Ultrasonic transducer and system and method for cooling an ultrasonic transducer array

Abstract

Ultrasound devices and systems are disclosed in which cooling of an active acoustic element of an ultrasound transducer is achieved via an electrically conductive member that extends beyond the proximal side of the active acoustic element and contacts a heat exchanger. The electrically conductive member transmits an electrical drive signal to the active acoustic element while conducting heat to the heat exchanger. Additionally, areas of the proximal surface of the active acoustic element that are not in contact with the electrically conductive member are also free of contact with liquids or solids, which may facilitate reflection of ultrasonic energy. The heat exchanger may include an electrically insulating fluid that contacts and removes heat conducted through the electrically conductive member. The active acoustic element may be a multilayer transverse mode element, and the electrically conductive member may form electrodes of the transverse mode element.

Description

Technical Field

[0001] The present disclosure relates to ultrasound-based therapy and imaging. In some aspects, the present disclosure relates to the cooling of ultrasonic transducers and ultrasonic transducer array elements.

[0002] [Cross-Reference to Related Applications] This application claims priority to U.S. Provisional Patent Application No. 62 / 913,351, entitled "Ultrasonic Transducer and System and Method for Cooling an Ultrasonic Transducer," filed on October 10, 2019, the entire contents of which are incorporated herein by reference.

Background Art

[0003] Generating ultrasound, particularly at high power, generates waste heat that must be dissipated to prevent damage to the transducer. Current mitigation approaches have limitations. For example, forced air cooling cannot remove heat quickly enough to be sufficient for use in high-power applications. Approaches that require contacting the transducer with a coolant, apart from the ultrasound radiating surface, significantly reduce the efficiency of the transducer. Similarly, attaching a heat sink or exchanger with a relatively large surface area to the transducer surface increases the mechanical load on the device and reduces its effectiveness.

Summary of the Invention

[0004] This specification discloses an ultrasonic device and system. Cooling of the active acoustic element of an ultrasonic transducer is achieved via a conductive member that extends beyond the proximal side of the active acoustic element and contacts a heat exchanger. The conductive member conducts heat to the heat exchanger while sending an electrical drive signal to the active acoustic element. Also, a region of the proximal surface of the active acoustic element that has no contact with the conductive member also has no contact with a liquid or solid, thereby facilitating reflection of ultrasonic energy. The heat exchanger may include an electrically insulating fluid that contacts the conductive member and removes heat conducted through the conductive member. The active acoustic element may be a multi-layer transverse mode element, and the conductive member may form an electrode of the transverse mode element.

[0005] Accordingly, in a first aspect, there is provided an ultrasonic device including the following. · An active acoustic element configured to generate ultrasonic energy when an electrical drive signal is applied, the active acoustic element having a distal surface for emitting ultrasonic energy in a distal direction and a proximal surface on the opposite side. · An electrically conductive member in contact with the active acoustic element for transmitting an electrical drive signal to the active acoustic element and conducting heat from the active acoustic element, wherein at least a portion of the proximal surface of the active acoustic element extends beyond the proximal surface so as not to be in contact with the electrically conductive member (the electrically conductive member is connectable to drive an electronic device for transmitting the electrical drive signal to the active acoustic element through the electrically conductive member). · A heat exchanger spatially offset in the proximal direction from the proximal surface, in contact with a portion of the electrically conductive member that exists beyond the proximal surface, transmitting the electrical drive signal to the active acoustic element through the conductive member while removing heat from the active acoustic element through the electrically conductive member.

[0006] In one embodiment of the device, the region of the proximal surface that does not contact the conductive member also does not contact a liquid or a solid, thereby facilitating the reflection of ultrasonic energy at a portion of the proximal surface. In one embodiment of the device, a gap exists between the proximal surface and the heat exchanger, thereby facilitating the reflection of ultrasonic energy at a portion of the proximal surface. Here, the conductive member extends across the gap and contacts the heat exchanger. The gap may be an air gap. Note that the gap may be filled with a gas other than air.

[0007] In one embodiment of the device, the proximal surface includes a signal electrode, and the distal end of the conductive member contacts the electrode. The distal end of the conductive member may contact the proximal surface within a small region having a surface area of less than 10% of the total surface area of the proximal surface. The distal end of the conductive member may contact the proximal surface within a small region having a surface area of less than 5% of the total surface area of the proximal surface. The distal end of the conductive member may contact the proximal surface within a small region having a surface area of less than 2% of the total surface area of the proximal surface.

[0008] The cross-sectional area of the conductive member within a portion of the conductive member that contacts the heat exchanger may be larger than the cross-sectional area of the conductive member at the distal end of the conductive member. The cross-sectional area of the conductive member within the portion of the conductive member that contacts the heat exchanger may be smaller than the cross-sectional area of the conductive member at the distal end of the conductive member. The cross-sectional area of the conductive member within the portion of the conductive member that contacts the heat exchanger may be variable and larger and / or smaller than the cross-sectional area of the conductive member at the distal end of the conductive member. The cross-sectional area of the conductive member within the portion of the conductive member that contacts the heat exchanger may be non-uniform, asymmetric, rough, or may have extensions or other structures, shapes, or surface patterns or microstructures for enhancing heat transfer.

[0009] In one embodiment of the device, a portion of the proximal surface that is not in contact with the conductive member contacts a material having an acoustic impedance selected such that at least 50% of the backward-propagating ultrasonic energy is reflected at the portion of the proximal surface. In one embodiment of the device, a portion of the proximal surface that is not in contact with the conductive member contacts a material having an acoustic impedance selected to match the acoustic impedance of the active acoustic element, such that the backward-propagating ultrasonic energy is suppressed at the portion of the proximal surface. In an implementation of an example of the device, a portion of the proximal surface that is not in contact with the conductive member contacts a material having an acoustic impedance selected such that less than 10% of the backward-propagating ultrasonic energy is reflected at the portion of the proximal surface. The conductive member may extend from the proximal surface and pass through the material before contacting the heat exchanger. The material may contact the heat exchanger to facilitate removal of heat conducted through the material. The material may be acoustically attenuating. In an implementation of an example of the device, the distal region of the conductive member contacts the electrode of the active acoustic element. In an implementation of an example of the device, the distal region of the conductive member forms the electrode of the active acoustic element.

[0010] In one embodiment of the device, the heat exchanger comprises an electrically insulating fluid that contacts a portion of the conductive member and removes heat conducted through the conductive member without contacting the active acoustic element. The portion of the conductive member that contacts the electrically insulating fluid may include a cylindrical segment. The portion of the conductive member that contacts the electrically insulating fluid may include a planar fin. The portion of the conductive member that contacts the electrically insulating fluid may include an elongated segment that extends across the heat exchanger, and the elongated segment has one or more lateral members that extend laterally therefrom.

[0011] The device can further include a pump configured to flow an electrically insulating fluid through a heat exchanger. The heat exchanger may be a first heat exchanger, and the ultrasonic device may further include a second heat exchanger located on the distal side of the distal surface. The second heat exchanger is in thermal communication with the active acoustic element, such that heat generated within the active acoustic element is removed proximal to the active acoustic element by the first heat exchanger and removed distal to the active acoustic element by the second heat exchanger. The heat exchanger can include a thermoelectric cooler.

[0012] In one embodiment, the active acoustic element is a lateral mode active acoustic element including a plurality of piezoelectric layers having electrodes provided therebetween to excite lateral mode ultrasonic radiation in the distal direction. The distal region of the conductive member may form the electrodes of the lateral mode active acoustic element. In one embodiment, the device can further include a printed circuit board present proximal to the heat exchanger, and the conductive member extends beyond the heat exchanger and is connected to the printed circuit board to transmit an electrical drive signal.

[0013] In one embodiment of the device, the conductive member can include a first segment that contacts the active acoustic element and a second segment that contacts the heat exchanger. The first segment is removably connected to the second segment to facilitate modular assembly of the ultrasonic device. The cross-sectional diameter of the first segment may be smaller than the cross-sectional diameter of the second segment. One of the first segment and the second segment can include a socket for receiving the other of the first segment and the second segment. The device may further include a housing configured to support the active acoustic element and the first segment of the conductive member.

[0014] In one embodiment of the device, the conductive member is a first conductive member, the ultrasonic device further includes a second conductive member, and the second conductive member is a second conductive member that extends beyond the proximal surface from the active acoustic element such that at least a portion of the proximal surface of the active acoustic element is released from contact with the second conductive member. The second conductive member is connectable to drive an electronic device for transmitting an electrical drive signal to the active acoustic element through the second conductive member. The first conductive member and the second conductive member may contact different regions of the proximal surface. The second conductive member may contact the ground electrode of the active acoustic element.

