Passive acoustic functional component of an ultrasonic transducer and method of manufacturing and use thereof

Abstract

The application belongs to the technical field of ultrasonic transducers, and particularly relates to a passive acoustic functional component of an ultrasonic transducer and a preparation method and application thereof. The passive acoustic functional component comprises an equivalent matching layer unit and a phase acoustic pixel layer arranged above the equivalent matching layer unit. The equivalent matching layer unit comprises N equivalent matching layers from bottom to top, and N is greater than or equal to 2. The equivalent matching layer comprises a first sublayer and a second sublayer. The raw material of the first sublayer comprises a high acoustic impedance material. The raw material of the second sublayer comprises a low acoustic impedance material. The raw material of the phase acoustic pixel layer comprises a low acoustic impedance material. The application solves the problem that impedance mismatch between a piezoelectric active material and a working medium leads to low transmission efficiency and the ultrasonic transducer cannot emit a broadband signal in water. The provided passive acoustic functional component can improve acoustic transmission rate, realize focusing of ultrasonic waves and improve transmission efficiency.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic transducer technology, specifically relating to a passive acoustic functional component of an ultrasonic transducer, its preparation method, and its application. Background Technology

[0002] With the continuous development of ultrasound technology, it is now widely used in industry, biomedicine, and national defense. Ultrasound can be mainly divided into biomedical ultrasound and detection ultrasound. The former is used in medicine as an important means of detection and treatment, and is often used for ultrasound imaging, medical lithotripsy, targeted ablation, etc.; while the latter is used in national defense for radar positioning, and in industry for defect detection such as welds and gas leaks.

[0003] An ultrasonic transducer is an electroacoustic conversion device that transmits and receives ultrasonic waves, and it is the core component of ultrasonic equipment. The bandwidth of an ultrasonic transducer is one of its most important performance characteristics, as various applications of ultrasound rely heavily on focusing. For example, in biomedical ultrasound, a well-focused ultrasonic beam can concentrate greater energy on a smaller spatial scale, minimizing its impact on the vicinity of the target area. This makes it suitable for targeted therapy or applications requiring high power in a localized space. In diagnostic ultrasound, the precision of the focused ultrasonic waves directly determines the spatial resolution of the image.

[0004] However, in biomedical ultrasound and diagnostic ultrasound, impedance mismatch between high acoustic impedance piezoelectric active materials and low acoustic impedance working media (water) can cause severe ultrasound reflection at different interfaces, resulting in a large loss of acoustic energy, low overall ultrasound transmission efficiency, and thus a small ultrasonic transducer bandwidth.

[0005] To address this issue, a matching layer needs to be added between the piezoelectric active material and the working medium. For example, Chinese Patent Publication No. CN116197102A discloses an ultrasonic transducer comprising a piezoelectric layer and a matching layer. The matching layer is disposed between the piezoelectric layer and the object under test (DUT), achieving acoustic matching between the piezoelectric layer and the DUT through the matching layer. The piezoelectric layer is used to convert ultrasonic waves into electrical energy. The sound velocity in the matching layer exhibits a gradient distribution in at least one direction. This technical solution, through the gradient distribution of the sound velocity in the matching layer, ensures that ultrasonic waves of different frequencies have the same wavelength within the matching layer. This allows for acoustic matching between piezoelectric layers with different structures and human tissue, improving the transmittance of ultrasonic waves in the matching layer and increasing the bandwidth of the ultrasonic transducer. Chinese Patent Publication No. CN117483217A discloses an ultrasonic transducer and its fabrication method. The ultrasonic transducer includes a substrate layer, a piezoelectric layer, and an acoustic matching layer stacked sequentially along the thickness direction. The piezoelectric layer includes a substrate, which includes a wiring area and multiple piezoelectric elements spaced in a row-column pattern along the row and column directions. Adjacent piezoelectric elements are bonded together with an insulating adhesive. The upper and lower surfaces of the piezoelectric elements and the insulating adhesive are formed by vacuum-deposited electrode layers to create row and column strip electrodes, which can be formed by cutting and photolithography. The end of the first electrode layer is electrically connected to a first conductive element; the end of the second electrode layer is electrically connected to a second conductive element. The substrate layer and the acoustic matching layer can directly contact the piezoelectric layer for acoustic matching, improving the acoustic matching effect between the piezoelectric elements and the substrate layer and acoustic matching layer.

