RU2799791C2 - Hand-held ultrasonic device for visualization - Google Patents

Abstract

FIELD: medical equipment.

SUBSTANCE: ultrasound transducer for a handheld ultrasound imaging device for therapeutic and diagnostic purposes comprises a transducer element containing an array of piezoelectric micromachined ultrasonic transducers (pMUTs), the transducer element being integrated on an application specific integrated circuit (ASIC) to form a transducer tile, and a cavity is formed under the transducer element to provide acoustic isolation of the transducer element from the ASIC. The handheld ultrasonic imaging device comprises: a) a housing; b) an ultrasonic transducer module located inside the housing and in contact with the first heat sink and associated with the first thermal zone; c) a plurality of receiver subsystems and transmitter subsystems located within the case and integrated into a multilayer stack, wherein the multilayer stack is in contact with a second heatsink and associated with a second thermal zone, wherein the second heatsink is connected to the case, the multilayer stack, and the first heatsink so that serve as a main structure providing an internal rigid structure for the handheld ultrasonic imaging instrument; d) an anisotropic thermal interface material configured to transfer heat from the first thermal zone to the second thermal zone, wherein the anisotropic thermal interface material reduces thermal coupling between the first heat sink and the second heat sink; and e) logic for actively monitoring the ultrasonic procedure to control the heating of the ultrasonic transducer module within the transient heating range by adjusting user available power to limit overheating.

EFFECT: inventions make it possible to obtain high-quality ultrasound images in a portable hand-held device.

40 cl, 19 dwg

Description

Link to related application

[001] This application claims priority under U.S. Provisional Application No. 62/823,452, filed March 25, 2019, which is incorporated herein by reference in its entirety.

Background of the Invention

[002] Medical imaging is a life-saving technology for medical diagnosis and therapy, and yet it is not yet available to about 75% of the world's population. Over the past few decades, imaging instruments have been introduced to the market using a variety of principles. The most common are X-ray tomography (XR), computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound imaging. The high cost and large amount of training prevented the widespread use of tomography.

The essence of the present invention

[003] The World Health Organization (WHO) recommends addressing the global medical imaging shortage with the introduction of ultrasound imaging devices. The American Institute of Ultrasound in Medicine (AIUM) has developed an "ultrasound first" program that encourages the use of ultrasound as an effective imaging tool for patient diagnosis. The Bill & Melinda Gates Foundation estimates that 99% of infant deaths under one year of age (1 million/year) in Africa could be prevented if ultrasound imaging devices were available (private communication).

[004] While each of the imaging/imaging techniques used has different advantages, the advantages of ultrasound tomography include:

[005] Safety: no radiation and no ionization;

[006] Cost: This is one of the most cost-effective methods available for medical imaging;

[007] Portability: the device can be brought to the patient;

[008] Speed: real-time imaging;

[009] Imaging applications: wide range of imaging applications;

[010] Therapeutic applications: a wide range of therapeutic applications such as High Intensity Focused Ultrasound (HIFU) and Low Intensity Focused Ultrasound (LIFU); And

[011] Diagnostic applications: a wide range of emerging diagnostic applications.

[012] Advances in both ultrasound and complementary imaging technologies promise to significantly improve image quality and resolution, reduce imaging device cost, and improve sizing (wearability), for example, through transmitted ultrasound (tomography) and combining ultrasound with radiation, enabling better and cheaper replacements for X-ray, MRI, and CT imaging devices in the near future. Combining such advances in instrumentation with artificial intelligence (AI) and machine learning (ML) technologies is leading to an innovative imaging revolution that will make it easier to use portable ultrasound machines and interpret the results.

[013] Combining low cost with high rendering quality creates numerous problems, including the following:

[014] 1) The possibility of low-cost mass production requires the use of assembly methods developed for mobile devices, as opposed to the traditional technologies of the ultrasonic industry; And

[015] 2) High-quality electronics consume significant power, which increases the temperature of the handheld device, so advanced thermal management solutions are needed.

[016] The subject matter described herein solves both problems with numerous new design techniques, with innovations in the following areas:

[017] A transducer head, including an ultrasonic transducer embedded in the ASIC and in contact with the human body;

[018] A lens on one side of the transducer that controls the focusing of ultrasonic beams in the body in a wide frequency range, for example, from 1 to 12 MHz;

[019] Acoustic absorbers on the other side of the transducer, reducing back acoustic reflections;

[020] A complete imaging instrument assembly that allows the system to be integrated into a probe; And

[021] Thermal management to reduce probe temperature while maintaining high quality imaging.

[022] Customizable probe shape to reduce re-injury common to sonographers.

