Ultrasonic probe

Abstract

Ultrasonic Probe This description relates to an ultrasonic probe (200) comprising: - an interconnecting substrate (230); - an array of ultrasonic transducers (201); - a control integrated circuit (202) electrically connected to the array of ultrasonic transducers and positioned on a first face (230A) of the interconnecting substrate; - a capacitive structure (210) positioned on a second face (230B) of the interconnecting substrate opposite the first face, the capacitive structure comprising a mechanically rigid insulating substrate, including at least one dielectric layer, and two metallic elements insulated from each other and positioned on either side of each dielectric layer, forming at least one capacitor. Figure for the abbreviation: Fig. 2A

Description

Title of the invention: Ultrasonic probe technical field

[0001] This description generally relates to ultrasonic probes comprising ultrasonic transducers, transducer control circuits, and generally passive electronic components.

[0002] This description may relate, in particular, to ultrasonic probes integrated into catheters, which may be referred to as ultrasound catheters. Previous technique

[0003] It has already been proposed to integrate a small ultrasound probe into a catheter, which can then be referred to as an ultrasound catheter. The ultrasound catheter can be intended to be introduced into a patient's body, for example into a blood vessel, particularly for imaging an anatomical region.

[0004] Ultrasound catheters have been designed for use in many anatomical regions, for example, for diagnostic, therapeutic, drug delivery, and / or surgical purposes. Among the known techniques are intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE). In both techniques, the ultrasound probe typically includes an array of ultrasound transducer elements, or ultrasound transducer array, positioned at one end of the catheter to emit ultrasound waves. This end is generally referred to as the distal end of the catheter, through which the catheter is guided into the region of the body to be examined. The transducers can then be used to receive ultrasound waves reflected back from specific features of the anatomical region.The reflected ultrasound waves can be transmitted to a processing device designed to process them and produce an image of the body region where the catheter is placed. The generated image is then either that of a plane or a volume. The generated image can also be one or more radiofrequency lines for measurement purposes such as Doppler and elastography modalities.

[0005] An IVUS catheter is generally used in a blood vessel, for example in a vein, or in a respiratory system, for example in the bronchi, and is generally associated with a guidewire having a flexible tip to guide the catheter into the vessel. An ICE catheter is generally used in a region of the heart, or even a surrounding structure, to image that region, for example to prepare, guide, and / or facilitate medical procedures. An ICE catheter is not generally designed to be associated with a guide wire, but rather typically includes a distal end which can be articulated by a guiding mechanism located in a handle at a proximal end of the catheter.

[0006] In addition to IVUS and ICE applications, other applications can be cited in transesophageal echocardiography (TEE), laparoscopy, and endocavitary exploration, including 4D with electronics.

[0007] The ultrasound probe generally includes a control circuit mounted near the transducer array. A control circuit can select individual transducer elements, or groups of transducer elements, to transmit ultrasound waves and / or receive ultrasound waves reflected by the tissues to be imaged or characterized.

[0008] To improve their performance, an increasing number of ultrasonic probes incorporate integrated circuits, particularly for control circuits. An integrated circuit is, for example, an application-specific integrated circuit, known by the acronym ASIC, from the English "Application-Specific Integrated Circuit." Integrated circuits can improve the signal-to-noise ratio of ultrasonic probes, significantly increase the number of channels for the transducer array, and / or provide reconfiguration capabilities.

[0009] Furthermore, it is generally necessary to add power reservoirs, commonly called decoupling capacitors, to integrated circuits so that these integrated circuits do not experience, or experience as few as possible, voltage fluctuations, regardless of operating conditions, particularly transient conditions, and the current consumption profile of the ultrasonic probe. Power reservoirs generally include capacitors, for example, capacitors in the form of surface-mounted devices (SMDs). Capacitors may be part of a set of passive electronic components, which may include other electronic components.

[0010] To be as efficient as possible, capacitors are preferably located as close as possible to the integrated circuits. Furthermore, the size of a capacitor is generally directly related to the average power and transient operating profile it can handle, preferably while remaining below a maximum voltage, or even a maximum temperature. As the number of transducers in the array increases, it may be necessary to increase the size of the capacitors, which can significantly impact their footprint in the ultrasonic probe, or even call into question the feasibility of integrating these capacitors into the ultrasonic probe.

[0011] Indeed, since the ultrasound probe is generally intended to be introduced, with the catheter, into an anatomical space of small section or small diameter, its external diameter is typically a few millimeters, for example an external diameter of 5 mm (15 French), or even less than or equal to 1.6 mm (5 French) for ICE applications, or 1 mm (3 French) for IVUS applications.

[0012] It can prove difficult to manufacture an ultrasonic probe that integrates, in addition to ultrasonic transducers, integrated circuits and electronic components such as capacitors within a diameter of a few millimeters. In other words, it can prove difficult to manufacture an ultrasonic probe with a small external diameter, typically a few millimeters, while integrating ultrasonic transducers, integrated circuits, electronic components such as capacitors, and the various electrical interconnections within that ultrasonic probe.

[0013] It would be desirable to have an ultrasonic probe that at least partially overcomes some of the disadvantages of known ultrasonic probes.

[0014] In particular, there is a need for an ultrasound probe, for example an ultrasound probe intended to be integrated into a catheter, which can integrate several electronic functionalities associated with the ultrasound transducer network, including control integrated circuits and passive electronic components such as capacitors, and this in a reduced diameter, while maintaining efficient assembly, interconnection and operation of the ultrasound probe. Summary of the invention

[0015] One embodiment overcomes all or part of the disadvantages of known ultrasonic probes.

[0016] One embodiment provides an ultrasonic probe comprising: - an interconnection substrate; - a network of ultrasonic transducers; - an integrated control circuit electrically connected to the ultrasonic transducer network and positioned on one face of the interconnection substrate; - a capacitive structure positioned on a second face of the interconnecting substrate opposite the first face, the capacitive structure comprising a mechanically rigid insulating substrate, including at least one dielectric layer, and two metallic elements insulated from each other and positioned on either side of each dielectric layer, forming at least one capacitance.

