Ultrasound transducer array and method of manufacturing the same

Abstract

The application provides an ultrasonic transducer array and a preparation method thereof. The preparation method comprises the following steps: providing a piezoelectric sheet, the piezoelectric sheet having a first surface and a second surface opposite to the first surface, a first electrode layer being formed on the first surface, and a second electrode layer being formed on the second surface; etching the first electrode layer to form a plurality of independent electrode units, the plurality of electrode units being arranged in an array mode; and forming an acoustic impedance matching layer on the second electrode layer. The preparation method forms the array distributed independent electrode units on the whole piezoelectric sheet through a micro-nano processing technology, so as to form an ultrasonic wave array element array which can be controlled individually, and the piezoelectric sheet does not need to be cut. Therefore, the manufacturing process is simplified, higher array density can be realized, the spatial resolution of the ultrasonic transducer array is improved, the application effects of high-precision acoustic imaging and high-resolution acoustic field control are improved, and the preparation method is suitable for large-scale production.

Description

Technical Field

[0001] This application relates to the field of ultrasonic manipulation technology, and in particular to an ultrasonic transducer array and its fabrication method. Background Technology

[0002] Dynamic holographic acoustic tweezers enable precise manipulation of micro and nano-sized objects without direct contact. Applicable to various materials, they offer high spatial resolution and allow for real-time dynamic adjustment, thus playing a crucial role in fields such as biology, materials science, and micro / nano fabrication. The realization of dynamic holographic acoustic tweezers primarily relies on array-type ultrasonic transducers.

[0003] The design of array-type ultrasonic transducers requires consideration of parameters such as array frequency, number of elements, arrangement, center-to-center distance between adjacent elements, and element width. Currently, there are two main types of array-type ultrasonic transducers:

[0004] 1) A phased array ultrasonic control system, which consists of ultrasonic probes arranged in a certain spatial pattern, is suitable for use in air, but has disadvantages such as large size, low spatial resolution and frequency, and limited expressive ability.

[0005] 2) Ultrasonic transducers made of piezoelectric composite materials are suitable for liquid environments, but their manufacturing process is complex. Since the density of the human body is close to that of water, ultrasonic transducers made of piezoelectric composite materials have greater application prospects in the fields of biology and medicine.

[0006] In existing technologies, the fabrication of piezoelectric ceramic ultrasonic transducer arrays typically involves the following steps: First, the piezoelectric ceramic material is cut into several rectangular units; then, the upper and lower electrodes are connected to the rectangular piezoelectric ceramic units respectively; finally, these connected units are arranged in a specific pattern to form a transducer array. This method requires maintaining a certain spacing between units during the cutting of the piezoelectric ceramic to avoid electromagnetic interference and mutual influence of sound fields between different units. However, this method is not only complex in its fabrication process but also limits the array density, i.e., the number of transducer units per unit area. This limitation in array density leads to a decrease in sound field resolution, thus affecting the application performance of ultrasonic transducer arrays in fields such as high-precision acoustic imaging and high-resolution sound field control. Summary of the Invention

[0007] In view of the problems in the prior art described above, the purpose of this application is to provide an ultrasonic transducer array and its fabrication method, so as to solve the technical problems of complex fabrication process and low array density of existing ultrasonic transducer arrays.

[0008] To achieve the above and other related objectives, this application provides a method for fabricating an ultrasonic transducer array, comprising:

[0009] A piezoelectric sheet is provided, the piezoelectric sheet having a first surface and a second surface opposite to a device, a first electrode layer being formed on the first surface and a second electrode layer being formed on the second surface;

[0010] The first electrode layer is etched to form multiple independent electrode units, which are arranged in an array at intervals.

[0011] An acoustic impedance matching layer is formed on the second electrode layer.

[0012] In an optional embodiment of this application, the first electrode layer is etched to form a plurality of independent electrode units, wherein the plurality of electrode units are arranged at intervals in an array, including:

[0013] The first electrode layer is etched using a dry etching process or a wet etching process to form multiple independent electrode units, which are arranged in an array at intervals.