[0015] In one embodiment of the device, the active acoustic element is a first active acoustic element, the conductive member is a first conductive member, the ultrasonic device further includes one or more additional acoustic active elements, and each additional acoustic active element has a respective additional conductive member that extends beyond its respective proximal surface such that a portion of each respective additional conductive member contacts the heat exchanger. The first active acoustic element and the additional acoustic active elements define a set of active acoustic elements, the first conductive member and the additional conductive members define a set of conductive members, and the set of active acoustic elements and the set of conductive members are spatially arranged to form an ultrasonic array. The heat exchanger may contain an electrically insulating fluid, and the electrically insulating fluid contacts a portion of each conductive member to remove heat conducted through the conductive member. The device may further include an insulating spacer present within the heat exchanger, and the insulating spacer is configured to prevent contact between the conductive members. The device may further include a housing configured to support a set of active acoustic elements.

[0016] Each conductive member of a set of conductive members can include a first segment that contacts a respective active acoustic element and a second segment that contacts a heat exchanger. Each first segment is supported by a housing, and the housing, a set of active acoustic elements, and a set of first segments form an array module. The set of second segments forms a cooling array supported by a heat exchanger. Each first segment is removably connected from the cooling array, facilitating modular assembly of the ultrasonic device by the heat exchanger.

[0017] The cross-sectional diameter of the first segment may be smaller than the cross-sectional diameter of the second segment. One of the first segment and the second segment can include a socket for receiving the other of the first segment and the second segment. The array module may be a first array module, the cooling array may be a first cooling array, and the ultrasonic device may further include one or more additional array modules and one or more respective cooling arrays. Each array module may be connected to a respective circuit board via a respective cooling array, and each circuit board is connected to dedicated drive electronics for each module.

[0018] In another aspect, an ultrasonic device is provided that includes the following. · An active acoustic element configured to generate ultrasonic energy when an electrical drive signal is applied, the active acoustic element having a distal surface for emitting ultrasonic energy in a distal direction and a proximal surface on the opposite side. · A conductive member that transmits an electrical drive signal to the active acoustic element and conducts heat from the active acoustic element, the conductive member extending beyond the proximal surface from the active acoustic element such that at least a portion of the proximal surface of the active acoustic element does not contact the conductive member. · A circuit board that is spatially offset proximally from the proximal surface, the proximal end of the conductive member being in electrical contact with the circuit board for transmitting the electrical drive signal to the active acoustic element. ·A heat exchanger in thermal contact with the circuit board to remove heat conducted through the circuit board via the conductive member

[0019] In another aspect, a lateral mode ultrasonic transducer is provided that includes the following. ·A piezoelectric stack including two or more piezoelectric layers, where the two or more piezoelectric layers are stacked along a first direction ·A plurality of electrodes including a pair of external electrodes formed on respective outer surfaces of the piezoelectric stack and a set of internal electrodes present between adjacent piezoelectric layers of the piezoelectric stack ·A first common electrode in electrical communication with a first subset of the plurality of electrodes ·A second common electrode in electrical communication with a second subset of the plurality of electrodes The first subset of the plurality of electrodes and the second subset of the plurality of electrodes are selected such that when a drive signal is applied between the first common electrode and the second common electrode, the drive signal is applied at a frequency associated with lateral mode coupled resonance of the piezoelectric stack. The drive signal is applied in opposite directions between adjacent piezoelectric layers of the piezoelectric stack, and the lateral mode coupling mechanically responds to the piezoelectric stack along a second direction perpendicular to the first direction, thereby generating ultrasonic radiation along the second direction. The first common electrode is at least partially present on the distal surface of the piezoelectric stack, the distal surface being perpendicular to the second direction, and the second common electrode is at least partially present on the proximal surface facing the distal surface. Each internal electrode of the second subset of electrodes is proximally present to the distal surface and is electrically insulated from the first common electrode by respective electrical insulating channels extending in the proximal direction from the distal surface, and each internal electrode of the first subset of electrodes is proximally present to the proximal surface and is electrically insulated from the second common electrode by respective electrical insulating channels extending in the distal direction from the proximal surface.

[0020] In another aspect, an ultrasonic device is provided having the following. ·A housing · An array of active acoustic elements supported by the housing, each active acoustic element having a distal ultrasonic radiation surface and a respective proximal surface, the array of active acoustic elements · A first array of first conductive members supported so as to be in electrical communication with a first conductive member for supplying an electrical drive signal, each first conductive member extending in the proximal direction beyond the respective proximal surface of the respective active acoustic element connected thereto, the first array of first conductive members · A heat exchanger · A second array of second conductive members supported by the heat exchanger and in thermal contact with the heat exchanger The first array of first conductive members is connectable to the second array of second conductive members for cooling the heat exchanger via conduction of heat from the array of active acoustic elements. The first array of second conductive members is connectable to the heat exchanger via the first array of conductive members and the second array of conductive members, and the second array of second conductive members extends through the heat exchanger and is connectable for driving an electronic device for transmitting an electrical drive signal to the array of active acoustic elements while simultaneously cooling the array of active acoustic elements.

Brief Description of the Drawings

[0021] A further understanding of the functional and advantageous aspects of the present disclosure can be realized by referring to the following detailed description and the drawings. The embodiments are described by way of example only with reference to the drawings.

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DETAILED DESCRIPTION OF THE INVENTION

[0022] Various embodiments and aspects of the present disclosure are described with reference to the details discussed below. The following description and drawings are illustrative of the present disclosure and should not be construed as limiting the present disclosure. A number of specific details are set forth in order to provide a thorough understanding of the various embodiments of the present disclosure. However, in some instances, well-known or conventional details are not described in order to provide a concise discussion of the embodiments of the present disclosure.

[0023] As used herein, the terms “comprising” and “including” should be construed as being inclusive and not limiting. Specifically, when used in this specification and the claims, the terms “comprise” and “comprising,” and variations thereof, mean that the specified features, steps, or components are included. These terms should not be construed to exclude the presence of other features, steps, or components.

[0024] As used herein, the term "exemplary" means "serving as an example, instance, or illustration" and should not be construed as being preferred or advantageous over other configurations disclosed herein. The terms "about" and "substantially" as used herein mean to include variations that may exist in the upper and lower limits of the range of values, such as variations in properties, parameters, and dimensions. Unless otherwise specified, the terms "about" and "approximately" mean within plus or minus 25 percent.

[0025] Unless otherwise specified, any particular range or group is to be understood as a concise way of referring to each and every member of the range or group, as well as to all sub-ranges or sub-groups included therein. Unless otherwise specified, this disclosure is directed to each and every particular member and combination of sub-ranges or sub-groups and is expressly incorporated herein.

[0026] As used herein, the term "on the order of" when used with an amount or parameter refers to a range that extends from about one-tenth to about ten times the recited amount or parameter.

[0027] The inventors have sought to overcome the aforementioned limitations of conventional ultrasonic transducer cooling methods. Instead of adopting a conventional approach where the ultrasonic transducer is cooled through direct contact with a cooling fluid, which can impede transducer performance due to acoustic coupling between the cooling fluid and the ultrasonic transducer, the inventors have sought a conductive cooling solution that achieves efficient cooling while avoiding unnecessary or excessive fluid or mechanical contact with the ultrasonic transducer. The inventors have also sought a compact solution that is adaptable to individual ultrasonic transducers and ultrasonic array elements.

[0028] The inventors have found that by employing an electrical conductor such that the ultrasonic transducer transmits an electrical drive signal to the ultrasonic transducer and also functions as a path for heat extraction via heat conduction, it can be cooled on its proximal side while having a minimal impact on its acoustic performance. Such an approach has been found by the inventors to be beneficial in reducing or minimizing mechanical contact with the ultrasonic transducer and avoiding fluid contact with the ultrasonic transducer.

[0029] An example of such an embodiment is shown in FIG. 1A, which shows an ultrasonic device including an active acoustic element 100 having a distal surface 110 for emitting ultrasonic energy and an opposite proximal surface 120. This figure schematically shows the proximal cooling of the active acoustic element 100 via a heat exchanger 140. Here, the heat exchanger 140 is in thermal contact with the active acoustic element 100 via a conductive member 130 that sends an electrical drive signal to the active acoustic element 100.

[0030] As shown in FIG. 1A, the conductive member 130 contacts the active acoustic element 100 to transmit an electrical drive signal to the active acoustic element 100 for the generation of ultrasonic energy and also contacts the heat exchanger 140 to remove the heat generated within the active acoustic element 100. In some embodiments where an ultrasonic transducer is employed for detection, the conductive member 130 can also be employed for transmitting the detected signal (e.g., for the generation of an ultrasonic image) to a detection circuit.

[0031] The conductive member 130 extends from the active acoustic element 100 beyond the proximal surface 120 of the active acoustic element 100 and contacts the heat exchanger 140 that is spatially offset (in the proximal direction) from the proximal surface 120. Thus, the heat generated within the active acoustic element 100 conducts through the conductive member 130 to the heat exchanger 140 while the electrical drive signal is being transmitted to the active acoustic element 100 via the conductive member 130.