[0017] According to one embodiment, the interconnecting substrate comprises a first portion and a second portion facing the first portion, said first and second portions being for example connected by a third portion forming a fold of the interconnecting substrate, the capacitive structure being positioned between said first portion and said second portion.

[0018] According to one embodiment, the ultrasonic transducer network is positioned on the control integrated circuit.

[0019] According to one embodiment, the control integrated circuit is between the ultrasonic transducer network and the capacitive structure.

[0020] According to one embodiment, the ultrasonic transducer network is positioned on a first portion of the interconnection substrate, and the control integrated circuit is positioned on a second portion of the interconnection substrate distinct from the first portion.

[0021] According to one embodiment, the ultrasonic transducer network is positioned on the first face of the interconnecting substrate.

[0022] According to one embodiment, the capacitive structure is between the ultrasonic transducer network and the control integrated circuit.

[0023] According to one embodiment, each dielectric layer of the insulating substrate is a ceramic layer or a ceramic sheet.

[0024] According to one embodiment, the insulating substrate is a stack of several layers or sheets of ceramic, the metallic elements being positioned on either side of each layer or sheet of ceramic.

[0025] According to one embodiment, the capacitive structure comprises, for example, a stack of co-fired metallized ceramic sheets, for example at low temperature.

[0026] According to one embodiment, the ceramic: - has a relative permittivity greater than 300; and / or - is non-piezoelectric; and / or - is paraelectric or ferroelectric.

[0027] According to one embodiment, the insulating substrate of the capacitive structure comprises, for example, a glass.

[0028] According to one embodiment, the insulating substrate of the capacitive structure comprises silicon, preferably oxidized to form a layer of dielectric material around the silicon.

[0029] According to one embodiment, the capacitive structure comprises a metallic structure which includes the metallic elements, the metallic structure being structured so as to form with the insulating substrate a plurality of capacitive elements.

[0030] According to one embodiment, the capacitive elements are individually connected and / or interconnected in series and / or interconnected in parallel, via the substrate interconnection, so as to configure multiple capacity values ​​in the capacitive structure. Brief description of the drawings

[0031] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0032] [Fig.1A] is a three-dimensional view representing an example of an ultrasonic probe;

[0033] [Fig.1B] is a side view of the ultrasonic probe of [Fig.1A];

[0034] [Fig.1C] is a top view of the ultrasonic probe of [Fig.1A];

[0035] [Fig. 1D] is a three-dimensional view representing an example of a capacitor which can be integrated into the ultrasonic probe in figures IA to IC;

[0036] [Fig. 1E] is a three-dimensional view representing another example of a capacitor that can be integrated into the ultrasonic probe of figures IA to IC;

[0037] [Fig.2A] is a three-dimensional view representing an ultrasonic probe according to one embodiment;

[0038] [Fig.2B] is a side view of the ultrasonic probe of [Fig.2A];

[0039] [Fig.2C] is a top view of the ultrasonic probe of [Fig.2A];

[0040] [Fig. 3A] is a top view representing an example of an embodiment of capacitive structure of an ultrasonic probe according to an embodiment;

[0041] [Fig.3B] is a three-dimensional view of the capacitive structure of [Fig.3A];

[0042] [Fig. 3C] and [Fig. 3D] are top and three-dimensional views representing an example of assembly and electrical connection of the capacitive structure of figures 3A and 3B to the interconnecting substrate of figures 2A to 2C;

[0043] [Fig.4] is a top view representing another example of an embodiment of a capacitive structure of an ultrasonic probe according to one embodiment;

[0044] [Fig.5A] is a partial three-dimensional view representing an ultrasonic probe according to another embodiment;

[0045] [Fig.5B] is a side view of the ultrasonic probe of [Fig.5A];

[0046] [Fig. 5C] is a bottom view of the ultrasonic probe of [Fig. 5A]; and

[0047] [Fig.5D] is a top view of the ultrasonic probe of [Fig.5A]. Description of the implementation methods

[0048] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0049] For the sake of clarity, only the steps and elements necessary for understanding the described embodiments have been shown and are detailed. In particular, the ultrasonic transducers of the described ultrasonic probes have not been detailed, as the described embodiments are compatible with all or most known ultrasonic transducer structures. Furthermore, the control integrated circuits of the described ultrasonic probes have not been detailed, as the described embodiments are compatible with all or most common control integrated circuits for ultrasonic transducers.

[0050] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") together, this means that these two elements can be connected or linked through one or more other elements.

[0051] Unless otherwise specified, when referring to two elements mounted, or positioned, one on top of the other, this does not necessarily mean that these two elements are mounted, or positioned, directly one on top of the other, one or more other elements may be positioned between these two elements.

[0052] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures or to an ultrasonic probe in a normal operating position.

[0053] Unless otherwise specified, the expressions "approximately", "roughly", and "on the order of" mean to within 10% or 10°, preferably to within 5% or 5°.

[0054] In the following description, when a longitudinal direction is referred to, it is a direction parallel to the axis of the ultrasonic probe. The longitudinal direction corresponds to the X direction shown in the figures. A transverse direction corresponds to a direction taken in a plane transverse to the longitudinal direction. The figures illustrate two transverse directions, Y and Z.

[0055] In the following description, when a transducer is referred to, unless otherwise specified, it refers to an ultrasonic transducer, and when a probe is referred to, unless otherwise specified, it refers to an ultrasonic probe. Furthermore, when a control integrated circuit, or control circuit, is referred to, the term "control" should be understood in a general sense consisting of the sending of signals, particularly for the control of elements electronics, as well as the reception of signals that it can process. The term control circuit, or integrated control circuit, can be used.