[0014] In an optional embodiment of this application, a wet etching process is used to etch the first electrode layer to form multiple independent electrode units, wherein the multiple electrode units are arranged in an array at intervals, including:

[0015] A patterned mask layer is formed on the first electrode layer. The patterned mask layer includes a plurality of independent mask units, which are arranged in an array at intervals. Each mask unit corresponds to one electrode unit.

[0016] The first electrode layer is etched based on the patterned mask layer to form multiple independent electrode units, which are arranged in an array at intervals.

[0017] In an optional embodiment of this application, the first electrode layer includes a nickel electrode layer;

[0018] Based on the patterned mask layer, the first electrode layer is wet-etched to form multiple independent electrode units, wherein the multiple electrode units are arranged in an array at intervals, including:

[0019] Based on the patterned mask layer, the first electrode layer is wet-etched using FeCl3 solution to form multiple independent electrode units, which are arranged in an array at intervals.

[0020] In an optional embodiment of this application, the piezoelectric sheet includes a piezoelectric single crystal sheet, a polycrystalline piezoelectric ceramic sheet, a polymer piezoelectric sheet, or a polymer-piezoelectric ceramic composite sheet.

[0021] In an optional embodiment of this application, an acoustic impedance matching layer is formed on the second electrode layer, comprising:

[0022] An epoxy resin layer or an epoxy resin composite layer doped with nano-metal oxides is formed on the second electrode layer as the acoustic impedance matching layer.

[0023] In an optional embodiment of this application, an acoustic impedance matching layer is formed on the second electrode layer, comprising:

[0024] An adhesive base layer is formed on the second electrode layer;

[0025] An epoxy resin layer or an epoxy resin composite layer doped with nano-metal oxides is formed on the adhesive base layer as the acoustic impedance matching layer.

[0026] In an optional embodiment of this application, the thickness of the acoustic impedance matching layer is between 290μm and 330μm, and the thickness of the piezoelectric sheet is between 0.8mm and 1.2mm.

[0027] In an optional embodiment of this application, in the step of etching the first electrode layer to form a plurality of independent electrode units, wherein the plurality of electrode units are arranged in an array at intervals, the array density of the electrode units is greater than or equal to 11 units / cm². 2 .

[0028] In an optional embodiment of this application, in the step of etching the first electrode layer to form a plurality of independent electrode units, and the plurality of electrode units being arranged in an array at intervals, the plurality of electrode units are arranged in a rectangular array at intervals, and the gap between two adjacent electrode units is between 1 / 4 and 1 / 2 of the wavelength of the sound wave in the ultrasonic propagation medium.

[0029] To achieve the above and other related objectives, this application provides an ultrasonic transducer array, which is prepared using the method described above.

[0030] The ultrasonic transducer array fabrication method of this application does not require cutting piezoelectric sheets. Instead, it uses micro-nano fabrication technology to form an array of independent electrode units distributed on a whole piezoelectric sheet to form an individually controllable ultrasonic array. This not only simplifies the fabrication process but also enables higher array density, improves the spatial resolution of the ultrasonic transducer, and enhances the application effects of high-precision acoustic imaging and high-resolution sound field control. It is also suitable for large-scale production.

[0031] The ultrasonic transducer array fabrication method of this application improves the acoustic performance of the ultrasonic transducer array by adding an acoustic impedance matching layer on the upper electrode layer. Furthermore, the thickness of the acoustic impedance matching layer can be precisely controlled through a specific fabrication process to meet different application requirements.

[0032] The ultrasonic transducer array fabrication method of this application can effectively reduce the crosstalk problem between adjacent array elements without cutting the piezoelectric sheet by selecting appropriate electrode unit size and gap. This overcomes the technical bias in the prior art that it is necessary to cut the array first and fill the cutting groove with polymer when making ultrasonic transducer arrays with piezoelectric materials.

[0033] The ultrasonic transducer array of this application is made of piezoelectric composite material, which is suitable for liquid environments and is more suitable for applications in the fields of biology and medicine. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the fabrication process of an ultrasonic transducer array in one embodiment of this application.

[0035] Figure 2a A schematic diagram of a piezoelectric element is provided.

[0036] Figure 2b A schematic diagram for forming a patterned mask layer on the first electrode layer.

[0037] Figure 2c This is a schematic diagram of wet etching of the first electrode layer based on the patterned mask layer.

