Flexible ultrasonic linear array transducer
By designing a flexible ultrasonic linear array transducer, using a combination of signal electrodes and ground electrodes on flexible circuit boards, and incorporating flexible isolation materials, the problem of detecting rigid transducers on non-planar surfaces was solved, achieving miniaturization and wearability, and improving detection flexibility and scanning accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
- Filing Date
- 2022-06-30
- Publication Date
- 2026-05-12
AI Technical Summary
Existing rigid ultrasonic transducers are difficult to use for detection on non-planar three-dimensional surfaces, and have disadvantages such as large size, thick shape, and difficulty in wearing.
A flexible ultrasonic linear array transducer is designed, which uses a flexible circuit board for signal electrodes to achieve independent excitation and a flexible circuit board for ground electrodes to achieve common ground connection. Combined with flexible isolation material to fill the gaps, an integrated flexible unit is formed, including a flexible backing layer, a flexible matching layer and a piezoelectric layer.
It has achieved miniaturization and thinning of ultrasonic transducers, making them wearable and suitable for the detection of complex surfaces, thus improving detection flexibility and scanning accuracy.
Smart Images
Figure CN117358560B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of flexible sensors, and more particularly to a flexible ultrasonic linear array transducer. Background Technology
[0002] Ultrasonic imaging technology boasts advantages such as safety, intuitiveness, wide applicability, strong soft tissue differentiation capabilities, repeatability, flexibility, and low cost, making it the preferred imaging technology in modern times. As a key component of an ultrasonic imaging system, the ultrasonic transducer accounts for 10% to 40% of the total system price. There are many types of ultrasonic transducers, with piezoelectric ultrasonic transducers being the most commonly used. These transducers utilize piezoelectric materials to generate ultrasonic signals and receive echo signals, subsequently processing the received echo signals to achieve ultrasonic imaging. The piezoelectric material is the core component of the entire transducer; high electromechanical coupling coefficients, piezoelectric constants, and suitable dielectric constants and acoustic impedances are important development directions for piezoelectric materials used in ultrasonic transducers. Lead zirconate titanate (PZT) ceramics, due to their high piezoelectric constant dp, are particularly valuable. 33 PZT ceramics, with their advantages of low cost and ease of manufacture, have been the primary material for piezoelectric ultrasonic transducers since their invention. However, PZT ceramics also suffer from excessively high acoustic impedance and low electromechanical coupling coefficient k. t This limitation restricts the performance of ultrasonic transducers made from PZT ceramics. Replacing pure ceramics with piezoelectric composites is a good way to improve transducer performance. Compared to ceramics, piezoelectric composites have higher electromechanical coupling coefficients, easily tunable acoustic impedance and dielectric constants, and lower mechanical quality factors, making them particularly suitable for fabricating high-sensitivity, high-bandwidth transducers.
[0003] Based on the number of elements, transducers can be divided into single-element and array transducers. Array transducers acquire images using electronic scanning methods, offering advantages such as high scanning frame rate, high scanning accuracy, and dynamic focusing capability compared to single-element transducers. Current transducers are generally rigid structures, which present limitations in practical applications, such as difficulty in detecting non-planar three-dimensional surfaces. Flexible ultrasonic transducers, however, can solve this problem. They can form conformal contact with complex surfaces and offer advantages such as small mass, ultra-thin shape, and wearable / implantable design. Summary of the Invention
[0004] To address the shortcomings of existing rigid ultrasonic transducers, this invention proposes a flexible ultrasonic linear array transducer. The flexible circuit board for the signal electrode enables independent excitation of each piezoelectric element, while the flexible circuit board for the ground electrode enables common ground connection of each piezoelectric element. The flexible circuit boards for the signal electrode and ground electrode, along with the flexible insulating material filling the gaps between the elements, achieve overall flexibility of the piezoelectric layer. The resulting flexible ultrasonic linear array transducer possesses integrated flexible units and offers advantages such as small size, thin profile, wearability, and ease of fabrication.
