A dual-frequency focusing ultrasonic transducer, a preparation method and application thereof

Abstract

The application provides a dual-frequency focusing ultrasonic transducer, which comprises a shell and sequentially arranged acoustic lens, matching layer, piezoelectric layer and backing layer, the piezoelectric layer comprises piezoelectric wafer I and piezoelectric part II, the piezoelectric part II comprises piezoelectric wafer II and a dematching part, the piezoelectric wafer I and the piezoelectric wafer II are side by side to form a flat upper surface of the piezoelectric layer to be focused by the acoustic lens; a preparation method comprises the following steps: the piezoelectric wafer I and the piezoelectric wafer II are side by side and the top surfaces are aligned to form a circular flat surface of the piezoelectric layer; the dematching part is bonded below the piezoelectric wafer II to form the piezoelectric layer; a coaxial cable is connected to the piezoelectric layer; the piezoelectric layer connected with the coaxial cable is fixed in the shell, the backing layer is arranged on the lower surface of the piezoelectric layer, and the acoustic lens and the matching layer are sequentially arranged on the upper surface, and the transducer is obtained. The transducer of the application only needs two same piezoelectric wafers, and the dual-frequency function is realized by adding the dematching part, and the treatment effect is good.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic transducer technology, and in particular to a dual-frequency focused ultrasonic transducer, its preparation method, and its application. Background Technology

[0002] Ultrasound is a wave-like phenomenon that can be used as a carrier or medium for detecting and transmitting information, and can be used for diagnosis. Ultrasound is also a form of energy; when its intensity exceeds a certain value, it can interact with the medium through which it propagates, disrupting the latter's state, properties, and structure for therapeutic purposes. However, in both ultrasound diagnosis and treatment, the performance of ultrasound will inevitably be attenuated during propagation, preventing it from achieving the desired effect.

[0003] To reduce the attenuation of ultrasound during propagation, focused ultrasound is usually used. Focused ultrasound can non-invasively concentrate low-energy ultrasound waves into an elliptical focal volume on a millimeter scale, and use the thermal or mechanical effects of ultrasound to treat the target tissue.

[0004] Based on the amount of focused energy, focused ultrasound can generally be divided into high-intensity focused ultrasound (HIFU) and low-intensity focused ultrasound (HIFU). HIFU typically uses thermal effects and cavitation effects to instantly raise the temperature of diseased tissue within the focused area to above 60°C, causing irreversible coagulative necrosis, while the temperature of normal tissue outside the focused area remains within a safe range. Low-intensity focused ultrasound currently shows broad application prospects in areas such as ultrasound neuromodulation and blood-brain barrier opening.

[0005] Whether it's high-intensity focused ultrasound (HIFU) or low-intensity focused ultrasound (HIFU), the focused ultrasound transducer is the most critical component of the treatment system, directly determining the treatment outcome. Currently, focused ultrasound transducers can be classified according to their focusing method into acoustic lenticular focusing transducers, spherical self-focusing transducers, multi-element self-focusing transducers, and electronic phased array focusing transducers. Among these, acoustic lenticular focusing transducers and spherical self-focusing transducers are simple to manufacture and their lens or wafer shapes can be modified according to specific requirements. They have particular advantages for certain superficial tissues or situations where the sound source size requirement is small, and therefore are widely used.

[0006] Focused ultrasound transducers can be classified into single-frequency, dual-frequency, and multi-frequency types according to their frequency modes. Single-frequency high-intensity focused ultrasound (HIFU) ablation of deep or large tumors results in longer treatment times and increases the risk of damage to surrounding tissues, leading to poor treatment outcomes. Dual-frequency or multi-frequency HIFU, however, significantly enhances cavitation, not only increasing temperature rise but also aiding in monitoring the location of heat deposition, thereby shortening treatment time. Under dual-frequency HIFU, the confocal zone tissue is subjected not only to the combined action of two incident ultrasound beams but also to the difference frequency wave caused by the two incident waves, thus greatly enhancing the cavitation effect.

[0007] Most dual-frequency focused ultrasound transducers currently in use employ acoustic lens focusing transducers and spherical self-focusing transducers. Regardless of the type, both require the fabrication of two piezoelectric wafers of different thicknesses. However, due to the different thicknesses of the piezoelectric wafers, it is difficult to ensure that the wafers of different thicknesses are positioned in the same location and that they are on the same concave spherical surface during fabrication. This makes it difficult to achieve reliable confocal integration of the two piezoelectric wafers and precise control of the ultrasound propagation direction, resulting in difficulty focusing the two ultrasound beams to the same point and poor therapeutic effects. Summary of the Invention

[0008] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a dual-frequency focusing ultrasonic transducer, its preparation method, and its application, which realizes reliable confocal integration of two piezoelectric crystals and precise control of the ultrasonic wave propagation direction.

