Ultrasound probe comprising array of transducer elements
By cutting a double-layer piezoelectric layer and using a collector electrode structure, the problems of electrical connection and bending of array ultrasonic probes at low frequencies were solved, achieving effective electrical connection and improved acoustic performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WAYMON CORP
- Filing Date
- 2024-09-24
- Publication Date
- 2026-05-08
AI Technical Summary
Existing array ultrasound probes have electrical connection problems when operating at low frequencies, making them prone to short circuits and difficult to achieve curved shapes.
It adopts a double-layer piezoelectric layer structure. Each piezoelectric layer is cut into piezoelectric elements on both sides of the ground plane and electrically connected through the collector and the ground plane. The collector uses an insulating substrate and a metal track for electrical coupling to avoid short circuits and allow the probe to bend.
Effective electrical connection of the ultrasonic probe at low frequency was achieved, avoiding short circuit problems, and flexible array ultrasonic probes were manufactured, improving acoustic and electrical performance.
Smart Images
Figure CN122003301A_ABST
Abstract
Description
[0001] This patent application is based on and claims priority to French patent application 2310965, filed on October 12, 2023, entitled “Ultrasonic probe with an array of transducer elements,” which is considered an integral part of this specification to the extent permitted by law. Technical Field
[0002] This disclosure generally relates to ultrasonic probes having an array of transducer elements, which may be referred to as "array ultrasonic probes," and particularly to low-frequency array ultrasonic probes, i.e., those suitable for operation at frequencies typically below 2 MHz. This specification particularly relates to convex array ultrasonic probes. Background Technology
[0003] An array ultrasound probe typically comprises multiple transducer elements arranged side-by-side in a matrix array.
[0004] The transducer elements of the matrix array are preferably addressed individually, rather than by row and column.
[0005] When the transducer element is a piezoelectric transducer element, each transducer element typically includes a layer of piezoelectric material (or piezoelectric layer), and front and rear electrodes adapted to apply an excitation electrical signal to the transducer element and / or recover a signal from the transducer element in order to convert it into an electrical signal. One of the front and rear electrodes may be connected to ground, and the other electrode may be dedicated to the signal.
[0006] Array ultrasound probes can be used for 2D and even 3D imaging, especially in medical imaging applications.
[0007] There is a need for an ultrasonic probe with an array of piezoelectric transducer elements that is suitable for operation at low frequencies, typically below 2 MHz, and that at least partially overcomes some of the drawbacks of known array ultrasonic probes.
[0008] The desired feature is an array of ultrasound probes that can also be bent. Summary of the Invention
[0009] One embodiment overcomes all or some of the disadvantages of known array ultrasound probes.
[0010] One embodiment provides an ultrasonic probe comprising an array of piezoelectric transducer elements, the array including: - A first piezoelectric layer is divided into a plurality of first piezoelectronic elements, each first piezoelectronic element including a first electrode located on a first surface of the first piezoelectric layer, and the first dielectric layer also includes a first ground electrode located on a second surface of the first piezoelectric layer opposite to the first surface; - A second piezoelectric layer is stacked on top of a first piezoelectric layer. The second dielectric layer includes a second ground electrode located on a first surface of the second piezoelectric layer and is divided into a plurality of second piezoelectric elements, each of which includes a second electrode located on a second surface of the second piezoelectric layer opposite to the first surface. The first and second piezoelectric layers extend along the main plane, and the second piezoelectric element is aligned with the first piezoelectric element in a direction transverse to the main plane; - A ground plane, which is located between and in contact with the second surface of the first piezoelectric layer and the first surface of the second piezoelectric layer; - A first collector electrode, which is assembled to a first surface of a first piezoelectric layer and includes a first conductive track coupled to the first electrode; - A second collector electrode, which is assembled to the second side of the second piezoelectric layer and includes a second conductive track coupled to the second electrode; Each piezoelectric transducer element includes a first piezoelectric element aligned with one of the second piezoelectric elements, and a portion of a ground plane located between the first aligned piezoelectric element and the second aligned piezoelectric element.
[0011] According to one embodiment, the first electrode and the second electrode of the same piezoelectric transducer element are electrically coupled to each other, for example, the first metal track and the second metal track coupled to the first electrode and the second electrode, respectively, are electrically coupled to each other.
[0012] According to one embodiment, the first piezoelectric layer and / or the second piezoelectric layer: -Including piezoelectric composite materials; and / or - It has a thickness between 0.5mm and 10mm.
[0013] According to one embodiment, the ground plane: - A metal layer, such as a metal plate, for example made of copper, aluminum, or brass; and / or - Extending beyond the stack of the first and second piezoelectric layers via a connecting tab, the connecting tab is adapted to electrically couple a ground plane to a ground outside the stack; and / or - The thickness ranges from 10µm to 500µm.
[0014] According to one embodiment, the array includes: - The first thickness of the piezoelectric material of the first piezoelectric layer located between two adjacent first piezoelectric elements on the first surface of the ground plane, wherein the first thickness is less than the thickness of the first piezoelectric layer; and / or - The second thickness of the piezoelectric material of the second piezoelectric layer located between two adjacent second piezoelectric elements on the second surface of the grounding plane opposite to the first surface of the grounding plane, the second thickness being less than the thickness of the second piezoelectric layer.
[0015] According to one embodiment, the array has a curved shape, and then the main plane is curved.
[0016] According to one embodiment, the array further includes a first acoustic impedance matching layer located between the first piezoelectric layer and the first collector electrode, the first acoustic impedance matching layer being configured such that each piezoelectric transducer element includes a portion of the first acoustic impedance matching layer located between the first electrode and the first collector electrode, the first acoustic impedance matching layer being made of, for example, graphite.
[0017] According to one embodiment, the probe further includes a second acoustic impedance matching layer, and the first collector is located between the first piezoelectric layer and the second acoustic impedance matching layer, for example, between the first acoustic impedance matching layer and the second acoustic impedance matching layer.
[0018] According to one embodiment: - The first collector electrode includes a first insulating substrate, such as a flexible insulating substrate, a first metal track located on or therein of the first insulating substrate, and coupled to a first contact pad coupled or connected to the first electrode; and / or - The second collector electrode includes a second insulating substrate, such as a flexible insulating substrate, a second metal track located on or therein on the second insulating substrate, and coupled to a second contact pad coupled or connected to the second electrode.
[0019] According to one embodiment, the first piezoelectric element and the second piezoelectric element of each piezoelectric transducer element are divided into multiple parts, and these parts of the same piezoelectric transducer element share the same first electrode and second electrode.
[0020] According to one embodiment, the first piezoelectronic element and the second piezoelectronic element are distributed in two orthogonal directions of the main plane.