[0005] The flexible ultrasonic linear array transducer includes a flexible backing layer, a flexible matching layer, and a piezoelectric layer between the flexible backing layer and the flexible matching layer; the piezoelectric layer includes a signal electrode flexible circuit board on the flexible matching layer side, a ground electrode flexible circuit board on the flexible backing layer side, and a plurality of piezoelectric array elements between the signal electrode flexible circuit board and the ground electrode flexible circuit board; gaps filled with flexible insulating material are disposed between the piezoelectric array elements.
[0006] Preferably, the signal electrode flexible circuit board is configured with multiple independent pads and signal electrodes that independently excite the corresponding piezoelectric elements, and the ground electrode flexible circuit board is configured with a single pad that connects multiple piezoelectric elements to a common ground and multiple interconnected ground electrodes.
[0007] Preferably, each piezoelectric element has a ground electrode on the ground electrode flexible circuit board side that is electrically connected to the electrode region of the ground electrode flexible circuit board, and a signal electrode on the signal electrode flexible circuit board side that is electrically connected to the electrode region of the signal electrode flexible circuit board.
[0008] Preferably, the electrode regions of the ground electrode flexible circuit board and the electrode regions of the signal electrode flexible circuit board overlap in the vertical direction.
[0009] Preferably, the piezoelectric array elements are arranged in a linear array in one dimension along the x-direction.
[0010] Preferably, each piezoelectric element has a plurality of piezoelectric ceramic pillars and epoxy resin filling the spaces between the piezoelectric ceramic pillars, wherein the spacing of the piezoelectric ceramic pillars in the x-direction is the same as the spacing of the piezoelectric element in the x-direction.
[0011] Preferably, the piezoelectric material of the piezoelectric array element is lead zirconate titanate ceramic.
[0012] Preferably, the flexible insulating material is polyurethane or polydimethylsiloxane.
[0013] Preferably, the flexible matching layer is made of epoxy resin containing zirconium oxide powder, wherein the zirconium oxide powder contains 120-160% epoxy resin by mass.
[0014] Preferably, the flexible backing layer is made of polydimethylsiloxane containing tungsten powder, wherein the tungsten powder accounts for 300-500% of the mass fraction of the polydimethylsiloxane. Attached Figure Description
[0015] Figure 1 This is a cross-sectional schematic diagram of a flexible ultrasonic linear array transducer. In the diagram: 1-flexible matching layer; 2-flexible circuit board for signal electrodes; 3-flexible isolation material; 4-piezoelectric array element; 5-flexible circuit board for ground electrodes; 6-flexible backing layer.
[0016] Figure 2 This is a partial structural diagram of the piezoelectric composite material. 7 represents the epoxy resin filling the spaces between the lead zirconate titanate piezoelectric ceramic pillars; 8 represents the lead zirconate titanate piezoelectric ceramic pillars.
[0017] Figure 3 This is a schematic diagram of the structure of the flexible circuit board for the ground electrode. 9 - the substrate of the flexible circuit board for the ground electrode; 10 - the pad of the flexible circuit board for the ground electrode; 11 - the lead of the flexible circuit board for the ground electrode; 12 - the electrode of the flexible circuit board for the ground electrode.
[0018] Figure 4 This is a schematic diagram of the flexible circuit board for signal electrodes. In the diagram, 13 is the substrate of the flexible circuit board for signal electrodes; 14 is the pad of the flexible circuit board for signal electrodes; 15 is the lead of the flexible circuit board for signal electrodes; and 16 is the electrode of the flexible circuit board for signal electrodes.
[0019] Figure 5 These are physical images of the flexible circuit boards for the signal electrode and the flexible circuit board for the ground electrode.
[0020] Figure 6 This is a photograph of the piezoelectric array elements before they are sealed and the flexible matching layer and flexible backing layer are fabricated. Detailed Implementation
[0021] To more clearly illustrate the technical solution of the present invention, the flexible ultrasonic linear array transducer will be further described below with reference to the accompanying drawings.
[0022] like Figure 1 As shown, the flexible ultrasonic linear array transducer includes a flexible matching layer 1, a piezoelectric layer, and a flexible backing layer 6 arranged sequentially.