[0006] However, the matching layer involved in the above technical solution does not have the function of focused ultrasound. If focused ultrasound is required, an acoustic lens needs to be added. Traditional acoustic lenses have disadvantages such as difficult curvature processing, insertion loss, and severe interface reflection between different materials, which leads to unconcentrated ultrasonic energy, poor focusing effect, and seriously affects the detection accuracy.

[0007] Therefore, how to solve the problem of low transmission efficiency caused by impedance mismatch between piezoelectric active materials and working medium, which prevents ultrasonic transducers from transmitting broadband signals in water, and at the same time focus ultrasonic waves efficiently, accurately and flexibly, is an important problem that needs to be solved to improve the performance of ultrasonic transducers. Summary of the Invention

[0008] This invention addresses the problem of low transmission efficiency caused by impedance mismatch between piezoelectric active materials and the working medium, which prevents ultrasonic transducers from transmitting broadband signals in water. It provides a passive acoustic functional component for an ultrasonic transducer, its preparation method, and its application.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] The first aspect of the present invention provides a passive acoustic functional component for an ultrasonic transducer, the passive acoustic functional component comprising an equivalent matching layer unit and a phase acoustic pixel layer disposed on the equivalent matching layer unit;

[0011] The equivalent matching layer unit comprises N equivalent matching layers from bottom to top, where N≥2;

[0012] The equivalent matching layer includes a first sub-layer and a second sub-layer; the first sub-layer is made of a high acoustic impedance material; the second sub-layer is made of a low acoustic impedance material; and the phase acoustic pixel layer is made of a low acoustic impedance material.

[0013] The volume fraction ratio of high acoustic impedance material to low acoustic impedance material in the Nth equivalent matching layer is n N satisfy:

[0014]

[0015] Where, x N and y N These are the lengths of the first and second sub-layers in the Nth equivalent matching layer, respectively; n N It exhibits a gradient distribution.

[0016] n N Gradient distribution refers to n N A gradually changing distribution in one direction, such as monotonically decreasing or monotonically increasing.

[0017] In some preferred embodiments, the n N The gradient distribution decreases or increases monotonically from the first equivalent matching layer to the Nth equivalent matching layer, preferably decreasing monotonically.

[0018] In some preferred embodiments, M equivalent matching layer units are arranged side by side; M ≥ 1.

[0019] In some preferred embodiments, the N equivalent matching layers have the same length and width.

[0020] The present invention does not specifically limit the thickness of the N equivalent matching layers. According to what is known in the art, the thickness of the equivalent matching layer is one-quarter wavelength.

[0021] In some preferred embodiments, the first sublayer and the second sublayer have the same thickness.

[0022] In some preferred embodiments, the high acoustic impedance material is selected from one or more of PZT (lead zirconate titanate), zirconium oxide, tungsten, tungsten oxide, aluminum oxide, zinc, zinc oxide and lithium niobate, preferably PZT.

[0023] In some preferred embodiments, the low acoustic impedance material is selected from one or more of epoxy resin, acrylate, methacrylate, HTV silicone (solid silicone rubber), RTV silicone (room temperature vulcanizing silicone rubber), PDMS (polydimethylsiloxane), and silica, preferably epoxy resin.

[0024] In some preferred embodiments, the raw materials of the first and second sub-layers in the N equivalent matching layers are the same; the low acoustic impedance material in the phase acoustic pixel layer is the same as the low acoustic impedance material in the second sub-layer of the equivalent matching layer.

[0025] The acoustic impedance Z of the Nth equivalent matching layer N satisfy:

[0026]

[0027] Where, n N Let ρ be the volume fraction ratio of high acoustic impedance material to low acoustic impedance material in the Nth equivalent matching layer, and let ρ and ρ′ be the densities of the high acoustic impedance material and the low acoustic impedance material, respectively. 11 e′ is the value in the first row and first column of the stiffness matrix of the high acoustic impedance material. 11 e represents the value in the first row and first column of the stiffness matrix of the low acoustic impedance material; 12 e′ represents the value in the first row and second column of the stiffness matrix of a high acoustic impedance material. 12 This represents the value in the first row and second column of the stiffness matrix for materials with low acoustic impedance.