[0021] According to one embodiment, the ultrasonic probe further includes an acoustic attenuation layer on the second collector electrode, a shaper on the acoustic attenuation layer, and a printed circuit board on the shaper. The ground plane is electrically coupled to ground via the printed circuit board, and the first and second electrodes of the same piezoelectric transducer element are also electrically coupled to each other, for example, via the printed circuit board.
[0022] One embodiment provides a method for manufacturing an array of piezoelectric transducer elements for an ultrasonic probe, the method comprising: - A stack is formed, the stack comprising: a first piezoelectric layer having a first ground electrode disposed on a second surface, a ground plane on the second surface of the first piezoelectric layer, and a second piezoelectric layer having a second ground electrode disposed on the first surface located on the ground plane, the first piezoelectric layer and the second piezoelectric layer extending along the main plane; - The first piezoelectric layer is cut into a plurality of first piezoelectric elements over its entire or part thickness, each first piezoelectric element including a first electrode located on a first surface of the first piezoelectric layer opposite to a second surface of the first piezoelectric layer; - The second piezoelectric layer is cut into a plurality of second piezoelectric elements over its entire or part thickness, each second piezoelectric element including a second electrode located on a second surface of the second piezoelectric layer opposite to a first surface of the second piezoelectric layer; The second piezoelectric element is aligned with the first piezoelectric element in a direction transverse to the main plane; The cutting of the first and second piezoelectric layers must stop at least before the ground plane; - Assemble a first collector electrode, including a first conductive track, onto a first surface of a cut first piezoelectric layer, the assembly including electrically connecting the first conductive track to the first electrode; - Assemble a second collector electrode, including a second conductive track, onto a second surface of a cut second piezoelectric layer, the assembly including electrically connecting the second conductive track to the second electrode; Each piezoelectric transducer element includes a first piezoelectric element aligned with one of the second piezoelectric elements, and a portion of a ground plane located between the aligned first piezoelectric element and the second piezoelectric element.
[0023] According to one embodiment, the method further includes forming an electrical connection between a first electrode and a second electrode of the same piezoelectric transducer element, for example by electrically coupling with a first metal track and a second metal track respectively coupled to the first electrode and the second electrode.
[0024] According to one embodiment, the first and second piezoelectric layers are not cut through their entire thickness so as to maintain the thickness of the piezoelectric material on at least one of the two faces of the ground plane.
[0025] According to one embodiment, the step of cutting the first piezoelectric layer and the second piezoelectric layer further includes performing a secondary cut on the first piezoelectric element and the second piezoelectric element to divide each piezoelectric transducer element into multiple portions sharing the same first electrode and second electrode, wherein the secondary cut is shallower than the cut used to form the first piezoelectric element and the second piezoelectric element.
[0026] According to one embodiment, the method further includes assembling a first acoustic impedance matching layer onto a first surface of a first piezoelectric layer prior to the step of assembling a first collector, such that the first acoustic impedance matching layer is located in an array between the first piezoelectric layer and the first collector, and cutting the first piezoelectric layer includes cutting the first acoustic impedance matching layer over its entire thickness.
[0027] According to one embodiment, the method further includes a convex array step after the steps of cutting the first piezoelectric layer and the second piezoelectric layer, and, for example, after the steps of assembling the first collector and the second collector. Attached Figure Description
[0028] The above-described features and advantages, as well as other features and advantages, will be described in detail below with reference to the accompanying drawings, which are provided on a non-limiting basis, wherein:
[0029] Figure 1A This is a highly schematic perspective view of an example of an array of piezoelectric transducer elements for an arrayed ultrasonic probe.
[0030] Figure 1B It shows the relationship with Figure 1A An exploded perspective view showing the details of an array of piezoelectric transducer elements similar to an array.
[0031] Figure 2A This is a schematic perspective view of the array of piezoelectric transducer elements of an ultrasonic probe according to one embodiment.
[0032] Figure 2B It is shown that... Figure 2A A perspective view showing the details of the collector of an array of piezoelectric transducer elements similar to an array;
[0033] Figure 3A , Figure 3B , Figure 3C and Figure 3D These are perspective and side views illustrating the successive steps of an example method for manufacturing an array of piezoelectric transducer elements for an ultrasonic probe according to one embodiment; and
[0034] Figure 4 This is a schematic perspective view of the height of an ultrasound probe according to one embodiment. Detailed Implementation
[0035] In the various figures, the same elements have been designated by the same reference numerals. In particular, structural and / or functional elements common to the various embodiments may have the same reference numerals and may have the same structure, dimensions, and material properties.
[0036] For clarity, only steps and elements useful for understanding the described embodiments are shown and described in detail. In particular, the construction of the transducer elements of the probe has not been described in detail because the described embodiments are compatible with all or most known piezoelectric transducer structures. Furthermore, the construction of the control circuitry for the piezoelectric transducer has not been described in detail because the described embodiments are compatible with conventional control circuitry for piezoelectric transducers, or the construction of the control circuitry is within the capabilities of those skilled in the art based on the information provided in this description.
[0037] Unless otherwise specified, when referring to two elements being connected to each other, it means that there is no direct connection between them except for the conductors, and when referring to two elements being coupled to each other, it means that the two elements can be connected or can be coupled through one or more other elements.
[0038] In the following description, when referring to absolute position qualifiers (such as “front,” “back,” “up,” “down,” “left,” “right,” etc.), or relative position qualifiers (such as “above,” “below,” “above,” and “below,” etc.), or direction qualifiers (such as “horizontal,” “vertical,” etc.), the direction of the figure shall be taken into account unless otherwise specified.
[0039] Unless otherwise specified, “approximately,” “roughly,” “significantly,” and “about” mean within 10%, preferably within 5%.
[0040] Unless otherwise stated, when referring to two components assembled together, this includes another component or one or more layers located between the two components.
[0041] In the following description, when referring to a plane or principal plane, the plane may be curved. A principal plane may be referred to as a principal surface.
[0042] In the following description, when "aligned" or "horizontally aligned" elements are mentioned, it means that these elements overlap each other and the edges of the overlapping elements roughly correspond, i.e., there is little or no overhang between the overlapping elements. It can also indicate that these elements face each other.
[0043] In the following description, when referring to a probe, ultrasonic probe, or array ultrasonic probe, unless otherwise stated, it refers to an ultrasonic probe that includes an array of piezoelectric transducer elements. Furthermore, when referring to a transducer element, piezoelectric element, or even a transducer, unless otherwise stated, it refers to a piezoelectric transducer element.
[0044] In the following description, when referring to a collector, unless otherwise stated, it refers to an electrical collector, which corresponds to a set of conductive tracks insulated from each other and arranged on an insulating substrate (e.g., a flexible substrate, such as one made of polyimide material).
[0045] Each conductive track typically terminates at one end on a metal surface that contacts the electrodes of the transducer element, and at the other end on a metal surface that couples the conductive track to the rest of the ultrasonic probe.
