Passive acoustic functional component of ultrasonic transducer and preparation method and application of passive acoustic functional component

Abstract

The invention 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 of the passive acoustic functional component. The passive acoustic functional component comprises an equivalent matching layer unit and a phase sound pixel layer arranged on 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 sub-layer and a second sub-layer; the raw material of the first sub-layer comprises a high acoustic impedance material; the raw material of the second sub-layer comprises a low acoustic impedance material; the raw material of the phase sound pixel layer comprises a low-acoustic-impedance material; according to the passive acoustic functional component, the problem that an ultrasonic transducer cannot transmit broadband signals in water due to low transmission efficiency caused by impedance mismatch between a piezoelectric active material and a working medium is solved, and the provided passive acoustic functional component can realize focusing of ultrasonic waves and improvement of transmission efficiency while improving acoustic transmissivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultrasonic transducers, and in particular relates to a passive acoustic functional component of an ultrasonic transducer and a preparation method and application thereof. Background Art

[0002] With the continuous development of ultrasound technology, it has been widely used in the fields of industry, biomedicine and national defense. Ultrasound can be mainly divided into biomedical ultrasound and detection ultrasound. The former is an important detection and treatment method in medicine, 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 weld, gas leakage and other defect detection.

[0003] Ultrasonic transducers are electroacoustic conversion devices that transmit and receive ultrasonic waves, and are the core components of ultrasonic equipment. The bandwidth of ultrasonic transducers is one of its most important performances, because various applications of ultrasound are inseparable from the focusing of ultrasound. For example, in biomedical ultrasound, a beam of ultrasound with good focusing performance can gather more energy on a smaller spatial scale, and the impact on the area near the target can be minimized. It is suitable for targeted therapy or application scenarios with high power requirements in local space. In terms of detecting ultrasound, the fineness of ultrasound focusing directly determines the spatial resolution of imaging.

[0004] However, in biomedical ultrasound and detection ultrasound, the impedance mismatch between the piezoelectric active material with high acoustic impedance and the working medium (water) with low acoustic impedance will cause severe reflection of ultrasound at different interfaces, resulting in a large amount of acoustic energy loss and low overall ultrasound transmission efficiency, which in turn leads to a small bandwidth of the ultrasonic transducer.

[0005] In order to solve this problem, it is necessary to add a matching layer between the piezoelectric active material and the working medium. For example, the Chinese patent with the publication number CN116197102A discloses an ultrasonic transducer, which includes: a piezoelectric layer and a matching layer, wherein the matching layer is arranged between the piezoelectric layer and the object to be measured, the piezoelectric layer realizes acoustic matching with the object to be measured through the matching layer, and the piezoelectric layer is used to realize the conversion between ultrasonic waves and electrical energy; the sound velocity of the matching layer is gradient distributed in at least one direction. This technical solution makes ultrasonic waves of different frequencies have the same wavelength in the matching layer through the gradient distribution of the sound velocity of the matching layer, thereby realizing acoustic matching between piezoelectric layers of different structures and human tissues, improving the transmittance of ultrasonic waves in the matching layer, and increasing the bandwidth of the ultrasonic transducer. The Chinese patent with publication number CN117483217A discloses an ultrasonic transducer and a method for preparing the same. The ultrasonic transducer includes a substrate layer, a piezoelectric layer and an acoustic matching layer stacked in sequence along the thickness direction; the piezoelectric layer includes a substrate, the substrate includes a wiring area and a plurality of piezoelectric array elements distributed in a determinant-like manner along the row direction and the column direction, and two adjacent piezoelectric array elements are bonded by an insulating adhesive, and the upper and lower surfaces of the piezoelectric array elements and the insulating adhesive are formed by vacuum-plated electrode layers to form row and column strip electrodes, which can be formed by cutting and photolithography. The end of the first electrode layer is electrically connected to the first conductive member; the end of the second electrode layer is electrically connected to the second conductive member. Among them, the substrate layer and the acoustic matching layer can be directly in contact with the piezoelectric layer for acoustic matching, respectively, which improves the acoustic matching effect between the piezoelectric array element and the substrate layer and the acoustic matching layer.

[0006] However, the matching layer involved in the above technical solution does not have the function of focusing ultrasound. If focusing ultrasound is required, an acoustic lens needs to be added. The traditional acoustic lens has the disadvantages of being difficult to process due to its curvature, having insertion loss, and severe interface reflection between different materials, which leads to the unconcentrated ultrasonic energy and poor focusing effect, seriously affecting the detection accuracy.