[0028] The acoustic impedance Z of the phase acoustic pixel layer in this invention h The acoustic impedance of the raw material of the phase acoustic pixel layer.

[0029] The sound velocity c of the Nth equivalent matching layer N satisfy:

[0030]

[0031] Where, n N Z represents the volume fraction ratio of high acoustic impedance material to low acoustic impedance material in the Nth equivalent matching layer, where ρ and ρ′ are the densities of the high acoustic impedance material and the low acoustic impedance material, respectively. N Let N be the acoustic impedance of the Nth equivalent matching layer.

[0032] The sound velocity c of the phase acoustic pixel layer satisfies:

[0033]

[0034] Where ρ′ is the density of the low acoustic impedance material, Z h The acoustic impedance of the phase acoustic pixel layer.

[0035] In some preferred embodiments, the acoustic impedance of the first equivalent matching layer is ≤40 MRayl, and the acoustic impedance of the phase acoustic pixel layer is ≥1.5 MRayl.

[0036] In a preferred embodiment, the acoustic impedance of the first equivalent matching layer is ≤30MRayl, and the acoustic impedance of the phase acoustic pixel layer is ≥2.5MRayl, so the acoustic impedance gradient of the passive acoustic functional component varies from 2.5MRayl to 30MRayl.

[0037] In some preferred embodiments, the equivalent matching layer unit comprises N equivalent matching layers from bottom to top, where N≥3.

[0038] Theoretically, traditional multi-layer matching layers can significantly improve the bandwidth of ultrasonic transducers compared to single-layer matching layers, and can further enhance ultrasonic transmittance. However, in practice, each additional matching layer introduces numerous manufacturing challenges, such as increased bonding difficulty and a higher probability of air bubbles. These factors can prevent the relative bandwidth from reaching the theoretical value. This invention achieves a gradient acoustic impedance structure by altering the volume fraction ratio of high-impedance to low-impedance materials. This precisely adjustable structure improves the transmittance of ultrasonic energy and the bandwidth of the ultrasonic transducer.

[0039] A second aspect of the present invention provides a method for preparing the above-mentioned passive acoustic functional component, comprising the following steps:

[0040] S1. A first sublayer is prepared using a high acoustic impedance material, and a second sublayer is prepared by injecting a low acoustic impedance material into the remaining space of the equivalent matching layer unit to obtain the equivalent matching layer unit.

[0041] S2. Prepare a mold for the phase acoustic pixel layer by injecting a low acoustic impedance material into the mold for the phase acoustic pixel layer.

[0042] S3. Connect the equivalent matching layer unit and the phase acoustic pixel layer to obtain a passive acoustic functional component.

[0043] In some preferred embodiments, step S1 specifically involves: firstly, a first sublayer with a similar stepped structure is prepared using a high acoustic impedance material; then, the prepared first sublayer is ultrasonically cleaned and placed in an oven to dry and stand; finally, a second sublayer is prepared by injecting a low acoustic impedance material into the remaining space of the equivalent matching layer unit, a steel block is placed to flatten it, and it is heated and pressurized to obtain the equivalent matching layer unit after curing.

[0044] In some preferred embodiments, the method for preparing the mold of the phase acoustic pixel layer in step S2 is as follows: a simulation numerical model of ultrasound is established by the K-space pseudospectral method. An acoustic pixel reconstruction surface is set in the model to record the ultrasound time-domain signal. A virtual excitation source is set to simulate the process of ultrasound propagating from the virtual excitation source to the acoustic pixel reconstruction surface. The distance between the virtual excitation source and the acoustic pixel reconstruction surface is the focal length F. The ultrasound signal recorded by the acoustic pixel reconstruction surface is flipped on the time axis. The processed signal is subjected to Fourier transform to extract the phase of the required frequency, thereby obtaining the phase distribution of the phase acoustic pixel layer. The surface of the phase acoustic pixel layer is divided into pixels with the same width Δh but different thicknesses h(i,j). The thickness of each pixel in the phase acoustic pixel layer is calculated through the phase distribution, and the number of pixels in the phase acoustic pixel layer is determined to obtain the mold of the phase acoustic pixel layer.