[0046] The following description relates to an ultrasonic probe having an array of piezoelectric transducer elements. The piezoelectric transducer elements can be made of a single layer of piezoelectric material or a piezoelectric layer, which is then divided into multiple piezoelectric elements.
[0047] The lower the operating frequency of the array ultrasound probe, the thicker the piezoelectric layer must be. For example, for 400 MHz, the thickness can be approximately 6 mm. However, the thicker the piezoelectric layer, the lower the capacitance of the piezoelectric transducer elements in the array. Furthermore, the surface area of each piezoelectric transducer element in the array can be very small, further reducing capacitance.
[0048] To improve the acoustic and electrical performance of the probe, one solution is to stack two layers of piezoelectric material, each layer positioned between two electrodes, one of which can be grounded, while the other is typically used for signal transmission. This solution aims to reduce the imaginary part of the probe's impedance. Depending on the electrode arrangement, the polarization of the two piezoelectric layers is typically perpendicular to the main surfaces of these layers and can be either opposite or in the same direction.
[0049] For example, two piezoelectric layers can be stacked, each half the thickness of a single piezoelectric layer, with each layer positioned between two electrodes. This forms two capacitors that can be stacked and added together. Then, the thickness of each piezoelectric layer is halved, and for the same total thickness, the stacked capacitance can be multiplied by four. Therefore, the imaginary part of the impedance can be divided by four.
[0050] Figure 1A This is a high-conceptual perspective view of an example array 100 of piezoelectric transducer elements of an array ultrasonic probe. Figure 1B It shows the relationship with Figure 1A An exploded perspective view showing the details of an array of 100 similar piezoelectric transducer elements.
[0051] The array 100 includes two piezoelectric layers stacked on top of each other: a first piezoelectric layer 110, which is topped by a second piezoelectric layer 120.
[0052] like Figure 1B As shown in more detail, the upper and lower surfaces of the first piezoelectric layer 110 are metallized, meaning the first piezoelectric layer 110 includes a piezoelectric material core 111, whose upper and lower surfaces are covered by metal layers: a first metal layer 112 on the upper surface and a second metal layer 113 on the lower surface. The first metal layer 112 is structured, i.e., divided in its thickness or lateral direction by a plurality of first notches 114 (cuts) to form a plurality of first electrodes 115 spaced apart from each other by these first notches, thereby forming a plurality of first piezoelectric transducer sub-elements. The first notches 114 thus correspond to the portion of the upper metallization of the first piezoelectric layer 110 that has been removed. The unstructured second metal layer 113 forms a first common ground electrode.
[0053] Similarly, the upper and lower surfaces of the second piezoelectric layer 120 are metallized; that is, the second piezoelectric layer 120 includes a piezoelectric material core 121, the upper and lower surfaces of which are covered with metal layers: a first metal layer 122 is covered on the lower surface and a second metal layer 123 is covered on the upper surface. The first metal layer 122 is structured, i.e., divided in its thickness direction by a plurality of second notches 124 (cuts) to form a plurality of second electrodes 125 spaced apart from each other by these second notches, thereby forming a plurality of second piezoelectric transducer sub-elements. The second notches 124 thus correspond to the portion of the lower metallization of the second piezoelectric layer 120 that is removed. The unstructured second metal layer 123 forms a second common ground electrode.
[0054] Preferably, the first notch 114 and the second notch 124 are arranged opposite to each other. Preferably, the first electrode 115 and the second electrode 125 are arranged opposite to each other.
[0055] The depth of each notch 114, 124 is greater than or equal to the metallization thickness of the first metal layers 112, 122, and can extend into the piezoelectric layer, or even through the entire thickness of the piezoelectric layer, or even through the second metal layers 113, 123, thereby forming multiple ground electrodes. In this case, it is generally ensured that these ground electrodes can be electrically coupled again.
[0056] The collector 130 is disposed between the first metallized piezoelectric layer and the second metallized piezoelectric layer. The collector 130 may include an insulating substrate, which is typically flexible (elastic).
[0057] like Figure 1B As shown in more detail below, the collector 130 includes: - Insulating substrate 131, for example, a flexible substrate, such as one made of polyimide material; - A first metal track 132 on the lower surface 131A (first side) of the insulating substrate, each first metal track 132 ending with a first metal pad 133 or a contact pad; - A second metal track 134 on the upper surface 131B (the second surface opposite the first surface) of the insulating substrate, each second metal track 134 ending with a second metal pad 135 or a contact pad.
[0058] Preferably, the second metal track 134 is arranged opposite to the first metal track 132. Preferably, the second metal pad 135 is arranged opposite to the first metal pad 133.
[0059] In order to form the first metal track, the second metal track, and the pad, the collector 130 can be locally metallized on each of its first and second surfaces.
[0060] Each first electrode 115 of the first piezoelectric layer 110 is electrically coupled to the first metal pad 133 of the collector, and each second electrode 125 of the second piezoelectric layer 120 is electrically coupled to the second metal pad 135 of the collector 130.
[0061] Preferably, the first metal pad 133, the second metal pad 135, the first electrode 115, and the second electrode 125 are aligned, and the assembly formed by the alignment of the first metal pad 133, the second metal pad 135, the first electrode 115, and the second electrode 125 forms the piezoelectric transducer element 101. The first notch 114 and the second notch 124 also contribute to this alignment.
[0062] The surface areas of the first metal pad 133 and the second metal pad 135 may be smaller than the surface areas of the first electrode 125 and the second electrode 115, respectively, in particular to compensate for any alignment errors during the stacking operation of the collector electrode 130 with the two piezoelectric layers 110, 120. In fact, excessively significant alignment errors may cause the first metal pad 133 to short-circuit the first electrode 115 with another adjacent first electrode, or the second metal pad 135 to short-circuit the second electrode 125 with another adjacent second electrode.
[0063] Furthermore, the array 100 includes one or more acoustic impedance matching layers 102, preferably located on the first surface 100A (front) of the array, facing one side toward the region of interest. The acoustic impedance matching layer 102 can thus be at least partially in contact with the first piezoelectric layer 110.
[0064] Conductive strips or sheets 103, such as metal, are provided at each end and on the outer side of the first metallized piezoelectric layer 110 and the second metallized piezoelectric layer 120 for grounding leads to the rest of the ultrasonic probe. Each conductive strip 103 for grounding leads contacts the second metal layers 113, 123 of the first piezoelectric layer 110 and the second piezoelectric layer 120, for example by folding over the second metal films 113, 123, and can therefore be positioned between the first piezoelectric layer 110 (e.g., the second metal layer 113 of the first piezoelectric layer 110) and the acoustic impedance matching layer 102.
