A method for manufacturing a broadband flexible array ultrasonic transducer and an ultrasonic transducer

Abstract

The application relates to the technical field of ultrasonic imaging, in particular to a preparation method of a wideband flexible array ultrasonic transducer and the ultrasonic transducer, wherein the method comprises the following steps: S10, preparing a piezoelectric layer, preparing a first electrode and a second electrode on two opposite surfaces of the piezoelectric layer, the piezoelectric layer being provided with a conductive structure connected with the first electrode and the second electrode, and the conductive structure forming an array layout on the opposite surfaces; S20, preparing a matching layer, performing first cutting on a first surface of the matching layer according to the array layout, the depth of the first cutting being not more than the thickness of the matching layer, the first surface being attached to the first electrode, and performing second cutting on a second surface of the matching layer according to the array layout, the second cutting cutting through the matching layer completely. The method can realize accurate and parallel alignment and firm bonding of at least two acoustic matching layers and each piezoelectric column under the premise of keeping the flexibility of the transducer as a whole, the working hours of a single process are significantly shortened, and the wafer-level batch production potential is possessed.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic imaging technology, and more specifically, to a method for fabricating a broadband flexible array ultrasonic transducer and the ultrasonic transducer itself. Background Technology

[0002] Flexible ultrasound transducers, used to achieve conformal high-resolution imaging on the surfaces of skin, blood vessels, or organs, require both wide acoustic bandwidth and excellent mechanical compliance. Traditional designs often face fundamental compromises: sacrificing the matching layer for flexibility leads to acoustic energy loss and signal trailing, while abandoning bandwidth limits imaging resolution and detection depth, resulting in a long-standing technical dilemma where bandwidth, flexibility, and scalable manufacturing are mutually exclusive. However, once this bottleneck is overcome, flexible ultrasound transducers will exhibit significant cross-domain advantages: in clinical diagnosis, they can conform to the curved surfaces of the human body to achieve artifact-free real-time tissue imaging, significantly improving the imaging quality of cardiovascular, musculoskeletal, and superficial organs; in the field of wearable medical devices, their excellent flexibility and stability support long-term, dynamic monitoring, providing new tools for chronic disease management and postoperative rehabilitation; in interventional surgery applications, miniaturized flexible arrays adapted to catheter tips can enter blood vessels or cavities to achieve high-contrast imaging from inside the cavity out, assisting in precise surgical decisions. Furthermore, in industrial non-destructive testing and biomechanical research, this technology can also achieve tight-coupled detection and dynamic response measurement of complex curved structures, expanding the application boundaries of ultrasound sensing.

[0003] Existing ultrasonic transducer manufacturing methods can be broadly categorized into four types, with their defects being mutually causal: 1. No Matching Layer – The no-matching-layer design omits a dedicated acoustic matching structure, relying solely on direct mechanical coupling between the piezoelectric composite material and the flexible encapsulation film (such as polyimide or PDMS). Due to the significant difference in acoustic impedance between the two, sound waves undergo strong reflection at the interface, resulting in severe pulse tailing. This not only significantly reduces the signal-to-noise ratio of the echo signal but also causes the axial resolution of the system to deteriorate sharply with increasing imaging depth, severely limiting the transducer's imaging capability in deep tissues.

[0004] 2. Monolithic Rigid Matching – The monolithic rigid matching layer strategy employs a high-hardness, high-density integral matching material (such as epoxy resin-tungsten powder composite material) adhered to the transducer surface, with mechanical slits used to partially release internal stress. However, under bending conditions, a significant mechanical deformation mismatch exists between the rigid matching layer and the underlying discrete piezoelectric micropillars, causing stress concentration at the bonding interface, which easily leads to microcracks or even debonding. This interface damage not only alters the acoustic boundary conditions of the system, resulting in center frequency drift and a significant decrease in sensitivity, but also causes the device to fail even at a small radius of curvature.