[0009] To achieve the above and other related objectives, in a first aspect, the present invention provides a dual-frequency focusing ultrasonic transducer, the dual-frequency focusing ultrasonic transducer comprising a housing and a transducer body disposed within the housing, the transducer body being configured from top to bottom as an acoustic lens, a matching layer, a piezoelectric layer and a backing layer, the piezoelectric layer comprising a piezoelectric part one and a piezoelectric part two, the piezoelectric part one comprising a piezoelectric crystal first, the piezoelectric part two comprising a piezoelectric crystal second and a dematching part, the piezoelectric crystal first and the piezoelectric crystal second being joined together on their horizontal sides and their top surfaces aligned to form a flat upper plane of the piezoelectric layer for confocal focusing by the acoustic lens.

[0010] By adding a metal dematching section to the bottom surface of a piezoelectric wafer, the resonant frequency of the wafer's vibration can be altered, resulting in two different resonant frequencies for wafers with and without the dematching section, thus achieving a dual-frequency focused ultrasonic transducer. The metal dematching section is made of a metal material with a larger mass and acoustic impedance than the piezoelectric wafer, such as tungsten or tungsten steel. Because the dematching section has a larger mass and acoustic impedance than the piezoelectric wafer, it has a stabilizing effect on the bottom surface of the piezoelectric wafer. According to vibration theory, the bottom surface of the piezoelectric wafer is unlikely to produce significant vibration displacement during vibration. Therefore, the bottom surface of the piezoelectric wafer changes from a free boundary condition to a fixed boundary condition. Compared to when both the top and bottom surfaces of the wafer are free boundary conditions without the dematching section, the top surface of the wafer with the dematching section is a free boundary condition, while the bottom surface is a fixed boundary condition. The resonant frequency of the piezoelectric wafer with the dematching section is half that of the wafer without the dematching section.

[0011] In some preferred embodiments, the resonant frequency of the second piezoelectric element is half the resonant frequency of the first piezoelectric element;

[0012] And / or, the piezoelectric wafer one and piezoelectric wafer two are made of the same material and have the same or symmetrical shape;

[0013] And / or, the upper plane of the piezoelectric layer is circular;

[0014] And / or, the de-matching portion is vertically aligned with the edge of the second piezoelectric wafer;

[0015] And / or, the de-matching portion completely covers the bottom surface of the second piezoelectric wafer.

[0016] In some specific embodiments, the materials of the second piezoelectric wafer and the first piezoelectric wafer are piezoelectric ceramics or piezoelectric single crystals;

[0017] And / or, the material of the dematching part is selected from metal, and the mass and acoustic impedance ratio of the metal are both greater than the mass and acoustic impedance ratio of the material of the piezoelectric wafer 2;

[0018] And / or, the thickness of the second piezoelectric wafer is 0.1-20 mm, and the diameter is 0.1-100 mm;

[0019] And / or, the thickness of the first piezoelectric wafer is 0.1-20 mm, and the diameter is 0.1-100 mm;

[0020] And / or, the material of the mating part is tungsten or tungsten steel;

[0021] And / or, the diameter of the unmatching part is 0.1-100mm and the thickness is 0.1-100mm.

[0022] In some preferred embodiments, the material of the mating part is tungsten carbide, and the density of the tungsten carbide is 12-20 g / cm³. 3 The acoustic impedance of the tungsten steel is 60-120 Mrayls.

[0023] And / or, the matching layer is set to at least one layer;

[0024] And / or, the thickness of each of the matching layers is 0.05-10 mm;

[0025] And / or, the material of the matching layer is an epoxy resin and filler composite material;

[0026] And / or, the dual-frequency ultrasonic transducer further includes coaxial cables corresponding to piezoelectric part one and piezoelectric part two respectively; the upper and lower surfaces of piezoelectric part two are respectively provided with positive and negative electrodes, the positive core wire of the corresponding coaxial cable is connected to the positive electrode of piezoelectric crystal two, and the negative ground wire of the corresponding coaxial cable is connected to the negative electrode of piezoelectric crystal two.

[0027] And / or, the upper and lower surfaces of the piezoelectric chip are respectively provided with a positive electrode and a negative electrode, the positive core wire of the corresponding coaxial cable is connected to the positive electrode of the piezoelectric chip, and the negative ground wire of the corresponding coaxial cable is connected to the negative electrode of the piezoelectric chip.