[0007] Therefore, how to solve the impedance mismatch between piezoelectric active materials and working media, which leads to low transmission efficiency and makes it impossible for ultrasonic transducers to transmit broadband signals in water, and at the same time focus ultrasonic waves efficiently, accurately and flexibly is an important issue that needs to be solved to improve the performance of ultrasonic transducers. Summary of the invention

[0008] Aiming at the problem that the impedance mismatch between the piezoelectric active material and the working medium leads to low transmission efficiency and the ultrasonic transducer cannot transmit broadband signals in water, the present invention provides a passive acoustic functional component of an ultrasonic transducer and a preparation method and application thereof.

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

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

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

[0012] The equivalent matching layer includes a first sublayer and a second sublayer; the material of the first sublayer includes a high acoustic impedance material; the material of the second sublayer includes a low acoustic impedance material; the material of the phase acoustic pixel layer includes a low acoustic impedance material;

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

[0014]

[0015] Among them, x N and N are the lengths of the first sublayer and the second sublayer in the Nth equivalent matching layer, respectively; N Distributed in a gradient.

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

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

[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 the common knowledge in the art, the thickness of the equivalent matching layer is one quarter of the 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 vulcanized silicone rubber), PDMS (polydimethylsiloxane) and silicon dioxide, preferably epoxy resin.

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

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

[0026]

[0027] Among them, n N is the volume fraction ratio of high acoustic impedance material to low acoustic impedance material in the Nth equivalent matching layer, ρ and ρ′ are the densities of high acoustic impedance material and low acoustic impedance material respectively, e 11 is the value of the first row and first column of the stiffness matrix of the high acoustic impedance material, e′ 11 is the value of the first row and first column of the stiffness matrix of the low acoustic impedance material; e 12 is the value of the first row and second column of the stiffness matrix of the high acoustic impedance material, e′ 12 is the value of the first row and second column of the stiffness matrix of the low acoustic impedance material.

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

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

[0030]

[0031] Among them, n N is the volume fraction ratio of high acoustic impedance material to low acoustic impedance material in the Nth equivalent matching layer, ρ and ρ′ are the densities of high acoustic impedance material and low acoustic impedance material respectively, and Z N is the acoustic impedance of the Nth equivalent matching layer.

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

[0033]

[0034] Where ρ′ is the density of the low acoustic impedance material, Z h is 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, and the acoustic impedance gradient of the passive acoustic functional component varies in the range of 2.5MRayl-30MRayl.

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

[0038] Theoretically, the traditional multi-layer matching layer can improve the bandwidth of the ultrasonic transducer to a greater extent than the single-layer matching layer, and can further improve the ultrasonic transmittance. But in fact, each additional matching layer brings many process problems, such as increased bonding difficulty, increased probability of bubbles, etc. These influencing factors will cause the relative bandwidth to fail to reach the theoretical value. The present invention realizes 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 the ultrasonic transducer.

[0039] The 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 by using a high acoustic impedance material, and a low acoustic impedance material is injected into the remaining space of the equivalent matching layer unit to prepare a second sublayer, thereby obtaining an equivalent matching layer unit;

[0041] S2, preparing an inverted mold of a phase acoustic pixel layer, and injecting a low acoustic impedance material into the inverted mold of the phase acoustic pixel layer to prepare 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 is specifically as follows: first, a first sublayer having a step-like structure is prepared using a high acoustic impedance material; then the prepared first sublayer is ultrasonically cleaned and placed in an oven for drying and standing; finally, a low acoustic impedance material is injected into the remaining space of the equivalent matching layer unit to prepare a second sublayer, a steel block is placed to flatten it, and heating and pressurizing are performed, and the equivalent matching layer unit is obtained after curing.

[0044] In some preferred embodiments, the method for preparing the reverse mold of the phase acoustic pixel layer in step S2 is specifically as follows: a simulated numerical model of ultrasound is established by a K-space pseudo-spectral method, an acoustic pixel reconstruction surface is set in the model for recording ultrasonic time domain signals, a virtual excitation source is set, and a process of ultrasound propagating from the virtual excitation source to the acoustic pixel reconstruction surface is simulated. The distance between the virtual excitation source and the acoustic pixel reconstruction surface is the focal length F. The ultrasonic signal recorded by the acoustic pixel reconstruction surface is flipped on the time axis, the processed signal is Fourier transformed, and the phase of the required frequency is extracted to obtain 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 of the phase acoustic pixel layer is calculated by the phase distribution, the number of pixels in the phase acoustic pixel layer is determined, and the reverse mold of the phase acoustic pixel layer is obtained.

[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, c w and c h are the sound speeds of the water and phase acoustic pixel layers, respectively.

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

[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 cross-linking agent at the contact surface, and the cross-linking agent is epoxy resin.