[0045] In some preferred embodiments, the thickness h(i, j) of the pixel satisfies:

[0046]

[0047] Where ω(i,j) is the phase of pixel (i,j), f is the ultrasonic frequency, and c w and c h These represent the sound speeds of water and the phase acoustic pixel layer, respectively.

[0048] In some preferred embodiments, step S2 specifically involves: preparing a mold for the phase acoustic pixel layer, injecting a low acoustic impedance material into the mold for the phase acoustic pixel layer, placing a steel block to flatten it, heating and pressurizing it, and curing it to obtain the phase acoustic pixel layer.

[0049] The preparation of the equivalent matching layer unit and the phase acoustic pixel layer is not specifically limited and can be obtained by 3D printing, etching, laser cutting, etc.

[0050] In some preferred embodiments, the equivalent matching layer unit and the phase acoustic pixel layer are obtained as passive acoustic functional components by spin-coating a crosslinking agent at the contact surface, wherein the crosslinking agent is epoxy resin.

[0051] Traditional matching layers lack the function of focusing ultrasound. If focusing is required, acoustic lenses are needed, but these lenses suffer from drawbacks such as difficulty in fabricating curvature, insertion loss, and severe interface reflection between different materials. This results in unconcentrated ultrasonic energy, poor focusing, and significantly impacts detection accuracy. This invention, however, designs a gradient acoustic impedance structure and adds a phase acoustic pixel layer to its low acoustic impedance side, enabling efficient, precise, and flexible focusing of ultrasonic waves, thus improving the performance of the ultrasonic transducer.

[0052] The third aspect of the present invention provides the application of the above-mentioned passive acoustic functional components in the fabrication of ultrasonic transducers.

[0053] In some preferred embodiments, the ultrasonic transducer includes passive acoustic functional components and piezoelectric active materials.

[0054] In some preferred embodiments, the passive acoustic functional component is fastened to the upper surface of the piezoelectric active material.

[0055] This invention does not specifically limit the piezoelectric active material; it can be a single element, a one-dimensional or two-dimensional array.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] 1. The passive functional component provided by this invention has a gradient acoustic impedance structure, including N equivalent matching layers, N≥2; and a phase acoustic pixel layer. The high acoustic impedance side can match the impedance of the piezoelectric excitation layer, while the phase acoustic pixel layer on the low acoustic impedance side can not only match the acoustic impedance (1.5MRayl) of the transmission medium (water), improving the transmission efficiency and bandwidth of the ultrasonic transducer and reducing ultrasonic loss caused by interface reflection, but also focus the ultrasound, realizing ultrasonic energy focusing and targeted control. This solves the problem of low transmission efficiency caused by impedance mismatch between piezoelectric active materials and water, which prevents the ultrasonic transducer from transmitting broadband signals in water. It improves the acoustic transmittance while realizing the focusing of ultrasonic waves and the improvement of transmission efficiency.

[0058] 2. The passive acoustic functional part provided by the present invention achieves a gradient acoustic impedance structure by changing the volume fraction ratio of high acoustic impedance material to low acoustic impedance material, which is precisely adjustable and improves the transmittance of ultrasonic energy and the bandwidth of ultrasonic transducer.

[0059] 3. The passive acoustic functional component provided by this invention can focus ultrasonic waves efficiently, accurately, and flexibly, thereby improving the performance of ultrasonic transducers. Attached Figure Description

[0060] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 This is a schematic diagram of the passive acoustic functional components of the ultrasonic transducer according to an embodiment of the present invention;

[0062] Figure 2 This is a schematic diagram of the phase acoustic pixel layer according to an embodiment of the present invention;

[0063] Figure 3This is a schematic diagram of the ultrasonic transducer structure in an application example of the present invention;

[0064] Figure 4 and Figure 5 The image shows a finite element acoustic field simulation of an ultrasonic transducer used in an application example of this invention. Detailed Implementation

[0065] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0066] Unless otherwise specified, all raw materials used in the following embodiments are commercially available or prepared by conventional methods in the art.