[0038] Figure 2d This is a schematic diagram of forming an acoustic impedance matching layer on the second electrode layer.

[0039] Figure 3 This is a three-dimensional structural diagram of an ultrasonic transducer array in one embodiment of this application.

[0040] Figure 4 This is an exploded view of an ultrasonic transducer array in one embodiment of this application.

[0041] Figure 5 for Figure 4 A magnified view of a portion of the image. Detailed Implementation

[0042] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application 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 this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0043] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. Therefore, the illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In 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.

[0044] This application proposes a novel method for fabricating ultrasonic transducer arrays. The main innovation of this method is that it eliminates the need for rectangular cutting of piezoelectric ceramics. Instead, it arranges the lower electrodes with spacing between each electrode unit, thereby achieving a larger and denser transducer array within the same area, thus effectively improving the performance of the ultrasonic transducer array.

[0045] Figure 1 The process flow diagram of the ultrasonic transducer array fabrication method of this application is shown, including steps S10-S30. Figures 2a-2d A diagram illustrating each step is provided. The following will combine... Figure 1 -2 will be used to explain the entire preparation process in detail.

[0046] In step S10, a piezoelectric sheet 12 is provided.

[0047] The piezoelectric element 12, as a key component of the ultrasonic transducer array, converts alternating voltage into alternating mechanical vibration, which is crucial for the generation of ultrasonic waves. The piezoelectric element 12 can be, for example, a piezoelectric single crystal sheet, a polycrystalline piezoelectric ceramic sheet, a polymer piezoelectric sheet, or a polymer-piezoelectric ceramic composite material, etc., made of materials with excellent piezoelectric properties. The polycrystalline piezoelectric ceramic sheet includes lead zirconate titanate, PZT-4, PZT-5, PZT-6, PZT-8, lead magnesium zirconate titanate of niobium, lead zinc niobate titanate, or lead nickel niobate titanate. The piezoelectric single crystal sheet can include, for example, quartz or water-soluble piezoelectric crystals (such as sodium potassium tartrate, diammonium vinyl tartrate, dipotassium tartrate, potassium sulfate, etc.). The polymer piezoelectric sheet includes piezoelectric sheets made of polar polymer materials such as polyvinylidene fluoride.

[0048] like Figure 2a As shown, the piezoelectric sheet 12 is, for example, a PZT-5 piezoelectric ceramic sheet. The piezoelectric sheet 12 has a first surface (lower surface) and a second surface (upper surface) disposed opposite to each other. A first electrode layer 11 is formed on the first surface, and a second electrode layer 13 is formed on the second surface.

[0049] The piezoelectric sheet 12 is a single, complete sheet, eliminating the need for cutting, unlike existing technologies that cut the entire piezoelectric sheet 12 and fill it with polymer to form multiple independent piezoelectric units. As an example, the thickness of the piezoelectric sheet 12 is between 0.8mm and 1.2mm, such as 0.8mm, 0.9mm, 1.0mm, 1.1mm, and 1.2mm.

[0050] The first electrode layer 11 and the second electrode layer 13 can be formed on the surface of the piezoelectric sheet 12, for example, by metal film deposition processes such as evaporation, magnetron sputtering, and chemical vapor deposition. The materials of the first electrode layer 11 and the second electrode layer 13 can be conductive materials such as gold, silver, copper, or nickel, for example, nickel.

[0051] It should be noted that, in an optional embodiment, in order to increase the adhesion between the first electrode layer 11 and the piezoelectric sheet 12 and increase the reliability of the electrode, an adhesion layer is also formed between the first electrode layer 11 and the piezoelectric sheet 12. The adhesion layer and the first electrode layer 11 together serve as the electrode layer. The material of the adhesion layer can be, for example, titanium or chromium.

[0052] It should be noted that, in an optional embodiment, in order to increase the adhesion between the second electrode layer 13 and the piezoelectric sheet 12 and increase the reliability of the electrode, an adhesion layer is also formed between the second electrode layer 13 and the piezoelectric sheet 12. The adhesion layer and the second electrode layer 13 together serve as the electrode layer. The material of the adhesion layer can be, for example, titanium or chromium.