[0023] In the example, the flexible matching layer is made of epoxy resin containing zirconia powder, wherein the mass fraction of the zirconia powder in the epoxy resin is 120-160%. The particle size of the zirconia powder can be 2000 mesh. The flexible matching layer can be prepared using the above material via a doctor blade method. For example, epoxy resin and curing agent are mixed uniformly in a certain proportion. Before the epoxy resin cures, zirconia powder is added and mixed evenly, and the mixture is collected. Air bubbles are removed from the mixture. The mixture after removing air bubbles is then used to form a thin sheet of a certain thickness using a doctor blade. The thin sheet is cured to obtain the flexible matching layer. The thickness of the flexible matching layer can be adjusted according to the blade height and travel speed of the doctor blade. In some technical solutions, the blade height of the doctor blade is 0.5mm-1.5mm, and the travel speed of the doctor blade is 0.5mm / s. Preferably, the thickness of the flexible matching layer can be 1mm-1.5mm. The acoustic impedance of the above flexible matching layer is 5MRayls-6MRayls, and the acoustic attenuation is 1.5dB / mm-2dB / mm.
[0024] The piezoelectric layer includes a signal electrode flexible circuit board 2 on the flexible matching layer side, a ground electrode flexible circuit board 5 on the flexible backing layer side, and a plurality of piezoelectric elements 4 between the signal electrode flexible circuit board and the ground electrode flexible circuit board. Gaps are provided between the piezoelectric elements, and these gaps are filled with a flexible insulating material 3.
[0025] like Figure 1 As shown, the piezoelectric layer has piezoelectric element regions and gap-filling regions between the elements. The gap-filling regions are filled with a flexible insulating material to seal the gaps in the piezoelectric layer. The type of flexible insulating material is not limited, and includes, but is not limited to, polyurethane, polydimethylsiloxane (PDMS), etc.
[0026] Each piezoelectric element consists of several piezoelectric ceramic pillars and epoxy resin filling the spaces between them. For example... Figure 2 As shown, each piezoelectric element consists of several lead zirconate titanate (PZT) ceramic pillars 8 and epoxy resin 7 filling the gaps between the ceramic pillars. Compared with pure PZT ceramic piezoelectric elements, the above-mentioned piezoelectric elements have a high thickness electromechanical coupling coefficient and low acoustic impedance.
[0027] Piezoelectric layers can be prepared using a cut-and-fill method. This includes preparing piezoelectric composite material sheets using the cut-and-fill method, and then using the cut-and-fill method to fabricate piezoelectric composite material sheets into piezoelectric layers with multiple piezoelectric elements.
[0028] The piezoelectric composite material sheet can be prepared by cutting and filling a lead zirconate titanate ceramic profile to form several ceramic pillars. Epoxy resin is then filled into the gaps created by the cutting process, and after removing air bubbles, the resin is cured to obtain the piezoelectric composite material profile. The composite material profile is then thinned to a suitable thickness, and electrodes are fabricated on the surface of the profile to obtain the piezoelectric composite material sheet.
[0029] Specifically, a ceramic plate is cut horizontally and vertically using a cutting tool to form multiple piezoelectric ceramic pillars 8. The piezoelectric ceramic pillars are preferably rectangular. The length and width of the ceramic plate can be adjusted according to the application, for example, a length of 16mm × a width of 6mm. The spacing of the piezoelectric ceramic pillars in the length and width directions is controlled by the blade's cutting distance. Epoxy resin 7 is filled into the gaps created by the cutting tool to form a piezoelectric composite profile. The piezoelectric composite profile is then thinned, and electrodes are fabricated on the upper and lower surfaces of the thinned profile to obtain a piezoelectric composite sheet. As an example, a 1mm thick ceramic plate is cut to a depth of 0.5mm (not through), and resin is filled into the gaps created by the cut. After removing air bubbles, the material is cured to obtain the piezoelectric composite profile. At this point, the piezoelectric composite profile still resembles a ceramic plate with a thickness of approximately 1mm. The ceramic plate is then further thinned to 0.32mm. When thinning ceramic plates, in addition to grinding away the parts that have not been cut and filled with epoxy resin, the epoxy resin-filled parts can also be appropriately ground to obtain a suitable thickness.