[0032] In the embodiment shown in FIG. 1A, the electrical drive signal is transmitted through the conductive member 130 via contact between the conductive member 130 and the circuit board 150 (e.g., a flexible printed circuit board). The circuit board may include drive electronics or may be located remotely The conductive path for driving the electric sub-device 。Electric and provide it. Alternatively, the conductive member 130 may contact a wire, cable, ball grid array of solder balls, or other electrical connector or conduit at its proximal end or region to facilitate the transmission of the electrical drive signal.

[0033] The conductive member 130 has sufficient conductivity to facilitate the transmission of an electrical drive signal to the active acoustic element 100. Non-limiting examples of conductive materials for forming a conductive member that is also thermally conductive include metals, alloys, doped semiconductors, and non-metallic electrical conductors such as graphite and conductive polymers, but are not limited thereto. In some exemplary embodiments, the conductive member has a conductivity of at least 10 5 S / m and a thermal conductivity of at least 1 W / m·K.

[0034] In some exemplary implementations, the conductive member 130 may contact an electrode of the active acoustic element 100 (such an electrode is not shown in FIG. 1A), while in other exemplary implementations, the conductive member 130 may itself form the electrode of the active acoustic element 100. FIG. 1B shows an exemplary configuration in which the conductive member 130 contacts the electrode 122 present on the surface of the active acoustic element. FIG. 1B shows the conductive member 130 contacting the electrode 122 present on the proximal surface 120, but in an alternative implementation, the conductive member 130 may contact an electrode present on the lateral surface of the active acoustic element, such as an electrode formed on the surface 124.

[0035] Although not shown in FIG. 1A, a separate conductive path may be employed to facilitate the connection of the electrodes of the active acoustic element 110 to ground. An example of a ground connection is shown in FIG. 1B, which connection is made to a ground electrode 112 present on the distal surface 110 of the active acoustic element 100. In the embodiment shown in FIG. 1B, the ground electrode 112 can be electrically communicated with an additional conductive member 135 that also penetrates and contacts the heat exchanger 140. In other exemplary embodiments, the ground connection can be made without contacting the heat exchanger 140.

[0036] The foregoing embodiments show and describe a circuit board (or cable / connector) disposed on the proximal side of the heat exchanger such that the heat exchanger is present between the circuit board and the proximal surface of the active acoustic element. Alternatively, the circuit board (or cable / connector) can be disposed between the proximal surface of the active acoustic element and the heat exchanger, and the conductive member penetrates the circuit board (or cable / connector) and contacts the conductive path of the circuit board (or cable / connector) to transmit an electrical drive signal, and further extends in the proximal direction to contact the heat exchanger. According to such an alternative exemplary embodiment shown in FIG. 1C, a portion of the heat conducted through the distal portion of the conductive member 130 present between the circuit board 150 and the proximal surface 120 of the active acoustic element 100 can be removed by the thermal mass of the circuit board (or cable / connector), and the remaining heat is removed by the heat exchanger 140. Alternatively, if the circuit board includes active electrical components that also generate heat, the heat exchanger may remove the heat generated by both the active acoustic element 100 and the circuit board 150.

[0037] The embodiment shown in FIG. 1C shows a gap present between the circuit board 150 and the heat exchanger 140, but it will be understood that the circuit board 150 may be in direct thermal contact with the heat exchanger 140. For example, as shown in FIG. 1D, the conductive member 130 may pass through the circuit board 150 before contacting the heat exchanger 140. Such an embodiment may be particularly useful when the circuit board 150 includes active electrical components that generate heat, in which case the heat exchanger 140 can be employed to remove heat from both the circuit board 150 and the active acoustic element 100.

[0038] Figure 1E shows an alternative embodiment in which the proximal end of the conductive member 130 contacts the circuit board 150, such that the conductive member 130 is in indirect thermal contact with the heat exchanger 150 via the intermediate circuit board 150. In such a case, heat generated within the active acoustic device 100 is conducted through the circuit board 150 and subsequently extracted by the heat exchanger 140. In the various embodiments illustrated herein, the conductive member 130 contacts the active acoustic device 100 such that at least a portion of the proximal surface 120 of the active acoustic device 100 does not contact the conductive member 130. Such limited contact or lack of contact between the proximal surface and the conductive member 130 respectively reduces or avoids the generation of reflected ultrasonic waves from the backward-propagating ultrasonic waves generated within the active acoustic device 100, and also reduces perturbation of the mechanical response of the active acoustic device 100 to the electrical drive signal caused by the presence of the conductive member 130.

[0039] Although not shown in FIG. 1A, the ultrasonic transducer can include one or more layers such as, but not limited to, one or more impedance matching layers, acoustic lenses, waterproof and / or electrically insulating distal membranes, one or more electrodes, and backing layers in addition to the active acoustic device 100.

[0040] In the exemplary embodiment shown in FIG. 1A, the distal end of the conductive member 130 contacts only a small region of the proximal surface 120 of the active acoustic device 100, such that a substantial portion of the surface area of the proximal surface 120 does not contact the conductive member 130. According to such an exemplary embodiment, the distal end of the conductive member 130 can contact a small region of the proximal surface 120 of the active acoustic device 100 that is a portion of the total surface area of the proximal surface 120, and this portion can be less than 50%, less than 40%, less than 30%, less than 20%, less than 10%, less than 5%, less than 2%, or less than 1%. In some embodiments, the distal end of the conductive member is 1 mm 2 less than, 0.5 mm 2 less than, 0.2 mm 2 less than, 0.01 mm 2 less than, 0.05 mm 2less than, less than 0.02 mm, or 0.01 mm 2 has an area less than.

[0041] The ability of the conductive member 130 to remove heat from the active acoustic element is not limited, but it will be understood to depend on a number of factors such as the thermal conductivity of the conductive member, the contact area between the conductive member of the active acoustic element 100 and the proximal surface 120, the contact area between the conductive member and the heat exchanger 140, and the thermal characteristics of the heat exchanger. These parameters can be varied by those skilled in the art to specify values suitable for a given application (e.g., to achieve a sufficient amount of heat extraction or to achieve a predetermined operating temperature of the active acoustic element 100).

[0042] In some exemplary embodiments disclosed herein, at least a portion of the region of the proximal surface 120 that is not in contact with the conductive member 130 is also not in contact with a liquid or a solid. Such a configuration facilitates the reflection of ultrasonic energy within the region of the non - contacting surface, which can increase the output acoustic output and provide an improvement in applications such as therapeutic ultrasonic treatment. Such an embodiment is shown in FIG. 1A, where a gap 125 exists between the proximal surface 120 of the active acoustic element 100 and the heat exchanger 140, and the gap is extended by a portion of the conductive member 130. In some exemplary embodiments, a gas such as air, or a gas other than air, may be present within the gap, or the gap may be a vacuum or a gas at less than atmospheric pressure (e.g., air). The gas may be actively flowed across the gap to remove heat from the portion of the conductive member spanning the gap and from the upper surface of the heat exchanger (e.g., forced fluid cooling).

[0043] The gap 125 only needs to be large enough to establish a hard acoustic reflection at the proximal surface 120. A suitable gap size can be determined experimentally, for example, by constructing or simulating a series of transducer devices having different gap sizes and determining the minimum gap size that facilitates a sufficiently large reflection (or a sufficiently large acoustic output power from the ultrasonic transducer). In one exemplary embodiment, the gap is at least 1 mm.

[0044] A further gap 145 is also shown between the heat exchanger 140 and the circuit board 150, but it will be understood that in other embodiments, the heat exchanger 140 may be in direct contact with the circuit board 150.

[0045] Figures 1A and 1B show an example of an embodiment that includes a single ultrasonic transducer (showing a single active acoustic element 100), but the proximal cooling transducer device may include a plurality of active acoustic elements. The plurality of active acoustic elements may be arranged in an ultrasonic array, such as a phased array of active acoustic elements. An example of such an embodiment is shown in FIG. 2, which shows a plurality of active acoustic elements 100A - 100C arranged in an array, and each active acoustic element is proximally cooled via element-specific conductive members 130A - 130C that contact a common heat exchanger 140. This figure shows an exemplary mounting configuration in which the element-specific conductive members 130A - 130C extend proximally beyond the common heat exchanger and contact a common circuit board 150 (or a common connector / cable), but in an alternative mounting configuration, the conductive members 130A - 130C can contact separate wires, cables, or connectors. The active acoustic elements may be arranged with a center-to-center spacing of less than half of their operating wavelength.

[0046] This figure shows an exemplary case including a linear array of ultrasonic transducers, but it will be understood that the array may alternatively be a two-dimensional array (such as a planar two-dimensional ultrasonic transducer array or a curved two-dimensional ultrasonic transducer array). As can be seen from FIG. 2, in this embodiment, conductive members 130A to 130C for each element that extend beyond the respective proximal surfaces in the proximal direction from each of the active acoustic elements 100A to 100C and contact a common heat exchanger 140 are employed, which enables a compact configuration for conductive cooling of the active acoustic elements 100A to 100C while avoiding unnecessary mechanical contact with the active acoustic elements, and thus reduces the mechanical load on the elements and related perturbations to the mechanical response of the elements.