[0053] In step S20, the first electrode layer 11 is etched to form a plurality of independent electrode units 111, and the plurality of electrode units 111 are arranged in an array at intervals.

[0054] Specifically, the first electrode layer 11 is etched to form a plurality of independent electrode units 111, which are arranged in an array at intervals, including the following steps:

[0055] like Figure 2b As shown, a patterned mask layer 15 is formed on the first electrode layer 11 by photolithography. The patterned mask layer 15 is used to define the shape and size of the electrode array. The patterned mask layer 15 includes multiple independent mask units, which are arranged in an array at intervals. Each mask unit corresponds to one electrode unit.

[0056] like Figure 2cAs shown, the first electrode layer 11 is etched by dry or wet etching based on the patterned mask layer 15 to remove the part outside the electrode array while retaining the part required for the electrode array, thereby forming multiple independent electrode units 111. The multiple electrode units 111 are arranged in an array at intervals. During etching, the corresponding etching process can be selected based on the different materials of the first electrode layer 11.

[0057] As an example, a patterned mask layer 15 is formed on the first electrode layer 11, including, for example:

[0058] (1) Spin coat AZ5214 photoresist onto the first electrode layer. When spin coating, first spin coat at a speed of 400 rpm for 5 seconds, and then spin coat at a speed of 1000 rpm for 60 seconds.

[0059] (2) Bake on a 95-degree hot plate for 90 seconds;

[0060] (3) Using a laser direct writing machine ML3, ultraviolet exposure was performed on a portion of the electrode array at a measurement of 180mJ / cm2.

[0061] (4) Reverse baking, bake on a hot plate at 120 degrees for 120 seconds;

[0062] (5) Expose for 120 seconds using an MJB4 UV exposure machine;

[0063] (6) Develop with developer for 60 seconds to wash away the photoresist in the non-electrode array portion, thereby forming a patterned mask layer 15 on the first electrode layer 11.

[0064] As an example, when the first electrode layer 11 is a nickel layer, the first electrode layer 11 is etched based on the patterned mask layer 15 to form a plurality of independent electrode units 111. The plurality of electrode units 111 are arranged in an array at intervals, for example including:

[0065] (1) Immerse the piezoelectric sheet with a patterned mask layer 15 formed on the first electrode layer 11 in FeCl3 solution for 60 seconds for etching;

[0066] (2) The patterned mask layer 15 is washed away with a stripper to expose multiple independent electrode units 111 arranged in an array.

[0067] In the ultrasonic transducer array, the piezoelectric sheet 12 region corresponding to each electrode unit 111 serves as an ultrasonic array element, thereby forming an individually controllable ultrasonic array element array. By independently modulating the sound field phase or amplitude of multiple ultrasonic array elements, an interference superposition sound field with complex pressure and phase distribution can be constructed to form a holographic dynamic acoustic tweezers.

[0068] It should be noted that when the ultrasonic transducer array is working, each array element needs to be controlled individually. Those skilled in the art generally believe that if adjacent array elements are directly connected and vibrate simultaneously, crosstalk will occur. Therefore, in the prior art, when using piezoelectric composite materials to fabricate ultrasonic transducer arrays, the piezoelectric sheet 12 needs to be matrix-cut, and then polymer is filled into the cut grooves to form independent piezoelectric units. These piezoelectric units, together with the electrodes on both sides, constitute an ultrasonic array element. This method reduces the crosstalk problem when adjacent array elements vibrate.

[0069] In this application, the inventors have creatively discovered that by setting the first electrode layer 11 in the form of an electrode unit array and selecting appropriate electrode unit 111 size and spacing, the crosstalk problem between adjacent array elements can be effectively reduced without cutting the piezoelectric sheet 12. In other words, this application overcomes technical bias.

[0070] Specifically, in order to effectively reduce the crosstalk problem between adjacent array elements, when the electrode unit 111 is square, the gap between two adjacent electrode units 111 needs to be between 1 / 4 and 1 / 2 of the wavelength of the sound wave in the ultrasonic propagation medium, for example, 1 / 4, 7 / 24, 1 / 3, 3 / 8, 5 / 12, 11 / 24, 1 / 2. The ratio of the thickness of the piezoelectric sheet 12 to the side length of the electrode unit 111 is between 0.8 and 1.2, for example, 0.8, 0.9, 1.0, 1.1, 1.2.