[0005] 3. Single-element "cut-then-attach" process: The "cut-then-attach" process first micro-fabricates the piezoelectric material to form an independent array of piezoelectric micropillars, achieving structural flexibility. Then, each micropillar must be individually aligned under a microscope and manually coated with adhesive to fix it in place. This process is a typical serial operation, requiring extremely high alignment accuracy and heavily relying on skilled operators, resulting in low production efficiency and difficulty in ensuring consistency. When this method is extended to two-dimensional large-scale arrays, the processing time and complexity increase exponentially, making stable and large-scale mass production virtually impossible.

[0006] 4. Laser-based "Pre-attach, Post-cut" process: This process involves first bonding the entire rigid matching layer to the transducer surface, then using laser cutting technology to carve isolation grooves. However, the laser focusing depth is difficult to control precisely, easily leading to over-cutting and causing thermal damage and performance degradation to the underlying piezoelectric functional layer. Simultaneously, the laser cut penetrates the underlying flexible substrate, creating localized stress concentration points during bending, causing brittle fracture of the matching layer material at the groove edges, ultimately significantly reducing the overall device flexibility.

[0007] Existing methods for fabricating ultrasound transducers cannot guarantee precise coupling with each micropillar without introducing new interface damage due to cutting or adhesive layers. Therefore, they cannot simultaneously meet the requirements of production efficiency and production quality, becoming a core bottleneck restricting the entry of flexible ultrasound imaging into clinical and wearable scenarios. Summary of the Invention

[0008] To overcome the problem that the existing ultrasonic transducer manufacturing methods cannot simultaneously meet the requirements of production efficiency and production quality, the first aspect of the present invention provides a method for preparing a broadband flexible array ultrasonic transducer.

[0009] A second aspect of the present invention provides a broadband flexible array ultrasonic transducer.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for fabricating a broadband flexible array ultrasonic transducer, comprising the following steps: S10: Prepare a piezoelectric layer, prepare a first electrode and a second electrode on two opposite surfaces of the piezoelectric layer, the piezoelectric layer has a conductive structure connecting the first electrode and the second electrode, and the conductive structure is arranged in an array on the opposite surfaces; S20: Prepare a matching layer. Make a first cut on the first surface of the matching layer according to the array layout. The depth of the first cut does not exceed the thickness of the matching layer. Adhere the first surface after the first cut to the first electrode. The matching layer has a second surface opposite to the first surface. Make a second cut on the second surface according to the array layout. The second cut completely cuts through the matching layer.

[0011] In the technical solution of this invention, the matching layer is first partially cut to form a "groove-island" distribution structure on the matching layer. Compared with the existing "attach first, then cut" method, this solution cuts the matching layer separately, so it will not cause damage to the first electrode. Since the matching layer is not completely cut through and the cut forms the same array layout, the half-cut matching layer can be accurately and quickly connected with the first electrode piezoelectric layer and the matching layer. Compared with the existing "cut first, then attach" method, the production efficiency is higher. Finally, the matching layer is completely cut through. This method retains the overall flexibility of the transducer, and the piezoelectric pillar is accurately coupled with the matching layer. The single-process time is significantly shortened, and it has the potential for wafer-level mass production.

[0012] Further, in step S10, the method for preparing the piezoelectric layer is to fill the spaces between multiple piezoelectric pillars in the array layout with a polymer phase material.

[0013] Further, in step S20, a plurality of cutting grooves are cut on the first surface of the matching layer, and each cutting groove divides the matching layer into a plurality of matching pillars, the distribution of each matching pillar conforming to the array layout.

[0014] Furthermore, the array layout is evenly spaced in both the X and Y directions.

[0015] Furthermore, the matching layer includes at least two matching sub-layers, and each matching sub-layer undergoes a bonding pre-processing to obtain the matching layer.

[0016] Furthermore, the bonding pretreatment is a hot pressing treatment, with a temperature of 70℃~85℃, a pressure of 0.2MPa~0.22MPa, and a time of 5min~7min.

[0017] Furthermore, the matching layer includes two matching sub-layers, namely a conductive matching sub-layer and a functional matching sub-layer.