[0065] Implementation Figure 1A and Figure 1B One drawback of array 100 is that the metal tracks 132, 134 and / or metal pads 133, 135 of collector 130 may short-circuit piezoelectric transducer element 101. Figure 1A and Figure 1BIn the example, the first electrode 115 and the second electrode 125, as well as the first metal pad 133 and the second metal pad 135, are correctly aligned to form a piezoelectric transducer element 101 that is isolated from each other, and the metal tracks 132 and 134 of the collector 130 are not covered by the metallized piezoelectric layers 110 and 120, which corresponds to an ideal configuration.
[0066] Conversely, when the piezoelectric transducer element array consists of piezoelectric elements in two directions, such as multiple rows and columns of piezoelectric elements, short circuits may occur. For example, the collector track coupled to the piezoelectric element at the very center of the array may come into contact with the electrodes of piezoelectric elements located on the periphery of the array. This drawback can be avoided, for example, by covering the outer surface of the track with an insulating layer that does not contact the insulating substrate of the collector, wherein the insulating layer is made of, for example, the same material as the collector insulating substrate, but does not cover the metal pads of the collector, in order to maintain electrical contact with the piezoelectric element electrodes. However, as the thickness of the layers between the piezoelectric layers increases, the performance of the piezoelectric transducer degrades because the acoustic impedance of these insulating layers is significantly different from that of the piezoelectric layers. This other drawback can be avoided, for example, by extending the collector track so that it extends only opposite to the notches 114, 124 or cutouts of the piezoelectric layers 110, 120. However, in the case of an array consisting of a large number of piezoelectric transducer elements, the passage of all tracks requires an increase in the width of the relative notch, and the performance of the probe may be reduced because this involves either reducing the effective surface area of the piezoelectric elements (while maintaining the distance between elements) or increasing the distance between elements (while maintaining the surface area of each piezoelectric element).
[0067] Furthermore, the stack consisting of two piezoelectric layers 110, 120 and a collector 130 may present alignment issues, for example, when such alignment is visually determined by an operator. The only visual markers located on the periphery of the array are, on the one hand, the ends of notches 114, 124 or cutouts leading to some sides of the piezoelectric layers 110, 120, and on the other hand, the patterns formed by the tracks 132, 134 of the collector 130 extending to the outside of the array 100. However, the collector 130 cannot extend from the sides of the piezoelectric layers 110, 120 covered by the conductive sheet 103 used for grounding leads, making it impossible to arrange visual markers on the collector to ensure alignment in the direction formed by the planes of the pads 133, 135 and the plane of the conductive sheet 103.
[0068] The inventors provide an array ultrasound probe that overcomes all or some of the above-mentioned disadvantages, particularly addressing the problem of individual electrical connections of piezoelectric transducer elements, preferably employing an easy-to-implement solution, such as a solution that avoids alignment problems and / or short circuits between piezoelectric transducer elements.
[0069] The presented embodiments may also provide a curved array ultrasound probe.
[0070] Embodiments of the array ultrasound probe will be described below. The described embodiments are non-limiting, and various variations will be apparent to those skilled in the art based on the information provided in this specification.
[0071] Figure 2A This is a schematic perspective view of an array 200 of piezoelectric transducer elements of an ultrasonic probe according to one embodiment. Figure 2B It is shown that... Figure 2A A perspective view of the collector of an array of 200 similar piezoelectric transducer elements.
[0072] Array 200 includes two piezoelectric layers, a first piezoelectric layer 210 and a second piezoelectric layer 220, which are stacked on top of each other. The first and second piezoelectric layers extend along a main plane, which may be curved.
[0073] The piezoelectric layer can be made of materials such as ceramics, composite ceramics, or crystals. Materials for the piezoelectric layer can also include, for example, PZT (lead zirconate titanate), lead-free piezoelectric materials such as BaTiO3 (barium titanate), or KNN (potassium sodium niobate).
[0074] The thickness of each piezoelectric layer can be between 0.5 and 10 mm, for example, approximately 1.8 mm.
[0075] The lower and upper surfaces of the piezoelectric layer can be metallized, for example by chemical deposition processes, by spraying one or more layers of gold, silver or nickel.
[0076] The ground plane 203, or ground plane, is positioned between two piezoelectric layers. The ground plane can be a conductive layer, such as a conductive plate.
[0077] The ground plane 203 extends laterally beyond the stack of piezoelectric layers at one end via a connecting piece 204 adapted to electrically connect the ground plane to the outside of the stack of piezoelectric layers.
[0078] The thickness of the ground plane 203 is, for example, between 10µm and 500µm, such as approximately 100µm.
[0079] The material of the grounding plane 203 is, for example, copper, aluminum, or brass. Advantageously, with Figure 1A and Figure 1B Compared to the example of an ultrasonic probe, the acoustic impedance of the material of the ground plane 203 is close to that of the piezoelectric layers 210 and 220, thereby promoting the propagation of ultrasonic waves within the ultrasonic probe.
[0080] Two piezoelectric layers 210 and 220 are constructed, i.e., divided into multiple piezoelectric transducer elements 201, in a direction transverse to the main plane of these piezoelectric layers.
[0081] In order to form the piezoelectric transducer element 201, each piezoelectric layer is cut along its entire or almost entire thickness on either side of the ground plane 203.
[0082] More specifically, the first piezoelectric layer 210 is divided (e.g., cut) into a plurality of first piezoelectric elements 211, and the second piezoelectric layer 220 is divided (e.g., cut) into a plurality of second piezoelectric elements 221, while the ground plane 203 is not cut. Therefore, the ground plane 203 is shared by all piezoelectric transducer elements 201. The first and second piezoelectric elements are aligned with each other in the lateral direction, i.e., each first piezoelectric element 211 is superimposed on a second piezoelectric element 221, wherein a portion of the ground plane 203 lies between the two piezoelectric elements with little or no overhang.
[0083] The piezoelectric transducer element 201 is formed by aligning a first piezoelectric element 211 and a second piezoelectric element 221 with a portion of a ground plane 203 between the two aligned piezoelectric elements in the lateral direction. In other words, the piezoelectric transducer element 201 includes a first piezoelectric element 211 and a second piezoelectric element 221 aligned with the first piezoelectric element, and a portion of a ground plane 203 between the two aligned piezoelectric elements.
[0084] This cutting method for cutting piezoelectric layers 210 and 220 on either side of the ground plane 203 enables good alignment of the two structured piezoelectric layers, i.e., precise alignment of the first piezoelectric element 211 cut in the first piezoelectric layer 210 with the second piezoelectric element 221 cut in the second piezoelectric layer 220.