[0067] The sources of raw materials in the embodiments of the present invention are shown in Table 1:

[0068] Table 1

[0069] PZT CTS Corporation Epoxy resin Epoxy Technology, Model EPO-TEK301 curing agent Epoxy Technology

[0070] like Figure 1 As shown, in one embodiment of the present invention, the passive acoustic functional component of the ultrasonic transducer includes six equivalent matching layer units arranged side by side and a phase acoustic pixel layer disposed on the equivalent matching layer units; the equivalent matching layer unit includes three equivalent matching layers from bottom to top, namely a first equivalent matching layer, a second equivalent matching layer and a third equivalent matching layer; the three equivalent matching layers have the same length and width, and a thickness of one-quarter wavelength; the equivalent matching layer includes a first sub-layer and a second sub-layer, and the first sub-layer and the second sub-layer have the same thickness.

[0071] In one embodiment of the present invention, the raw materials of the first sub-layer and the second sub-layer in the three equivalent matching layers are PZT and epoxy resin, respectively; the raw material of the phase acoustic pixel layer is epoxy resin.

[0072] The volume fraction ratio of PZT to epoxy resin in the Nth equivalent matching layer is n N satisfy:

[0073]

[0074] Where, x N and y N These are the lengths of the first and second sub-layers in the Nth equivalent matching layer, respectively;

[0075] In the first equivalent matching layer, x1 = 3.6 mm and y1 = 1.2 mm, so n1 = 0.5625; in the second equivalent matching layer, x2 = 2.4 mm and y2 = 2.4 mm, so n2 = 0.25; in the third equivalent matching layer, x3 = 1.2 mm and y3 = 3.6 mm, so n3 = 0.0625.

[0076] The acoustic impedance Z of the Nth equivalent matching layer N satisfy:

[0077]

[0078] Where, n N Let be the volume fraction ratio of PZT and epoxy resin in the Nth equivalent matching layer, and ρ and ρ′ be the densities of PZT and epoxy resin, respectively. 11 e′ is the value in the first row and first column of the stiffness matrix of PZT. 11 e represents the value in the first row and first column of the epoxy resin stiffness matrix; 12 e′ is the value in the first row and second column of the stiffness matrix of PZT. 12 This represents the value in the first row and second column of the epoxy resin stiffness matrix.

[0079] The stiffness matrix of PZT is:

[0080]

[0081] The stiffness matrix of epoxy resin is:

[0082]

[0083] Based on the density of PZT ρ = 7772 kg / m³ 3 The density of epoxy resin ρ′ = 1110 kg / m³ 3 Given n1 = 0.5625, n2 = 0.25, and n3 = 0.0625, the acoustic impedance of the first equivalent matching layer is Z1 = 21.99 MRayl, the acoustic impedance of the second equivalent matching layer is Z2 = 10.99 MRayl, and the acoustic impedance of the third equivalent matching layer is Z3 = 4.43 MRayl.

[0084] The acoustic impedance Z of the phase acoustic pixel layer h The acoustic impedance of epoxy resin, i.e., Z h =2.7MRayl;

[0085] Therefore, in this embodiment, the acoustic impedance gradient of the passive acoustic functional component varies from 2.7MRayl to 21.99MRayl.

[0086] The sound velocity c of the Nth equivalent matching layer N satisfy:

[0087]

[0088] Where, n N Z represents the volume fraction ratio of PZT to epoxy resin in the Nth equivalent matching layer, where ρ and ρ′ are the densities of PZT and epoxy resin, respectively. N Let N be the acoustic impedance of the Nth equivalent matching layer;

[0089] Based on the density of PZT ρ = 7772 kg / m³ 3 The density of epoxy resin ρ′ = 1110 kg / m³ 3 Given n1 = 0.5625, n2 = 0.25, n3 = 0.0625, Z1 = 21.99 MRayl, Z2 = 10.99 MRayl, Z3 = 4.43 MRayl; then the sound velocity of the first equivalent matching layer is c1 = 4397 m / s, the sound velocity of the second equivalent matching layer is c2 = 3880 m / s, and the sound velocity of the third equivalent matching layer is c3 = 2888 m / s.