[0056] In the following description, references to a catheter are made, broadly defined, to a thin, rod-shaped device, generally flexible, hollow or solid, intended for insertion into a region of a human or animal body (e.g., a cavity, a lumen, a duct), generally for the purpose of injecting a fluid and / or draining its contents. An ultrasound catheter is defined as a catheter equipped with an ultrasound probe, generally intended for imaging a region of a human or animal body.

[0057] In the following description, a distal end refers to an end through which an ultrasound probe, or catheter, is introduced into a medium to be analyzed, and a proximal end refers to an end opposite the distal end. The proximal end generally corresponds to an electrical connection, or wiring, end of the ultrasound probe, or catheter.

[0058] Fig. 1A is a three-dimensional view representing an example of an ultrasonic probe 100. Fig. 1B is a side view of the ultrasonic probe 100 of Fig. 1A. Fig. 1C is a top view of the ultrasonic probe 100 of Fig. 1A.

[0059] The ultrasound probe 100 is intended to be integrated into a catheter, at the distal end of the catheter, to form an ultrasound catheter.

[0060] The ultrasonic probe 100 comprises an array of ultrasonic transducers 101 arranged on a control integrated circuit 102 in a vertically integrated configuration. The control integrated circuit 102 may be an application-specific integrated circuit, known as an ASIC (Application-Specific Integrated Circuit). The control integrated circuit 102 is arranged on a flexible interconnect substrate 103. An upper portion 103A of the interconnect substrate 103 is arranged on an elongated parallelepiped-shaped stiffener 104. The interconnect substrate 103 is folded under the stiffener 104. In other words, the stiffener 104 is positioned between the upper portion 103A of the interconnect substrate 103 and a lower portion 103B of the interconnect substrate 103.

[0061] The stiffener 104 provides mechanical support and secures / mounts ultrasonic transducers, for example, to ensure flatness and correct positioning of the transducers. The stiffener 104 can also provide rigidity to the ultrasonic probe 100. The stiffener 104 generally lacks electrical connection functions, which are performed in particular by the interconnecting substrate 103. To ensure good mechanical strength and / or rigidity, the stiffener 104 is preferably solid, i.e., not entirely hollow.

[0062] The ultrasonic probe 100 comprises two modules 105 of electronic components, which are positioned on either side of the stiffener 104, and of the stack formed by the network of transducers 101 and the control integrated circuit 102.

[0063] The modules 105 are enveloped by the interconnecting substrate 103, which can ensure an interconnection between the modules 105 and the control integrated circuit 102. More specifically, the modules 105 are enveloped by the upper portion 103A of the interconnecting substrate 103, the lower portion 103B of the interconnecting substrate 103, and transverse portions 103C, 103D which can connect the upper and lower portions.

[0064] For example, one of the modules 105 is located at a first end 100A of the ultrasonic probe 100, which may correspond to a distal end, and is wrapped at the fold of the interconnecting substrate 103, between the upper portion 103A, the lower portion 103B and a first transverse portion 103C connecting the upper and lower portions at this first end, and another of the modules 105 is located at a second end 100B of the ultrasonic probe 100, which may correspond to a proximal end, is wrapped between the upper portion 103A, the lower portion 103B and a second transverse portion 103D which corresponds to an extension of the upper portion 103A joining the lower portion 103B at this second end. However, it is possible to consider that the upper portion 103A and lower portion 103B do not meet in the second end 100B, and that there is no second transverse portion 103D.

[0065] The modules 105 include passive electronic components, in particular capacitors, forming power reservoirs for the control integrated circuit 102. Each module 105 may include several capacitors, typically in the form of surface-mount components (SMD), and the capacitors in this module may have several capacitance values, for example, ranging from 100F to 100F.

[0066] The modules 105 of electronic components may be capacitive modules or include other passive electronic components, for example inductors and / or resistors.

[0067] To manage hundreds of ultrasonic transducers in the transducer array 101 while minimizing voltage fluctuations, the control integrated circuit 102, such as an ASIC, may require numerous capacitors, for example, with different capacitance values. Consequently, the modules 105 can be quite large, for example, forming parallelepipeds with length / width / height dimensions between 0.6 mm / 0.3 mm / 0.3 mm and 3.5 mm / 3 mm / 3 mm, respectively. Considering their integration into a probe with a small outer diameter, the configuration shown in Figures IA to IC allows such parallelepiped modules 105 to be positioned as close as possible to the control integrated circuit 102, while ensuring their interconnection, thanks to the interconnection substrate 103.

[0068] Figure 1D is a three-dimensional view showing an example of a capacitor 150 that can be integrated into the ultrasonic probe shown in Figures IA to IC. Figure 1E is a three-dimensional view showing another example of a capacitor 150' that can be integrated into the ultrasonic probe shown in Figures IA to IC. The capacitors in Figures 1D and 1E can make up the module 105 shown in Figures IA to IC.

[0069] As shown in Figures 1D and 1E, the capacitors 150, 150' are multilayer structures comprising several layers 151, for example, between 1 and 10 layers, of ferroelectric material. The ferromagnetic material is ceramic, with average relative permittivities between 600 and 6000. The layers 151 are electrically connected in parallel to each other, either by through-conducting vias or by lateral conductive elements 152 arranged around the layers 151, as shown in Figures 1D and 1E. A structure of these conductive elements 152, which is in the form of grooves 153 in the examples shown, allows precise control of the surface area over which each capacitance is expressed. The conductive elements can be referred to as "electrodes". Such capacitors are suitable for operation at high voltage, typically between 20V and 100V.

[0070] Fig. 1D shows a capacitor 150 comprising four layers 151 of ferroelectric material, each 0.7 mm thick, the multilayer structure with the conducting elements 152 forming a parallelepiped with a length of 3.2 mm, a width of 2.5 mm and a thickness (height) of 2.8 mm. The capacitance of this capacitor 150 is, for example, approximately 1 pF.