[0028] In some preferred embodiments, the acoustic lens includes a concave lens surface and a flat lens surface, the concave lens surface having a spherical structure, and the flat lens surface being bonded to the piezoelectric layer;

[0029] And / or, the material of the acoustic lens is epoxy resin;

[0030] And / or, the radius of curvature of the acoustic lens is 0.1-50 mm.

[0031] In some specific embodiments, the upper surface of the backing layer matches the lower surface of the piezoelectric layer to adhere the piezoelectric layer; the material of the backing layer is an epoxy resin and filler composite material;

[0032] And / or, the backing layer is integrally formed, including a backing portion one and a backing portion two that matches the mating portion;

[0033] And / or, the thickness of the second backing portion is the same as the thickness of the mating portion.

[0034] Secondly, the present invention also provides a method for fabricating a dual-frequency focused ultrasonic transducer, comprising the following steps:

[0035] (1) The sides of piezoelectric wafer one and piezoelectric wafer two are bonded together and their top surfaces are aligned so that the upper surface of the piezoelectric layer forms a plane. Preferably, the plane is a circular plane.

[0036] (2) The matching part is bonded to the bottom of the second piezoelectric wafer and vertically aligned with the edge of the second piezoelectric wafer to form a piezoelectric layer;

[0037] (3) Electrodes are plated on the upper and lower surfaces of the piezoelectric wafer one, and the electrodes are respectively connected to the positive core wire and the negative ground wire of the corresponding coaxial cable; electrodes are plated on the upper and lower surfaces of the piezoelectric part two, and the electrodes are respectively connected to the positive core wire and the negative ground wire of the corresponding coaxial cable.

[0038] (4) Fix the piezoelectric layer with the coaxial cable inside the housing, pour the backing material into the lower surface of the piezoelectric layer, and after curing, form a backing layer fixed inside the housing.

[0039] (5) The matching material is poured into the upper surface of the piezoelectric layer and cured to form a matching layer fixed inside the shell;

[0040] (6) Cast the acoustic lens material onto the acoustic lens fixture, and after curing, form an acoustic lens. Then, bond the acoustic lens to the upper end of the matching layer to obtain a dual-frequency focused ultrasonic transducer.

[0041] Thirdly, the present invention also provides a dual-frequency focused ultrasonic transducer array, including a concave spherical surface, wherein an array of through holes is formed on the concave spherical surface, and a dual-frequency focused ultrasonic transducer as described above is fixed in the through holes of the array of through holes.

[0042] Fourthly, the present invention also provides a method for fabricating a dual-frequency focusing ultrasonic transducer array, comprising the following steps:

[0043] S1. Design a three-dimensional model of a concave spherical surface;

[0044] S2. Print a concave spherical surface from the three-dimensional model designed in step S1 using 3D printing technology.

[0045] S3. Fix the above dual-frequency focused ultrasonic transducer in the concave spherical surface of step S2 of 3D printing to obtain the dual-frequency focused ultrasonic transducer array.

[0046] Fifthly, the present invention also provides a medical ultrasound therapy device, including a dual-frequency focused ultrasound transducer, wherein the dual-frequency focused ultrasound transducer is a dual-frequency focused ultrasound transducer as described above or a dual-frequency focused ultrasound transducer array as described above.

[0047] As described above, the dual-frequency focused ultrasonic transducer of the present invention, its preparation and application, have the following beneficial effects:

[0048] (1) The dual-frequency focusing ultrasonic transducer of the present invention combines piezoelectric wafer one and piezoelectric wafer two to form a circular planar piezoelectric layer. The setting of the dematching part makes the resonant frequency of piezoelectric wafer two half the resonant frequency of piezoelectric wafer one. At the same time, the use of acoustic lens confocalization makes it easier to ensure the confocal point, thereby improving the performance of the ultrasonic transducer.

[0049] (2) The piezoelectric crystals 2 and 1 of the dual-frequency focused ultrasound transducer of the present invention are identical. Compared with using planar piezoelectric crystals of different thicknesses to adjust the frequency, it is easier to ensure the common focus. The structure is simple and easy to process and manufacture. Only two piezoelectric crystals of the same size and thickness are needed. The dual-frequency function can be achieved by adding a dematching part, so as to better improve the treatment effect. Attached Figure Description

[0050] Figure 1 The diagram shown is a schematic diagram of the overall structure of a dual-frequency focused ultrasonic transducer according to the present invention.

[0051] Figure 2 The image shown is a cross-sectional view of the overall structure of a dual-frequency focused ultrasonic transducer according to the present invention.

[0052] Figure 3 The image shown is an exploded view of the overall structure of a dual-frequency focused ultrasonic transducer according to the present invention.