[0090] The sound velocity c of the phase acoustic pixel layer satisfies:

[0091]

[0092] Where ρ′ is the density of epoxy resin, Z h The acoustic impedance of epoxy resin.

[0093] Based on the epoxy resin density ρ′=1110kg / m³ 3 The acoustic impedance Z of epoxy resin h =2.7MRayl; then the sound velocity of the phase acoustic pixel layer is c = 2450m / s.

[0094] This invention also provides a method for preparing the above-mentioned passive acoustic functional component, comprising the following steps:

[0095] S1. Preparation of the first sublayer using PZT: Set the laser cutting processing path and laser parameters, and use laser cutting to process the first sublayer with a similar stepped structure. The prepared first sublayer is ultrasonically cleaned and placed in an oven to dry and stand. Epoxy resin (epoxy resin is pre-mixed with curing agent at a ratio of 100:35 and stirred for 3 minutes, and defoamed) is injected into the remaining space of the equivalent matching layer unit to prepare the second sublayer. A steel block is placed and flattened, and the pressure is applied and heated to 80℃ and 2MPa. The pressure is maintained at 80℃ and 2MPa for 8 hours. After curing, the equivalent matching layer unit is obtained.

[0096] S2. A simulation numerical model of ultrasound is established using the K-space pseudospectral method. An acoustic pixel reconstruction surface is set in the model to record the ultrasound time-domain signal. A virtual excitation source is set to simulate the process of ultrasound propagating from the virtual excitation source to the acoustic pixel reconstruction surface. The distance between the virtual excitation source and the acoustic pixel reconstruction surface is the focal length F. The ultrasound signal recorded by the acoustic pixel reconstruction surface is flipped on the time axis. The processed signal is subjected to Fourier transform to extract the phase of the required frequency, thereby obtaining the phase distribution of the phase acoustic pixel layer. The surface of the phase acoustic pixel layer is divided into pixels with the same width Δh but different thicknesses h(i,j). The thickness of each pixel in the phase acoustic pixel layer is calculated through the phase distribution. In this embodiment, the number of pixels in the phase acoustic pixel layer is 14×14. After drawing the model in the three-dimensional structure drawing software, a mold of the phase acoustic pixel layer is prepared by 3D printing.

[0097] The thickness h(i,j) of the pixel satisfies:

[0098]

[0099] Where ω(i,j) is the phase of pixel (i,j), f is the ultrasonic frequency, and c w and c h The velocity of sound for water and the phase acoustic pixel layer are respectively; in this embodiment, f = 1 MHz, c w =1500m / s, c h =c = 2450m / s, focal length F = 10mm;

[0100] Epoxy resin and curing agent were mixed at a ratio of 100:35 and injected into a mold for the phase acoustic pixel layer. A steel block was placed on top to flatten the mixture, and the mixture was pressurized and heated to 80°C and 2MPa. The mixture was then kept at a constant temperature and pressure of 80°C and 2MPa for 8 hours to cure, resulting in the phase acoustic pixel layer. A schematic diagram of the phase acoustic pixel layer is shown below. Figure 2 As shown;

[0101] S3. The equivalent matching layer unit and the phase acoustic pixel layer are connected to form a passive acoustic functional component by spin-coating a crosslinking agent at the contact surface. The crosslinking agent is epoxy resin.

[0102] Application examples

[0103] like Figure 3 As shown, in one application example of the present invention, the ultrasonic transducer includes a passive acoustic functional component and a piezoelectric active material; the passive acoustic functional component is fastened to the upper surface of the piezoelectric active material; in this embodiment, the piezoelectric active material is PMN-PT (lead magnesium niobate), and the finite element acoustic field simulation diagram of the ultrasonic transducer in this application example is shown below. Figure 4 and Figure 5 As shown.