[023] According to one aspect, the present document discloses ultrasonic transducers for a handheld ultrasonic imaging instrument, comprising a transducer element comprising an array of piezoelectric micromachined ultrasonic transducers (pMUTs). According to some embodiments, the array contains at least 1 transducer pixel. In other embodiments, the array contains 4096 or more transducer pixels. In some embodiments, the transducer element is part of an application specific integrated circuit (ASIC) to form a transducer tile. In other embodiments, a cavity is formed below the transducer element to provide acoustic isolation of the ultrasonic transducer element from the ASIC. According to other additional options for implementation, inside the cavity is a gas, vapor, liquid or vacuum. In some embodiments, the combination of the transducer element and the ASIC is implemented with a flip chip/transducer chip to ASIC wafer (C2W), transducer chip to ASIC chip (C2C), or transducer wafer to ASIC wafer (W2W) direct connection. In some embodiments, the ASIC module includes connectors that allow connection to external signal processing electronics via wired connections connected to dedicated pads on the ASIC, or through silicon through holes (TSV) directly to a high-density printed circuit board (PCB). In some embodiments, the transducer tile is mounted on the transducer substrate. In other embodiments, the transducer tile is mounted on the transducer substrate via an acoustic absorber with high acoustic attenuation and high thermal conductivity. According to other embodiments, the transducer tile is mounted on the transducer substrate through a foamed porous metal material. In other further embodiments, the foamed porous metal material is filled with a solid, the solid optionally containing a mixture of high acoustic impedance and low acoustic impedance powders to provide acoustic dispersion. In some embodiments, the converter substrate is mounted on a heatsink. In other embodiments, the heatsink comprises a multilayer heatsink structure with alternating electrically conductive and insulating layers that both remove heat from the transducer tile and provide multiple independent electrical power connections. In other embodiments, the heatsink provides a resilient mount to improve reliability against shock and vibration. In some embodiments, the transducer substrate is affixed to one or more high-density flexible circuits with a mounting pitch of less than 50 microns, allowing connection to external signal processing electronics. According to some embodiments, the ultrasonic transducer further comprises an overmolded multilayer lens, wherein the multilayer lens consists of a plurality of layers comprising at least a first layer and a second layer, wherein the acoustic impedance of the first layer is higher than that of the transducer element and lower than that of the second layer, and the acoustic impedance of the second layer is higher than that of the first layer and lower than that of the target being rendered; additionally, the top-molded multilayer lens may be configured to focus the imaging beams. In other embodiments, the plurality of layers have thicknesses that are multiples of 1/4 of the target wavelength or set of wavelengths to achieve maximum acoustic transmission of ultrasonic energy and improve efficiency through the use of low to high impedance materials. In other embodiments, the first layer comprises a silicone-based material. According to other additional embodiments, the second layer comprises a silicone-based material and an added higher density material to increase the acoustic impedance of the second layer. In a particular embodiment, the higher density material comprises rare earth doped amorphous alumina.

[024] According to another aspect, hand-held ultrasonic imaging devices are disclosed herein, comprising: a housing; an ultrasonic transducer module located within the housing and containing an array of capacitive micromachined ultrasonic transducers (cMUTs) or piezoelectric micromachined ultrasonic transducers (pMUTs), the ultrasonic transducer module being in contact with the first heat sink and associated with the first thermal zone; a plurality of receiver subsystems and transmitter subsystems located within the housing and combined into a multilayer stack, the multilayer stack being in contact with the second heatsink and associated with the second thermal zone; and an anisotropic heat transfer material configured to transfer heat from the first thermal zone to the second thermal zone. In some embodiments, the anisotropic thermal interface material comprises one or more heat pipes. In some embodiments, the anisotropic thermally conductive material comprises one or more pyrographite sheets (PGLs). In some embodiments, a handheld ultrasound imaging device can be configured to generate one or more 2D, 3D, 4D, Doppler images with power consumption below 11 W peak and below 7 W average. In some embodiments, the handheld ultrasonic imaging tool further comprises an anisotropic thermal interface material to reduce thermal coupling between the first heatsink and the second heatsink. According to some embodiments, the first heatsink comprises a phase change material. In other embodiments, the phase change material comprises wax, a metal matrix, or a combination thereof. In some embodiments, the second heatsink comprises a phase change material. In other embodiments, the phase change material comprises wax, a metal matrix, or a combination thereof. In some embodiments, the second heatsink acts as the main structure creating an internal rigid structure. In some embodiments, the housing is a multi-material housing comprising a high thermal conductivity material and a low thermal conductivity material, wherein the multi-material housing facilitates heat transfer from the first thermal zone to the second thermal zone. In some embodiments, the handheld ultrasound imaging device further comprises logic for actively monitoring the ultrasound procedure to control heating of the ultrasound transducer module within transient heating by adjusting user available power to limit overheating. In some embodiments, the handheld ultrasonic imaging device further comprises a frame configured to secure an ultrasonic transducer module disposed within the housing. According to other embodiments, the handheld ultrasonic imaging device further comprises a frame seal structure comprising a spring structure to generate a uniform force. In some embodiments, the handheld ultrasound imaging device further comprises a flexible pad between the ultrasound transducer module and the housing to absorb force and improve drop resistance. In some embodiments, the multilayer stack acts as a support structure to improve drop resistance. In some embodiments, the housing provides access for battery replacement through a non-breakable window cut into the housing, which can be ultrasonically sealed again after the battery has been replaced. In some embodiments, the inner surface of the housing comprises a heat insulating material that selectively insulates internal heat sources from the outer surface of the housing where it is gripped by the user. In some embodiments, the interior surface of the package includes a metallized thin film shield to shield the electronics within the package from electromagnetic interference (EMI). According to some embodiments, the outer surface of the body contains a hydrophobic material. In some embodiments, the handheld ultrasound imaging device further comprises a removable operator's handle. According to other embodiments, the operator's handle is configured to fit the hand of an individual operator.