[0053] Figure 4 The diagram shown is a schematic diagram of a concave spherical structure for the application of a dual-frequency focused ultrasonic transducer according to the present invention.

[0054] Figure 5 The diagram shows the position of a dual-frequency focused ultrasonic transducer on a concave spherical surface according to the present invention.

[0055] Figure 6 The diagram shown is a flowchart of the manufacturing process of a dual-frequency focused ultrasonic transducer array according to the present invention.

[0056] Figure label:

[0057] 1. Outer shell; 2. Piezoelectric layer; 21. Piezoelectric wafer one; 22. Piezoelectric part two; 221. Piezoelectric wafer two; 222. Matching part; 3. Matching layer; 4. Acoustic lens; 5. Backing layer; 51. Backing part one; 52. Backing part two; 6. Coaxial cable; 7. Concave spherical surface. Detailed Implementation

[0058] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0059] Please see Figure 1-6 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0060] See Figure 1-6 This invention provides a dual-frequency focused ultrasonic transducer, its preparation method, and its application.

[0061] See Figure 1-2A dual-frequency focusing ultrasonic transducer includes a housing 1 and a transducer body placed inside the housing 1. The transducer body includes an acoustic lens 4, a matching layer 3, a piezoelectric layer 2, and a backing layer 5 connected in sequence. The piezoelectric layer 2 includes a first piezoelectric part and a second piezoelectric part 22. The first piezoelectric part includes a first piezoelectric crystal 21, and the second piezoelectric part 22 includes a second piezoelectric crystal 221 and a dematching part 222. The first piezoelectric crystal 21 and the second piezoelectric crystal 221 are identical. The dematching part 222 is located below the second piezoelectric crystal 221 and is fixedly connected to the second piezoelectric crystal 221 so that the resonant frequency of the second piezoelectric crystal 221 is different from the resonant frequency of the first piezoelectric crystal 21. The sides of the first piezoelectric crystal 21 and the second piezoelectric crystal 221 are joined together, and their top surfaces are aligned to form a flat upper plane of the piezoelectric layer 2 for confocal focusing by the acoustic lens 4. Under the action of the dematching part 222, the resonant frequency of the second piezoelectric crystal 221 is lower than that of the first piezoelectric crystal. The present invention achieves resonance of pulse sources of two frequencies by setting up the first piezoelectric crystal and the second piezoelectric crystal 22. At the same time, the acoustic lens 4 compresses the axial length of the acoustic focal domain. When treating thin-layer lesions, it can avoid or reduce damage to normal tissues, reduce safety risks during treatment, solve the problem that it is difficult to place the dual-frequency transducer combination in the same position, and facilitate the reliable confocal integration of the two piezoelectric crystals and the precise control of the direction of ultrasonic wave propagation.

[0062] In some embodiments of the present invention, see Figure 2 and Figure 3 Piezoelectric wafer 221 and piezoelectric wafer 21 are two identical planar semi-circular piezoelectric wafers. The sides of piezoelectric wafer 21 and piezoelectric wafer 221 are joined together, and their top surfaces are aligned to form a flat upper surface of the piezoelectric layer 2. The shape, coverage area, radius, and thickness of piezoelectric wafer 21 are exactly the same as those of piezoelectric wafer 221. Piezoelectric wafer 221 and piezoelectric wafer 21 are made of the same material, either piezoelectric ceramic or piezoelectric single crystal; preferably, the material is piezoelectric ceramic. The mating part 222 is perpendicularly aligned with the edge of piezoelectric wafer 221, and the mating part 222 completely covers the bottom surface of piezoelectric wafer 221. The material of the mating part 222 is... The material is selected from metals, and the mass and acoustic impedance ratio of the metal are greater than those of the piezoelectric wafer 221, such as tungsten, tungsten steel, etc. Preferably, the material of the dematching part 222 is tungsten steel. The upper and lower surfaces of the piezoelectric wafer 1 21 are both free boundary conditions. The upper surface of the piezoelectric wafer 221 is a free boundary condition, and the lower surface is connected to the dematching part 222. Since the mass and acoustic impedance of the dematching part 222 are greater than those of the piezoelectric wafer 221, it will have a fixing effect on the lower surface of the piezoelectric wafer 221, so that the lower surface of the piezoelectric wafer 221 changes from a free boundary condition to a fixed boundary condition, thereby making the resonant frequency of the piezoelectric wafer 221 less than that of the piezoelectric wafer 1 21.