[0071] As can be seen from the above, since multiple electrode units 111 are formed using micro-nano fabrication technology, the array density of the electrode units 111 in the first electrode layer 11 can be made denser, that is, the density of the ultrasonic element array of the ultrasonic transducer array can be made denser, thereby achieving higher ultrasonic element array density, spatial resolution, and improving the application effects of high-precision acoustic imaging, high-resolution sound field control, etc.

[0072] Specifically, in the first electrode layer 11, the array density of the electrode units 111 can be greater than or equal to 11 units / cm². 2 For example, 11 per cm 2 35 pieces / cm 2 60 pieces / cm 2 80 pieces / cm 2 100 pieces / cm 2 More than 100 / cm 2 That is, the density of the ultrasonic element array of the ultrasonic transducer array can be greater than or equal to 11 elements / cm². 2 For example, 11 per cm 2 35 pieces / cm 2 60 pieces / cm 280 pieces / cm 2 100 pieces / cm 2 More than 100 / cm 2 .

[0073] In step S30, as Figure 2d As shown, an acoustic impedance matching layer 14 is formed on the second electrode layer 13.

[0074] When ultrasound propagates in different media, partial reflection and refraction occur due to differences in acoustic impedance, leading to energy loss and waveform distortion. Therefore, an acoustic impedance matching layer 14 needs to be formed on the second electrode layer 13. The acoustic impedance matching layer 14 is a dielectric layer located between the vibrating end face of the ultrasonic transducer array and the load medium. Its main function is to reduce ultrasonic wave reflection and interference, improve ultrasonic wave transmission efficiency, and thus enhance the performance of the ultrasonic transducer array.

[0075] The presence of the acoustic impedance matching layer 14 can reduce the acoustic impedance mismatch between the ultrasonic transducer array and the propagation medium, reduce ultrasonic wave reflection and scattering, and improve the energy transmission efficiency of the ultrasonic wave. Furthermore, the acoustic impedance matching layer 14 can also improve the signal-to-noise ratio. Additionally, the acoustic impedance matching layer 14 can improve the mechanical stiffness of the ultrasonic transducer array, increase its frequency response range, and enhance its stability and reliability.

[0076] By selecting a suitable material and thickness for the acoustic impedance matching layer 14, the acoustic impedance matching degree can be maximized, reflection minimized, and the energy of ultrasonic waves transmitted to the maximum extent. The material of the acoustic impedance matching layer 14 can be, for example, an epoxy resin composite doped with nano-metal oxides (such as strontium titanate); that is, the acoustic impedance matching layer 14 can be an epoxy resin layer or an epoxy resin composite layer doped with nano-metal oxides. The thickness of the acoustic impedance matching layer 14 is between 290 μm and 330 μm, for example, 290 μm, 300 μm, 310 μm, 320 μm, or 330 μm. It should be noted that using an epoxy resin acoustic impedance matching layer 14 doped with nano-metal oxides can achieve a higher energy transmission rate than using an epoxy resin ring acoustic impedance matching layer 14, but the manufacturing process and cost will be higher.

[0077] In one specific embodiment, the material of the acoustic impedance matching layer 14 can be, for example, SU-8 photoresist or SU-8 photoresist doped with nano-metal oxides; that is, the acoustic impedance matching layer 14 can be an SU-8 photoresist layer or an SU-8 composite layer doped with nano-metal oxides. SU-8 photoresist is a negative, epoxy resin-type, near-ultraviolet photoresist; it has good mechanical properties, chemical corrosion resistance, and thermal stability; SU-8 photoresist is non-conductive and can be used directly as an insulator during electroplating, and can be used immersed in an aqueous medium.