[0018] Furthermore, the functional matching sublayer is a 2-2 type functional matching sublayer, which includes conductive phase material bodies and polymer matrixes that are continuous in the X and Z directions, respectively. Each conductive phase material body and each polymer matrix is ​​spaced apart in the Y direction, and the width of the conductive phase material body in the Y direction is smaller than the spacing of the array layout.

[0019] Furthermore, the functional matching sublayer is a type 1-3 functional matching sublayer, which includes multiple continuous columnar or fibrous conductive phase material bodies in the Z direction. Each conductive phase material body is arranged in an array in the XY plane, and a polymer matrix is ​​filled between each conductive phase material body. The width of each conductive phase material body in both the X and Y directions is smaller than the interval of the array arrangement.

[0020] An ultrasonic transducer, manufactured using the method described above, comprises: a piezoelectric layer, wherein a first electrode and a second electrode are respectively disposed on two opposing surfaces of the piezoelectric layer; the piezoelectric layer includes a plurality of piezoelectric pillars arranged in an array and a polymer phase material filled between each of the piezoelectric pillars; a plurality of matching units are connected to the side of the first electrode away from the piezoelectric layer; each matching unit is arranged in an array and corresponds to the position of each of the piezoelectric pillars; each matching unit includes a conductive matching unit and a functional matching unit; the conductive matching unit is connected to the first electrode, and the functional matching unit is connected to the conductive matching unit.

[0021] Compared with the prior art, the beneficial effects of the present invention are: I. The fabrication method of the multi-layer matched broadband flexible array ultrasonic transducer of the present invention can achieve precise, parallel alignment and firm bonding of at least two acoustic matching layers with each piezoelectric column while retaining the overall flexibility of the transducer. The single-process time is significantly shortened, and it has the potential for wafer-level mass production.

[0022] II. The ultrasonic transducer of the present invention has the following advantages: ultra-wideband transmission / reception performance, effectively suppressing axial pulse tailing and improving axial resolution; small curvature repeated bending capability, suitable for long-term attachment to dynamic curved surfaces such as joints and hearts; high element density and scalable manufacturing capability, meeting the requirements of high frame rate and large field of view imaging, and providing core component support for next-generation wearable ultrasound, disposable surgical navigation patches and intracavitary ultrasound catheters. Attached Figure Description

[0023] Figure 1 This is a flowchart of the fabrication method of the broadband flexible array ultrasonic transducer of the present invention; Figure 2 This is an exploded view of the ultrasonic transducer of the present invention in its uncut state; Figure 3 This is a schematic diagram of the piezoelectric layer structure; Figure 4 This is a schematic diagram of the structure connecting the piezoelectric layer to the first and second electrodes; Figure 5 This is a schematic diagram of the structure of the type 1-3 functional matching sublayer; Figure 6 This is a schematic diagram of the structure of the 2-2 type functional matching sublayer; Figure 7 This is a schematic diagram of the matching layer structure formed by bonding type 1-3 functional matching sublayers and conductive matching sublayers; Figure 8 yes Figure 7 A schematic diagram of the structure after the matching layer is half-cut; Figure 9 This is a schematic diagram of the structure where the matching layer and the piezoelectric layer are bonded together after being partially cut; Figure 10 It is Figure 9 A schematic diagram of the structure after the matching layer is cut through.

[0024] In the attached figures: 1. First electrode; 2. Piezoelectric layer; 3. Second electrode; 4. Conductive matching sublayer; 5. Functional matching sublayer; 6. Polymer matrix; 7. Conductive phase material body; 8. Piezoelectric pillar; 9. Polymer phase material. Detailed Implementation

[0025] The accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0026] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "long," and "short" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0027] The technical solution of the present invention will be further described in detail below through specific embodiments and with reference to the accompanying drawings: Example 1 refer to Figure 1 and combined Figures 2 to 10 This embodiment discloses a method for fabricating a broadband flexible array ultrasonic transducer, including the following steps: S10: Reference Figure 3 and Figure 4A piezoelectric layer 2 is prepared, and a first electrode 1 and a second electrode 3 are prepared on two opposite surfaces of the piezoelectric layer 2. The piezoelectric layer 2 has a conductive structure connecting the first electrode 1 and the second electrode 3, and the conductive structure is arranged in an array on the opposite surfaces.