[0047] It will be understood that the heat exchanger 140 may be any device capable of removing heat from the conductive members and transmitting that heat to a fluid. An example of a heat exchanger is a heat sink that is in thermal communication with a coolant flowing relative to a fluid such as air or the heat sink. In such a case, the region of the heat sink contacted by the conductive members may be electrically insulated (block the flow of current) while allowing heat conduction. The heat exchanger can include an active cooling device such as a thermoelectric cooler.

[0048] Figure 3A shows an embodiment of a heat exchanger in which an electrically insulating (yet thermally conductive) fluid introduced through inlet 141 of heat exchanger housing 145 thermally contacts conductive member 130 to remove heat from conductive member 130. The electrically insulating fluid flows through outlet 142 in heat exchanger housing 145 to remove heat. After flowing through outlet 142, the electrically insulating fluid is externally cooled (e.g., via an external heat exchanger that transfers heat to another fluid or via dissipation and / or contact with a remote fluid reservoir) and recirculated by a pump (not shown). In some embodiments, the temperature of the electrically insulating fluid may be externally controlled (e.g., via direct cooling or via an external heat exchanger with feedback from a temperature sensor). Conductive member 130 may contact an O-ring as it enters and exits the heat exchanger housing to prevent leakage around the interface between heat exchanger housing 145 and conductive member 130. Alternatively, such an interface may be sealed with an adhesive such as epoxy.

[0049] Examples of electrically insulating fluids include air or other gases and non-conductive liquids. Non-limiting examples of electrically insulating liquids include oils, deionized water, or specially designed heat transfer fluids such as the 3M Novec series. Example of Heat exchanger employing a gas-insulating liquid The In which, the conductive member can be in direct electrical and thermal contact with the electrically insulating fluid within the heat exchanger housing.

[0050] In some embodiments, an additional active forced-flow fluid heat exchanger 160 may contact the ultrasonic transducer on the distal side of the active acoustic element 100 as shown in Figure 3B. The fluid flowing through this additional heat exchanger may be different from the fluid flowing through proximal heat exchanger 140 since distal heat exchanger 160 need not contact any conductive portion of the ultrasonic element. Instead, it may simply be in thermal contact with the distal surface of the ultrasonic transducer (e.g., the distal surface of active acoustic element 100 or the distal surface of a refractive index matching layer or acoustic lens). This distal fluid may also be used as an acoustic coupling medium between active acoustic element 100 and the target region.

[0051] The embodiment shown in the previous figure shows an example where the conductive member has a constant cross-sectional diameter along its length. However, it will be understood that the conductive member may have a varying diameter and / or shape (e.g., along its elongated direction). FIG. 4 shows an example of an embodiment where the conductive member varies in cross-sectional diameter, showing an example where the conductive member includes a first elongated portion 131 and a second elongated portion 132 having different cross-sectional diameters. In particular, this figure shows an example of an embodiment where the cross-sectional diameter of the conductive member at the contact position with the proximal surface of the active acoustic element is smaller than the cross-sectional diameter within the region in contact with the heat exchanger. Such an embodiment may be beneficial in reducing the contact area between the conductive member of the active acoustic element 130 and the proximal surface 120 while providing a larger surface area for heat conduction in the vicinity of the heat exchanger. In another embodiment, the cross-sectional diameter of the conductive member at the contact position with the proximal surface of the active acoustic element may be larger than the cross-sectional diameter within the region in contact with the heat exchanger. In another exemplary embodiment, the cross-sectional diameter of the conductive member at the contact position with the proximal surface of the active acoustic element may be smaller than the cross-sectional diameter within the region in contact with the heat exchanger.

[0052] In some exemplary embodiments, the first and second portions of the conductive member may be formed from different materials. For example, the distal portion 131 of the conductive member having a smaller cross-sectional area may be formed from a material having a higher thermal conductivity than the thermal conductivity of the proximal portion 132.

[0053] In some embodiments, two or more conductive members may contact the active acoustic element. This embodiment is shown in FIG. 5A, which depicts an exemplary proximal cooling ultrasonic transducer device in which two conductive members 130 and 130' extend beyond the proximal surface of the active acoustic element and contact the heat exchanger. Such an embodiment may be beneficial in enabling extraction of heat from different spatial regions of the active acoustic element 100. The two conductive members 130 and 130' may be connected in parallel to a common electrode of the active acoustic element 130, or may contact different electrodes such as a signal electrode and a ground electrode. For example, in some cases, the signal electrode and the ground electrode may be disposed in different spatial regions on the proximal surface 120 of the active acoustic element 100. FIG. 5B shows an alternative embodiment in which a plurality of conductive members (131 and 131') extend beyond the proximal surface 120 and are integrated into a common proximal conductive segment 132 that contacts the heat exchanger 140.

[0054] Furthermore, it will be understood that the conductive member(s) can take a wide variety of possible shapes. In some embodiments, at least a portion of the conductive member (e.g., the portion of the conductive member that contacts the heat exchanger) has a cylindrical shape (e.g., a pin). In other embodiments, at least a portion of the conductive member (e.g., the portion of the conductive member that contacts the heat exchanger) has a planar surface such as a foil or fin. In other embodiments, one or more lateral members (e.g., fins) extend laterally from at least a portion of the conductive member (e.g., the portion of the conductive member that contacts the heat exchanger). In some embodiments, the portion of the conductive member that contacts the heat exchanger may have a cross-sectional diameter that varies along its length of contact with the heat exchanger. The cross-sectional area of this portion of the conductive member varies along its length and may be larger or smaller than the cross-sectional area of the conductive member at its distal end. In some embodiments, the portion of the conductive member that contacts the heat exchanger may have irregularities, asymmetry, roughness, and / or extensions or other structures, shapes, or surface patterns or microstructures in order to enhance heat transfer. It will be understood that the active acoustic element of the ultrasonic transducer device may be any suitable element capable of converting an electrical signal into an acoustic vibration. Suitable exemplary active acoustic elements can include piezoelectric materials such as lead zirconate titanate or lithium niobate, or capacitive drive structures such as CMUT.

[0055] In some embodiments, the active acoustic element may be a lateral mode piezoelectric transducer formed from a stack of piezoelectric layers, where adjacent layers have opposing poling directions. Such an approach can be beneficial in avoiding the need for electrical matching circuitry. An example of such a lateral mode active acoustic element is shown in FIG. 6A, which shows a piezoelectric stack including a plurality of piezoelectric layers 200 stacked along a horizontal direction 205. The piezoelectric stack includes a plurality of electrodes including a pair of outer electrodes 210 formed on respective outer side surfaces of the piezoelectric stack, and a set of internal electrodes, each internal electrode being present between adjacent piezoelectric layers of the piezoelectric stack. Also, the piezoelectric stack includes a first common electrode 215 in electrical communication with a first subset of the plurality of electrodes, and a second common electrode 220 in electrical communication with a second subset of the plurality of electrodes. As can be seen from the figure, the first electrode subset and the second electrode subset are selected such that when a drive signal is applied between the first common electrode 215 and the second common electrode 220, the drive signal is applied in opposing directions between adjacent piezoelectric layers of the piezoelectric stack. Further, when the drive signal is applied at a frequency associated with the lateral mode coupling resonance of the piezoelectric stack, due to the lateral mode coupling, the piezoelectric stack mechanically responds along a second direction (distal-proximal vertical direction 225) perpendicular to the horizontal direction 205, thereby generating ultrasonic radiation along the vertical direction.

[0056] As shown in FIG. 6A, each internal electrode of the second subset of electrodes (the second and fourth electrodes) is present on the proximal side of the distal face and is electrically insulated from the first common electrode 215 by respective electrical insulation channels 232 extending in the proximal direction from the distal face, and each internal electrode of the first subset of electrodes (the single central electrode in the figure) is present on the proximal side of the proximal face and is electrically insulated from the second common electrode 220 by respective electrical insulation channels 234 extending in the distal direction from the proximal face.

[0057] In some embodiments, one or more of the electrodes of the lateral-mode active acoustic element may be formed from a conductive foil. In some exemplary embodiments, one or more electrodes of the lateral-mode ultrasonic transducer may extend beyond the proximal surface of the active acoustic element so as to contact a heat exchanger, such that the one or more electrodes are employed both for providing an electrical drive signal and for heat conduction heat removal. An example of such an embodiment is shown in FIG. 6B, where two electrodes 138 and 139 of the exemplary lateral-mode active acoustic element extend proximally across a gap to contact a heat exchanger 140 and also contact a circuit board 150 (or connector / cable) for transmission of an electrical drive signal.