[0078] It should be noted that, in order to increase the adhesion between the acoustic impedance matching layer 14 and the second electrode layer 13 and improve the structural stability of the ultrasonic transducer array, a primer adhesive layer can be formed on the second electrode layer 13 before forming the acoustic impedance matching layer 14; subsequently, the acoustic impedance matching layer 14 is formed on the primer adhesive layer. The primer adhesive layer can be, for example, an LOR-5A adhesive layer, where LOR-5A is a lift-off primer. The LOR-5A adhesive layer can increase the adhesion between the second electrode layer 13 and the acoustic impedance matching layer 14, thereby enhancing the structural stability of the ultrasonic transducer array. It should be noted that other lift-off primer adhesives can also be used instead of LOR-5A.

[0079] As an example, an acoustic impedance matching layer 14 is formed on the second electrode layer 13, specifically including:

[0080] (1) Spin-coat LOR-5A as a base adhesive layer on the second electrode layer 13. When spin-coating, first spin-coat at a speed of 400 rpm for 5 seconds, and then spin-coat at a speed of 1000 rpm for 60 seconds.

[0081] (2) Bake on a hot plate at 95 degrees Celsius for 5 minutes;

[0082] (3) Spin coat SU-8 on LOR-5A layer. When spin coating, spin at 400 rpm for 5 seconds and at 1000 rpm for 60 seconds.

[0083] (4) The hot plate is heated from 65 degrees to 95 degrees and then from 95 degrees to 65 degrees, at a gradient of 1°C / min.

[0084] (5) Repeat steps (3) and (4) three times in total (depending on the required thickness of SU-8) to obtain a SU-8 film of about 310 micrometers.

[0085] (6) Finally, use an MJB4 UV exposure machine to expose for 4 minutes to form the sound and acoustic impedance matching layer 14.

[0086] In an optional embodiment, after forming the acoustic impedance matching layer 14, at least one ground wire needs to be led out from the second electrode layer 13 of the ultrasonic transducer array 10. Subsequently, a waterproof layer is formed on the upper surface of the ultrasonic transducer array 10 to achieve electrical insulation between the ultrasonic transducer array 10 and the medium (e.g., water), allowing the ultrasonic transducer array 10 to be used while immersed in the medium (e.g., water) and reducing energy loss. The waterproof layer can be, for example, a polymer film waterproof layer, such as a parylene waterproof layer.

[0087] Figure 3 An ultrasonic transducer array 10 fabricated using the fabrication process of this application is shown. Figure 4 for Figure 3 An exploded schematic diagram of an ultrasonic transducer array. Figure 5 for Figure 4 A magnified view of a portion of the image. For example... Figure 3-5 As shown, the ultrasonic transducer array 10 includes a piezoelectric element 12, a first electrode layer 11, a second electrode layer 13, and an acoustic impedance matching layer 14.

[0088] The piezoelectric sheet 12 has a first surface (lower surface) and a second surface (upper surface) disposed opposite to each other; the first electrode layer 11 is formed on the first surface of the piezoelectric sheet 12, and the first electrode layer 11 includes a plurality of independent electrode units 111, which are arranged in an array at intervals; the second electrode layer 13 is disposed on the second surface of the piezoelectric sheet 12; the acoustic impedance matching layer 14 is disposed on the surface of the second electrode layer 13 away from the piezoelectric sheet 12.

[0089] In an optional embodiment, the ultrasonic transducer array 10 further includes a waterproof layer (not shown) coated on the upper surface of the ultrasonic transducer array 10 to provide electrical insulation between the ultrasonic transducer array 10 and a medium (e.g., water), allowing the ultrasonic transducer array 10 to be used while immersed in the medium (e.g., water) and reducing energy loss. The waterproof layer may be, for example, a polymer film waterproof layer, such as a parylene waterproof layer.

[0090] The detailed structure of the ultrasonic transducer array 10 is described in the preparation method section above, and will not be repeated here.

[0091] The piezoelectric element 12 in the ultrasonic transducer array 10 converts electrical energy into mechanical vibration energy through electro-mechanical-acoustic conversion, thereby generating ultrasonic waves. Taking piezoelectric ceramics as an example, applying an electric field to the piezoelectric ceramic causes the positive and negative ions in the piezoelectric ceramic lattice to shift. Under the action of the applied electric field, the piezoelectric ceramic undergoes a size change, which in turn causes the diaphragm fixed to it to deform. The deformation of the diaphragm further causes the adjacent medium (such as water, air, etc.) to vibrate, thereby generating ultrasonic waves. By changing the frequency and amplitude of the electric field signal applied to the piezoelectric ceramic, the frequency and intensity of the ultrasonic waves generated by the transducer array can be controlled, thereby meeting different application requirements. In order to transmit the generated ultrasonic waves from the piezoelectric ceramic to an object or fluid (such as in air or water), matching is required through the acoustic matching layer 14 to match the acoustic impedance between the piezoelectric ceramic and the medium, thereby enabling the ultrasonic energy to be effectively transmitted into the medium.