[025] According to another aspect, ultrasonic transducer assemblies are disclosed herein comprising: an acoustic matching layer, a micromachined ultrasonic transducer, and an intermediate layer. In some embodiments, the acoustic matching layer has a first compliance value. In some embodiments, the acoustic matching layer is configured to be positioned against the subject's skin. In some embodiments, the micromachined ultrasonic transducer has a second compliance value. In some embodiments, the intermediate lens is positioned between the acoustic matching layer and the micromachined ultrasonic transducer. In some embodiments, the intermediate lens comprises a first material whose compliance is greater than the first and second compliance values. According to other embodiments, the Young's modulus of the first material is less than 100 megapascals (MPa). In other embodiments, the first material comprises a first plurality of micrometer-sized particles and a second plurality of nanometer-sized particles.

[026] According to other embodiments, the first material comprises an elastomeric material. In other embodiments, the first material comprises polydimethylsiloxane (PDMS) type silicone. In other embodiments, the first material comprises one of Sylgard 182, RTV 615, RTV 630, Med-6016 and/or Med-6755, or a combination thereof. According to other embodiments, the acoustic impedance of the intermediate lens is different from the acoustic impedance of the first material.

[027] In some embodiments, the micromachined ultrasonic transducer is a capacitive micromachined ultrasonic transducer (cMUT). In some embodiments, the micromachined ultrasonic transducer is a piezoelectric micromachined ultrasonic transducer (pMUT).

Brief description of the figures

[028] A better understanding of the features and advantages of the present invention can be achieved by studying the following detailed descriptions, which set forth explanatory embodiments, and the accompanying figures, and:

[029] In FIG. 1 is a non-limiting example of an exploded view of an ultrasonic transducer head assembly according to embodiments of the present invention;

[030] In FIG. 2 is a non-limiting example of an exploded perspective view of a heatsink assembly according to embodiments of the present invention;

[031] In FIG. 3 is a non-limiting example of a perspective view of an ultrasonic transducer module, including microwiring to a substrate, according to embodiments of the present invention;

[032] In FIG. 4A-4C are non-limiting exemplary perspective views (FIGS. 4A, 4B) and side views (FIGS. 4C) of an ultrasonic transducer module, including a flexible circuit and a heatsink with resilient attachment functions, according to embodiments of the present invention;

[033] In FIG. 5 is a non-limiting first exemplary side sectional view of a circuit diagram of an ultrasonic transducer module including a multilayer lens according to embodiments of the present invention;

[034] In FIG. 6A and 6B show a non-limiting second example side sectional diagram of an ultrasonic transducer module including a multilayer lens according to embodiments of the present invention;

[035] In FIG. 7 is a non-limiting example of a sectional side view of a circuit diagram of an ultrasonic transducer module, including an air cavity, according to embodiments of the present invention;

[036] In FIG. 8 is a non-limiting example of a sectional side view of a circuit diagram of an ultrasonic transducer module, including a foamed metal absorber, according to embodiments of the present invention;

[037] In FIG. 9 is a non-limiting example of an exploded view of a handheld ultrasonic imaging device assembly according to embodiments of the present invention;

[038] In FIG. 10 is a non-limiting example of a perspective view of an ultrasonic transducer assembly, including a frame and a frame seal structure, according to embodiments of the present invention;

[039] In FIG. 11 is a non-limiting example of an exploded view of an ultrasonic transducer assembly, including a frame and retaining springs, in accordance with embodiments of the present invention;

[040] In FIG. 12 is a non-limiting example of a side sectional view of an ultrasonic transducer assembly, including a frame and retaining springs, in accordance with embodiments of the present invention;

[041] In FIG. 13 is a non-limiting example of an exploded view of a body and frame of a handheld ultrasonic imaging instrument, including a shock-absorbing body interface, in accordance with embodiments of the present invention;