[0071] Fig. 1E shows a capacitor 150' comprising 6 layers 151 of ferroelectric material, each 0.08 mm thick, the multilayer structure with the conducting elements 152 forming a parallelepiped 1 mm long, 0.5 mm wide, and 0.5 mm thick (height). The capacitance of this capacitor 150' is, for example, approximately 1 pF.

[0072] All these elements 101, 102, 103, 104, 105 of the ultrasonic probe 100 are integrated inside a sheath made of an acoustically transparent material, or having at least a portion made of an acoustically transparent material opposite the transducer array 101. The sheath being intended to be in contact with the tissues of the anatomical region into which the catheter is introduced, it is preferably biocompatible.

[0073] Since the ultrasound probe 100 is intended to be introduced, with the catheter, into an anatomical space of small cross-section or small diameter, the external diameter of The ultrasonic probe and its sheath are typically a few millimeters in diameter, for example, an external diameter of 5 mm (15 French) or less, or even 3 mm (9 French), or 1.6 mm (5 French) or less for ICE applications, or 1 mm (3 French) for IVUS applications. The internal diameter of the ultrasonic probe varies depending on the sheath wall thickness and can be 4.5 mm or less, or even 1 mm or 0.7 mm.

[0074] Thus, in the configuration shown in Figures IA to IC, it can be seen that the modules 105 already occupy a considerable volume, and that this volume can hardly be increased within a constrained internal diameter. On the contrary, it may be necessary to reduce the volume occupied by the modules 105 in order to reduce the size of the ultrasonic probe 100.

[0075] There is a need for an ultrasound probe, for example an ultrasound probe intended to be integrated into a catheter, which can integrate a control integrated circuit and passive electronic components such as capacitors, in a reduced diameter, while maintaining efficient assembly, interconnection and operation of the ultrasound probe.

[0076] Figure 2A is a three-dimensional view representing an ultrasonic probe 200 according to one embodiment. Figure 2B is a side view of the ultrasonic probe 200 of Figure 2A. Figure 2C is a top view of the ultrasonic probe of Figure 2A.

[0077] Similar to the ultrasonic probe 100 of Figures IA to IC, the ultrasonic probe 200 of Figures 2A to 2C comprises a transducer array 201, or acoustic component, comprising ultrasonic transducers adapted to emit and receive ultrasonic waves.

[0078] All or part of the ultrasonic waves emitted by the transducers of the transducer array 201 may be reflected by particular elements of the medium into which the ultrasonic probe 200 is introduced, for example, particular elements of a region of a vessel, a heart, or more generally, of a structure surrounding the ultrasonic probe. The reflected ultrasonic waves may be received by the transducers. These reflected ultrasonic waves may be processed by a processing device to produce an image of the medium in which the ultrasonic probe is placed, for example, to visualize particular elements. The processing device may be located in all or part of the control integrated circuits 202 described later.

[0079] An ultrasonic transducer is a transducer adapted to convert an electrical signal into an ultrasonic wave, and conversely, to convert an ultrasonic wave into an electrical signal. Depending on the type of transducer, the electrical signal may correspond to a voltage, a current, or an electrical charge.

[0080] The transducer network 201 may include any type of ultrasonic transducer, or even several types of ultrasonic transducers.

[0081] Ultrasonic transducers may consist of a layer of single-crystal or polycrystalline piezoelectric material, for example PZT (lead-zirconia titaniumate), or a composite structure comprising at least one layer of piezoelectric material, for example a PZT layer including polymer-filled grooves. The resting thickness of the piezoelectric material layer may, for example, be between 0.05 and 1 mm, knowing that this thickness varies when a voltage is applied to it. The thickness of an ultrasonic transducer including electrodes and other layers may, however, be between 0.1 and 2 mm.

[0082] Ultrasonic transducers can be microelectromechanical systems, or MEMS, implementing microelectronic production technologies. A MEMS-type transducer generally consists of a deformable membrane suspended above a cavity. In one embodiment, the deformable membrane is displaced or deformed by capacitive force using an electrode attached to the membrane and an electrode separated by the cavity. This type of ultrasonic transducer is known by the acronym CMUT, for Capacitive Micro-machined Ultrasonic Transducer, i.e., a micro-machined capacitive ultrasonic transducer, or membrane capacitive transducer. In another embodiment, the deformable membrane is displaced or deformed by piezoelectric force using a layer of piezoelectric material equipped with two electrodes attached to the membrane.This type of ultrasonic transducer is known by the acronym PMUT, from the English Piezoelectric Micro-machined Ultrasonic Transducer, i.e. a micro-machined piezoelectric ultrasonic transducer, or membrane piezoelectric transducer.

[0083] The transducer array 201 can include any number of ultrasonic transducers, for example between 50 and 400 transducers aligned along the longitudinal direction X. The transducer array 201 can be a matrix consisting of several dozen rows and columns, i.e. several hundred or even thousands of transducers, for example a matrix of 12x64 transducers, i.e. 768 transducers.

[0084] The transducer array 201 has a length L1 and a width 11. The length and width L1 and 11 depend on the number of transducers and the array pitch. The array pitch itself depends on the center frequency of the ultrasonic signals. For example, the length L1 is between 10 and 20 mm, for example approximately 15 mm, and the width 11 is between 0.5 and 4 mm, for example approximately 2 mm.

[0085] Similar to the ultrasonic probe 100 of Figures IA to IC, the ultrasonic probe 200 of Figures 2A to 2C further comprises a control integrated circuit 202, or control circuit 202. The control integrated circuit 202 can be an application-specific integrated circuit, or ASIC, or any other integrated circuit suitable for controlling multiple ultrasonic transducers.

[0086] The control integrated circuit 202 is, for example, configured to control all the transducers of the transducer network 201. The control integrated circuit 202 can include several electronic circuits enabling it to perform different functionalities, the electronic circuits being able to be grouped into several cells, each associated with one or more transducers of the transducer network 201.