[0085] This cutting method can also construct the external metallization (first metal layer) of the first and second piezoelectric layers to form the first and second electrodes. In fact, although Figure 2A Not shown in detail, but each piezoelectric layer 210, 220 is in a similar manner to Figure 1A and Figure 1B The piezoelectric layers 110 and 120 are metallized in a manner that differs in that the first metal layer is on the outside, and thus the first electrode and the second electrode are in contact with the first metal pad 234 and the first metal pad 244 of the first collector electrode 230 and the second collector electrode 240, respectively, as further described below, and the second metal layer and therefore the common ground electrode are in contact with the ground plane 203 on the inside.
[0086] Therefore, the upper surface 210B and the lower surface 210A of the first piezoelectric layer 210 are metallized, that is, each surface is covered by a metal layer: -A first metal layer on the lower 210A (first surface), which is structured, i.e., divided in its thickness direction or transverse direction by a plurality of first notches (cuts) 214 to form a plurality of first electrodes 215 spaced apart from each other by these first notches; and - The second metal layer on the upper 210B (second surface), which is unstructured, forms the first common ground electrode 213 in contact with the ground plane 203; The whole assembly forms the first piezoelectronic component 211.
[0087] Similarly, the top and bottom surfaces of the second piezoelectric layer 220 are metallized, meaning each surface is covered by a metal layer: - A first metal layer on the upper 220B (second surface), which is structured, i.e., divided in its thickness direction by a plurality of second notches (cuts) 224 to form a plurality of second electrodes 225 spaced apart from each other by these second notches; and - A second metal layer on the lower 220A (first surface), which is unstructured, forms a second common ground electrode 223 in contact with the ground plane 203; The whole assembly forms the second piezoelectronic component 221.
[0088] Therefore, the grounding plane 203 is located between the second surface 210B of the first piezoelectric layer 210 and the first surface 221A of the second piezoelectric layer 220, and is in contact with the first common grounding electrode 213 and the second common grounding electrode 223.
[0089] Furthermore, this cutting method can facilitate the deformation of ultrasonic probes, such as achieving curved shapes. This cutting method is particularly relevant for stacks of curved piezoelectric layers when the stack also includes an acoustic impedance matching layer (e.g., made of graphite), as described below. In fact, the combination of the thickness of the piezoelectric stack and the thickness of the graphite can render the material non-deformable without damaging it.
[0090] In the case of a bent probe, such as a concave or convex shape, the width of the cut can be adjusted so that the first and second piezoelectronic components do not come into contact with each other or short-circuit during deformation.
[0091] like Figure 2A As shown in the enlarged portion, the first piezoelectric layer 210 and the second piezoelectric layer 220 do not need to penetrate their thickness, that is, a small piezoelectric material thickness e1, e2 can be maintained between the two piezoelectric transducer elements 201 on both sides of the grounding plane 203, and a piezoelectric material stump with a thickness of e1 or e2 can be formed on either side of the grounding panel 203.
[0092] The residual posts with a thickness of e1 or e2 allow for the avoidance of cutting the ground plane 203 during the cutting of the first piezoelectric layer 210 and the second piezoelectric layer 220. The thickness e1, e2 of each residual post is at least equal to the tolerance of the cutting method. This tolerance depends on factors such as the cutting depth, cutting width, and the size of the transducer element. For example, this tolerance is less than 50 µm, or even less than 10 µm.
[0093] This residual stake also ensures that the piezoelectric material between the grounding plane 203 and the first piezoelectric layer 210 and the second piezoelectric layer 220 does not break (loss of adhesion). For this reason, it is appropriate for the residual stake thicknesses e1 and e2 to be less than 10µm, or even less than 1µm.
[0094] During the fabrication steps of the transducer element array after cutting the first piezoelectric layer 210 and the second piezoelectric layer 220, each stump, together with the ground plane 203, can also help maintain the stiffness of the assembly. For this purpose, stump thicknesses e1 and e2 are calculated such that the Young's modulus generated by the stacking of the two stumps of piezoelectric material and the ground plane 203 ensures that the vertical deformation of the transducer element array 200 is, for example, less than 10% or 5% of the total array thickness.
[0095] By adjusting the characteristics of the ground plane 203, such as its thickness and its material, the residual stake can facilitate the formation and maintenance of the curvature of the stack of cut piezoelectric layers, thereby obtaining a bent probe.
[0096] The uncut thicknesses e1 and e2 of each piezoelectric layer 210, 220 can be defined to ensure the rigidity of the assembly prior to deformation and / or to enable the piezoelectric layers to deform without fracturing, even if these piezoelectric layers exceed a limit thickness at which they may fracture depending on the desired radius of curvature, and then maintain this deformation. Therefore, the thickness of the residual post can be defined according to this limit thickness, for example, less than or equal to this limit thickness, while being greater than the value required to ensure rigidity before and after deformation. Thicknesses e1 and / or e2 are, for example, between 5 µm and 100 µm.
[0097] As a variant, the first and second piezoelectric layers can be cut along their entire thickness down to the ground plane.
[0098] In addition to its grounding function, once the two piezoelectric layers 210 and 220 are constructed, the grounding plane 203 can also provide them with mechanical support.
[0099] For a curved probe, the ground plane 203 can be adapted to cause the curvature of the two piezoelectric layers 210, 220 of the piezoelectric transducer element 201 to be given.
[0100] The ground plane 203 can form a neutral fiber between the two piezoelectric layers 210 and 220.
[0101] The ground plane 203 can also improve the heat dissipation of the piezoelectric transducer element 201. Therefore, the ground plane can be used as a highly efficient heat sink because it is placed directly on the surface that exchanges with the two piezoelectric layers 210, 220 and is located within the heat source.
[0102] The first collector electrode 230 is positioned on the lower (first side) 210A of the first piezoelectric layer 210, at the first surface 200A of the array 200, for example, corresponding to the front side of the probe, which is the surface to be oriented toward the region of interest. This first surface 210A of the first piezoelectric layer 210 is opposite to the second surface 210B of the first piezoelectric layer that is in contact with the ground plane 203.
[0103] The second collector electrode 220 is positioned on the upper surface (second surface) 220B of the second piezoelectric layer 220, at the second surface 200B of the array 200, for example, corresponding to the rear of the probe, which is the surface opposite to the front surface 200A of the probe. This second surface 220B of the second piezoelectric layer 220 is opposite to the first surface 220A of the second piezoelectric layer that is in contact with the ground plane 203.
[0104] like Figure 2B As shown, the first collector 230 includes: - A first insulating substrate 231, for example flexible, made of, for example polyimide material, has a lower surface 231A (first side) and an upper surface 231B (second side). - First metal tracks 232 on the lower 231A of the first insulating substrate 231, each first metal track 232 being used to couple the piezoelectric transducer element 201 of the array 200 to the remainder of the probe and terminating at a first metal pad 233, each first metal pad 233 being coupled to a first contact pad 234 on the upper 231B of the first insulating substrate 231 through a through-hole 235.