[042] In FIG. 14 is a non-limiting example of an enlarged, assembled view of a body (probe body) and frame of a handheld ultrasonic imaging instrument, including an shock-absorbing body-to-frame interface, in accordance with embodiments of the present invention;

[043] In FIG. 15 is a non-limiting example of a schematic partial interior view of a handheld ultrasonic imaging instrument, including discrete thermal zones with directed heat flow, in accordance with embodiments of the present invention;

[044] In FIG. 16 is a non-limiting example of a schematic partial interior view of a handheld ultrasound imaging device, including dual heat sinks, each associated with a discrete thermal zone, in accordance with embodiments of the present invention;

[045] In FIG. 17 is a non-limiting example of a schematic exploded view of a handheld ultrasound imaging device, including dual heat sinks, each associated with a discrete thermal zone, in accordance with embodiments of the present invention;

[046] In FIG. 18 is a non-limiting example of a schematic partial interior view of a handheld ultrasonic imaging instrument, including thermal materials used to guide heat flow, in accordance with embodiments of the present invention;

[047] In FIG. 19 is a non-limiting example of a schematic exploded view of a hand-held ultrasound imaging device, including an operator-adjustable handle, in accordance with embodiments of the present invention.

Detailed description of the present invention

Some definitions

[048] Unless otherwise defined, all technical terms used in this document have such meanings as are commonly understood by a person of ordinary skill in the field of technology to which the present invention pertains. As used in this specification and in the appended claims, all singular forms include references to the plural, unless the context clearly indicates otherwise. Any use of "or" in this document is considered to include "and/or" unless otherwise noted.

Ultrasonic transducer

[049] In some embodiments, the handheld ultrasound imaging device comprises an ultrasound transducer module. According to other embodiments, the ultrasonic transducer module comprises a transducer element. According to other additional embodiments, the transducer element is included in the electronic circuitry to form the transducer tile by one of many suitable methods. According to specific embodiments, the ultrasonic transducer module includes functions to attenuate acoustic and/or thermal energy transmission, attenuate shock and/or vibrations, and to provide resilient attachment.

[050] As shown in FIG. 1, according to a particular embodiment, the ultrasound transducer module is part of a handheld ultrasound imaging device. According to this embodiment, the ultrasound transducer module is located between the probe module of the imaging system and the patient's body. The transducer element 1 respectively comprises a plurality of capacitive micromachined ultrasonic transducers (cMUTs) or piezoelectric micromachined ultrasonic transducers (pMUTs). Moreover, according to this embodiment, the transducer tile is mounted on the transducer substrate through an acoustic absorber 5 with high acoustic attenuation and high thermal conductivity.

[051] As shown in FIG. 5, according to a specific embodiment, the converter element 1 is included in the electronic circuit (ASIC) 2, forming a converter tile. According to this embodiment, the interconnection between the transducer and the ASIC is implemented by one of many suitable means, including, as non-limiting examples, reverse chip/transducer chip to ASIC wafer (C2W), transducer chip to ASIC chip (C2C) or transducer wafer to ASIC wafer (W2W) direct connection. Moreover, according to this embodiment, the air cavity 10 is provided below the transducer 1 with a distributed baffle 9 around the perimeter of the transducer die to provide acoustic isolation of the transducer from the ASIC. It is possible to use the connection structure between the ASIC and the converter to achieve a specific mechanical damping or frequency tuning of the converter structure by adjusting the shape, dimensions and materials of the connection structure.

[052] As shown in FIG. 2, according to a particular embodiment, a heat sink sandwich structure 8 with electrical insulation layers (e.g., dielectric materials 210, an electrical and thermal conductor layer including electrical and thermal conductor 220 connected to a first voltage source, electrical and thermal conductor 221 connected to ground or to a GND connection (reference voltage and current return path for the first and second voltage sources), and electrical and thermal conductor 222 connected to a second at the voltage source) provides heat dissipation from the tile and connection of electrical power to the system. According to this embodiment, the converter substrate is mounted on a heatsink 8 which has resilient mounting functions to improve system reliability during shock and vibration, see FIG. 1, 2 and 4.

[053] As shown in FIG. 3, in a particular embodiment, the ASIC connects external electronics via wire connections 6 connected to dedicated pads on the ASIC, or through via conductive holes in silicon directly to the printed circuit board (PCB). The advantage of the design and manufacturing method described herein is that the transducer tile can be fully inspected prior to further assembly and before being incorporated into a handheld ultrasonic imaging instrument.

[054] In FIG. 4A-4C show a non-limiting example of an ultrasonic transducer module, including a flexible circuit 410 connected to the transducers and to the PW 420, and a heatsink 430 with resilient attachment features, such as notch groove 440, as shown. In a particular embodiment, the transducer substrate is attached to one or more high-density flexible circuits 410 to allow connection to external signal processing electronics. According to one embodiment, the multilayer flex circuit 410 may include inductors and other components to improve local power management. According to another embodiment, the flexible circuit may contain inductors and other components to improve the bandwidth of the converter.