[0058] In one example, at least the internal electrodes of the lateral-mode active acoustic element may be formed via a conductive adhesive (e.g., a conductive epoxy) used to bond a plurality of piezoelectric layers 200. Electrical insulation channels (e.g., channels 232 and 234 in FIG. 6A) may be formed within a given surface (e.g., proximal or distal) by dicing adjacent thin trenches along an initial portion of the internal electrode, thereby removing it, and then filling the trenches with an electrical insulation adhesive. A common electrode associated with the given surface may then be formed over the filled trenches to connect appropriate like electrodes. This exemplary method of manufacturing a lateral-mode active acoustic element ensures that a conductive adhesive layer for a signal electrode does not contact a ground electrode (e.g., the left and right sides of the element in the case of an element having an even number of layers). Further, unlike the method disclosed in U.S. Patent No. 9,327,317, titled "Ultrasonic Transducer, and Method of Manufacturing the Same," the method of this example enables the manufacture of elements that can be easily assembled into a two-dimensional array.

[0059] Conventional transducer manufacturing methods involve the processing of large pieces of transducer material that will remain together as monolithic building blocks to form a transducer array, and involve various processes that are carried out to define the elements into components. This conventional method is a top-down approach, where smaller features are defined within larger parts. In contrast to such methods, multilayer lateral mode active acoustic elements may instead be formed by processing a large piece of material to define a plurality of individual elements (it has been found that such a method can produce up to about 300 elements at a time). For example, individual acoustically active plates (e.g., the piezoelectric layer 200 of FIG. 6A having a size of about 40 mm×40 mm) may be adhered together with conductive epoxy to form a large multilayer plate (laminate). This plate may then be processed into smaller elements (e.g., having a size of about 1.3 mm×3.2 mm). The third dimension of the element depends on the thickness of the laminate of plates (plate thickness, epoxy thickness, and number of plates).

[0060] This approach produces individual loose elements that can be assembled into any array shape as individual parts. This bottom-up approach uses individual pieces to build a larger parts array. The bottom-up assembly approach is not limited to these types of elements. The present invention applies to any transducer element that can be tested, operated on, and assembled as an individual component. For example, thickness mode elements, non-layered elements, or tube-shaped elements can be used with this assembly technique.

[0061] Many of the prior art embodiments involving contact between the conductive member and the proximal surface of the active acoustic element will be understood to provide other embodiments in which the conductive member contacts the lateral surface of the active acoustic element. One embodiment is shown in FIG. 7, where the conductive member contacts the lateral surface of the active acoustic element and extends proximally beyond the proximal surface of the active acoustic element to contact the heat exchanger 140. In the embodiment shown in the figure, the conductive member includes a distal segment 131 and a proximal segment 132, where the distal segment 131 contacts the lateral surface of the active acoustic element and the proximal segment 132 extends from the distal segment 131 to contact the heat exchanger 140. In the exemplary embodiment shown in the figure, at least the distal segment 131 (and optionally the proximal segment) has a planar surface. Unlike some of the previously described and illustrated embodiments involving contact of the conductive member with the proximal surface of the active acoustic element 100, this exemplary embodiment may be advantageous in that the proximal surface does not contact the conductive member, which may be beneficial in increasing the output power and mechanical response of the ultrasonic transducer.

[0062] The foregoing exemplary embodiments show an exemplary configuration in which the portion of the proximal surface that does not contact the conductive member does not contact another liquid or solid material or medium, but in some cases it may be beneficial for the proximal surface to contact another material. An example of such an embodiment is shown in FIG. 8, where the material 180 is shown contacting the proximal surface 120 of the active acoustic element 100, and where the conductive member 130 is shown extending through the material 180 from the proximal surface 120 before contacting the heat exchanger 140. This figure shows an example where there is a gap 126 between the proximal surfaces 182 of the material, although the gap may not be present, such that the proximal surface 182 of the material contacts the heat exchanger 140 directly and, optionally, in addition to the heat removed through the conductive member 130, facilitates additional heat removal through the material 180.

[0063] For example, when it is desirable for the backward-propagating ultrasonic energy generated within the active acoustic element to be reflected at the near plane (e.g., to increase the acoustic output power from the far plane), the near plane may be contacted with a material having an acoustic impedance that is mismatched with the acoustic impedance of the active acoustic element. For example, the acoustic impedance of the material can be selected such that at least 50%, preferably 90% or more, or 99% of the backward-propagating ultrasonic energy is reflected at the near plane. Examples of suitable materials for enhancing acoustic reflection include air or other gases, or a multilayer matching structure of a tuned thickness.

[0064] For example, when the ultrasonic device is employed for imaging applications, it may be desirable to prevent or at least partially suppress the reflection of the backward-propagating ultrasonic energy generated within the active acoustic element at the near plane. This can be achieved, for example, by contacting the near plane with an acoustic damping material having an acoustic impedance selected to prevent or reduce reflection at the near plane. For example, the acoustic impedance of the material may be selected such that less than 50%, preferably less than 10% of the backward-propagating ultrasonic energy is reflected at the near plane. This material may also have high acoustic damping. Examples of suitable backing materials for imaging applications include silicone or epoxy, which may optionally be filled with powder.

[0065] In some exemplary embodiments, the active acoustic element may be supported by a housing. An exemplary embodiment is shown in FIG. 9, where the active acoustic element 100 is housed and supported within the housing 115. As shown in the figure, the housing 115 can support the active acoustic element 100 and, optionally, can be supported by a conductive member such that a gap 190 exists between the near plane of the active acoustic element and the housing and the conductive member extends across the gap.

[0066] FIG. 9 shows an exemplary embodiment in which the conductive member includes a first segment 131 and a second segment 132. The first segment 131 may be supported by the housing 180 such that the distal end or region of the first segment 131 contacts the active acoustic element 100. In some exemplary embodiments, the second segment 132 may be supported by the heat exchanger 140. In such a case, the distal end of the second segment 132 is removably connectable to the proximal end of the first segment 131, thereby facilitating a modular design that allows the active acoustic element 100 to be manufactured, incorporated into the housing 115, brought into contact with the first segment, and optionally tested prior to assembly with the heat exchanger 140. An example of this embodiment is shown in FIGS. 10A and 10B, where the conductive member includes a first segment 131 that is removably connected to the second segment 132. In one example, one or both of the housing 115 and the heat exchanger can support a socket that facilitates the connection between the first segment 131 and the second segment 132. FIGS. 10A and 10B show an example configuration in which the housing is electrically connected to or formed monolithically with the first segment 131 and supports a socket 133 configured to receive the distal end of the second segment 132. FIG. 10(A) shows the connected state and FIG. 10(b) shows the disconnected state.

[0067] FIG. 11 shows an example of an embodiment in which an array of active acoustic elements 100A - 100C is proximally cooled via a conductive member for each element in contact with a common heat exchanger 140. As in the exemplary embodiments shown in FIGS. 10A and 10B, each conductive member includes a first segment 131A - 131C that contacts sockets 133A - 133C supported by a common housing 115. The housing 115, the first conductive segments 131A - 131C, and the sockets 133A - 133C form an ultrasonic array module 300. The heat exchanger 140 supports an array of second conductive segments 132A - 132C such that the array of second conductive segments 132A - 132C forms a cooling array that is removably connectable to the array module.

[0068] The circuit board 150 may be replaced by a connector or a cable, or may be a flexible printed circuit board consisting of electrical traces for transmitting an electrical drive signal to the active acoustic elements 100A to 100C, and the electrical traces may be separated and shielded by a common ground trace. The electrical wiring may be present on a plurality of layers of the printed circuit board 150. One end of the printed circuit board 150 may include a connector that conforms to the position of the conductive member. The other end of the flex cable is connected to or connectable to the drive electronics.

[0069] In some exemplary embodiments, the plurality of array modules 300 may be arranged such that each array module defines a sub - array of active acoustic elements that together form an ultrasonic array. An example of such an embodiment is shown in FIG. 12, where the array modules 300A to 300F are arranged and supported by a common frame 315. As shown in this figure, a first conductive element extending from the proximal surface of each active acoustic element of each array module is removably connectable to a respective cooling array (one such array configured to be removably connected to the array module 300A is shown as 310A) defined by an array of second conductive elements in contact with a common heat exchanger 140. The array modules may be connected to a common circuit board via their corresponding conductive members, but FIG. 12 shows an example where each of the array modules 300A to 300F is connected to a module - specific circuit board 150 (or a module - specific connector or cable). Each module circuit board 150 for each array may support, be connected to, or be connectable to a respective module drive electronics. As will be described in more detail below, such an example facilitates the use of a separate remote cooling assembly for the drive electronics corresponding to each array module.