[0104] In other application examples, piezoelectric active materials can also be PZT, LiNbO3, or PIN-PMN-PT (lead indium niobate-lead magnesium niobate-lead titanate).

[0105] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A passive acoustic functional component of an ultrasonic transducer, characterized in that, The passive acoustic functional component includes an equivalent matching layer unit and a phase acoustic pixel layer disposed on the equivalent matching layer unit; The equivalent matching layer unit includes N equivalent matching layers from bottom to top, where N≥2, with the bottommost equivalent matching layer being the first equivalent matching layer and the topmost being the Nth equivalent matching layer. The equivalent matching layer includes a first sub-layer and a second sub-layer; the first sub-layer is made of a high acoustic impedance material; the second sub-layer is made of a low acoustic impedance material; and the phase acoustic pixel layer is made of a low acoustic impedance material. The volume fraction ratio of high acoustic impedance material to low acoustic impedance material in the Nth equivalent matching layer satisfy: ； in, and These are the lengths of the first and second sub-layers in the Nth equivalent matching layer, respectively; It exhibits a gradient distribution that is either monotonically decreasing or monotonically increasing from the first equivalent matching layer to the Nth equivalent matching layer.

2. The passive acoustic functional component according to claim 1, characterized in that, The equivalent matching layer unit comprises N equivalent matching layers from bottom to top, where N≥3.

3. The passive acoustic functional component according to claim 2, characterized in that, The high acoustic impedance material is selected from one or more of PZT, zirconium oxide, tungsten, tungsten oxide, aluminum oxide, zinc, zinc oxide and lithium niobate.

4. The passive acoustic functional component according to any one of claims 1-3, characterized in that, The low acoustic impedance material is selected from one or more of epoxy resin, acrylate, methacrylate, HTV silicone, RTV silicone, PDMS and silica.

5. The passive acoustic functional component according to claim 4, characterized in that, The acoustic impedance Z of the Nth equivalent matching layer N satisfy: ； in, Let ρ and ρ' be the volume fraction ratio of high acoustic impedance material to low acoustic impedance material in the Nth equivalent matching layer. The densities of high acoustic impedance materials and low acoustic impedance materials are respectively, e 11 e represents the value in the first row and first column of the stiffness matrix of the high acoustic impedance material. 11 e represents the value in the first row and first column of the stiffness matrix of the low acoustic impedance material; 12 e represents the value in the first row and second column of the stiffness matrix of a high acoustic impedance material. 12 This represents the value in the first row and second column of the stiffness matrix for materials with low acoustic impedance.

6. The passive acoustic functional component according to claim 5, characterized in that, The sound speed of the Nth equivalent matching layer satisfy: ； in, Let ρ and ρ' be the volume fraction ratio of high acoustic impedance material to low acoustic impedance material in the Nth equivalent matching layer. The densities of high acoustic impedance materials and low acoustic impedance materials are respectively. Let N be the acoustic impedance of the Nth equivalent matching layer.

7. The passive acoustic functional component according to claim 6, characterized in that, The sound velocity c of the phase acoustic pixel layer satisfies: ； Where, ρ For low acoustic impedance material density, The acoustic impedance of the phase acoustic pixel layer.

8. The passive acoustic functional component according to claim 7, characterized in that, The acoustic impedance of the first equivalent matching layer is ≤40 MRayl, and the acoustic impedance of the phase acoustic pixel layer is ≥1.5 MRayl.

9. A method for preparing a passive acoustic functional component according to any one of claims 1-8, characterized in that, Includes the following steps: S1. A first sublayer is prepared using a high acoustic impedance material, and a second sublayer is prepared by injecting a low acoustic impedance material into the remaining space of the equivalent matching layer unit to obtain the equivalent matching layer unit. S2. Prepare a mold for the phase acoustic pixel layer by injecting a low acoustic impedance material into the mold to prepare the phase acoustic pixel layer. S3. Connect the equivalent matching layer unit and the phase acoustic pixel layer to obtain a passive acoustic functional component.

10. The use of the passive acoustic functional component according to any one of claims 1-8 in the manufacture of an ultrasonic transducer.

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