[0030] When preparing piezoelectric composite material sheets using the cut-and-fill method, it is preferable to have different tool spacings in the length direction (x-direction) and width direction (y-direction). For example, when cutting with a tool with a blade width of 0.05 mm, the tool spacing in the x-direction is 0.6 mm, the size of the ceramic pillar in the x-direction is 0.55 mm, the tool spacing in the y-direction is 0.13 mm, and the size of the ceramic pillar in the y-direction is 0.08 mm. In this case, the piezoelectric ceramic pillars are spaced 0.6 mm apart in the length direction and 0.13 mm apart in the width direction.
[0031] A piezoelectric layer with multiple piezoelectric elements can be fabricated from a piezoelectric composite sheet using a cutting and filling method. A flexible ground electrode circuit board and a flexible signal electrode circuit board are then bonded to both sides of the piezoelectric composite sheet, respectively, to obtain the piezoelectric layer. The piezoelectric layer is then cut, cutting from the surface of the flexible ground electrode circuit board without penetrating the flexible signal electrode circuit board. This ensures that the piezoelectric layer is a single unit and that multiple piezoelectric elements share a single flexible signal electrode circuit board. After cutting, a flexible insulating material is used to fill the gaps.
[0032] The electrode regions of the ground electrode flexible circuit board and the signal electrode flexible circuit board are projected to coincide in the vertical direction. As mentioned earlier, the piezoelectric composite sheet has electrodes on both the side facing the signal electrode flexible circuit board and the side facing the ground electrode flexible circuit board; the side facing the signal electrode flexible circuit board is the signal electrode, and the side facing the ground electrode flexible circuit board is the ground electrode. The electrode regions of the ground electrode flexible circuit board and the ground electrode of the piezoelectric composite sheet are electrically connected, and the electrode regions of the signal electrode flexible circuit board and the signal electrode of the piezoelectric composite sheet are electrically connected.
[0033] Specifically, one side of the piezoelectric composite sheet is bonded to the flexible circuit board for the ground electrode, and the other side of the piezoelectric composite sheet is bonded to the flexible circuit board for the signal electrode. The electrodes of the flexible circuit board for the ground electrode are electrically connected to the ground electrode of the piezoelectric array element, and the electrodes of the flexible circuit board for the signal electrode are electrically connected to the signal electrode of the piezoelectric array element. The electrode regions of the flexible circuit boards for the ground electrode and the signal electrode coincide in the vertical direction. A cut is made from the location of the flexible circuit board for the ground electrode, but without cutting through the flexible circuit board for the signal electrode, to ensure that the piezoelectric layer is a single unit. The gaps between the array elements are filled using a flexible insulating material, polyurethane, while a glass slide is used to press down one side of the flexible circuit board for the ground electrode to ensure the piezoelectric layer is flat. After the polyurethane cures, a flexible piezoelectric layer is obtained.
[0034] The piezoelectric elements of the flexible transducer are spaced at the same length as the piezoelectric ceramic pillars. During fabrication, a single sheet of piezoelectric composite material is cut. The dicing machine cuts in only one direction (y-axis), but after removing each electrode gap (element gap), the blade is raised, then moved along the x-axis by one element spacing (element width + blade kerf), and then cut again along the y-axis. This process is repeated to obtain a linear array of elements arranged one-dimensionally along the x-axis. For example, using a dicing machine, the blade is advanced 6mm, then raised, and moved 0.6mm along the x-axis. This process is repeated until all piezoelectric elements are cut. The resulting array forms a one-dimensional linear array along the x-axis without cutting through the flexible circuit board of the signal electrodes, ensuring the piezoelectric layer remains intact. The blade width can be 0.1mm to 0.3mm, for example, 0.2mm. After cutting, the gaps are filled with flexible polyurethane material to create the final product. Figure 1 The piezoelectric layer is shown in the middle. As an example, the sum of the width of a single piezoelectric element and the width of the flexible insulating material beside it is 0.6 mm. The feed rate can be varied as needed, for example, to 0.3 mm / s.