[0070] FIG. 13 is a block diagram showing an exemplary system for performing diagnostic and / or therapeutic ultrasonic procedures. A control and processing circuit 400 is operably connected to an ultrasonic transducer array 350 via transducer driver electronics / circuitry 500 that sends electrical signals to the ultrasonic transducer array 350 to generate and emit ultrasonic energy. The ultrasonic transducer array is proximally cooled in accordance with the exemplary embodiments described herein, and the exemplary system illustrates the use of an exchanger connected to an external transducer cooling system that recirculates an electrically insulating fluid. Here, the electrically insulating fluid flows through a heat exchanger that is contacted via a conductive member extending from the active acoustic elements of the ultrasonic array. The transducer cooling system 530 can include a pump, an optional temperature sensor, a fluid reservoir, and / or a cooling device (e.g., a thermoelectric cooler or a heat sink), and can be operably connected and controlled by the control and processing circuit 400.

[0071] The transducer driver electronics / circuitry 500 can include, for example, but not limited to, a Tx / Rx switch, a transmit and / or receive beamformer. For example, a transmit / receive switch can be included and configured to receive reflected ultrasonic energy signals detected by the ultrasonic transducer array 350. The transducer driver electronics circuitry can be cooled via an electronics cooling system (e.g., an active heat exchanger such as a forced fluid flow heat exchanger or a thermoelectric cooler) that is operably connected to and can be controlled by the control and processing circuit 400.

[0072] In an embodiment where the ultrasonic transducer array 350 includes a plurality of array modules (such as those described above), each array module may be interfaced with individual and dedicated drive electronics, and each of the individual and dedicated drive electronics may have its own electronics cooling system (e.g., a dedicated thermoelectric cooler and heat sink). For example, each array module may be operably connected to one or more application-specific integrated circuits (ASICs) having a plurality (e.g., 64) of channels, and each channel can generate an independent output. The ASIC may be connected to an amplifier via a flexible printed circuit board for amplification of each ASIC output. The ASIC and the amplifier may be attached to a heat sink and cooled by forced air circulation or a cooled liquid. The plurality of ASICs may be connected via a backplane to a common per-array module controller, and the plurality of per-array module controllers may be connected (e.g., via a network) to the control and processing circuit 400 so as to be synchronized by a common clock. In one embodiment, at least a portion of the drive electronics may be housed within a Faraday cage (e.g., a Faraday cage having a high cutoff frequency beyond the operating bandwidth of a magnetic resonance scanning device employed during an ultrasonic procedure that includes an ultrasonic array).

[0073] The control and processing circuit 400 may include one or more processors 410 (e.g., a CPU / microprocessor), a bus 405, a memory 415 (including random access memory (RAM) and / or read-only memory (ROM)), a data acquisition interface 420, a display 425, an external storage device 430, one or more communication interfaces 435, a power supply 440, and one or more input / output devices and / or interfaces 445 (e.g., a speaker, a keyboard, a keypad, a mouse, a position tracking stylus, a position tracking probe, a foot switch, and / or a microphone for capturing voice commands, etc.).

[0074] The control and processing circuit 400 can be programmed with a program, subroutine, application, or module 450, which, when executed by one or more processors 410, includes executable instructions that cause the system to perform one or more of the methods described in this disclosure. Such instructions may be stored, for example, in the memory 415 and / or other storage devices.

[0075] In an example of the illustrated embodiment, the transducer control module 455 includes executable instructions for controlling the transducers of the ultrasonic transducer array 350 to transmit energy to a target location or region. In some exemplary implementations, the transmission of ultrasonic energy to the target location can be based on registration of the volumetric image data 490 with the transducer position and orientation. For example, the ultrasonic array 350 can support a plurality of phased array transducers, and the transducer control module 455 can control beamforming (transmission and / or reception) applied to send one or more focused energy beams to the region of interest based on the known position and orientation of the phased array transducers with respect to the volumetric image data 490. The region of interest may be specified by the user during surgery (e.g., via a user interface controlled by the control and processing circuit 400) or according to a pre-established surgical plan.

[0076] In an exemplary system, a registration module 470 may optionally be used to register the volumetric image data 490 to an intraoperative reference frame associated with the tracking system 510. The volumetric image data 490 and registration data related to the position of the ultrasonic transducer array may be stored in an external database or in the memory 415 or storage device 430 of the control and processing circuit 400.

[0077] An optional image processing module 475 may be employed to generate an ultrasonic image by processing ultrasonic signals detected by an ultrasonic transducer array (e.g., by performing received beamforming on a set of received ultrasonic signals). An optional navigation user interface module 480 includes executable instructions for displaying a user interface that shows a spatially registered volumetric image for an image-guided procedure.

[0078] A tracking system 510 can optionally be used to track a patient's position and orientation via detection of one or more fiducial markers 560 optionally attached to the patient 10 and, optionally, one or more medical instruments or devices to which the fiducial markers are attached. For example, passive or active signals emitted from the fiducial markers can be detected by a stereographic tracking system employing two tracking cameras.

[0079] As shown in the figures, the exemplary system may be configured to be used with a magnetic resonance imaging scanner 520. For example, the ultrasonic array 350 may be manufactured from a magnetic resonance imaging compatible material, and the electrical circuit board and / or cable that transmits drive signals to the ultrasonic transducer array may be electrically shielded.

[0080] In some exemplary embodiments, intraoperative volumetric data may be acquired via a magnetic resonance imaging scanner, and a known spatial relationship (registration) between the ultrasonic transducer array 350 and the magnetic resonance imaging scanner 520 may be used to facilitate intraoperative control of the focusing of therapeutic ultrasonic energy at a desired target location during a therapeutic focused ultrasound procedure. The target location may be determined based on intraoperative images by optionally performing image registration between intraoperative magnetic resonance images and preoperative volumetrics associated with the surgical plan. In some exemplary embodiments, magnetic resonance images acquired during surgery are registered during surgery and displayed together with intraoperative ultrasonic images acquired via the ultrasonic array 350 to facilitate intraoperative monitoring of a therapeutic focused ultrasound procedure with multiple image modalities.

[0081] Only one of each component is shown in FIG. 13, but any number of each component can be included in the control circuit and processing circuit 400. For example, a computer typically includes a number of different data storage media. Further, although bus 405 is shown as a single connection between all of the components, it will be understood that bus 405 may represent one or more circuits, devices, or communication channels that link two or more of the components. For example, in a personal computer, bus 405 often includes or is the motherboard. The control and processing circuit 400 can include more or fewer components than those shown.

[0082] The control and processing circuit 400 may be implemented as one or more physical devices coupled to the processor 410 via one or more communication channels or interfaces. For example, the control and processing circuit 400 can be implemented using an application specific integrated circuit (ASIC). Alternatively, the control and processing circuit 400 can be implemented as a combination of hardware and software, and the software is loaded into the processor from memory or via a network connection.

[0083] Some aspects of the present disclosure can be implemented, at least in part, in software that, when executed on a computing system, transforms the computing system into a special-purpose computing system capable of executing the methods disclosed herein. That is, the technology can be executed on a computer system or other data processing system that, in response to its processor, such as a microprocessor, executes a sequence of instructions contained in memory such as ROM, volatile RAM, non-volatile memory, cache, magnetic and optical disks, or remote storage devices. Further, the instructions can be downloaded to the computing device via a data network in the form of a compiled and linked version. Alternatively, the logic for performing the processes as described above can be implemented in additional computers and / or machine-readable media such as discrete hardware components such as large scale integrated circuits, application specific integrated circuits, or firmware such as electrically erasable programmable read only memory and field programmable gate arrays.

[0084] A computer-readable medium can be used to store software and data for causing a data processing system to execute various methods when executed by the system. Executable software and data can be stored in various locations, including, for example, ROM, volatile RAM, non-volatile memory, and / or cache. Portions of this software and / or data can be stored in any of these storage devices. In general, a machine-readable medium includes any mechanism that provides information (i.e., stores and / or transmits) in a form accessible by a machine (e.g., a computer, network device, portable information terminal, manufacturing tool, any device having a set of one or more processors, etc.).

[0085] Examples of computer-readable media include, but are not limited to, volatile and non-volatile memory devices, read-only memory, random access memory, flash memory devices, floppy and other removable disks, magnetic disk storage media, optical storage media (such as compact disks (CDs), digital versatile disks (DVDs), etc.), and other recordable and non-recordable media. Instructions can be embodied in digital and analog communication links for electrical, optical, acoustic, or other forms of propagated signals, such as carrier waves, infrared signals, digital signals, etc. As used herein, the terms "computer-readable material" and "computer-readable storage medium" refer to all computer-readable media except the transient propagated signals themselves.

[0086] [Embodiment] The following embodiments are presented to enable those skilled in the art to understand and implement the embodiments of the present disclosure. They should not be regarded as limiting the scope of the present disclosure, but rather as merely illustrative and representative thereof.

[0087] This embodiment is provided to illustrate various aspects of the present disclosure through non-limiting embodiments of an ultrasonic system incorporating a plurality of ultrasonic array modules. Each array module defines a sub-array of active acoustic elements, where the array modules are assembled to form an ultrasonic array that is proximally cooled via a common heat exchanger, as described above with reference to FIG. 12.