[0092] The ultrasonic transducer array 10 can be used to fabricate acoustic tweezers. By controlling the ultrasonic transducer array 10 to generate and modulate sound waves, acoustic tweezers can achieve non-contact manipulation of particles or cells in liquids through acoustic levitation. This method offers advantages such as safety, non-contact operation, low energy consumption, technological simplicity, and miniaturization, demonstrating significant advantages in materials science, biology, and physics. Particularly in the biomedical field, acoustic tweezers technology promises to solve many bottleneck problems.

[0093] In summary, the ultrasonic transducer array and its fabrication method of this application do not require cutting piezoelectric sheets. Instead, they form independently distributed electrode units on a whole piezoelectric sheet using micro-nano fabrication technology to create an array of individually controllable ultrasonic elements. This not only simplifies the fabrication process but also enables higher array density, improves the spatial resolution of the ultrasonic transducer array, and enhances applications such as high-precision acoustic imaging and high-resolution sound field control. Furthermore, it is suitable for large-scale production.

[0094] The ultrasonic transducer array and its fabrication method disclosed in this application improve the acoustic performance of the ultrasonic transducer array by adding an acoustic impedance matching layer on the upper electrode layer. Furthermore, the thickness of the acoustic impedance matching layer can be precisely controlled through a specific fabrication process to meet different application requirements.

[0095] The ultrasonic transducer array and its fabrication method of this application can effectively reduce the crosstalk problem between adjacent array elements without cutting the piezoelectric sheet by selecting appropriate electrode unit size and gap. This overcomes the technical bias in the prior art that it is necessary to first perform matrix cutting and fill the cutting groove with polymer when making ultrasonic transducer arrays with piezoelectric materials.

[0096] The ultrasonic transducer array of this application is made of piezoelectric composite material, which is suitable for liquid environments and is more suitable for applications in the fields of biology and medicine.

[0097] Throughout this description, numerous specific details, such as examples of components and / or methods, are provided to provide a complete understanding of the embodiments of this application. However, those skilled in the art will recognize that the embodiments of this application may be practiced without one or more of these specific details or by other devices, systems, components, methods, parts, materials, components, etc. In other instances, well-known structures, materials, or operations have not been specifically shown or described in detail to avoid obscuring aspects of the embodiments of this application.

[0098] Throughout this specification, the terms "an embodiment," "embodiment," or "specific embodiment" refer to a particular feature, structure, or characteristic described in connection with an embodiment that is included in at least one embodiment of this application, but not necessarily in all embodiments. Therefore, the various representations of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different places throughout this specification do not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic of any specific embodiment of this application may be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein may be based on the teachings herein and will be considered part of the spirit and scope of this application.

[0099] It should also be understood that one or more of the elements shown in the figures may be implemented in a more separate or more integrated manner, or may even be removed because they are inoperable in certain circumstances or provided because they may be useful for a particular application.

[0100] Furthermore, unless otherwise expressly stated, any arrows in the accompanying drawings should be considered illustrative only and not limiting. Additionally, unless otherwise stated, the term "or" as used herein is generally intended to mean "and / or". Where a term is anticipated to provide a separation or combination capability that is unclear, a combination of components or steps will also be considered as indicated.

[0101] As used herein and throughout the claims below, unless otherwise specified, “a” and “the” include the plural references. Similarly, as used herein and throughout the claims below, unless otherwise specified, “in” means “in” and “on”.

[0102] The above description of the embodiments shown in this application (including the content set forth in the abstract of the specification) is not intended to be an exhaustive enumeration or to limit this application to the precise forms disclosed herein. Although specific embodiments and examples of this application have been described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of this application, as will be recognized and understood by those skilled in the art. As indicated, these modifications can be made to this application in accordance with the above description of the embodiments described herein, and such modifications will be within the spirit and scope of this application.