[0028] The first electrode 1 is a Ti / Au composite thin film with a thickness of 50–100 nm, used for external excitation / receiving electrical connection. The second electrode 3 is symmetrical to the first electrode 1, forming an upper and lower electrode pair.

[0029] S20: Reference Figures 8 to 10 A matching layer is prepared. The first surface of the matching layer is cut in an array layout. The depth of the first cut does not exceed the thickness of the matching layer. The first surface after the first cut is attached to the first electrode 1. The matching layer has a second surface opposite to the first surface. The matching layer is cut in an array layout on the second surface. The second cut completely cuts through the matching layer.

[0030] When bonding the piezoelectric layer 2 and the first electrode 1 of the matching layer, existing professional bonding tools and techniques are used to ensure tight contact between the matching layer and the first electrode 1 of the piezoelectric layer 2, avoiding air bubbles or gaps. This tight bonding ensures good acoustic and electrical connection between the two, enabling efficient signal transmission between the matching layer and the piezoelectric layer 2, thereby ensuring the performance of the transducer.

[0031] When cutting the matching layer, laser cutting technology can be used. The position and width of the second cut correspond to the first cut, completely cutting through the matching layer according to the array layout to form multiple independent units. In this way, a flexible array of "one pillar, one matching" is obtained, which ensures that the matching layer is precisely covered on each conductive structure of the piezoelectric layer 2. This not only ensures the effective bonding between the matching layer and the piezoelectric layer 2, but also realizes the flexible characteristics of the transducer, and helps to improve the operating bandwidth of the transducer.

[0032] In this embodiment, reference Figure 8 First, the matching layer is partially cut to form a "groove-island" distribution structure on the matching layer. Compared to the existing "attach first, then cut" method, this solution cuts the matching layer separately, thus avoiding damage to the first electrode 1. (Reference) Figure 9 Because the matching layer is not completely cut through and the cuts form the same array layout, the partially cut matching layer can be precisely and quickly connected to the first electrode 1, resulting in higher production efficiency compared to the existing "cut-then-attach" method. (Reference) Figure 10 Finally, the matching layer is completely cut through. This method, while preserving the overall flexibility of the transducer, precisely couples the piezoelectric column 8 with the matching layer, significantly shortening the single-process time and possessing the potential for wafer-level mass production.

[0033] refer to Figure 3In step S10, the method for preparing the piezoelectric layer 2 is to fill the spaces between multiple piezoelectric pillars 8 arranged in an array with polymer phase material 9. In this embodiment, based on the theoretically designed dimensional parameters of the piezoelectric layer 2, the piezoelectric material is laser-cut to form the array of piezoelectric pillars 8, and the piezoelectric material is a piezoelectric wafer. For example, the piezoelectric wafer is first cut along the X direction with a step size of 25 μm, and then polymer phase material 9, such as epoxy resin, is poured into the cut groove, and air is removed in a vacuum for 30 minutes. Next, the material is placed in an oven at 45°C for 24 hours to cure. The cured material is then cut along the Y direction with a step size of 25 μm and polymer phase material 9, such as epoxy resin, is poured in. After curing in the oven, excess single crystal and epoxy resin are ground off to obtain the required piezoelectric material thickness. Finally, electrodes are deposited on the upper and lower surfaces of the piezoelectric layer 2 using a magnetron sputtering instrument and polarized to form the first electrode 1 and the second electrode 3.

[0034] Piezoelectric materials exhibit the piezoelectric effect and serve as the core component for energy conversion in the piezoelectric layer 2. The spaces between the piezoelectric pillars 8 are filled with a polymer phase material 9, such as epoxy resin. Under the influence of an external electric field, the piezoelectric layer 2 can generate mechanical vibrations, thereby emitting ultrasonic waves; conversely, when receiving ultrasonic waves, it can convert mechanical energy into electrical energy, thus achieving signal reception.