[0051] The traditional matching layer does not have the function of focusing ultrasound. If focusing ultrasound is required, an acoustic lens needs to be added. However, the acoustic lens has the disadvantages of difficult curvature processing, insertion loss, and severe interface reflection between different materials, which leads to poor focusing effect of ultrasound energy, which seriously affects the detection accuracy. The present invention, by designing a gradient acoustic impedance structure and adding a phase acoustic pixel layer on the low acoustic impedance side, can focus ultrasound efficiently, accurately, and flexibly, thereby improving the performance of the ultrasonic transducer.

[0052] The third aspect of the present invention provides the use of the above-mentioned passive acoustic functional component in the preparation of an ultrasonic transducer.

[0053] In some preferred embodiments, the ultrasonic transducer includes a passive acoustic functional component and a piezoelectric active material.

[0054] In some preferred embodiments, the passive acoustic functional component is located on the upper surface of the piezoelectric active material and is firmly connected.

[0055] The present invention does not impose any specific limitation on the piezoelectric active material, and it may be a single element, a one-dimensional or a 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 the present invention has a gradient acoustic impedance structure, including N equivalent matching layers, N≥2; and a phase acoustic pixel layer, wherein the high acoustic impedance side can match the impedance of the piezoelectric excitation layer, and 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), thereby improving the transmission efficiency and bandwidth of the ultrasonic transducer and reducing the ultrasonic loss caused by interface reflection, but also can focus ultrasound to achieve ultrasonic energy focusing and targeted control, thereby solving the problem that the impedance mismatch between the piezoelectric active material and water leads to low transmission efficiency and the inability to realize the ultrasonic transducer to transmit broadband signals in water, thereby improving the acoustic transmittance and achieving the focusing of ultrasonic waves and the improvement of transmission efficiency.

[0058] 2. The passive acoustic functional part provided by the present invention realizes 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 the ultrasonic transducer.

[0059] 3. The passive acoustic functional component provided by the present invention can focus ultrasound efficiently, accurately and flexibly, thereby improving the performance of the ultrasonic transducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0061] Figure 1 Schematic diagram of the structure of the passive acoustic functional components of the ultrasonic transducer according to an embodiment of the present invention;

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

[0063] Figure 3A schematic diagram of the structure of an ultrasonic transducer according to an application example of the present invention;

[0064] Figure 4 and Figure 5 This is a finite element sound field simulation diagram of an ultrasonic transducer in an application example of the present invention. DETAILED DESCRIPTION

[0065] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0066] In the following examples, unless otherwise specified, all raw materials used were purchased from commercial sources 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] source 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 6 equivalent matching layer units arranged side by side and a phase sound pixel layer arranged on the equivalent matching layer unit; the equivalent matching layer unit includes 3 equivalent matching layers from bottom to top, namely the first equivalent matching layer, the second equivalent matching layer and the third equivalent matching layer; the three equivalent matching layers have the same length and width, and the thickness is one quarter of the wavelength; the equivalent matching layer includes a first sublayer and a second sublayer, and the thickness of the first sublayer and the second sublayer are the same.

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

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

[0073]

[0074] Among them, x N and N are the lengths of the first sublayer and the second sublayer in the Nth equivalent matching layer, respectively;

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

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

[0077]

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

[0079] The stiffness matrix of PZT is:

[0080]

[0081] The stiffness matrix of epoxy resin is:

[0082]

[0083] According to PZT density ρ = 7772 kg / m 3 , epoxy resin density ρ′=1110kg / m 3 , n1=0.5625, n2=0.25, n3=0.0625; then the acoustic impedance of the first equivalent matching layer Z1=21.99MRayl, the acoustic impedance of the second equivalent matching layer Z2=10.99MRayl, and the acoustic impedance of the third equivalent matching layer Z3=4.43MRayl;

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

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

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

[0087]

[0088] Among them, n N is the volume fraction ratio of PZT to epoxy resin in the Nth equivalent matching layer, ρ and ρ′ are the densities of PZT and epoxy resin, respectively, and Z N is the acoustic impedance of the Nth equivalent matching layer;

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

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

[0091]

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

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

[0094] The embodiment of the present invention also provides a method for preparing the above passive acoustic functional component, comprising the following steps:

[0095] S1. Prepare the first sublayer using PZT: set the laser cutting processing path and laser parameters, use laser cutting to process the first sublayer with a similar step-like structure, ultrasonically clean the prepared first sublayer and put it into an oven for drying and standing; inject epoxy resin (epoxy resin and curing agent are pre-mixed in a ratio of 100:35 and stirred for 3 minutes, and defoamed) into the remaining space of the equivalent matching layer unit to prepare the second sublayer, place a steel block to flatten it, pressurize and heat it to 80°C and 2MPa, and keep it at a constant temperature and pressure of 80°C and 2MPa for 8 hours, and obtain the equivalent matching layer unit after curing;