[0035] The flexible circuit board for the ground electrode is configured with a single pad that connects multiple piezoelectric elements to a common ground and multiple interconnected ground electrodes. For example... Figure 3 As shown, the flexible ground electrode circuit board includes a substrate 9, pads 10, leads 11 (between element electrodes), and electrodes 12 (element electrodes). As an example, the flexible ground electrode circuit board includes a polyimide substrate, pads, leads, and Au / Ni electrode regions. The electrode regions of the flexible ground electrode circuit board are electrically connected to the ground electrode of the piezoelectric composite sheet (piezoelectric element). Connecting pads are correspondingly connected to external leads. For the flexible ground electrode circuit board, since each electrode 12 is connected to a pad 10 via connected leads 11, the ground electrodes are connected to a common ground.
[0036] The flexible circuit board for signal electrodes is configured with multiple independent pads and signal electrodes that independently excite the corresponding piezoelectric elements. For example... Figure 4 As shown, the flexible circuit board for signal electrodes includes a substrate 13, pads 14, leads 15 (between element electrodes), and electrodes 16 (element electrodes). As an example, the flexible circuit board for signal electrodes includes a polyimide substrate, pads, leads, and Au / Ni electrode regions. The electrode regions of the flexible circuit board for signal electrodes are electrically connected to the signal electrodes of the piezoelectric composite sheet (piezoelectric elements). The pads can be multiple connection pads arranged in an array. The connection pads are connected to the corresponding external leads. For the flexible circuit board for signal electrodes, although it is shared by the piezoelectric elements, each electrode 15 corresponds to a pad 14 and is connected by non-interconnected leads 15, therefore each element electrode is independent, and the signal electrode surface of the piezoelectric element is independent.
[0037] Specifically, during the fabrication process, the flexible circuit board for the signal electrodes is not cut through to prevent the flexible linear array from disintegrating. However, despite not being cut through, the signal electrodes remain independent. The blank portions between the electrodes 12 of the flexible circuit board for the ground electrodes are removed, without cutting the leads 11. The individual electrodes still function as a whole through the uncut portions. The lead structure of the flexible circuit board for the ground electrodes is simple; therefore, even though the electrode gaps are removed on the cut side, the individual ground electrodes are still connected to the same pad via leads.
[0038] The flexible backing layer can be made of polydimethylsiloxane containing tungsten powder, wherein the tungsten powder accounts for 300-500% of the mass fraction of the polydimethylsiloxane. For example, the particle size of the tungsten powder is 800 mesh. The flexible backing layer can be prepared using the above material via a scraper method. For instance, tungsten powder and polydimethylsiloxane are mixed uniformly in a certain proportion. Before the polydimethylsiloxane is cured, tungsten powder is added and mixed thoroughly, and the mixture is collected. Air bubbles are removed from the mixture. The mixture after air bubble removal is then used to form a sheet of a certain thickness using a scraper. The sheet is then cured to obtain the flexible backing layer. The thickness of the flexible backing layer can be adjusted according to the blade height and travel speed of the scraper. In some technical solutions, the blade height of the scraper is 1mm-3mm, and the scraper travel speed is 0.5mm / s. Preferably, the thickness of the flexible matching layer can be 1mm-2mm. The acoustic impedance of the above flexible backing layer is 3MRayls-4MRayls, and the acoustic attenuation is 40dB / mm-60dB / mm.
[0039] By configuring the electrodes of each piezoelectric element to be independently led out from a flexible circuit board, integrated independent piezoelectric elements are obtained. The signal electrode flexible circuit board enables independent excitation of each piezoelectric element, while the ground electrode flexible circuit board enables a common ground connection between the piezoelectric elements. The flexible insulating material filling the gaps between the signal electrode flexible circuit board, the ground electrode flexible circuit board, and the flexible insulating material achieves overall flexibility of the piezoelectric layer. This results in the highly flexible linear array transducer described in this invention, which has advantages such as small size, thin profile, wearability, and ease of fabrication.
[0040] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values in the examples below.
[0041] The flexible ultrasonic linear array transducer includes a flexible backing layer, a flexible matching layer, and a piezoelectric layer between the flexible backing layer and the flexible matching layer. The piezoelectric layer includes a signal electrode flexible circuit board on the flexible matching layer side, a ground electrode flexible circuit board on the flexible backing layer side, and multiple piezoelectric array elements between the signal electrode flexible circuit board and the ground electrode flexible circuit board.