[0035] refer to Figure 8 In step S20, multiple cutting grooves are formed on the first surface of the matching layer. Each cutting groove divides the matching layer into multiple matching pillars, and the distribution of the matching pillars conforms to an array layout. The array layout is evenly spaced in the X and Y directions. In this embodiment, the X and Y directions are perpendicular to each other. Multiple evenly distributed cutting grooves are formed along the X and Y directions respectively, and the cutting depth is precisely controlled so that the depth of the cutting grooves does not exceed the thickness of the matching layer, ensuring that the cutting depth does not penetrate the matching layer. Regular cutting grooves are formed on the surface of the matching layer, preparing for subsequent bonding and through-cutting steps. In some other embodiments, the X and Y directions may have other included angles.

[0036] The mating layer comprises at least two mating sublayers, each of which undergoes a bonding pretreatment to form the mating layer. The bonding pretreatment is a hot-pressing process, in which at least two mating sublayers are placed in a hot-pressing apparatus and hot-pressed at a temperature of 70℃–85℃, a pressure of 0.2MPa–0.22MPa, and a time of 5min–7min to form an integrated multilayer sheet. This integrated multilayer sheet can serve as the base material for subsequent processing, providing stable structural support for subsequent fabrication.

[0037] For details, please refer to Figure 7In this embodiment, the matching layer includes two matching sub-layers: a conductive matching sub-layer 4 and a functional matching sub-layer 5. The conductive matching layer used in this embodiment is composed of silver and epoxy resin, and it is tightly bonded to the first electrode 1. It not only serves as a channel for electrical signal transmission, accurately transmitting external excitation signals to the piezoelectric layer 2, but also provides acoustic matching, reducing sound wave reflection at the interface and improving sound wave transmission efficiency.

[0038] Example 2 refer to Figure 10 This embodiment discloses an ultrasonic transducer, which is fabricated using the method of Embodiment 1. It includes a piezoelectric layer 2, with a first electrode 1 and a second electrode 3 respectively disposed on two opposing surfaces of the piezoelectric layer 2. The piezoelectric layer 2 includes a plurality of piezoelectric pillars 8 arranged in an array and a polymer phase material 9 filled between each piezoelectric pillar 8. A plurality of matching units are connected to the side of the first electrode 1 away from the piezoelectric layer 2. Each matching unit is arranged in an array and corresponds to the position of each piezoelectric pillar 8. The matching unit includes a conductive matching unit and a functional matching unit. The conductive matching unit is connected to the first electrode 1, and the functional matching unit is connected to the conductive matching unit.

[0039] The functional matching unit is formed by cutting the functional matching sublayer 5, and the conductive matching unit is formed by cutting the conductive matching sublayer 4. (Reference) Figure 6 In this embodiment, the functional matching sublayer 5 is a 2-2 type functional matching sublayer. The 2-2 type functional matching sublayer includes conductive phase material bodies 7 and polymer matrix 6, which are continuous in the X and Z directions respectively. The conductive phase material bodies 7 and polymer matrix 6 are spaced apart in the Y direction, and the width of the conductive phase material bodies 7 in the Y direction is smaller than the spacing of the array arrangement. By filling the polymer matrix 6, such as epoxy resin, with low-density photosensitive resin, its low modulus characteristics are utilized to reduce the equivalent density of the matching layer, thereby adjusting the acoustic impedance, allowing for better matching with the surrounding medium and broadening the working bandwidth.

[0040] In the 2-2 type functional matching sublayer, the width T of the polymer matrix 6 in the Y direction is smaller than the array layout spacing, which is the distance between adjacent piezoelectric pillars 8, called the element spacing. Taking a center frequency of 2.5MHz as an example, the element spacing is approximately 0.3mm (sound velocity / frequency), therefore T ≤ 0.3mm. This ensures that each element maintains a high degree of independence in electrical, acoustic, and mechanical structure, achieving high bandwidth, high resolution, and excellent flexibility. If the width T > the element spacing, a single conductive channel may physically cross and contact adjacent piezoelectric micropillars. This can cause aliasing (short circuit) of the excitation signals between adjacent elements, preventing the array from achieving independent phase control and directly causing the transducer to lose its ability to focus electrons and deflect images. When T > the element spacing, the acoustic wave emission surface is no longer confined to directly above the piezoelectric pillars 8 but diffuses outwards, causing a sharp decrease in the lateral resolution of the image. When T > the element spacing, the wide conductive layer may experience brittle fracture due to stress concentration or delamination of the bonding interface during small curvature bending.