[0087] The control integrated circuit 202 can be configured to select certain transducers of the transducer array 201 for use in transmitting / receiving ultrasonic waves, to transmit control signals to the selected transducers so that they generate and transmit ultrasonic waves, and / or to accept or even amplify return signals from the selected transducers when they receive reflected ultrasonic waves, or even to perform operations on the return signals, for example, beamforming and / or scanning operations. More generally, several types of signals, such as control, power, and / or data signals, can be exchanged between the transducers of the transducer array 201 and the control integrated circuit 202.

[0088] The control integrated circuit 202 has a length L2 and a width 12. For example, the length L2 is between 15 and 30 mm, for example approximately 20 mm, and the width 12 is between 1 and 4 mm, for example approximately 2 mm. Preferably, the length L2 is greater than the length L1 to allow access to contact pads on the control integrated circuit 202, for example, digital control, synchronization, power supply pads, and other signals related to the transmission and reception phases of ultrasonic waves.

[0089] In the example shown in Figures 2A to 2C, similarly to Figures IA to IC, the transducer array 201 is connected to the control circuit 202 via a so-called vertical integration, but this is not a limiting factor, as shown in the variant in Figures 4A to 4D described later. For example, the electrical connections between the transducer array 201 and the control circuit 202 are made using solder balls or an anisotropic conductive film.

[0090] Similar to the ultrasonic probe 100 of Figures IA to IC, the ultrasonic probe 200 of Figures 2A to 2C comprises an interconnect substrate 230 on which the control integrated circuit 202 is disposed. The control integrated circuit 202 is disposed on an upper portion 231 of the interconnect substrate 230, and on a first face 230A, or outer face, of the interconnect substrate 230. The substrate The interconnecting substrate 230 is folded (folded portion 233) at a first end 200A of the ultrasonic probe 200, which may be a distal end, to form a lower portion 232 below the upper portion 231. The lower portion 232 extends to a second end 200B of the ultrasonic probe 200, which may be a proximal end. The folded portion 233 of the interconnecting substrate 230 connects the upper portion 231 and the lower portion 232.

[0091] The interconnecting substrate 230 is preferably flexible enough to be folded as described above. The interconnecting substrate 230 can be a flexible printed circuit board, or "FPCB". To limit stresses in the interconnecting substrate 230, the folding areas preferably have a minimum radius of curvature of a few micrometers.

[0092] In the example shown in Figures 2A to 2C, the upper and lower portions 231 and 232 of the interconnecting substrate 230 meet at the second end 200B. However, it is possible for the upper 231 and lower 232 portions of the interconnecting substrate 230 not to meet at the second end 200B. In all cases, the upper and lower portions 231 and 232 of the interconnecting substrate 230 can form connecting tabs, blades, strips, or flats at the second end 200B. The connecting flats can be used to couple the interconnecting substrate 230 to circuits, cables, connectors, and / or components external or internal to the ultrasonic probe 200. Other configurations can be considered by those skilled in the art.

[0093] The ultrasonic probe 200 of Figures 2A to 2C differs from the ultrasonic probe 100 of Figures IA to IC in that it does not include the modules 105 on either side of the stiffener 104, and the stack formed by the network of transducers 101 and the control integrated circuit 102, but it includes a capacitive structure 210 positioned between the upper portion 231 and the lower portion 232 of the interconnecting substrate 230, replacing the stiffener 104.

[0094] The capacitive structure 210 is connected to a second face 230B, or inner face, of the interconnecting substrate 230, opposite to the first face 230A, in each of the upper 231 and lower 232 portions.

[0095] The capacitive structure 210 fulfills at least the functions of a power reservoir for the control integrated circuit 202, i.e., it provides capacitance, and of mechanical rigidity for the ultrasonic probe 200, acting as a mechanical stiffener. This may include a function of mechanically holding, or even fixing / mounting, the ultrasonic transducers.

[0096] The capacitive structure 210 may have a shape adapted to fit into the space between the upper portion 231 and the lower portion 232 of the substrate Interconnection 230. The form factor of the capacitive structure can be optimized, its size reduced, and its positioning within the ultrasonic probe optimized, for example, to reduce the size of the ultrasonic probe and / or to increase the electrical capacitance of this capacitive structure. For example, the capacitive structure 210 is approximately parallelepiped in shape.

[0097] As can be seen in Figures 2A and 2B, the capacitive structure 210 replaces the stiffener 104 shown in Figures IA to IC, without the need to add the modules 105, which have a considerable size. This allows for a reduction in the height of the ultrasonic probe, and potentially its length as well. Alternatively, for an equivalent ultrasonic probe length, this allows for an increase in the length of the control integrated circuit and / or the transducer array. More broadly, this allows for optimization of the arrangement of the various components of the ultrasonic probe, with a view to limiting the overall size of these components within the probe.

[0098] The capacitive structure 210 has a length L3 and a width 13. By way of example, the length L3 is between 18 and 40 mm, for example approximately 22 mm, and the width 13 is between 0.3 and 4.5 mm, for example approximately 2 mm. Preferably, the length L3 is greater than or equal to the length L1.

[0099] To fulfill the functions of capacitance and mechanical stiffness, the capacitive structure 210 may comprise an insulating substrate made of, or comprising, a dielectric material with a relative permittivity epsilon, for example greater than 1, for example greater than 1.3, the insulating substrate being covered with inter-insulated metallic elements forming electrodes, for example on each of its lower and upper faces. The insulating substrate imparts mechanical stiffness to the capacitive structure, while the metal / dielectric / metal stacking forms at least one capacitance. The insulating substrate may be a multilayer structure, in which case metallic elements are also positioned between the layers of the insulating substrate.

[0100] The capacitive structure 210 can be realized in different ways. Three embodiments of capacitive structures are described below, although a person skilled in the art may consider variations of these embodiments, or even other embodiments.