Lens

[055] Ultrasonic transducers are typically in contact with organisms, such as the human body, which have a typical impedance of approximately 1.5 Mrail. cMUTs and pMUTs typically have an impedance of less than 1.5 Mrail. For efficient input of power from ultrasonic transducers into organisms, it is useful to use one or more acoustic impedance matching layers. Additionally, the ultrasonic transducer may need to focus its acoustic energy to a certain depth in the body. For multi-element (eg grating) ultrasonic transducers, we may need to focus the beams of all elements at a certain depth in the body. In some embodiments of the handheld ultrasound imaging device and ultrasound transducer described herein, these functions, along with others, are performed by lenses fabricated on the surface of the ultrasonic transducers. An additional problem in performing such functions arises from the need to operate over a wide frequency range, eg 1-12 MHz, as opposed to a narrow frequency range, eg 1-5 MHz.

[056] As shown in FIG. 6a, according to a specific embodiment, a lens 12 is molded on top of the transducer module, containing several layers (layer 1 and layer 2 in Fig. 6a) with selected impedances and sound velocities that perform acoustic matching with the imaged object and focus the imaging beams. In this embodiment, layer 1 forms the lens while layer 2 forms the matching layer and does not provide significant focusing effects. Layer 1 and layer 2 impedance values are chosen between transducer and body impedance values, gradually increasing or decreasing from one to the other. For example, in a typical case where the cMUT or pMUT transducer has low impedance compared to the organism, layer 1 will have an impedance greater than that of the transducer, and layer 2 will have an impedance greater than layer 1 but less than that of the organism. Optionally, in this embodiment, the layer 2 thickness may be a multiple of 1/4 of the target wavelength to achieve maximum acoustic energy transfer by ultrasonic waves and improve efficiency by using low to high impedance materials for the broadband transducer, particularly at target wavelengths. Moreover, transducer imaging frequencies can be chosen to be an odd integer multiple of one frequency, since the thickness of the layer 2 in Va wavelength is suitable for all imaging frequencies. For example, such a set of frequencies can be frequencies: 1.8 MHz, 5.4 MHz, 9.0 MHz, 12.6 MHz, and so on. Alternatively, the thickness may be chosen to be an odd integer multiple of Vi of the wavelengths (1/4, 3/4, 5/4, 7/4, etc.) at all imaging frequencies.

[057] According to another embodiment, the transducer module may have a single layer lens (as in FIG. 6a, but with layer 1 only, without layer 2). Such a lens can act as both a lens and a matching layer.

[058] As shown in FIG. 6a embodiment, layer 1 and layer 2 compliances are generally higher than those of the cMUTs and/or pMUTs on which they are located. Moreover, layer 2 is designed to withstand normal wear and tear as it is exposed to the outside world, including frequent and prolonged contact with organisms, accidental drop impacts, and exposure to many chemicals, including cleaning fluids. As a result, to protect against such normal wear, the outer layer will often have a compliance lower than that of layer 1. In some embodiments, the Young's modulus of layer 1 lies between 0.1 and 100 MPa; layer 2 is more rigid than layer 1 and may, for example, have a Young's modulus value between 0.1 and 100 MPa; and the additional layers above layer 2 may be even more rigid, for example having a Young's modulus value between 0.1 and 100 MPa.

[059] Shown in FIG. 6a, the basic embodiment can be extended to multiple layers, as shown in FIG. 6b with layers 3 to n-2, layer n-1 and layer n, for example. Each layer can act as a lens and as a matching layer if its thickness varies across the surface to focus or defocus the acoustic wave from the transducer (e.g., be spherical or cylindrical, as shown by layer 1 and layer n-1 in Fig. 6b). If a layer has essentially the same thickness value (particularly layer 2 and layer n), then such a layer performs basically an impedance matching function (as opposed to a focusing function). Each layer may optionally contain nanometer-sized particles, such as LCP (liquid crystal polymer), corundum beads, tungsten beads, vacuum nanobeads, and the like.

[060] In some embodiments, the overlying multilayer lens is created in a process in which the first layer is formed by creating a baffle around the pMUT and filling the interior of the baffle with silicone-based material. In other embodiments, the layer is formed as a flat layer that not only protects the padded microwires and the pMUT, but also has an impedance close to the low impedance of the pMUT (eg, about 1 Mrail). The lens can also be fabricated using a prefabricated frame that provides stability to the transducer design and allows lens materials to be applied to the frame structure. The frame dimensions are chosen so that the thickness of the lens and fill materials can be chosen and the lens is formed with different surface tensions between the lens and frame materials. This first lens design can then be molded over the top to create the design and shapes of the secondary lens.