[0105] like Figure 2B As shown, the second collector 240 includes: - A second insulating substrate 241, for example flexible, made of, for example polyimide material, has a lower surface 241A (first surface) and an upper surface 241B (second surface). - Second metal tracks 242 on the upper 241B of the second insulating substrate 241, each second metal track 242 being used to couple the piezoelectric transducer element 201 of the array 200 to the remainder of the probe and terminating at a second metal pad 243, each second metal pad 243A being coupled to a second contact pad 244 on the lower 241A of the second insulating substrate 241 through a through-hole 245.
[0106] Preferably, the second contact pad 244 is arranged opposite to the first contact pad 234. Preferably, the second metal pad 243 is arranged opposite to the first metal pad 233.
[0107] When present between the first piezoelectric layer 210 and the first collector 230 (described further below), the first electrode 215 of each first piezoelectric element 211 is coupled to the first contact pad 234 of the first collector 230, for example, through or via the first acoustic impedance matching layer 202. Similarly, the second electrode 225 of each second piezoelectric element 221 is connected to the second contact pad 244 of the second collector 240.
[0108] Preferably, the first contact pad 234, the second contact pad 244, the first electrode 215 and the second electrode 225 are aligned, and the assembly formed by the alignment of the first contact pad 234, the second contact pad 244, the first electrode 215 and the second electrode 225, together with the ground plane 203 and portions of the first common ground electrode 213 and the second common ground electrode 223, forms the piezoelectric transducer element 201.
[0109] Therefore, each piezoelectric transducer element 201 of the matrix array 200 includes a first electrode 215 coupled to a first track 232 of a first collector 230 and a second electrode 225 coupled to a second track 242 of a second collector 240, and includes common ground electrodes 213, 223 coupled to a ground plane 203. The metallic tracks 232, 242 of the collectors 230, 240 are adapted for electrical coupling and individual coupling of each piezoelectric transducer element 201. Each transducer element 201 can therefore be individually controlled, rather than being addressed by rows and columns.
[0110] The first and second collectors are not necessarily the same. For example, in the case of a curved probe, the collectors can be adapted to the curvature. For example, the spacing between the track and the pad of the collector closest to the center of curvature can advantageously be smaller than the spacing between the track and the pad of the collector furthest from the center of curvature.
[0111] The thickness of each collector can be between 10µm and 500µm, for example, between 10 and 100µm, or for example, approximately 20µm.
[0112] The first electrode 215 and the second electrode 225 of the same piezoelectric transducer element 201 are preferably electrically coupled to each other via collectors, for example, connected, preferably outside the stack of piezoelectric layers, ground planes and collectors, and the two piezoelectric elements 211, 221 of the same piezoelectric transducer element are then driven simultaneously.
[0113] For example, the first electrode 215 and the second electrode 225 of the same piezoelectric transducer element 201 are coupled to each other via a printed circuit board (PCB) assembled to the array 200, as shown below. Figure 4 Further explanation and description: Ground plane 203 can also be coupled to ground via a printed circuit board.
[0114] In one embodiment, piezoelectric layers 210, 220 are oriented such that their respective polarizations are opposite, such that each piezoelectric layer expands or contracts in a similar manner when the same voltage is applied to the first electrode 215 and the second electrode 225 of each identical piezoelectric transducer element 201.
[0115] In addition, the probe 200 includes a first acoustic impedance matching layer 202, which is preferably located on the front side 200A of the probe.
[0116] In the illustrated example, a first acoustic impedance matching layer 202 is disposed between the first piezoelectric layer 210 and the first collector 230. This allows for electrical contact offset and thus prevents acoustic impedance breakage between the piezoelectric material of the first piezoelectric layer 210 and the first collector 230. The first impedance matching layer 202 is preferably conductive. The acoustic impedance of the first impedance matching layer 202 is preferably between the acoustic impedance of the first collector 230 and the acoustic impedance of the first piezoelectric layer 210, for example, at about 3.10 for a polyimide collector. 6 The values are between Pa.s / m (Rayl) and approximately 30.10 for piezoelectric ceramics. 6 Between Pa.s / m, or for piezoelectric composites at approximately 20.10 Pa.s / m. 6 Pa.s / m. The first impedance matching layer 202 may be a matching blade with decreasing acoustic impedance between the first piezoelectric layer 210 and the first collector 230, for example, having multiple layers of different materials.
[0117] The thickness of the first impedance matching layer 202 can be calculated, for example, as a quarter-wavelength blade, for which interference facilitates the passage of waves near the operating frequency.
[0118] The material of the first impedance matching layer 202 can be conductive.
[0119] For example, the first impedance matching layer 202 is made of graphite. For example, the acoustic impedance of the first impedance matching layer 202 is 3.10. 6 Pa.s / m and 6.10 6 Between Pa.s / m.
[0120] Each piezoelectric transducer element 201 may include a portion of a first acoustic impedance matching layer 202. During the formation of the first piezoelectric element 211, the first impedance matching layer 202 may be cut simultaneously with the first piezoelectric layer 210.
[0121] As a variant or additional, the probe may include a second acoustic impedance matching layer, arranged such that the first collector is located between the first piezoelectric layer or the first acoustic impedance matching layer and the second acoustic impedance matching layer. The acoustic impedance of the second acoustic impedance matching layer is then preferably between the acoustic impedance of the first collector and the acoustic impedance of the medium on which the probe is mounted, for example, approximately 3.10 for the polyimide collector. 6 Pa·s / m (Rayl) is approximately 1.5.10 that of water. 6 Between Pa.s / m.
[0122] The material of the second impedance matching layer is preferably non-conductive. This material can be, for example, a polymer, such as an epoxy resin, or a filled polymer.
[0123] The thickness of each acoustic impedance matching layer is, for example, equal to one-quarter of the center wavelength of the sound wave. The thickness of each acoustic impedance matching layer can be between 1 mm and 5 mm, for example, approximately 2 mm.
[0124] Each piezoelectric transducer element 201 can also be divided (e.g., cut) into multiple parts sharing the same first and second electrodes, for example, divided into four parts, as further described below. Figure 3D As shown in the diagram. This allows for a reduction in the influence of lateral modes that may be caused by the geometry of the piezoelectric transducer elements.
[0125] Figure 3A , Figure 3B , Figure 3C and Figure 3D These are perspective and side views illustrating the sequential steps of an example method for manufacturing an ultrasonic probe according to one embodiment. Example Method Reference Figure 2A and Figure 2B The ultrasonic probe 200 is described herein, but may be adapted to produce any other ultrasonic probe according to the embodiments.
[0126] Figure 3A The structure obtained by stacking the second piezoelectric layer 220, the ground plane 203, the first piezoelectric layer 210 and the first acoustic impedance matching layer 202 from top to bottom is shown.