[0063] In some embodiments of the present invention, see Figure 3 The frequency combinations of piezoelectric layer 2 are 500kHz / 1MHz, 600kHz / 1.2MHz, and 1MHz / 2MHz. Preferably, the frequency combination of piezoelectric layer 2 is 500kHz / 1MHz. The resonant frequency of piezoelectric crystal 1 21 is 1MHz, and the resonant frequency of piezoelectric part 22 is 500kHz. The planar piezoelectric crystal 221 and piezoelectric crystal 1 21 are identical. The two planar piezoelectric crystals with the same frequency are combined. Piezoelectric crystal 221 is connected to a de-matching part 222 made of tungsten steel. The de-matching part 222 makes the frequency of the planar piezoelectric crystal used in piezoelectric crystal 221 different from the frequency of the planar piezoelectric crystal used in piezoelectric crystal 1 21. The acoustic lens 4 is used for confocal focusing. Compared with using planar piezoelectric crystals of different thicknesses to adjust the frequency, it is easier to ensure the confocal focus and reduce the manufacturing difficulty of the ultrasonic transducer.

[0064] In some embodiments of the present invention, see Figure 3 The piezoelectric wafer 221 is made of PZT-4 piezoelectric ceramic, with a thickness of 0.1-20 mm and a diameter of 0.1-100 mm. Specifically, the piezoelectric wafer 221 has a thickness of 4 mm and a diameter of 20 mm. The piezoelectric wafer 21 is also made of PZT-4 piezoelectric ceramic, with a thickness of 0.1-20 mm and a diameter of 0.1-100 mm. Specifically, the piezoelectric wafer 21 has a thickness of 4 mm and a diameter of 20 mm. The mating part 222 is made of tungsten carbide, wherein the density of the tungsten carbide is 12-20 g / cm³. 3 Specifically, the density of tungsten steel is approximately 15 g / cm³. 3 The acoustic impedance of the tungsten steel is 60-120 Mrayls, specifically, the acoustic impedance of the tungsten steel is about 100 Mrayls, and the thickness of the dematching part 222 is 4 mm. The dematching part 222 is semi-circular and completely covers the bottom surface of the piezoelectric wafer 221. The diameter of the dematching part 222 is 0.1-100 mm, specifically, the diameter of the dematching part 222 is 20 mm.

[0065] In some embodiments of the present invention, see Figure 2 and Figure 3Two coaxial cables 6 are provided on the piezoelectric layer 2. The upper and lower surfaces of the second piezoelectric crystal 221 are respectively provided with positive and negative electrodes. The positive core wire of the coaxial cable 6 is connected to the positive electrode of the second piezoelectric crystal 221, and the negative ground wire of the coaxial cable 6 is connected to the negative electrode of the second piezoelectric crystal 221. The upper and lower surfaces of the first piezoelectric crystal 21 are respectively provided with positive and negative electrodes. The positive core wire of the coaxial cable 6 is connected to the positive electrode of the first piezoelectric crystal 21, and the negative ground wire of the coaxial cable 6 is connected to the negative electrode of the first piezoelectric crystal 21. The first piezoelectric crystal 21 and the second piezoelectric crystal 221 are combined in a plane. The sound field of the dual-frequency transducer is focused to the same position through the acoustic lens 4, thereby improving the sound field intensity at the focal position.

[0066] In some embodiments of the present invention, see [reference] Figure 1 and Figure 2 The acoustic lens 4 includes a concave lens surface and a flat lens surface. The concave lens surface has a spherical structure, and the flat lens surface is bonded to the piezoelectric layer 2. The material of the acoustic lens 4 is epoxy resin; the radius of curvature of the acoustic lens 4 is 0.1-50 mm, specifically, the radius of curvature of the acoustic lens 4 is 25 mm. The acoustic lens 4 is used to ensure the common focal point of piezoelectric wafers at different frequencies.

[0067] In some embodiments of the present invention, see [reference] Figure 2 and Figure 3 The matching layer 3 is located between the piezoelectric layer 2 and the acoustic lens 4, and is connected to both the piezoelectric layer 2 and the acoustic lens 4. The material of the matching layer 3 is a composite material of epoxy resin and filler, wherein the mass ratio of epoxy resin to filler is (4-10):(1-3); specifically, the mass ratio of epoxy resin to filler is 4:1; the filler is alumina powder or tungsten powder, specifically, the filler is tungsten powder. The matching layer 3 is at least one layer, specifically, the matching layer 3 is one layer, and the thickness of the matching layer 3 is 0.7-0.8 mm, specifically, the thickness of the matching layer 3 is 0.75 mm. The matching layer 3 is set to achieve acoustic impedance matching and increase the acoustic propagation efficiency of the ultrasonic transducer.