[061] According to other embodiments, additional layers are glued to a flat layer and are chosen such that their impedance values are stepped up to the impedance of the human body, and they are shaped to achieve maximum transmission over a wide range of frequencies and depths of focus. The overmolding method reduces costs and facilitates mass production to meet the worldwide demand for medical imaging. To isolate adjacent transducers in the array from transmitted acoustic energy, the molding process can be used to fill acoustic isolation channels between transducers that are created during the transducer fabrication process.

[062] As shown in FIG. 6a and 6b, according to specific embodiments, the top-molded multilayer lens 12 has an impedance stepwise from low impedance pMUT to high impedance of the human body. In other embodiments, the first layer contains a silicone-based material, while the second, third, etc. layers, the second, third, etc. are used. materials containing the same silicone-based material with the addition of one or more higher density materials to increase the impedance closer to that of the human body. In particular embodiments, the higher density materials comprise alumina doped with amorphous rare earth elements, resulting in less scattering because the structures of the two materials are similar to each other. Additionally, the geometric structure of the material is spherical and glassy, which reduces agglomeration and therefore reduces attenuation losses associated with the scattering of ultrasonic energy.

Acoustic Management

[063] In general, the ultrasound transducer radiates energy in two directions - forward towards the patient's body and back towards the device. The image of the patient is obtained from the ultrasonic reflections from the flow of energy radiated forward. If strong back reflections are present, they distort the patient image. The handheld ultrasonic imaging devices and ultrasonic transducer modules described herein optionally include one or more of the numerous features that reduce back reflections.

[064] As shown in FIG. 7, in one embodiment, an air cavity of the acoustic mirror 15 or a vacuum structure 15 is formed under the transducer tile 22 to produce a uniform acoustic reflection that reduces back reflections that distort the patient image.

[065] As shown in FIG. 7, in another embodiment, a high thermal conductivity substrate 21 with a central air cavity or vacuum cavity within the substrate is secured between transducer tile 22 and a heatsink (not shown in FIG. 7) such that the air or vacuum cavity transmits little or no acoustic energy while heat can be transferred perimeterly around the air or vacuum cavity through the top, bottom, and edges of substrate 21. In some embodiments, the substrate ka 21 with high thermal conductivity can be placed between a film of diallyl fumarate (DAP) attached to the crystal.

[066] According to some embodiments, the reduction of back reflections is achieved using etched pockets on the back surface of the ASIC. In other embodiments, the ASIC is located below the acoustic transducer, with the front face of the ASIC mounted flush against the transducer and the rear face of the ASIC mounted flush against a heatsink, which may contain sound absorbing material. According to other additional embodiments, the rear surface of the ASIC chip includes pockets etched into the surface to create an air cavity between the ASIC and the heatsink to reduce propagation of acoustic energy from the ASIC to the heatsink. A coating can also be made on the rear surface of the PMUT transducer to create acoustic absorption caused by many layers of material with different densities.

[067] According to some embodiments, the reduction of back reflections is achieved using etched pockets on the back surface of the ASIC and pockets in the acoustic absorber. According to other embodiments, the ASIC chip is located under the acoustic transducer and the front surface of the ASIC is mounted against the transducer, and the rear surface of the ASIC is mounted against a heatsink containing sound absorbing material. In other additional embodiments, the back surface of the ASIC includes pockets etched into the surface to create an air cavity between the ASIC and the heatsink, and the heatsink design includes pockets containing sound absorbing material. In such embodiments, the two structures are aligned such that the ribs between the sound absorbing material pockets overlap with the cavities etched into the ASIC. The goal is to improve heat transfer from the ASIC to the reference acoustic absorber, while at the same time reducing the transfer of acoustic energy between these substrates.

[068] As shown in FIG. 8, in a particular embodiment, the transducer tile 22 is mounted on the printed circuit board 23 by a metal foam structure 24 that combines low and high density materials to act as an acoustic absorber while providing high thermal conductivity. According to this embodiment, a foamed porous metal member 18 is positioned behind the acoustic transducer to create a thermal path allowing heat from the ASIC to flow into a heatsink located behind the ASIC. Moreover, according to this embodiment, the foamed porous metal body is filled with a solid 19, such as epoxy or polyurethane or silicone, and the solid optionally contains a mixture of high acoustic impedance and low acoustic impedance powders to provide acoustic dispersion.

[069] As shown in FIG. 8, according to another embodiment, the acoustic absorber 23 reduces the consequences of the mismatch of the temperature coefficient of linear expansion (TKLR) between the tiles of 22 converters and the PP 23. According to this embodiment, the tclr binding between the ASIC and the PP is compensated by the choice of acoustic absorber with the intermediate value of the TCLR, so that the acoustic absorber is fulfilled not only Sytik energy transmitted from ASIC to PP, but also reduces thermal mechanical stresses on the interface. The absorber can also be configured to obtain a specific TLEC to tune the voltages to a specific level in order to achieve a transducer curvature with a specific target value.