[0042] Prepare a flexible matching layer. Mix epoxy resin Epo-Tek 301-2 and curing agent at a mass ratio of 100:35 and stir until homogeneous. Before curing the mixed epoxy resin, add 2000-mesh zirconia powder (140% of the epoxy resin mass) and stir thoroughly until the zirconia powder and epoxy resin are uniformly mixed. Degas the mixture of zirconia powder and epoxy resin using a vacuum drying oven until no more bubbles remain. Using a doctor blade method, form the degassed zirconia powder and epoxy resin mixture into a thin sheet of uniform thickness, with a blade height of 1.0 mm and a blade travel speed of 0.5 mm / s. Allow the mixture to cure completely at 45°C for 8 hours to obtain the flexible matching layer.
[0043] Piezoelectric composite material sheets were prepared using a cut-and-fill method. A 1 mm thick, fully polarized bulk PZT ceramic was cut using a 50 μm wide blade. A DISCO DAD 321 dicing machine was used for cutting, with a kerf depth of 0.5 mm, a feed rate of 0.4 mm / s, and a water flow rate of 0.6 L / min, forming PZT ceramic pillars. The gaps in the PZT ceramic pillars were then filled with a prepared epoxy resin, Epo-Tek 301-2 (epoxy resin to curing agent mass ratio of 100:35). After filling, air bubbles in the ceramic pillar gaps were removed in a vacuum drying oven, and then cured at 45 °C for 8 hours to obtain a piezoelectric composite material profile. The piezoelectric composite material profile was then thinned by grinding away excess PZT ceramic and epoxy resin until the composite material profile thickness reached 0.32 mm. Using magnetron sputtering, the upper and lower surface electrodes (signal electrodes and ground electrodes) of the piezoelectric composite material profile are fabricated to obtain a piezoelectric composite material sheet.
[0044] A piezoelectric composite sheet was prepared into a piezoelectric layer with multiple piezoelectric elements using a cutting and filling method. One side of a 0.32 mm thick, 16 mm long, and 6 mm wide piezoelectric composite sheet was bonded to a flexible ground electrode circuit board, and the other side was bonded to a flexible signal electrode circuit board. The electrodes of the flexible ground electrode circuit board were electrically connected to the ground electrodes of the piezoelectric elements, and the electrodes of the flexible signal electrode circuit board were electrically connected to the signal electrodes of the piezoelectric elements. The vertical projections of the electrode regions of the flexible ground electrode circuit board and the flexible signal electrode circuit board coincided. The sample with bonded electrodes was cut along its length using a dicing machine with a blade width of 0.2 mm, a feed spacing of 0.6 mm, and a feed speed of 0.3 mm / s. Cutting was performed from the position of the flexible ground electrode circuit board, but without cutting through the flexible signal electrode circuit board, to ensure the piezoelectric layer remained integral. The gaps between the elements were filled using a flexible insulating material, polyurethane, while a glass slide was used to press down one side of the flexible ground electrode circuit board to ensure the piezoelectric layer remained flat. After the polyurethane cures, a flexible piezoelectric layer is obtained. The spacing of the piezoelectric elements along the length direction is the same as the spacing of the piezoelectric ceramic pillars along the length direction. In this example, the spacing of the piezoelectric elements along the length direction is 0.6 mm.
[0045] Prepare a flexible backing layer. Mix PDMS and curing agent at a mass ratio of 10:1 and stir until homogeneous. Before curing the mixed PDMS, add 800-mesh zirconia powder (400% by mass of PDMS) and stir thoroughly until the tungsten powder and PDMS are uniformly mixed. Degas the mixture of tungsten powder and PDMS using a vacuum drying oven until no more bubbles are present. Use a doctor blade method to form a thin sheet of uniform thickness from the degassed mixture of tungsten powder and PDMS, with a blade height of 2 mm and a blade travel speed of 0.5 mm / s. Allow the sheet to cure completely at 60°C for 8 hours to obtain the flexible backing layer.