[0103] This document has generally described the systems and methods in detail to aid in understanding the present application. Furthermore, various specific details have been provided to offer a general understanding of the embodiments of this application. However, those skilled in the art will recognize that embodiments of this application can be practiced without one or more specific details, or using other means, systems, accessories, methods, components, materials, parts, etc. In other instances, well-known structures, materials, and / or operations have not been specifically shown or described in detail to avoid obscuring various aspects of the embodiments of this application.

[0104] Therefore, although this application has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are also within the scope of the above disclosure, and it should be understood that in some cases, certain features of this application may be adopted without departing from the scope and spirit of the invention and without corresponding use of other features. Thus, many modifications can be made to adapt a particular environment or material to the essential scope and spirit of this application. This application is not intended to be limited to the specific terminology used in the following claims and / or the specific embodiments disclosed as the best mode of carrying out this application, but this application will include any and all embodiments and equivalents falling within the scope of the appended claims. Therefore, the scope of this application will be determined only by the appended claims.

Claims

1. A method for fabricating an ultrasonic transducer array, characterized in that, The application relates to an ultrasonic transducer array, comprising: a piezoelectric sheet having a first surface and a second surface opposite to the first surface, a first electrode layer formed on the first surface, and a second electrode layer formed on the second surface, the piezoelectric sheet being an uncut whole piezoelectric sheet; the first electrode layer is etched to form a plurality of independent electrode units, and the electrode units are arranged in a rectangular array, each electrode unit is square, the gap between two adjacent electrode units is 1 / 4 to 1 / 2 of the wavelength of sound waves in an ultrasonic wave propagation medium, the ratio of the thickness of the piezoelectric sheet to the side length of the electrode unit is 0.8-1.2, and the thickness of the piezoelectric sheet is 0.8-1.2 mm; an acoustic impedance matching layer is formed on the second electrode layer; the ultrasonic transducer array is used for an acoustic tweezer device.

2. The method of claim 1, wherein the ultrasound transducer array is prepared by a method comprising: The first electrode layer is etched to form a plurality of independent electrode units, and the electrode units are arranged in an array, comprising: the first electrode layer is etched by a dry etching process or a wet etching process to form a plurality of independent electrode units, and the electrode units are arranged in an array.

3. The method of claim 1, wherein the ultrasound transducer array is prepared by a method comprising: The first electrode layer is etched to form a plurality of independent electrode units, and the electrode units are arranged in an array, comprising: a patterned mask layer is formed on the first electrode layer, the patterned mask layer comprises a plurality of independent mask units, and the mask units are arranged in an array, and each mask unit corresponds to an electrode unit; the first electrode layer is etched based on the patterned mask layer to form a plurality of independent electrode units, and the electrode units are arranged in an array.

4. The method of claim 1, wherein the ultrasound transducer array is prepared by, The piezoelectric sheet comprises a piezoelectric single crystal sheet, a polycrystal piezoelectric ceramic sheet, a high polymer piezoelectric sheet, or a polymer-piezoelectric ceramic composite sheet.

5. The method of claim 1, wherein the ultrasound transducer array is prepared by a method comprising: The acoustic impedance matching layer formed on the second electrode layer comprises: an epoxy resin layer or an epoxy resin composite layer doped with nano metal oxide is formed on the second electrode layer as the acoustic impedance matching layer.

6. The method of claim 1, wherein, The acoustic impedance matching layer formed on the second electrode layer comprises: a primer adhesion layer is formed on the second electrode layer; the acoustic impedance matching layer is formed on the primer adhesion layer.

7. The method of claim 1, wherein the ultrasound transducer array is prepared by a method comprising: The thickness of the acoustic impedance matching layer is 290-330 mu m. ​ 8. The method of claim 1, wherein the ultrasound transducer array is prepared by, In the step of etching the first electrode layer to form a plurality of independent electrode units, the electrode units are arranged in an array with an array density of 11 / cm2 or more. 2 .

9. An ultrasonic transducer array, characterized by The ultrasonic transducer array is prepared by the method in any one of claims 1-8.

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