[070] As shown in FIG. 7 and 8, in another embodiment, a high acoustic impedance acoustic material 24 is placed between ASIC 2 and PCB 23 to form an acoustic reflector (FIG. 7, pos. 20). According to this embodiment, acoustic energy passing through the ASIC is largely reflected back towards the patient due to impedance matching at the interface between the reflector and the ASIC. High impedance material candidates include, but are not limited to, tungsten and tungsten carbide. Acoustic reflector 20 may be used alone in place of an acoustic absorber (FIG. 8, pos. 24) or may be used in conjunction with an acoustic absorber.

Handheld Ultrasonic Imaging Instrument

[071] According to some embodiments, the hand-held ultrasound imaging devices described herein are capable of scanning a patient's body with a transducer module and reconstructing an image derived from transducer signals in the probe and sending the image for viewing and post-processing to a mobile device, in particular a smartphone. To create a high quality 2D/3D/4D/Doppler image, the transducer module must contain a large number of transducer pixels (eg 4096) and many transmit and receive channels (eg 128). In such situations, a large number of channels increases the power consumption, which in turn increases the temperature of the probe. Moreover, 2D/3D/4D/Doppler image processing further increases the power requirements. The US Food and Drug Administration (FDA) limits the temperature of the surface that touches the patient's body to 42°C, and the surface of the operator's handle to 48°C. Legacy handheld 2D imaging devices consume less than 2 watts of power. Legacy 3D/4D/Doppler ultrasound imaging devices consume about 1000 watts of power. To comply with FDA temperature requirements, the 2D/3D/4D/Doppler handheld ultrasound imaging device described herein, in some embodiments, uses advanced electronics to reduce power consumption to less than 10 W, and uses, in some embodiments, improved thermal management and design layout to keep the temperature of the device within the specified temperature limits. In some embodiments, the handheld ultrasound imaging devices described herein have an average maximum power consumption of about 6 watts to about 7 watts. In some embodiments, the handheld ultrasound imaging devices described herein have a peak power consumption of about 10 watts.

[072] As shown in FIG. 9, in a particular embodiment, a handheld ultrasound imaging instrument comprises a multi-material housing 28 having a shaped housing cover 25 held together by a single fastener accessed through a rear USB-C port. According to this embodiment, the internal structure 27 of the heatsink acts as a primary structure for the probe to provide an internal rigid structure that allows the body to be made thinner. According to this embodiment, the multi-layer stacks of the receiver and transmitter subsystems are combined into a multi-layer stack 26 which is a support structure to improve drop resistance. The design of housing 28, in some embodiments, selectively insulates internal heat sources from the surface of the housing at user grips by providing thermal insulation within the housing between the grips and the outer housing. The shape of the housing 28, in some embodiments, reduces re-injury by using a minimal housing neck and locating grip points to limit hand movement from a neutral position during user application of force to a patient.

[073] As shown in FIG. 10-12, in a particular embodiment, the handheld ultrasonic imaging instrument comprises a frame seal structure 30 that, by means of a spring structure or detent springs 1110, generates a uniform force such that the spring force 1210 acts on the frame seal structure 30, which in response acts with a perpendicular force on the heatsink/sensor module assembly.

[074] As shown in FIG. 13 and 14, according to a particular embodiment, the handheld ultrasonic imaging instrument includes a resilient spacer structure 31, 32 between the sensor module assembly 1310 and the main probe body 1410 to absorb force during drop testing, which improves reliability.

[075] In some embodiments, the package includes a metallized thin film shield structure on the inside surface of the package that provides electromagnetic interference (EMI) shielding to the internal electronics. According to some embodiments, the housing comprises a hydrophobic surface. In some embodiments, the housing provides access for battery replacement through a non-breakable window cut into the housing, which can be ultrasonically sealed again after the battery has been replaced.

Thermal management

[076] Handheld ultrasonic imaging devices must operate within the maximum safe temperature set by the US FDA of 42°C for the patient touch surface and 48°C for the handle used by the operator. In simple terms, high image quality requires higher power consumption by the electronics, which in turn increases the temperature of the probe. The handheld ultrasound imaging instruments described herein, in various embodiments, employ numerous new temperature reduction technologies to achieve better image quality in a portable, handheld package size.

[077] As shown in FIG. 15, in a particular embodiment, the handheld ultrasound imaging instrument utilizes directed heat flow between discrete thermal zones 33.

