.

The positions of the focus formed by the multi-frequency transducers which set the second transducer assembly 2 on the left and right sides of the first transducer assembly 1 have a certain law:

in the dual-frequency transducer according to the present embodiment, the second transducer assemblies 2 on both sides of the first transducer assembly 1 are respectively a first low-frequency unit and a second low-frequency unit. The ultrasonic waves emitted by the first low-frequency unit and the second low-frequency unit are focused in a first direction by the integrated acoustic lens 7. The ultrasonic waves emitted by the first low-frequency unit and the second low-frequency unit pass through the integrated acoustic lens 7 to form a focusing focus on the central line of the first transducer assembly 1 or in the ultrasonic wave action region of the first transducer assembly 1.

If the first low frequency unit, the second low frequency unit and the first transducer assembly 1 all emit ultrasonic waves outwards, the ultrasonic waves are focused in a first direction by the integral acoustic lens 7. The ultrasonic waves emitted by the first low-frequency unit, the second low-frequency unit and the first transducer assembly 1 pass through the integrated acoustic lens 7 to form focused focal points which are overlapped in the first direction, or are arranged at different positions on the center line of the first transducer assembly 1 in the first direction.

The double-frequency transducer of the embodiment can simultaneously carry out the ultra-harmonic imaging and the elastic imaging modes of low-frequency excitation and high-frequency imaging and the non-interference synchronous high-quality ultrasonic imaging mode of the multi-band transducer because the transducers are not influenced with each other, and has the multi-mode imaging characteristic. For example, as shown in fig. 4a, the multi-band transducer performs multi-band synchronous imaging on a single target point by using confocal characteristics, thereby improving imaging quality; as shown in fig. 4b, the target points at different positions and depths on the same cross section or different cross sections are synchronously imaged by using the multi-frequency characteristic, so that the imaging range and the imaging efficiency of the transducer are enhanced; FIG. 5a shows an ultra-harmonic imaging and elastography for low-frequency signal excitation and high-frequency signal reception at the same focused target location; as shown in fig. 5b, simultaneous low frequency excitation and high frequency imaging of target locations at different depths, or simultaneous super harmonic/elastography of the same target location using a pair of high and low frequency elements and simultaneous fundamental imaging or guidance with another transducer.

The present invention is applicable to array ultrasonic transducers in all frequency ranges, and the present embodiment provides only a specific structure of a dual-frequency transducer, and according to the principle of the present invention, a person skilled in the art can combine multiple transducers into a multi-frequency ultrasonic transducer in a manner that the second transducer assembly 2 surrounds the first transducer assembly 1 or the second transducer assembly 2 is arranged side by side with the first transducer assembly 1. Wherein the number of second transducer assemblies 2 is not limited.

Example 2

The present embodiment provides a method for manufacturing a dual-frequency ultrasonic transducer composed of a first transducer assembly 1 and two second transducer assemblies 2 on two sides as shown in fig. 6, which specifically includes the following steps:

manufacturing one-dimensional linear array elements on the ground electrode surface of the piezoelectric layer 5, sputtering electrodes on the ground electrode surface:

and (4) grinding two surfaces of the piezoelectric sheet to be flat, wherein the thickness of the piezoelectric sheet is larger than a first preset thickness. And cutting in one-dimensional direction on the ground electrode surface according to the preset array element number and the array element interval, wherein the cutting depth is greater than the final expected depth, but the piezoelectric sheet is not cut through. And filling insulating epoxy resin in the cutting seam as an acoustic decoupling material, grinding off redundant epoxy resin on the surface after the epoxy resin is dried and cured until the surface of the piezoelectric material is exposed, and then polishing the piezoelectric material to obtain the one-dimensional linear array type piezoelectric layer 5. And sputtering an upper electrode on the surface of the ground electrode surface, and recording the thickness of the sample. Specifically, the number of array elements and the array element spacing of the first transducer assembly 1 and the second transducer assembly 2 are different, and different transducers are cut on the surface of the piezoelectric sheet according to the number of the array elements and the array element spacing of the transducers respectively. In the present embodiment, the material of the piezoelectric layer 5 is ceramic.

And (3) superposing and manufacturing a matching layer 6 on the ground electrode surface of the piezoelectric layer 5, sputtering an electrode of a signal electrode surface:

and depositing a matching layer 6 with a prepared component on the surface of the ground electrode by using a centrifugal method, drying and solidifying the matching layer, grinding the thickness of the matching layer to a second preset thickness, and recording the total thickness of the laminated sample of the piezoelectric layer 5 and the first matching layer 6. And then continuously depositing a second matching layer 6 on the first matching layer 6 by using a centrifugal method, drying and solidifying, and grinding the thickness of the second matching layer 6 to a second preset thickness. The laminated sample is turned over with the signal electrode facing upward, and the piezoelectric sheet is ground to a first predetermined thickness and polished. After sputtering the electrode on the surface of the signal electrode surface, the electrode on the surface is cut along the shallow lancing of the one-dimensional linear array on the ground electrode surface of the piezoelectric layer 5, so that the electric signals between the array elements are independent.