[0068] In some embodiments of the present invention, see [reference] Figure 2 and Figure 3The backing layer 5 is disposed at the rear end of the piezoelectric layer 2. The material of the backing layer 5 is a composite material of epoxy resin and filler, wherein the mass ratio of epoxy resin to filler is (4-10):(1-3); specifically, the mass ratio of epoxy resin to filler is 4:1; the filler is alumina powder or tungsten powder, preferably tungsten powder; the backing layer 5 includes a first backing part 51 and a second backing part 52 corresponding to the matching part 222. The first backing part 51 and the second backing part 52 are integrally formed. The second backing part 52 is semi-circular and has the same radius as the first backing part 51. The thickness ratio of the second backing part 52 to the first backing part 51 is (4-5). (15-16) Specifically, the thickness of the second backing portion 52 is 4mm, and the thickness of the first backing portion 51 is 16mm. The second backing portion 52 is located above the first backing portion 51, and their edges are vertically aligned. The unmatching portion 222 is semi-circular. The unmatching portion 222 and the second backing portion 52 are located on the same horizontal plane and have the same area and thickness. The unmatching portion 222 is located on the upper surface of the first backing portion 51 and is bonded to the upper surface of the first backing portion 51. The unmatching portion 222 and the second backing portion 52 are bonded to form a circular plane, which facilitates the placement of the circular plane formed by the first piezoelectric wafer 21 and the second piezoelectric wafer 221. The backing layer 5 serves two purposes: firstly, to absorb back-propagating sound waves, thereby increasing the bandwidth of the transducer and thus improving the axial resolution; and secondly, to increase the stability of the transducer while reducing energy loss.

[0069] In some embodiments of the present invention, see [reference] Figure 2 and Figure 3 The piezoelectric chip 21 is located above the backing portion 2 52 and is bonded to the backing portion 2 52, and the piezoelectric chip 21 completely covers the upper surface of the backing portion 2 52.

[0070] This embodiment also provides a method for fabricating a dual-frequency focused ultrasonic transducer, including the following steps:

[0071] (1) The sides of piezoelectric wafer 1 21 and piezoelectric wafer 221 are bonded together and their top surfaces are aligned so that the upper surface of the piezoelectric layer 2 forms a circular plane. Specifically, an adhesive material is used for bonding, specifically, the adhesive material is epoxy resin.

[0072] (2) The matching part 222 is attached to the bottom of the piezoelectric wafer 221 and vertically aligned with the edge of the piezoelectric wafer 221 to form a piezoelectric layer 2;

[0073] (3) Electrodes are deposited on the front and back surfaces of the planar piezoelectric wafer used in piezoelectric wafer 1 21, and the electrodes are respectively connected to the positive and negative terminals of the corresponding coaxial cable 6; Electrodes are deposited on the front and back surfaces of the planar piezoelectric wafer used in piezoelectric wafer 221, and the electrodes are respectively connected to the positive and negative terminals of the corresponding coaxial cable 6; Specifically, in step (3), electrodes are deposited on the front and back surfaces of the planar piezoelectric wafers used in piezoelectric wafer 1 21 and piezoelectric wafer 221 to form wafer positive and wafer negative electrodes, and each wafer positive electrode is connected to the positive terminal of the corresponding coaxial cable 6; each wafer negative electrode is connected to the negative terminal of each corresponding coaxial cable 6;

[0074] (4) Fix the piezoelectric layer 2 connected with the coaxial cable 6 inside the outer shell 1, pour the backing material into the lower surface of the piezoelectric layer 2, and after curing, form the backing layer 5 fixed inside the outer shell 1.

[0075] (5) The matching material is poured into the upper surface of the piezoelectric layer 2 and cured to form a matching layer 3 fixed inside the shell 1; wherein the matching material is preferably a composite material of epoxy resin and filler.

[0076] (6) The acoustic lens 4 material is cast onto the acoustic lens 4 fixture, and after curing, the acoustic lens 4 is formed. The acoustic lens 4 is then bonded to the upper end of the matching layer 3 to obtain the dual-frequency focusing ultrasonic transducer. The acoustic lens 4 is used to ensure that the piezoelectric crystals of different frequencies have a common focal point.

[0077] See Figure 4-6 This embodiment also provides a dual-frequency focused ultrasonic transducer array, including a concave spherical surface 7, on which a through-hole array is formed, and a dual-frequency focused ultrasonic transducer as described above is fixed in the through-holes of the through-hole array.

[0078] See Figure 4-6 This embodiment also provides a method for fabricating a dual-frequency focused ultrasonic transducer array, comprising the following steps:

[0079] S1. Use 3D design software to design a 3D model of the concave spherical surface 7; the radius of curvature of the concave spherical surface 7 can be designed according to the actual location and size of the lesion, and the number and accurate arrangement of the transducer array elements in the concave spherical surface 7 can also be designed according to the actual treatment application needs; based on the designed size of the concave spherical surface 7 and the number and position of the transducers.