[0088] An example ultrasonic array module 300 for use in assembling a larger ultrasonic array system is shown in FIG. 14A. The exemplary array module 300 includes an array module housing that supports a plurality of active acoustic elements 100 within a two-dimensional sub-array. The exemplary module housing includes two components, namely, an electrically insulating grid frame 600 for supporting the active acoustic elements 100 in a spaced-apart configuration that forms a two-dimensional sub-array, and an electrically insulating insert 610 formed on the underside of the grid frame 600 and received within an opening recessed within the grid frame 600. The insert 610 supports an array of first segments 131 of conductive members, as shown in more detail by FIG. 14C. FIG. 14B shows the grid frame 600 prior to insertion of the active acoustic elements and shows the array of first segments 131 of conductive members supported by the insert 610.

[0089] FIGS. 14D and 14E show cross-sectional views of the array module. As can be seen from the figures, the first segments 131 of the conductive members are supported by the receptacle 610 such that each first segment 131 contacts the proximal surface of a respective active acoustic element 100 and can supply an electrical drive signal to the active acoustic element 100 while also removing heat from the active acoustic element 100 via heat conduction. As also shown in FIG. 14D, the insert 610 also supports sockets 133 that are in electrical contact with respective first segments of the conductive members for receiving the distal end portions of the second segments of the conductive members.

[0090] At the distal end of the device, the ground connection may be provided by a thin metal wire or foil that exists between the active acoustic elements, contacts the ground electrodes of each element (e.g., with a conductive adhesive such as conductive epoxy), thereby forming a common ground connection. In one exemplary embodiment, the common ground connection can be implemented by a foil that exists between columns of active acoustic elements. Other non-limiting exemplary embodiments include (i) contacting a conductive film with the distal surface of the active acoustic element (which can also function as a waterproofing), using an array of spring contacts between the elements, or manufacturing each active acoustic element such that the signal and ground electrodes are in different regions of the proximal surface of the active acoustic element, and including a second conductive pin that contacts the ground electrode and extends from the proximal surface.

[0091] Figures 14A and 14B show slots 640 in the grid housing 600 for supporting and routing the ground lines between the active acoustic elements 100, although the ground lines are not shown in the figures.

[0092] Figure 14F is a photograph showing a top view of an exemplary array module, showing the connection of the ground lines and the routing in the proximal direction through the ground line heat exchanger. The wires 630 run horizontally between each column of active acoustic elements 100. Each wire 630 is connected to the external ground electrode of the active acoustic element adjacent to the wire by a small amount of conductive epoxy (although alternative configurations such as spring connections are possible as described above). The wires 630 exit the grid housing 600 through slots 640 in the sides of the grid housing (these slots are visible, for example, in Figure 14A). The wires 630 extend along the edge of the grid (vertical in the photograph) and are bundled into a single wire grouping (shown at the bottom of the module, 650 in the photograph). This ground wire bundle is soldered to a ground connection 660 that passes through the heat exchanger and is electrically connected to the circuit board after passing through the heat exchanger. A thin film may be included across the water contact surfaces of the active acoustic elements 100 and the grid frame 600. Such a film provides waterproofing and electrical insulation from the target medium.

[0093] The use of the grid frame 600 and the insert 610 can be beneficial in facilitating a bottom-up array manufacturing approach. Through such an approach, each individual active acoustic element 100 has a position mechanically defined by the grid frame 600 and the insert 610. During assembly, each active acoustic element 100 is inserted into its respective support position within the grid frame 600. This example uses a square grid of active acoustic elements, although other element sizes and shapes may be employed in different grid configurations. For example, elements having a hollow cylindrical shape may be arranged in a hexagonal array.

[0094] In an embodiment of this example, the first segment 131 of the conductive member is a metal pin. A given active acoustic element 100 can be mechanically and electrically fixed to its respective pins by a small application of conductive epoxy. As described above, the pins are one example of a conductive member for contacting the active acoustic element, but only one example. Other exemplary implementations include conductive foils (introduced as part of the manufacture of the active acoustic element or added during array assembly), balls of low-temperature solder, anisotropic conductive epoxy, or spring contacts aligned with the axis of the active acoustic element or pressed against the side of the active acoustic element, but are not limited thereto.

[0095] This exemplary embodiment employs a configuration in which most of the active acoustic element is not in contact with a solid or a liquid (e.g., air-backed). This configuration enables optimal ultrasonic power transmission to the target medium. As described above, alternatively, a backing material, such as an epoxy backing for use in diagnostic applications, can be used depending on the requirements of the application.

[0096] As shown in FIGS. 11 and 12, the socket 133 of the array module 300 may be in direct contact with the distal end of the cooling array of the second segment of the conductive member that contacts the heat exchanger within the modular assembly of the ultrasonic array system. However, as shown in FIGS. 14D and 14E, in an alternative example, the socket 133 can receive the pins of the intermediate connection board 670. As shown in the figures, the intermediate connection board 670 includes additional proximal sockets that can receive either the pins of the second segment of the conductive member (cooling pins) or the pins of yet another intermediate connection board 670. The intermediate connection board 670 can facilitate modular assembly and may be beneficial in varying the offset of one component with respect to other components in the proximal direction.

[0097] FIG. 15 illustrates how the exemplary array module 300 can be tested prior to assembly with the heat exchanger by electrically interfacing with a flexible printed circuit board 680. This can be accomplished, for example, using a printed circuit board having an array of pins that can be received by each socket of the array module. Filament As described above, a single array module may be interfaced with the second segment of the conductive member that contacts the heat exchanger (e.g., as shown in FIG. 11), but in some embodiments, two or more array modules can be combined into a larger ultrasonic array, whereby each array module contributes to a sub - array of the active acoustic elements with respect to the larger ultrasonic array. Such exemplary embodiments are shown in FIGS. 16, 17, and 18.

[0098]

[0099] ​Referring initially to FIG. 16, an exemplary multi-module transducer array system is shown in which a plurality of array modules 300 are assembled to form a large ultrasonic array. The system of the embodiment has an internal chamber defined by an upper plate 700, a bottom plate 705, and side walls 706, and includes a proximal heat exchanger having an inlet 710 and an outlet 720. An electrically insulating fluid flows through the heat exchanger. A set of array modules 300 is supported on the distal side of the heat exchanger. According to some of the foregoing embodiments, the conductive member extends from the proximal surface of the active acoustic element of the array module 300 and contacts the heat exchanger to remove heat from the active acoustic element.

[0100] FIGS. 17 and 18 show that an optional distal heat exchanger 800 having an inlet port 810 and an outlet port 820 is included. An additional cover plate (not shown) surrounds a recessed area formed across the distal surface of the array module 300, and the cooling fluid enters the cavity through an inlet 815 in fluid communication with the inlet port 810. The cooling fluid flows across the distal surface of the array module 300 to provide distal side cooling. The distal heat exchanger may circulate a volume of cold degassed water that provides coupling to the target tissue and cooling of the array elements. Next, referring to FIG. 18, a cross-sectional view of the ultrasonic array system of FIG. 17 is shown. Three array modules are present between the proximal heat exchanger and the distal heat exchanger, and multi-segment pins (conductive members) extend from the proximal surface of each active acoustic element through the distal heat exchanger and the distal heat exchanger contacts the electrically insulating fluid and appears on the proximal side of the proximal heat exchanger where it can be connected to drive electronics (e.g., via connection to one or more connectors, cables, or circuit boards).

[0101] FIG. 19 shows a detailed view of the area enclosed within the dashed rectangle 850 of FIG. 18 and is centered on a single array module. The active acoustic element 100 of the array module is located below the distal heat exchanger 800, and the grid frame of the array module establishes a gap 125 on the proximal side of each active acoustic element such that the first segment 131 of each conductive member crosses the gap. The socket 133 supported by the grid frame receives the distal pins of the intermediate connection board 670, which passes through the heat exchanger (enclosed by the distal plate 700 and the proximal plate 705) and provides an additional socket 673 that receives the second segment 132 of the conductive member that contacts the electrically insulating fluid. As shown in the figure, an intermediate electrical insulation spacer 850 may be provided to maintain a spatial separation between the conductive members within the internal region of the heat exchanger.

[0102] After passing through the heat exchanger, the second segment 132 of the conductive member may be connected to the drive electronics via a cable or a printed circuit board (such as a flexible printed circuit board). This ground wire bundle is soldered to the ground connection 660 that passes through the heat exchanger (not shown in FIG. 19). On the opposite side of the heat exchanger, the ground connection 660 is connected to the ground wire of a connector, cable, or circuit board. Thus, once assembled into the final overall array, electrical connections can be made to the back side of each set of long pins. In an alternative embodiment including an ultrasonic array system assembled without the proximal heat exchanger, electrical connections can be made directly to the array module. In this embodiment, a flexible printed circuit board cable is attached to a mating connector that can be connected to each array module on the proximal side of the heat exchanger. And this cable is wired to the drive electronics. Another embodiment includes mounting the device on a PCB that either integrates the drive electronics or couples the connection of two or more array modules to a larger cable for connection to the electronics.