[0101] According to a first embodiment, the capacitive structure comprises a ceramic substrate, for example, a ceramic layer or a stack of ceramic layers. The ceramic preferably has a high permittivity or a high dielectric constant, typically with a relative permittivity (or dielectric constant) between 300 and 18,000. The ceramic is preferably non-piezoelectric. The ceramic may be paraelectric or ferroelectric, with or without dopants. The ceramic substrate may be a bulk ceramic.

[0102] Examples of ceramics include: barium titanate, for example in percentages from 10% to 98% of the ceramic composition, for example with rare-earth additives (neodymium, samarium), oxides, for example titanium oxide, dopants. Examples of ceramics may include other ceramic formulations such as calcium titanate, calcium zirconate, magnesium titanate, strontium titanate...

[0103] To form the capacitive structure, a conductive structure, for example metallic, can be formed around the ceramic substrate, for example on each of the upper and lower faces, or even between the ceramic layers in the case of a stack of several ceramic layers. The metallic structure can be structured so as to form metallic elements insulated from each other, or electrodes, on either side of each ceramic layer. The metallic structure can also be structured to form, with the ceramic substrate, several unitary capacitive elements, each equipped with electrodes.

[0104] The insulating substrate, for example the ceramic substrate, is preferably chosen to provide significant mechanical stiffness, for example whose Young's modulus is greater than 100 GPa, or even greater than 200 GPa.

[0105] The capacitance of the capacitive structure can be determined by the ceramic used, its dielectric constant, the dimensions (length, width, and thickness) of the ceramic substrate, the characteristics of the metallic structure, and, as described later, the number of capacitive elements and the electrical connection of these capacitive elements. The dimensions of the ceramic substrate can also influence the rigidity of the capacitive structure.

[0106] The metallic structure can be produced mechanically, or by dry engraving, or by laser engraving, or by any other structuring technique.

[0107] The metal structure can be produced by an additive manufacturing technique.

[0108] An example of an embodiment of this first embodiment is illustrated in the figures 3A and 3B.

[0109] Figure 3A is a top view representing an example of an embodiment of a capacitive structure 300 of an ultrasonic probe. Figure 3B is a partial three-dimensional view of the capacitive structure 300 of Figure 3A.

[0110] In the example of Figures 3A and 3B, the capacitive structure 300 comprises in stacking 310 of four layers of ceramic 311, but this number of layers of ceramic 311 is not limiting, the number of layers of ceramic 311 can vary, for example be between 1 and 100. The thickness of each layer of ceramic 311 can be between 0.02 and 2 mm, for example be about 0.2 mm.

[0111] The ceramic layers 311 are embedded in a metallic structure 320. The metal structure 320 includes a metal envelope 321 which surrounds the stack 310 of ceramic layers 311 and intercalated metal layers 322 which are positioned between the ceramic layers 311, and which are in contact with the metal envelope 321.

[0112] The metal structure 320 is structured by cutting patterns allowing access to the stack 310 of the ceramic layers 311.

[0113] In the example of Figures 3A and 3B, the cutting patterns include longitudinal grooves 323 extending in the X direction: a longitudinal groove 323A is formed in the metal casing 321 on the upper face 310A of the stack 310, a longitudinal groove 323B is formed in the metal casing 321 on the lower face 310B of the stack 310, and longitudinal grooves 323C are formed in each metal layer 322 intercalated between the ceramic layers 311. Preferably, as shown in [Fig. 3B], two successive longitudinal grooves are offset from each other in the Y direction. These longitudinal grooves 323 make it possible to form, for each ceramic layer 311, two upper electrodes 325 insulated from each other, and two lower electrodes 326 insulated from each other. The electrodes located to the right of the grooves 323 are connected to each other by the right side of the metal casing 321.The electrodes located to the left of the grooves 323 are connected to each other by the left side of the metal casing 321. The metal structure 320 thus structured makes it possible to form for each layer of ceramic 311 a capacitance on the metal / ceramic / metal stacking areas which are between the grooves 323 and to put the capacitances thus created in parallel, while making two terminal links (upper and lower faces of the metal casing 321) appear on each face of the stack 310.

[0114] Each electrode can typically have a thickness between 0.1 and 50 µm.

[0115] In the example shown in Figures 3A and 3B, the cutting patterns further include transverse grooves 324 all around the stack 310, in the Y and Z directions. In the Y direction, the grooves 324 extend in depth from each of the two lateral faces of the capacitive structure 300 until they reach the nearest longitudinal groove 323B, 323C. This allows the internal electrodes to be separated from the sides to separate the individual capacitances. These transverse grooves 324 allow several capacitive elements 301 to be formed along the X direction. In the example shown in Figures 3A and 3B, 25 capacitive elements 301 are formed along the X direction by these transverse grooves 324.

[0116] The metal of the metallic structure 320 comprises, for example, gold, copper, and / or nickel. This metallic structure 320 can be produced by a physical vapor deposition (PVD) technique, or a chemical vapor deposition (CVD) technique, or by chemical deposition.

[0117] The assembly of the ceramic layers 311 with the metallic layers 322 together can be carried out by bonding, co-sintering, aerosol, or tape casting.

[0118] These details of the metal structure 320 are given by way of non-limiting example; other types of metal structures, and for example other cutting patterns, may be considered by a person skilled in the art. For example, instead of having lower and upper electrodes, a person skilled in the art may consider having interdigitated electrodes arranged on the same face of each ceramic layer 311.

[0119] The capacitive structure 300 can form the capacitive structure 210 of figures 2A to 2C, or of figures 5A to 5D described later.

[0120] By way of non-limiting example, the capacitive structure 300 has a length of about 18 mm and a width of about 2 mm.

[0121] It is possible to use, and connect, all or part of the capacitive elements 301 individually, and / or to connect all or part of the capacitive elements 301 together, in series and / or in parallel, for example to control the capacitance value of the capacitive structure 300.