[0080] S2. The three-dimensional model designed in step S1 is accurately printed using 3D printing technology to produce the designed concave spherical surface 7; the material of the concave spherical surface 7 is selected from resin material.

[0081] S3. Fix the aforementioned dual-frequency focused ultrasonic transducer into the concave spherical surface 7 from step S2 of the 3D printing process to obtain the dual-frequency focused ultrasonic transducer array. The spherical self-focusing transducer array contains a total of 64 dual-frequency ultrasonic transducer elements, arranged in 5 rings. The number of elements in each ring from bottom to top is 7, 10, 13, 16, and 18, respectively. The spherical surface is hemispherical with a diameter of 200 mm.

[0082] This embodiment also provides a medical ultrasound therapy device, including a dual-frequency focused ultrasound transducer component, wherein the dual-frequency focused ultrasound transducer component is the dual-frequency focused ultrasound transducer described above or a dual-frequency focused ultrasound transducer array as described above.

[0083] In this invention, the piezoelectric layer 2 of the dual-frequency focusing ultrasound transducer array vibrates under the action of piezoelectric crystal 21 and piezoelectric crystal 221 upon receiving an electrical signal, subsequently generating an acoustic signal. This signal is then reduced by the matching layer 3 and the backing layer 5, and subsequently focused by the acoustic lens 4 to improve therapeutic efficacy. Furthermore, the excitation signal generated by the signal generator is amplified by a power amplifier and used to drive the dual-frequency focusing ultrasound transducer array for the treatment of diseases such as brain tumors, neuropathic pain, Parkinson's disease with tremor, obsessive-compulsive disorder, and stroke.

[0084] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A dual-frequency focused ultrasonic transducer, characterized in that, The dual-frequency focused ultrasonic transducer includes a housing (1) and a transducer body placed inside the housing (1). The transducer body is arranged from top to bottom as an acoustic lens (4), a matching layer (3), a piezoelectric layer (2), and a backing layer (5). The piezoelectric layer (2) includes a piezoelectric part one and a piezoelectric part two (22). The piezoelectric part one includes a piezoelectric crystal first (21), and the piezoelectric part two (22) includes a piezoelectric crystal second (221) and a dematching part (222). The piezoelectric crystal first (21) and the piezoelectric crystal second (221) are completely identical. The matching part (222) is located below the second piezoelectric chip (221) and is fixedly connected to the second piezoelectric chip (221) so that the resonant frequency of the second piezoelectric chip (221) is different from the resonant frequency of the first piezoelectric chip (21). The first piezoelectric chip (21) and the second piezoelectric chip (221) are side-joined and their top surfaces are aligned to form a flat upper plane of the piezoelectric layer (2) for co-focusing by the acoustic lens (4). The shape, coverage area, radius and thickness of the first piezoelectric chip (21) are exactly the same as those of the second piezoelectric chip (221).

2. The dual-frequency focused ultrasonic transducer according to claim 1, characterized in that: The resonant frequency of the second piezoelectric part (22) is half the resonant frequency of the first piezoelectric part; And / or, the piezoelectric wafer one (21) and the piezoelectric wafer two (221) are made of the same material and have the same or symmetrical shape; And / or, the upper plane of the piezoelectric layer (2) is circular; And / or, the de-matching portion (222) is vertically aligned with the edge of the second piezoelectric wafer (221); And / or, the de-matching part (222) completely covers the bottom surface of the second piezoelectric wafer (221).

3. The dual-frequency focused ultrasonic transducer according to claim 1, characterized in that: The materials of the second piezoelectric wafer (221) and the first piezoelectric wafer (21) are piezoelectric ceramics or piezoelectric single crystals; And / or, the material of the dematching part (222) is selected from metal, and the mass and acoustic impedance ratio of the metal are both greater than the mass and acoustic impedance ratio of the material of the piezoelectric wafer two (221); And / or, the thickness of the second piezoelectric wafer (221) is 0.1-20 mm and the diameter is 0.1-100 mm; And / or, the thickness of the piezoelectric wafer one (21) is 0.1-20 mm and the diameter is 0.1-100 mm; And / or, the material of the de-matching part (222) is tungsten or tungsten steel; And / or, the diameter of the unmatching part (222) is 0.1-100 mm and the thickness is 0.1-100 mm.