[0096] S2. A simulation numerical model of ultrasound is established by using a K-space pseudo-spectral method. An acoustic pixel reconstruction surface is set in the model to record ultrasound time domain signals. 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 ultrasonic signal recorded by the acoustic pixel reconstruction surface is flipped on the time axis. The processed signal is subjected to a Fourier transform. The phase of the required frequency is extracted to obtain 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 of the phase acoustic pixel layer is calculated by the phase distribution. In this embodiment, the number of pixels in the phase acoustic pixel layer is 14×14. After the model is drawn in a three-dimensional structure drawing software, a reverse 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, c w and c h are the sound velocities of water and phase acoustic pixel layers, respectively. In this embodiment, f=1 MHz, c w =1500m / s,c h =c=2450m / s, focal length F=10mm;

[0100] The epoxy resin and curing agent were mixed in a ratio of 100:35 and then injected into the inverted mold of the phase acoustic pixel layer. A steel block was placed to flatten it, and it was heated under pressure to 80°C and 2MPa. It was kept at a constant temperature and pressure of 80°C and 2MPa for 8 hours. After curing, the phase acoustic pixel layer was obtained. The schematic diagram of the phase acoustic pixel layer is shown in FIG. Figure 2 As shown;

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

[0102] Application Examples

[0103] like Figure 3 As shown, in an 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 located on the upper surface of the piezoelectric active material and is fastened; in this embodiment, the piezoelectric active material is PMN-PT (lead magnesium niobate), and the finite element sound field simulation diagram of the ultrasonic transducer in this application example is shown in FIG. Figure 4 and Figure 5 shown.

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

[0105] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions 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 arranged on the equivalent matching layer unit; The equivalent matching layer unit includes N equivalent matching layers from bottom to top, N≥2; The equivalent matching layer includes a first sublayer and a second sublayer; the material of the first sublayer includes a high acoustic impedance material; the material of the second sublayer includes a low acoustic impedance material; the material of the phase acoustic pixel layer includes a low acoustic impedance material; The volume fraction ratio n of the high acoustic impedance material and the low acoustic impedance material in the Nth equivalent matching layer N satisfy: Among them, x N and N are the lengths of the first sublayer and the second sublayer in the Nth equivalent matching layer, respectively; The N Distributed in a gradient.

2. The passive acoustic functional component according to claim 1, characterized in that: The equivalent matching layer unit includes 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 to 3, wherein the low acoustic impedance material is selected from one or more of epoxy resin, acrylate, methacrylate, HTV silicone, RTV silicone, PDMS and silicon dioxide.

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: Among them, n N is the volume fraction ratio of high acoustic impedance material to low acoustic impedance material in the Nth equivalent matching layer, ρ and ρ′ are the densities of high acoustic impedance material and low acoustic impedance material respectively, e 11 is the value of the first row and first column of the stiffness matrix of the high acoustic impedance material, e′ 11 is the value of the first row and first column of the stiffness matrix of the low acoustic impedance material; e 12 is the value of the first row and second column of the stiffness matrix of the high acoustic impedance material, e′ 12 is the value of the first row and second column of the stiffness matrix of the low acoustic impedance material.

6. The passive acoustic functional component according to claim 5, characterized in that: The acoustic velocity c of the Nth equivalent matching layer N satisfy: Among them, n N is the volume fraction ratio of high acoustic impedance material to low acoustic impedance material in the Nth equivalent matching layer, ρ and ρ′ are the densities of high acoustic impedance material and low acoustic impedance material respectively, and Z N is the acoustic impedance of the Nth equivalent matching layer.

7. The passive acoustic functional component according to claim 6, characterized in that: The acoustic velocity c of the phase acoustic pixel layer satisfies: Where ρ′ is the density of the low acoustic impedance material, Z h is 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 to 8, characterized in that: The following steps are involved: S1. A first sublayer is prepared by using a high acoustic impedance material, and a low acoustic impedance material is injected into the remaining space of the equivalent matching layer unit to prepare a second sublayer, thereby obtaining an equivalent matching layer unit; S2, preparing an inverted mold of a phase acoustic pixel layer, and injecting a low acoustic impedance material into the inverted mold of the phase acoustic pixel layer 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. Use of the passive acoustic functional component according to any one of claims 1 to 8 in the preparation of an ultrasonic transducer.

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