[0122] For example, for a ceramic with a relative permittivity of 3000, a capacitance of 1 pF can be obtained for each capacitive element 301. If all these capacitive elements 301 are connected in parallel on the same electrical circuit, the capacitive structure 300 can be considered as a single capacitance of approximately 25 pF. If all these capacitive elements 301 are connected in series, the capacitive structure 300 can be considered as a single capacitance of approximately 40 nF. Therefore, all combinations are possible for connecting the capacitive elements 301 together and / or individually, to obtain different capacitance values.

[0123] The interconnection of the various capacitive elements 301 is generally achieved via an interconnection substrate, for example the interconnection substrate 230 of Figures 2A to 2C. The interconnection substrate can thus make the electrical connections of the capacitive elements in series, in parallel and / or individually, so as to configure several capacitance values ​​in the capacitive structure 300. The interconnection substrate 230 also allows the resulting capacitances to be connected to the control integrated circuit 202 or to an equipotential, for example ground or a reference potential of a supply voltage.

[0124] Fig. 3C and Fig. 3D are top and three-dimensional views representing an example of assembly and electrical connection of the capacitive structure 300 of Figures 3A and 3B to the interconnecting substrate 230 of Figures 2A to 2C.

[0125] Figures 3C and 3D illustrate three types of electrical connections: a cell 302 of three capacitive elements 301 connected in parallel, a cell 303 of three capacitive elements 301 connected in series, and several individually connected capacitive elements 301. Three approximately 1 pF capacitive elements connected in parallel form a capacitance of 3 pF, while three 1 pF capacitive elements connected in series form a capacitance of approximately 0.33 pF.

[0126] The assembly and electrical connections to the interconnecting substrate are made in this example via the lower electrodes 326 which are positioned on the lower face 310B of the stack 310.

[0127] The first embodiment can make it possible to obtain several capacitance values ​​in the same capacitive structure by adapting the metallic structure, in particular by adapting the patterns, forming several unitary capacitive elements, and by organizing the interconnection of these capacitive elements. One way to configure different capacitance values ​​in the capacitive structure can be to organize the interconnections in series and / or in parallel between the different capacitive elements, and / or to connect some of these capacitive elements individually, via the interconnecting substrate.

[0128] According to a second embodiment, the capacitive structure can be fabricated using microelectronic technologies. This type of structure is known as an IPD, from the English "Integrated Passive Device". The capacitive structure may comprise a glass, quartz, or silicon-based substrate, instead of a bulk ceramic substrate. The silicon-based substrate is preferably oxidized to form at least one insulating dielectric layer (silicon oxide) on each of its upper and lower faces, or around the substrate. A metallic structure can be fabricated by a deposition technique on the substrate, for example, by a PVD or CVD technique, and then the metallic structure can be structured into cutting patterns to form several electrodes on the substrate. The capacitive structure may include an encapsulation layer, for example, with low permittivity, to encapsulate the metallized insulating substrate.This encapsulation layer can be achieved by anodic bonding for a glass-based substrate, or by another bonding technique, for example wafer bonding, for a silicon-based substrate. The interconnection can be formed by etching techniques to expose the electrodes to be connected.

[0129] A glass- or silicon-based substrate can provide greater rigidity to the capacitive structure compared to a bulk ceramic substrate. Furthermore, IPD technology allows for the production of other types of passive components such as inductors or resistors.

[0130] According to a third embodiment, the capacitive structure may comprise metallized ceramic sheets stacked one on top of the other, the stack being sintered using the so-called LTCC (Low Temperature Co-fired Ceramic) technique. The metallization of the ceramic sheets may be carried out in such a way as to form interdigitated electrodes between the ceramic sheets.

[0131] A capacitive structure of the LTCC type can provide much more rigidity, compared to a solid ceramic substrate.

[0132] Figure 4 is a top view representing another embodiment of a capacitive structure 400 of an ultrasonic probe according to one embodiment. This other embodiment corresponds to the third embodiment of the capacitive structure.

[0133] The capacitive structure 400 comprises a stack 410 of several ceramic sheets 411, in this example seven ceramic sheets, but this number is not limiting, the number of ceramic sheets 411 can vary, for example be between 1 and 100. The thickness of each ceramic sheet 411 can be between 20 pm and 1 mm.

[0134] The capacitive structure 400 further comprises, on either side of each ceramic sheet 411, a pair of upper electrodes 425 and lower electrodes 426. The upper electrodes 425 and lower electrodes 426 are part of a metallic structure 420 which further comprises a chain of vias 427 for connecting the upper electrodes 425 to each other, and a chain of vias 428 for connecting the lower electrodes 426 to each other. Grooves 423 are formed in the metallic structure 420 so as to isolate the upper electrodes 425 from the lower electrodes 426, and the chain of vias 427 from the chain of vias 428.

[0135] The metal structure 420 thus structured makes it possible to form a capacity on the area of ​​the metal / ceramic / metal stacks which is located between the grooves 423.

[0136] The capacitive structure 400 can form the capacitive structure 210 of figures 2A to 2C, or of figures 5A to 5D described later.

[0137] The embodiment shown in Figures 2A to 2C is particularly advantageous for acoustic components that do not require acoustic attenuating material on the rear face of the transducers. Indeed, the ultrasonic waves on the rear face of the transducers of the array 201 can be reflected by the control circuit 202 and come to disrupt the electrical signal generated by the waves received by the transducers on the front panel.

[0138] Figure 5A is a three-dimensional view representing an ultrasonic probe 500 according to another embodiment. Figure 5B is a side view of the ultrasonic probe 500 of Figure 5A. Figure 5C is a bottom view of the ultrasonic probe 500 of Figure 5A. Figure 5D is a top view of the ultrasonic probe 500 of Figure 5A.