4. The dual-frequency focused ultrasonic transducer according to claim 3, characterized in that: The material of the unmatching part (222) is tungsten carbide, and the density of the tungsten carbide is 12-20 g / cm³. 3 The acoustic impedance of the tungsten steel is 60-120 Mrayls. And / or, the matching layer (3) is set to at least one layer; And / or, the thickness of each of the matching layers (3) is 0.05-10 mm; And / or, the material of the matching layer (3) is an epoxy resin and filler composite material; And / or, the dual-frequency ultrasonic transducer further includes coaxial cables (6) corresponding to piezoelectric part one and piezoelectric part two (22) respectively; the upper and lower surfaces of piezoelectric part two (22) are respectively provided with positive and negative electrodes, the positive electrode core wire of the corresponding coaxial cable (6) is connected to the positive electrode of piezoelectric crystal two (221), and the negative electrode ground wire of the corresponding coaxial cable (6) is connected to the negative electrode of piezoelectric crystal two (221); And / or, the upper and lower surfaces of the piezoelectric chip (21) are respectively provided with a positive electrode and a negative electrode, the positive core wire of the corresponding coaxial cable (6) is connected to the positive electrode of the piezoelectric chip (21), and the negative ground wire of the corresponding coaxial cable (6) is connected to the negative electrode of the piezoelectric chip (21).

5. The dual-frequency focused ultrasonic transducer according to claim 1, characterized in that: The acoustic lens (4) includes a concave lens surface and a flat lens surface. The concave lens surface has a spherical structure, and the flat lens surface is attached to the piezoelectric layer (2). And / or, the material of the acoustic lens (4) is epoxy resin; And / or, the radius of curvature of the acoustic lens (4) is 0.1-50 mm.

6. The dual-frequency focused ultrasonic transducer according to claim 1, characterized in that: The upper surface of the backing layer (5) matches the lower surface of the piezoelectric layer (2) to adhere the piezoelectric layer (2); the material of the backing layer (5) is an epoxy resin and filler composite material; And / or, the backing layer (5) is integrally formed, including a backing part one (51) and a backing part two (52) that matches the mating part (222). And / or, the thickness of the backing portion two (52) is the same as the thickness of the matching portion (222).

7. A method for manufacturing a dual-frequency focused ultrasonic transducer as described in any one of claims 1-6, characterized in that: Includes the following steps: (1) The sides of piezoelectric wafer one (21) and piezoelectric wafer two (221) are bonded together and their top surfaces are aligned so that the upper surface of the piezoelectric layer (2) forms a plane. (2) The matching part (222) is attached to the bottom of the piezoelectric wafer 2 (221) and vertically aligned with the edge of the piezoelectric wafer 2 (221) to form a piezoelectric layer (2). (3) Electrodes are plated on the upper and lower surfaces of the piezoelectric wafer (21), and the electrodes are respectively connected to the positive core wire and the negative ground wire of the corresponding coaxial cable (6); Electrodes are plated on the upper and lower surfaces of the piezoelectric part (22), and the electrodes are respectively connected to the positive core wire and the negative ground wire of the corresponding coaxial cable (6); (4) Fix the piezoelectric layer (2) connected with the coaxial cable (6) inside the shell (1), pour the backing material into the lower surface of the piezoelectric layer (2), and after curing, form a backing layer (5) fixed inside the shell (1). (5) The matching material is poured into the upper surface of the piezoelectric layer (2) and cured to form a matching layer (3) fixed in the shell (1). (6) Cast the acoustic lens (4) material onto the acoustic lens (4) tooling, and after curing, form the acoustic lens (4). Then, bond the acoustic lens (4) to the upper end of the matching layer (3) to obtain the dual-frequency focused ultrasonic transducer.

8. A dual-frequency focused ultrasonic transducer array, characterized in that: It includes a concave spherical surface (7), on which a through-hole array is provided, and a dual-frequency focused ultrasonic transducer as described in any one of claims 1-6 is fixed in the through-holes of the through-hole array.

9. The method for fabricating a dual-frequency focused ultrasonic transducer array as described in claim 8, characterized in that: Includes the following steps: S1. Design a three-dimensional model of the concave spherical surface (7); S2. Print the concave spherical surface (7) using 3D printing technology from the three-dimensional model designed in step S1. S3. Fix the dual-frequency focused ultrasonic transducer according to any one of claims 1-6 in the concave spherical surface (7) in step S2 of 3D printing to obtain the dual-frequency focused ultrasonic transducer array.

10. A medical ultrasound therapy device, comprising a dual-frequency focused ultrasound transducer, wherein the dual-frequency focused ultrasound transducer is the dual-frequency focused ultrasound transducer as described in any one of claims 1-6 or the dual-frequency focused ultrasound transducer array as described in claim 8.

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