[0103] In this embodiment, epoxy was used to seal the locations where each long pin passes through the proximal and distal plates of the heat exchanger. Alternative embodiments may include the use of circulating cooling gas or embedding the pins in a thermally conductive solid cooled by other means (such as an active cooling thermal device like a fluid heat exchanger or a thermoelectric cooler). The modular design of this embodiment can significantly simplify the assembly of several modules into a larger array because the positioning of the array modules and subsequent steps (such as waterproofing) can be performed without the need to include cable wiring. Also, holding the cables on separate connectors reduces the vulnerability of the transducer modules because the modules do not have the weight and torque of the cables. The cables may be included and supported after the complete array assembly is finished.

[0104] In this embodiment, the position of the array module (and the active acoustic element) is defined through the arrangement of the second segment of the pins housed within the heat exchanger. In an alternative exemplary embodiment, a grid structure can be used where the array module is assembled in a predetermined position (e.g., by an adhesive or other attachment method) prior to electrical connection to the heat exchanger. In another exemplary embodiment, the position of the array module may be defined by a rigid PCB.

[0105] The inventors have found that the cold degassed water provided by the distal heat exchanger in the distal region of the ultrasonic array assembly is combined with the proximal cooling provided by the proximal heat exchanger that contacts the active acoustic element through the conductive member, providing a cooling effect on both sides of each transducer element and improving both the internal transducer temperature and the array cooling time. In the case of a focused ultrasound treatment procedure, this design has been found to shorten the overall focused ultrasound treatment time.

[0106] The system of this embodiment was implemented using a conductive member having a first segment with a diameter of 150 μm. This represents approximately 1% of the surface area of the element, yet remains thick enough to support the current required to drive the element at high power (e.g., approximately 70 mA in an implemented exemplary system). The exemplary system was found to achieve a maximum output power of approximately 170 mW per element of acoustic power, or approximately 11 W for a 64 - element array module. This maximum power was found to be maintained for at least 30 - 60 seconds. Further tests demonstrated that the module was approximately 50% efficient, resulting in the generation of approximately 170 mW of heat per element.

[0107] It should be understood that the specific embodiments described above are presented by way of example, and that these embodiments may be capable of various modifications and alternative forms. Furthermore, it is intended that the claims not be limited to the specific forms disclosed, but rather that the claims be construed to cover all modifications, equivalents, and alternative forms falling within the spirit and scope of the present disclosure.

Claims

1. An active acoustic element configured to generate ultrasonic energy when an electrical drive signal is applied, having a distal surface for emitting ultrasonic energy in a distal direction and a proximal surface on the opposite side; A conductive member that contacts the active acoustic element, transmits an electrical drive signal to the active acoustic element, and conducts heat from the active acoustic element, extending beyond the proximal surface from the active acoustic element so that at least a part of the proximal surface of the active acoustic element does not contact the conductive member, and being connectable to a drive electronic device for transmitting an electrical drive signal to the active acoustic element via the conductive member; A heat exchanger that is spatially offset in the proximal direction from the proximal surface, contacts a part of the conductive member that exists beyond the proximal surface for transmitting an electrical drive signal to the active acoustic element via the conductive member, removes heat from the active acoustic element via the conductive member, and transmits the electrical drive signal to the active acoustic element via the conductive member An ultrasonic device comprising the above.

2. The ultrasonic device according to claim 1, wherein the region of the proximal surface that does not contact the conductive member also does not contact a liquid or a solid, thereby facilitating reflection of ultrasonic energy at the part of the proximal surface.

3. The ultrasonic device according to claim 1, wherein a gap exists between the proximal surface and the heat exchanger, thereby facilitating reflection of ultrasonic energy at the part of the proximal surface, and the conductive member extends across the gap and contacts the heat exchanger.

4. The proximal surface includes a signal electrode, and the distal end of the conductive member contacts the signal electrode. Optionally, the distal end of the conductive member contacts the proximal surface within a small region having a surface area of less than 10% of the total surface area of the proximal surface. The ultrasonic device according to any one of claims 1 to 3.

5. The part of the conductive member that contacts the heat exchanger has a variable cross-sectional area, larger and / or smaller than the cross-sectional area of the conductive member at the distal end of the conductive member. Optionally, the part of the conductive member that contacts the heat exchanger has a non-uniform, asymmetric, rough, or extended or other structure, shape, surface pattern, or microstructure to improve heat transfer. The ultrasonic device according to claim 4.

6. A part of the proximal surface that does not contact the conductive member contacts a material having an acoustic impedance selected such that at least 50% of the backward-propagating ultrasonic energy is reflected by the part of the proximal surface. The ultrasonic device according to any one of claims 1 to 5.

7. A part of the proximal surface that does not contact the conductive member contacts a material having an acoustic impedance selected to match the acoustic impedance of the active acoustic element, and the backward-propagating ultrasonic energy is suppressed at the part of the proximal surface. The ultrasonic device according to any one of claims 1 to 5.

8. To facilitate removal of heat conducted through the material, the material contacts the heat exchanger. The ultrasonic device according to claim 6 or 7.

9. The heat exchanger includes an electrically insulating fluid, and the electrically insulating fluid contacts the part of the conductive member and removes heat conducted through the conductive member without contacting the active acoustic element. Optionally, the ultrasonic device further includes a pump configured to flow the electrically insulating fluid through the heat exchanger. The ultrasonic device according to any one of claims 1 to 8.

10. The heat exchanger is a first heat exchanger, and the ultrasonic device further includes a second heat exchanger disposed on the distal side of the distal surface. The second heat exchanger is in thermal communication with the active acoustic element such that heat generated within the active acoustic element is removed on the proximal side of the active acoustic element by the first heat exchanger and on the distal side of the active acoustic element by the second heat exchanger. The ultrasonic device according to claim 9.

11. The ultrasonic device further includes a printed circuit board present on the proximal side of the heat exchanger. The conductive member extends beyond the heat exchanger and is connected to the printed circuit board for transmitting the electrical drive signal. The ultrasonic device according to any one of claims 1 to 10.

12. The conductive member includes a first segment that contacts the active acoustic element and a second segment that contacts the heat exchanger. The first segment is detachably connected to the second segment to facilitate modular assembly of the ultrasonic device. Optionally, one of the first segment and the second segment includes a socket for receiving the other of the first segment and the second segment. Optionally, the ultrasonic device further comprises a housing configured to support the active acoustic element and the first segment of the conductive member, the ultrasonic device according to any one of claims 1 to 11.

13. The conductive member is a first conductive member, the ultrasonic device further includes a second conductive member, the second conductive member extends from the active acoustic element beyond the proximal surface so that at least a part of the proximal surface of the active acoustic element does not contact the second conductive member, and is connectable to drive electronics for transmitting an electrical drive signal to the active acoustic element via the second conductive member, the ultrasonic device according to any one of claims 1 to 12.

14. The active acoustic element is a first active acoustic element, the conductive member is a first conductive member, the ultrasonic device further includes one or more additional acoustic active elements, each additional acoustic active element has an additional conductive member that extends beyond its respective proximal surface such that a part of each respective additional conductive member contacts the heat exchanger, the first active acoustic element and the additional acoustic active elements define a set of active acoustic elements, the first conductive member and the additional conductive members define a set of conductive members, and the set of active acoustic elements and the set of conductive members are spatially arranged to form an ultrasonic array, the ultrasonic device according to any one of claims 1 to 8.

15. The heat exchanger contains an electrically insulating fluid, the electrically insulating fluid contacts the part of each conductive member to remove heat conducted through the conductive member, Optionally, the ultrasonic device further includes an insulating spacer present in the heat exchanger, the insulating spacer being configured to prevent contact between the conductive members, the ultrasonic device according to claim 14.

16. further comprising a housing configured to support the set of active acoustic elements, each conductive member of the set of conductive members includes a first segment that contacts a respective active acoustic element and a second segment that contacts the heat exchanger, each first segment being supported by the housing, the housing, the set of active acoustic elements and the set of first segments form an array module, the set of second segments forms a cooling array supported by the heat exchanger, Each first segment is removably connected to a respective second segment, the array module is removable from the cooling array, facilitating modular assembly of the ultrasonic device with the heat exchanger of the ultrasonic device, Optionally, a cross-sectional diameter of the first segment is smaller than a cross-sectional diameter of the second segment, Optionally, one of the first segment and the second segment comprises a socket for receiving the other of the first segment and the second segment, the ultrasonic device according to claim 14.

17. The array module is a first array module, the cooling array is a first cooling array, and the ultrasonic device further comprises one or more additional array modules and one or more respective cooling arrays, Optionally, each array module is connected to a respective circuit board via a respective cooling array, and each circuit board is connected to dedicated drive electronics for each module, the ultrasonic device according to claim 16.

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