[0139] The ultrasonic probe 500 of Figures 5A to 5D differs from the ultrasonic probe 200 of Figures 2A to 2C primarily in that the transducer array 201 is not positioned on the control integrated circuit 202, but on the interconnecting substrate 230. The transducer array 201 is arranged on the upper portion 231 of the interconnecting substrate 230, and on the first face 230A, or outer face, of the interconnecting substrate 230. The control integrated circuit 202 is positioned on the lower portion 232 of the interconnecting substrate 230, and on the first face 230A of the interconnecting substrate 230.

[0140] This integration is said to be horizontal, referring to an integration of the transducer network 201 and the control integrated circuit 202 on the interconnection substrate 230 when the latter is not folded.

[0141] This type of integration allows, for example, better thermal management of the ultrasonic probe. Indeed, the heat exchange surface with the outside of the ultrasonic probe is increased since it is made up of both the external surface of the transducer array 201 and the external surface of the control circuit 202. On the other hand, the capacitive structure 210 interposed between the transducer array 201 and the control circuit 202 also serves as a thermal drain.

[0142] The positioning of the capacitive structure 210 is similar to that of figures 2A to 2C, that is to say between the upper portion 231 and the lower portion 232 of the interconnecting substrate 230, the capacitive structure 210 being connected to the second face 230B, or inner face, of the interconnecting substrate 230, and this in each of the upper portion 231 and lower portion 232.

[0143] The embodiment examples described show that the capacitive structure according to the embodiments makes it possible to realize other form factors in relation to capacitive modules such as the 105 modules described in connection with figures IA to IC, while finding the same capacitance values, or even increasing them, or adapting them as needed.

[0144] For each of the examples and embodiments described above, and more generally for a capacitive structure according to any embodiment, an insulating layer may be provided on the electrodes of the capacitive structure, at least on the faces of the capacitive structure that are opposite the interconnecting substrate, to prevent any short circuit with this interconnect substrate. Alternatively, the insulating layer can be provided on each face of the interconnect substrate that is opposite the capacitive structure.

[0145] The ultrasound probe according to the embodiments can find applications in the field of intracardiac echocardiography (ICE), or in the field of intravascular ultrasound imaging (IVUS), or even in the field of high-intensity ultrasound therapy (HIFU), the ultrasound probe being integrated into a catheter, or even in the field of transesophageal echocardiography (TEE), laparoscopy, and endocavitary exploration.

[0146] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0147] Finally, the practical implementation of the embodiments and variants described is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

Demands

1. Ultrasonic probe (200; 500) comprising: - an interconnecting substrate (230); - an array of ultrasonic transducers (201); - a control integrated circuit (202) electrically connected to the array of ultrasonic transducers and positioned on a first face (230A) of the interconnecting substrate; - a capacitive structure (210; 300; 400) positioned on a second face (230B) of the interconnecting substrate opposite to the first face, the capacitive structure comprising a mechanically rigid insulating substrate (310, 410), comprising at least one dielectric layer (311; 411), and two metallic elements (325, 326; 425, 426) insulated from each other and positioned on either side of each dielectric layer, forming at least one capacitor (301; 401).

2. Ultrasonic probe (200; 500) according to claim 1, wherein the interconnecting substrate (230) comprises a first portion (231) and a second portion (232) facing the first portion, said first and second portions being for example connected by a third portion (233) forming a fold of the interconnecting substrate, the capacitive structure (210) being positioned between said first portion and said second portion.

3. Ultrasonic probe (200) according to claim 1 or 2, wherein the ultrasonic transducer array (201) is positioned on the control integrated circuit (202).

4. Ultrasonic probe (200) according to claim 3, wherein the control integrated circuit (202) is between the ultrasonic transducer array (201) and the capacitive structure (210).

5. Ultrasonic probe (500) according to claim 1 or 2, wherein the ultrasonic transducer array (201) is positioned on a first portion (231) of the interconnecting substrate (230), and the control integrated circuit (202) is positioned on a second portion (232) of the interconnecting substrate (230) distinct from the first portion.

6. Ultrasonic probe (500) according to claim 5, wherein the ultrasonic transducer array (201) is positioned on the first face (230A) of the interconnecting substrate (230).

7. Ultrasonic probe (500) according to claim 5 or 6, wherein the capacitive structure (210) is between the ultrasonic transducer array (201) and the control integrated circuit (202).

8. Ultrasonic probe according to any one of claims 1 to 7, wherein each dielectric layer (311, 411) of the insulating substrate (310, 410) is a ceramic layer or a ceramic foil.

9. Ultrasonic probe according to claim 8, wherein the insulating substrate (310; 410) is a stack of several layers or sheets of ceramic (311, 411), the metallic elements (325, 326; 425, 426) being positioned on either side of each layer or sheet of ceramic.

10. Ultrasonic probe according to claim 8 or 9, wherein the capacitive structure (400) comprises, for example, consists of a stack of co-baked metallized ceramic sheets (411), for example at low temperature.

11. Ultrasonic probe according to any one of claims 8 to 10, wherein the ceramic: - has a relative permittivity greater than 300; and / or - is non-piezoelectric; and / or - is paraelectric or ferroelectric.

12. Ultrasonic probe according to any one of claims 1 to 7, wherein the insulating substrate of the capacitive structure comprises, for example, consists of a glass.

13. Ultrasonic probe according to any one of claims 1 to 7, wherein the insulating substrate of the capacitive structure comprises silicon, preferably oxidized to form a layer of dielectric material around the silicon.

14. Ultrasonic probe according to any one of claims 1 to 13, wherein the capacitive structure (300; 400) comprises a metallic structure (320, 420) which includes the metallic elements (325, 326; 425, 426), the metallic structure being structured so as to form with the insulating substrate (310, 410) a plurality of capacitive elements (301; 401).

15. Ultrasonic probe according to claim 14, wherein the capacitive elements (301; 401) are individually connected and / or interconnected in series and / or interconnected in parallel, via the interconnect substrate (230), so as to configure several capacitance values ​​in the capacitive structure (300; 400).

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