[0041] In this embodiment, the conductive phase material of the 2-2 type functional matching sublayer is directly bonded to the first electrode 1, achieving near-lossless transmission of electrical signals. The gaps between adjacent conductive phase materials are filled with low-density photosensitive resin, which reduces the overall equivalent density of the matching layer due to its low modulus characteristics. Conductive phase materials such as silver powder can reduce the overall density of the matching layer, adjust the acoustic impedance, and better match it with the surrounding medium, thereby broadening the operating bandwidth of the ultrasonic transducer. The polymer matrix 6, such as epoxy resin, gives the matching layer good flexibility, enabling the ultrasonic transducer to adapt to surfaces with different curvatures and achieve flexible characteristics.

[0042] Example 3 refer to Figure 10 Similar to Example 2, this example discloses an ultrasonic transducer, which is fabricated using the method of Example 1. It includes a piezoelectric layer 2, with a first electrode 1 and a second electrode 3 respectively disposed on two opposing surfaces of the piezoelectric layer 2. The piezoelectric layer 2 includes a plurality of piezoelectric pillars 8 arranged in an array and a polymer phase material 9 filled between each piezoelectric pillar 8. A plurality of matching units are connected to the side of the first electrode 1 away from the piezoelectric layer 2. Each matching unit is arranged in an array and corresponds to the position of each piezoelectric pillar 8. The matching unit includes a conductive matching unit and a functional matching unit. The conductive matching unit is connected to the first electrode 1, and the functional matching unit is connected to the conductive matching unit.

[0043] The difference between this embodiment and Embodiment 2 is that, referring to... Figure 5 and Figure 7The functional matching sublayer 5 adopts a type 1-3 functional matching sublayer. The type 1-3 functional matching sublayer includes multiple continuous columnar or fibrous conductive phase material bodies 7 in the Z direction. Each conductive phase material body 7 is arranged in an array in the XY plane. A polymer matrix 6 is filled between each conductive phase material body 7, and the width of the conductive phase material body 7 in both the X and Y directions is smaller than the interval of the array arrangement.

[0044] Similarly, the conductive phase material body 7 of the type 1-3 functional matching sublayer has a width in both the X and Y directions that is smaller than the spacing of the array layout. This ensures that each array element maintains a high degree of independence in electrical, acoustic and mechanical structure, thereby achieving high bandwidth, high resolution and excellent flexibility.

[0045] In this embodiment, the low in-plane shear stiffness of the type 1-3 matching layer and the mechanical cuts present in the type 1-3 matching layer reduce the in-plane shear stiffness, giving the transducer excellent small curvature bending capability and endowing the ultrasonic transducer with "flexible and bendable" function. The continuous phase forms a straight acoustic path, and the acoustic impedance can be precisely designed along the thickness direction, improving the bandwidth. The one-dimensional conductive path simultaneously realizes the triple functions of "matching + grounding + EMI shielding", saving additional electrode layers.

[0046] According to the equivalent medium theory, the acoustic impedance Z of the matching layer depends on the volume fraction ratio of the conductive phase to the polymer matrix 6. The conductive phase has high impedance, while the polymer matrix 6 has low impedance. By adjusting this ratio, an ideal intermediate impedance between the piezoelectric layer 2 and human tissue can be prepared, thereby significantly reducing sound wave reflection at the interface. The reduction of reflected waves can significantly suppress axial pulse tailing. The narrower the pulse, the wider the bandwidth in the frequency domain, thus improving the axial resolution of the system. Type 1-3 matching layers can form an all-around electromagnetic shielding network, with good grounding consistency and EMI shielding effect.