[0127] The ground plane 203 extends beyond the stack of piezoelectric layers via a connecting piece 204, which is adapted to electrically connect the ground plane 203 to ground outside the stack of piezoelectric layers. Figures 3A to 3C Four connecting pieces 204 are shown, but this is not limiting and there can be fewer or more.
[0128] Figure 3BThe structure obtained after cutting 301 on the thickness of the second piezoelectric layer 220 to form the second piezoelectric element 221 is shown. Cutting 301 stops at least before the uncut ground plane 203. The thickness e2 of the second piezoelectric layer 220 can be maintained, as per [reference to...]. Figure 2A The cut extends along two orthogonal directions along the main plane. When viewed from above, the second piezoelectronic element 221 forms, for example, a square, but other shapes are also possible.
[0129] Figure 3C Showing flip Figure 3B The structure is obtained by aligning the first piezoelectric layer 210 and the first impedance matching layer 202 with the second piezoelectric element 221, and then cutting 302 after the first piezoelectric element 211. Cutting 302 stops at least before the uncut ground plane 203. The thickness e1 of the first piezoelectric layer 210 can be maintained, as per [reference to...]. Figure 2A The cutting is performed along two orthogonal directions along the main plane. When viewed from above, the first piezoelectronic element 211 forms, for example, a square, but other shapes are also possible.
[0130] The two piezoelectric layers 210 and 220 do not need to penetrate the thickness of the material, i.e., as... Figure 2A As shown, a small piezoelectric material thickness e1, e2 can be maintained between two adjacent piezoelectric elements on each of the two surfaces of the grounding plane 203 to retain piezoelectric material stumps, for example, one hundred or several hundred micrometers, on either side of the grounding panel 203. (See also: Regarding...) Figure 2A As explained further, this allows for reinforcement of the stack and, in the case of a bent probe, facilitates deformation without breakage, while maintaining the radius obtained after deformation (bending) as described below.
[0131] Figure 3D The bending was shown Figure 3C The structure obtained after the structure.
[0132] Curvature can be obtained by heating the piezoelectric material to deform it, for example at about 80°C. The shape of the curvature can be, for example, cylindrical, spherical, parabolic, and more generally, a shape that varies in each direction of the array.
[0133] Figure 3D The structure also shows that a secondary cut 303 has been performed prior to bending to divide each piezoelectric transducer element 201 into multiple sections, such as four sections. The secondary cut is preferably shallower than the cut that forms the piezoelectric transducer element. These secondary cuts are optional but can be advantageous, particularly for reducing the effect of any lateral patterns caused by the element geometry.
[0134] Next, the first collector electrode 230 is assembled onto the first acoustic impedance matching layer 202 on the front side 200A of the array 200, and the second collector electrode 240 is assembled onto the second piezoelectric layer 220 on the back side 200B of the array 200. Then, the first contact pad of the first collector electrode 230 and the second contact pad of the second collector electrode 240 are electrically coupled to the first electrode or the second electrode, respectively. The first electrode and the second electrode of the same piezoelectric transducer element 201 can be coupled to each other via the first collector electrode and the second collector electrode. Figure 1A and Figure 1B Compared to the example shown, the array according to this embodiment advantageously facilitates the visual alignment of the collector and the piezoelectric layer.
[0135] Next, to form the array ultrasound probe, a second acoustic impedance matching layer 311 can be added to the first collector 230 on the front side 200A of the array 200, and an acoustic attenuation layer 312, which can be called a "backing", can be added to the second collector 240 on the back side 200B of the array 200. The other components of the array ultrasound probe will be combined below. Figure 4 Further description is provided. The second impedance matching layer 311 is preferably non-conductive to avoid short circuits in the tracks of the opposing first collector 230. Otherwise, an insulating layer is inserted between the first collector 230 and the second acoustic impedance matching layer 311.
[0136] Figure 4 This is a schematic perspective view of an ultrasonic probe 400 according to one embodiment. The ultrasonic probe 400 includes an array of transducer elements, which may be the array 200 of FIG. 2 or FIG. 3.
[0137] The ultrasonic probe 400 also includes a second acoustic impedance matching layer 311 on the first collector 230 on the front side 200A of the array 200, an acoustic attenuation layer 312 (or backing) on the second collector 240 on the back side 200B of the array, a shaper 413 on the acoustic attenuation layer 312, and a printed circuit board 414 (or PCB) on the shaper 413.
[0138] The ground plane 203 can be connected to ground via the connector 204 through the printed circuit board 414. The first and second electrodes of the same piezoelectric transducer element can also be connected to each other through the printed circuit board 414.
[0139] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations can be combined, and other variations will be apparent to those skilled in the art.
[0140] Finally, based on the functional indications given above, the actual implementation of the embodiments and variations is within the capabilities of those skilled in the art.
Claims
1. An ultrasonic probe (400) comprising an array (200) of piezoelectric transducer elements (201), the array comprising: - A first piezoelectric layer (210) is divided into a plurality of first piezoelectric elements (211), each first piezoelectric element including a first electrode (215) located on a first surface (210A) of the first piezoelectric layer (210), and the first dielectric layer also includes a first ground electrode (213) on a second surface (210B) opposite to the first surface of the first piezoelectric layer. - A second piezoelectric layer (220) is stacked on top of a first piezoelectric layer. The second dielectric layer includes a second ground electrode (223) located on a first side (220A) of the second piezoelectric layer and is divided into a plurality of second piezoelectric elements (221). Each second piezoelectric element includes a second electrode (225) located on a second side (220B) opposite to the first side of the second piezoelectric layer. The first piezoelectric layer and the second piezoelectric layer extend along the main plane, and the second piezoelectric element (221) is aligned with the first piezoelectric element (211) in a direction transverse to the main plane; - A ground plane (203) is located between and in contact with the second surface (210B) of the first piezoelectric layer (210) and the first surface (220A) of the second piezoelectric layer (220); - A first collector electrode (230) is assembled onto a first surface (210A) of the first piezoelectric layer (210) and includes a first conductive track (232) coupled to the first electrode (215). - A second collector electrode (240) is assembled onto the second side (220B) of the second piezoelectric layer (220) and includes a second conductive track (242) coupled to the second electrode (225). Each piezoelectric transducer element (201) includes a first piezoelectric element (211) aligned with one of the second piezoelectric elements (221), and a portion of the ground plane (203) between the aligned first and second piezoelectric elements.
2. The ultrasonic probe according to claim 1, wherein, The first and second electrodes (215, 225) of the same piezoelectric transducer element (201) are electrically coupled to each other, for example, the first and second metal tracks (232, 242) coupled to the first and second electrodes respectively are electrically coupled to each other.
3. The ultrasonic probe according to claim 1 or 2, wherein, The first piezoelectric layer (210) and / or the second piezoelectric layer (220): -Including piezoelectric composite materials; and / or - It has a thickness between 0.5mm and 10mm.