The piezoelectric layer 5 is electrically connected with the flexible circuit board 4, and leads out the piezoelectric layer 5 circuit:

customizing corresponding flexible circuit board 4 according to the array element interval and the quantity that second transducer subassembly 2 and first transducer subassembly 1 are different, according to array element size, figure and mode of arranging, designing flexible circuit board 4's circuit design drawing, wherein, flexible circuit board 4 contains a plurality of electrode lead and 2 ground wires, and the wire in the circuit board can laminate with every array element one-to-one, and every wire width will be less than the array element width.

The flexible circuit board 4 covers the surface of the signal electrode surface to lead out a piezoelectric layer 5 circuit, and particularly, the flexible circuit board leads out an array element lead of the second transducer component 2 from one side; the first transducer assembly 1 adopts the lead wires which are inserted from two sides because the spacing between the array elements is too small and the density of the lead wires on one side is too large, and the lead wires are conducted once every other array element on one side. The leads of two adjacent array elements are respectively led out from two sides, and the two leads mutually differ by the position of an array element interval in the direction vertical to the array element leads. In some embodiments, the flexible circuit board 4 of the second transducer assembly 2 directly covers the entire signal electrode face; the middle of the flexible circuit board 4 of the first transducer assembly 1 is hollowed, and the electrical signals of the array elements are connected with the flexible circuit board 4 by reserving extra connecting areas on two sides of the array elements. And bonding the flexible circuit board 4 and the signal electrode surface according to the one-to-one correspondence relationship between the conducting wires and the array elements. Specifically, epoxy resin may be used for bonding.

Preparing a back lining layer 3:

the materials of the backing layer 3 are uniformly mixed, centrifuged and cured according to a certain proportioning relationship, and are polished to be flat to a required size, and the manufactured backing block is adhered to the flexible circuit board 4 through epoxy resin by using a clamp to form the backing layer 3. In some embodiments, the backing layer 4 is superimposed on the signal electrode surface, such that when a small additional connecting area is reserved on the piezoelectric layer 5 to connect with the flexible circuit board 4, the backing layer 4 is in direct contact with the signal electrode surface.

Making an integrated acoustic lens 7, integrating a dual-frequency transducer:

the preparation of the integral acoustic lens 7 includes two ways: the first mode is to adopt independent processing, use TPX material or process the epoxy resin after solidifying to the size and the concave curvature that lens predetermine, thickness processing is slightly thicker than the third predetermined thickness, the appearance is the prolate cuboid that one side is the plane, the other side is the interior arch. The arched surface is placed on a die with the same curvature and size but in a convex shape to be completely attached and fixed, the flat surface is polished, and the integrated acoustic lens 7 is polished to a third preset thickness. The surface size of the integral acoustic lens 7 is in conformity with the size formed after the arrangement of the dual frequency transducers. In this embodiment, the second transducer assembly 2 comprises two low frequency units, which are arranged in parallel and side by side next to the two sides of the first transducer assembly 1, and the dual frequency transducer is bonded by the side of the transducer using an insulating adhesive, ensuring that one side of the dual frequency transducer matching layer 6 is flat. And then, the prepared acoustic lens is attached and fixed with the surface of the matching layer 6 of the transducer through epoxy resin for a clamp.

The preparation method of the second mode is a pouring mode, the transducers are firstly arranged and combined, and the transducers are bonded by using an insulating adhesive, so that the second matching layer 6 of the dual-frequency transducer is ensured to be on the same plane. In this embodiment, the two low frequency units of the second transducer assembly 2 are arranged side by side in parallel on both sides next to the first transducer assembly 1, and the dual frequency transducers are bonded by the sides of the transducers. The transducer which is well connected and fixed is placed into a special customized die, the die has the same curvature as the needed lens but is in a convex shape, a layer of gap is formed between the transducer and the die after the transducer is placed, the shape and the size of the gap are the shape and the thickness needed by the lens, then the flowing epoxy resin is filled into the gap, and the excessive burrs are removed after the curing.

And (3) putting the prepared sample into an insulating shell for packaging, and connecting the flexible circuit board 4 with an external circuit through a standard interface.