[0047] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for fabricating a broadband flexible array ultrasonic transducer, characterized in that: Includes the following steps: S10: Prepare a piezoelectric layer (2), prepare a first electrode (1) and a second electrode (3) on two opposite surfaces of the piezoelectric layer (2), the piezoelectric layer (2) has a conductive structure connecting the first electrode (1) and the second electrode (3), and the conductive structure forms an array on the opposite surfaces; S20: Prepare a matching layer. Make a first cut on the first surface of the matching layer according to the array layout. The depth of the first cut does not exceed the thickness of the matching layer. Adhere the first surface after the first cut to the first electrode (1). The matching layer has a second surface opposite to the first surface. Make a second cut on the second surface according to the array layout. The second cut completely cuts through the matching layer.

2. The method for fabricating a broadband flexible array ultrasonic transducer according to claim 1, characterized in that: In step S10, the piezoelectric layer (2) is prepared by filling polymer phase material (9) between multiple piezoelectric pillars (8) arranged in an array.

3. The method for fabricating a broadband flexible array ultrasonic transducer according to claim 1, characterized in that: In step S20, a plurality of cutting grooves are cut on the first surface of the matching layer, and each cutting groove divides the matching layer into a plurality of matching pillars, the distribution of each matching pillar conforming to the array layout.

4. The method for fabricating a broadband flexible array ultrasonic transducer according to claim 1, characterized in that: The array layout is evenly spaced in both the X and Y directions.

5. The method for fabricating a broadband flexible array ultrasonic transducer according to claim 1, characterized in that: The matching layer includes at least two matching sub-layers, and each matching sub-layer is subjected to bonding preprocessing to obtain the matching layer.

6. The method for fabricating a broadband flexible array ultrasonic transducer according to claim 5, characterized in that: The bonding pretreatment is a hot pressing treatment, with a temperature of 70℃~85℃, a pressure of 0.2MPa~0.22MPa, and a time of 5min~7min.

7. The method for fabricating a broadband flexible array ultrasonic transducer according to claim 5, characterized in that: The matching layer includes two matching sub-layers, namely a conductive matching sub-layer (4) and a functional matching sub-layer (5).

8. The method for fabricating a broadband flexible array ultrasonic transducer according to claim 7, characterized in that: The functional matching sublayer (5) is a 2-2 type functional matching sublayer. The 2-2 type functional matching sublayer includes conductive phase material bodies (7) and polymer matrix (6) that are continuous in the X and Z directions, respectively. Each conductive phase material body (7) and each polymer matrix (6) are spaced apart in the Y direction, and the width of the conductive phase material body (7) in the Y direction is smaller than the spacing of the array layout.

9. The method for fabricating a broadband flexible array ultrasonic transducer according to claim 7, characterized in that: The functional matching sublayer (5) is a type 1-3 functional matching sublayer. The type 1-3 functional matching sublayer includes multiple continuous columnar or fibrous conductive phase material bodies (7) in the Z direction. Each conductive phase material body (7) is arranged in an array in the XY plane. A polymer matrix (6) is filled between each conductive phase material body (7). The width of each conductive phase material body (7) in the X and Y directions is smaller than the interval of the array arrangement.

10. An ultrasonic transducer, manufactured using the method described in any one of claims 1 to 9, characterized in that: The piezoelectric layer (2) includes a first electrode (1) and a second electrode (3) on two opposite surfaces. The piezoelectric layer (2) includes a plurality of piezoelectric pillars (8) arranged in an array and a polymer phase material (9) filled between each of the piezoelectric pillars (8). The side of the first electrode (1) away from the piezoelectric layer (2) is connected to a plurality of matching units. Each matching unit is arranged in an array and corresponds to the position of each of the piezoelectric pillars (8). Each matching unit includes a conductive matching unit and a functional matching unit. The conductive matching unit is connected to the first electrode (1), and the functional matching unit is connected to the conductive matching unit.

Images