4. The ultrasonic probe according to any one of claims 1 to 3, wherein, The grounding plane (203): - is a metal layer, such as a metal plate, for example, made of copper, aluminum, or brass; and / or - A connecting tab (204) adapted to electrically couple the ground plane to the outside of the stack extends beyond the stack of the first piezoelectric layer and the second piezoelectric layer (210, 220); and / or - The thickness ranges from 10µm to 500µm.
5. The ultrasonic probe according to any one of claims 1 to 4, wherein, The array (200) includes: - The first thickness (e1) of the piezoelectric material of the first piezoelectric layer (210) between two adjacent first piezoelectric elements (211) on the first surface of the ground plane (203), wherein the first thickness is less than the thickness of the first piezoelectric layer; and / or - The second thickness (e2) of the piezoelectric material of the second piezoelectric layer (220) between two adjacent second piezoelectric elements (221) on the second surface of the ground plane (203) opposite to the first surface of the ground plane, the second thickness being less than the thickness of the second piezoelectric layer.
6. The ultrasonic probe according to any one of claims 1 to 5, wherein, The array (200) has a curved shape, and the main plane is curved.
7. The ultrasonic probe (400) according to any one of claims 1 to 6, wherein, The array (200) further includes a first acoustic impedance matching layer (202) located between the first piezoelectric layer (210) and the first collector electrode (230), the first acoustic impedance matching layer being configured such that each piezoelectric transducer element (201) includes a portion of the first acoustic impedance matching layer located between the first electrode (215) and the first collector electrode, the first acoustic impedance matching layer being made of, for example, graphite.
8. The ultrasonic probe (400) according to any one of claims 1 to 7 further includes a second acoustic impedance matching layer (311), wherein the first collector (230) is located between the first piezoelectric layer (210) and the second acoustic impedance matching layer, for example, between the first acoustic impedance matching layer (202) and the second acoustic impedance matching layer.
9. The ultrasonic probe according to any one of claims 1 to 8, wherein: - The first collector electrode (230) includes a first insulating substrate (231), such as a flexible insulating substrate, the first metal track (232) being located on or therein of the first insulating substrate and coupled to a first contact pad (234) coupled to or connected to the first electrode (215); and / or - The second collector electrode (240) includes a second insulating substrate (241), such as a flexible insulating substrate, and the second metal track (242) is located on or therein on the second insulating substrate and coupled to a second contact pad (244) coupled to or connected to the second electrode (225).
10. The ultrasonic probe (400) according to any one of claims 1 to 9, wherein, Each piezoelectric transducer element's first and second piezoelectric elements are divided into multiple parts, and these parts of the same piezoelectric transducer element share the same first and second electrodes.
11. The ultrasonic probe according to any one of claims 1 to 10, wherein, The first piezoelectric element (211) and the second piezoelectric element (221) are distributed in two orthogonal directions of the main plane.
12. The ultrasonic probe (400) according to any one of claims 1 to 11 further includes an acoustic attenuation layer (312) on the second collector electrode (240), a shaper (413) on the acoustic attenuation layer, and a printed circuit board (414) on the shaper, wherein the ground plane (203) is electrically coupled to ground via the printed circuit board, and the first electrode and the second electrode of the same piezoelectric transducer element are also electrically coupled to each other, for example, via the printed circuit board.
13. A method for manufacturing an array (200) of piezoelectric transducer elements (201) for an ultrasonic probe, the method comprising: - A stack is formed, the stack including a first piezoelectric layer (210) having a first ground electrode (213) disposed on a second surface (210B), a ground plane (203) on the second surface (210B) of the first piezoelectric layer, and a second piezoelectric layer (220) having a second ground electrode (223) disposed on a first surface (220A) located on the ground plane, the first piezoelectric layer and the second piezoelectric layer extending along the main plane; - The first piezoelectric layer (210) is cut into a plurality of first piezoelectric elements (211) over its entire or part thickness, each of the first piezoelectric elements including a first electrode (215) located on a first surface of the first piezoelectric layer (210) opposite to the second surface of the first piezoelectric layer. - The second piezoelectric layer (220) is cut into a plurality of second piezoelectric elements (221) over its entire or part thickness, each second piezoelectric element including a second electrode (225) connected to a second side (220B) opposite to the first side of the second piezoelectric layer (220). The second piezoelectric element is aligned with the first piezoelectric element in a direction transverse to the main plane; The cutting of the first piezoelectric layer and the second piezoelectric layer stops at least before the ground plane; - Assemble a first collector (230) including a first conductive track (232) onto a first face (210A) of a cut first piezoelectric layer (210), said assembly including electrically connecting the first conductive track (232) to the first electrode (215). - Assemble a second collector (240) including a second conductive track (242) to a second side (220B) of a cut second piezoelectric layer (220), said assembly including electrically connecting the second conductive track (242) to the second electrode (225); Each piezoelectric transducer element (201) includes a first piezoelectric element (211) aligned with one of the second piezoelectric elements (221), and a portion of a ground plane (203) between the aligned first piezoelectric element and the second piezoelectric element.
14. The method of claim 13 further comprises forming an electrical connection between the first electrode and the second electrode of the same piezoelectric transducer element (201), for example by electrically coupling with a first metal track and a second metal track respectively coupled to the first electrode and the second electrode.
15. The method according to claim 13 or 14, wherein, The first and second piezoelectric layers (210, 220) are not cut through their entire thickness so as to maintain the thickness (e1, e2) of the piezoelectric material on at least one of the two faces of the ground plane (203).
16. The method according to any one of claims 13 to 15, wherein, The step of cutting the first piezoelectric layer and the second piezoelectric layer (210, 220) further includes performing a secondary cut on the first piezoelectric element and the second piezoelectric element (211, 221) to divide each piezoelectric transducer element (201) into multiple portions sharing the same first electrode and second electrode (215, 225), the secondary cut being shallower than the cut used to form the first piezoelectric element and the second piezoelectric element.
17. The method according to any one of claims 13 to 16, further comprising: Prior to the step of assembling the first collector electrode (230), a first acoustic impedance matching layer (202) is assembled onto the first surface (210A) of the first piezoelectric layer (210) such that the first acoustic impedance matching layer is located in the array (200) between the first piezoelectric layer and the first collector electrode, and cutting the first piezoelectric layer includes cutting the first acoustic impedance matching layer through its entire thickness.
18. The method according to any one of claims 13 to 17, further comprising: After the step of cutting the first piezoelectric layer and the second piezoelectric layer, for example after the step of assembling the first collector and the second collector, the step of bending the array (200) is performed.
Citation Information
Patent Citations
Cyanogen chloride prepn. free of oxygen - by reacting hydrogen cyanide, hydrogen chloride and hydrogen peroxide in water under pressure
FR2310965A1