The present embodiment provides a method for rapidly manufacturing a transducer meeting the requirements of the present invention, wherein some steps can be adjusted, for example, a piezoelectric sheet is firstly processed, electrodes are respectively sputtered on a ground electrode surface and a signal electrode surface, then a piezoelectric layer 5 is electrically connected with a flexible circuit board 4, and then a matching layer 6 is manufactured on the ground electrode surface in an overlapping manner.

In this embodiment, taking the fabrication of a dual-frequency transducer as an example, and combining the structure of the multi-frequency ultrasonic transducer of the present invention and the process of this embodiment, a person skilled in the art can fabricate more transducers to combine into a multi-frequency ultrasonic transducer.

Example 3

The present embodiment provides an ultrasound imaging system comprising the multi-frequency ultrasound transducer of embodiment 1.

The integral acoustic lens 7 enables focusing of the first transducer assembly 1 and the second transducer assembly 2 in the first direction. The change of the focus positions of the ultrasonic waves with different frequencies emitted by the first transducer assembly 1 and the second transducer assembly 2 along the first direction can be realized by adjusting the physical parameters of the integrated acoustic lens 7, and the focus positions are located at different positions of the same depth in the first direction or at different depths in the first direction. Adjusting the physical parameters of the integral acoustic lens 7 can also focus the ultrasonic waves of different frequencies emitted by the first transducer assembly 1 and the second transducer assembly 2 at different positions in the third direction. The ultrasonic imaging system is further provided with a control unit for generating focusing adjustment signals for the first transducer assembly 1 and the second transducer assembly 2 along the second direction, so that the multi-frequency ultrasonic transducer can realize focusing with a variable focal position along the second direction. In particular, the control unit regulates the operation of the excitation system of the multi-frequency transducer, and is capable of adjusting the electronic beam forming, and the variation of the focal position in the second direction is achieved by adjusting the electronic beam forming (i.e. the electronic phased array delay of the array).

The ultrasonic imaging system of the present embodiment can implement multiple imaging modes by controlling the focal positions of the first transducer assembly 1 and the second transducer assembly 2 and imaging the control of the first transducer assembly 1 and the second transducer assembly 2, and specifically includes:

the first imaging mode: the focusing of the first transducer assembly 1 and the second transducer assembly 2 along the first direction is focused on a preset single target point through the structural characteristics of the integrated acoustic lens 7, the focal positions of the first transducer assembly 1 and the second transducer assembly 2 along the second direction are adjusted 1, the focal positions of the first transducer assembly 1 and the second transducer assembly 2 along the second direction are also the preset single target point, the frequency of the first transducer assembly 1 and the frequency of the second transducer assembly 2 are controlled, and multi-frequency synchronous imaging is carried out on the single target point.

A second imaging mode: through the structural characteristics of the integrated acoustic lens 7 and the control of the frequency of the first transducer assembly 1 and the frequency of the second transducer assembly 2, the first transducer assembly 1 and the second transducer assembly 2 are focused on a plurality of target points with different positions and depths on the same cross section or different cross sections, and the target points are synchronously imaged.

In summary, the present invention provides a multi-frequency ultrasonic transducer in which a second transducer assembly is arranged around a first transducer assembly, and an integral acoustic lens is simultaneously laminated on the first transducer assembly to the front side of a matching layer of the second transducer assembly. Because the transducers do not influence each other, the multi-mode imaging mode of multi-band high-quality ultrasonic imaging, ultra-harmonic imaging and elastography can be simultaneously carried out. The array design of the piezoelectric layers provides the transducer with the capability of electronic focusing, so that the focal positions of the transducer in two dimensions are variable, and the focusing efficiency and the focusing range of the transducer are greatly improved. Furthermore, due to the array design of the piezoelectric layer and the existence of the acoustic lens, the electronic focusing and the physical focusing can be simultaneously realized by the first transducer assembly and the second transducer assembly, and the accuracy of the target position and the resolution of an image are greatly improved. The multi-frequency ultrasonic transducer can be suitable for array ultrasonic transducers in all working frequency ranges, has no built-in mechanical structure, simple process, high reliability and strong operability, and the integrated structural design of the acoustic lens simplifies the preparation process and difficulty of equipment and improves the integration and consistency of the equipment. An ultrasonic imaging system using the multi-frequency transducer can realize a plurality of imaging modes through controlling the first transducer assembly and the second transducer assembly.

The above-mentioned embodiments are only preferred embodiments of the present invention, and not intended to limit the present invention, and various modifications other than the above-mentioned embodiments may be made, and the technical features of the above-mentioned embodiments may be combined with each other, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.