[0046] The fabricated flexible backing layer, piezoelectric layer, and flexible matching layer were sequentially bonded together to form a flexible linear array piezoelectric transducer. The fabricated flexible linear array piezoelectric transducer was tested using the pulse-echo method, showing a center frequency of 3.4 MHz and a -6 dB bandwidth of 57.2%, exhibiting high bandwidth.
[0047] It should be stated that the above-described invention content and specific embodiments are intended to demonstrate the practical application of the technical solution provided by this invention and should not be construed as limiting the scope of protection of this invention. Those skilled in the art can make various modifications, equivalent substitutions, or improvements within the spirit and principles of this invention.
Claims
1. A flexible ultrasonic linear array transducer, characterized in that, The flexible ultrasonic linear array transducer includes a flexible backing layer, a flexible matching layer, and a piezoelectric layer between the flexible backing layer and the flexible matching layer; the flexible matching layer is made of epoxy resin containing zirconium oxide powder; the flexible backing layer is made of polydimethylsiloxane containing tungsten powder; the piezoelectric layer includes a signal electrode flexible circuit board on the flexible matching layer side, a ground electrode flexible circuit board on the flexible backing layer side, and multiple piezoelectric array elements between the signal electrode flexible circuit board and the ground electrode flexible circuit board; The piezoelectric array elements are configured with gaps filled with flexible insulating material; The flexible insulating material is polyurethane or polydimethylsiloxane; The piezoelectric layer is prepared using a cut-and-fill method, comprising: preparing a piezoelectric composite material sheet by the cut-and-fill method, and then forming a piezoelectric layer with multiple independent piezoelectric elements from the piezoelectric composite material sheet using the cut-and-fill method; wherein, the method of forming a piezoelectric layer with multiple independent piezoelectric elements from the piezoelectric composite material sheet by the cut-and-fill method is to further bond a ground electrode flexible circuit board and a signal electrode flexible circuit board to both sides of the piezoelectric composite material sheet to obtain a piezoelectric layer; when cutting the piezoelectric layer, the cut is made from the surface of the ground electrode flexible circuit board without penetrating the signal electrode flexible circuit board, so that multiple independent piezoelectric elements share a single signal electrode flexible circuit board; after cutting, a flexible insulating material is used for filling the gaps; in addition, the signal electrode flexible circuit board shared by the piezoelectric elements is configured with multiple independent pads and signal electrodes that independently excite the corresponding piezoelectric elements, and the ground electrode flexible circuit board is configured with a single pad that connects multiple piezoelectric elements to a common ground and multiple interconnected ground electrodes.
2. The flexible ultrasonic linear array transducer according to claim 1, characterized in that, Each piezoelectric element has a ground electrode on the ground electrode flexible circuit board side that is electrically connected to the electrode region of the ground electrode flexible circuit board, and a signal electrode on the signal electrode flexible circuit board side that is electrically connected to the electrode region of the signal electrode flexible circuit board.
3. The flexible ultrasonic linear array transducer according to claim 1, characterized in that, The electrode regions of the ground electrode flexible circuit board and the signal electrode flexible circuit board are projected to overlap in the vertical direction.
4. The flexible ultrasonic linear array transducer according to claim 1, characterized in that, The piezoelectric array elements are arranged in a linear array in one dimension along the x-direction.
5. The flexible ultrasonic linear array transducer according to claim 1, characterized in that, Each piezoelectric element has several piezoelectric ceramic pillars and epoxy resin filling the spaces between them. The spacing of the piezoelectric ceramic pillars in the x-direction is the same as the spacing of the piezoelectric elements in the x-direction.
6. The flexible ultrasonic linear array transducer according to claim 1, characterized in that, The piezoelectric material of the piezoelectric array element is lead zirconate titanate ceramic.
7. The flexible ultrasonic linear array transducer according to claim 1, characterized in that, In the material of the flexible matching layer, the zirconium oxide powder contains 120%-160% epoxy resin by mass.
8. The flexible ultrasonic linear array transducer according to claim 1, characterized in that, In the material of the flexible backing layer, tungsten powder accounts for 300%-500% of the mass fraction of polydimethylsiloxane.