[078] As shown in FIG. 16 and 17, according to a particular embodiment, the handheld ultrasound imaging instrument comprises two separate thermal zones with separate heat sinks. According to this embodiment, thermal zone 1 34 includes a transducer head circuit assembly. And, according to this embodiment, thermal zone 2 35 includes the electronics of the system. Heat sink 1 36 is only attached to components in thermal zone 1 34. Heat sink 2 37 is only attached to components in thermal zone 2 35. Thermal zones 1 and 2 are thermally insulated by interrupting any high thermal conductive link from thermal zone 1 34 to thermal zone 2 35. to body 2 39 using materials 40 with high anisotropic thermal conductivity. Heat transfer in one direction is improved while heat transfer in the other direction is reduced. This allows efficient removal of heat from thermal zone 1 34 using commonly available materials, while heat transfer from and to thermal zone 2 35 is limited. Heat can propagate through anisotropic materials in a specific direction, allowing discrete thermal zones to be organized.

[079] As shown in FIG. 18, in a specific embodiment, a handheld ultrasonic imaging tool includes an anisotropic thermal interface material 40 secured between the chip 41 and motherboard 42 (which are bonded together with adhesive 1810) to remove heat from the semiconductor chip and reduce thermal coupling between heat sink 1 36 and heat sink 2 37. In some embodiments, the anisotropic thermal interface material 40 comprises a pyrographite sheet (PG L), heat pipes or combinations thereof.

[080] In some embodiments, the handheld ultrasonic imaging instrument comprises phase change materials to control transient heat transfer. According to other embodiments, the handheld ultrasonic imaging instrument comprises a heat sink with an embedded phase change material that enhances transient thermal performance of the transducer by utilizing the latent heat phenomenon. The heatsink provides a longer time constant than a solid copper or aluminum heatsink due to a solidified material reservoir with a melting point of ~40°C. The volume of phase change material inside the heatsink determines the transient behavior of the interface near the base of the heatsink. In other embodiments, suitable phase change materials include paraffin (wax), which can be configured to have different melting points, and a metal matrix, such as bismuth, indium, and other low melting point materials.

[081] In some embodiments, the handheld ultrasonic imaging instrument comprises a combination of an acoustic absorber and a thermal management solution. According to other embodiments, the handheld ultrasonic imaging instrument comprises a heat transfer device utilizing the latent heat phenomenon, such as a steam chamber or a flat heat pipe. Optionally, the apparatus includes an outer copper casing with "wick" elements on the walls to promote evaporation/condensation at a particular temperature. The apparatus has a sealed internal volume to hold a small amount of liquid at a certain barometric pressure necessary to obtain boiling at the desired temperatures. An essential design feature is an internal air gap that can be used to reflect or attenuate incoming acoustic waves. The inclusion of an air gap is in some cases the key to obtaining the desired acoustic properties of the structure. According to such embodiments, the benefits of using a steam chamber are improved heat transfer while allowing absorption or reflection of acoustic waves. The heat transfer when using a steam chamber is much higher than with a solid copper block. This optional feature allows for a highly thermally conductive design and still have an air gap directly below the described device.

[082] In some embodiments, the handheld ultrasound imaging instrument comprises a two-piece probe body with an integral heat sink. In other embodiments, the handheld ultrasonic imaging instrument comprises a handheld probe body of various materials used to improve separation of heat streams from two or more discrete heat sources. Such an embodiment includes a low thermal conductivity material bonded to a high thermal conductivity material such that heat can be transferred to the high thermal conductivity portion while thermally insulating a separate heat source. As a result, it is possible to separate the heat transfer flows of two or more sources in the same envelope. A material with high thermal conductivity may add mechanical features such as fins or spikes to achieve increased convection heat dissipation. Such an embodiment is optionally used in conjunction with other thermal management options described herein to provide a separate and directed heat flow.

[083] In some embodiments, temperature during ultrasonic procedures is actively monitored and transient heat limits are applied to adjust available power to limit overheating.

[084] According to some embodiments, the heatsink includes a finned section under the converter substrate and an extension plate that removes heat from the converter substrate. In some embodiments, the heat sink in contact with the ultrasonic transducer module includes pyramid-shaped fins to remove heat from the transducer substrate.

Battery

[085] Providing battery operation is a challenge in a handheld ultrasonic imaging instrument. A handheld ultrasound imaging device must be small and light enough to reduce and prevent injury to the operator, but must provide enough power to produce medically useful images and even therapeutic effects. In some embodiments, the handheld ultrasound imaging devices described herein comprise a primary battery and a spare battery to provide battery redundancy.

[086] In some embodiments, one or more batteries comprise an external flat pack/coherent style to allow connection using a USB-C port. According to such embodiments, the battery becomes a new outer shell and increases overall dimensions. According to other embodiments, the battery provides mechanical shock absorption with elements molded in a plastic case.

[087] In some embodiments, one or more batteries comprise fast charging capability using built-in 120/240V outlet pins. In other embodiments, the handheld ultrasound imaging device uses internal circuitry to effect charging. In various embodiments, the USB-C port includes a USB-C plug or receptacle that provides connection to a power source for charging.

[088] In some embodiments, the handheld ultrasonic imaging instrument includes an internal battery compartment that is separated from the rest of the interior and sealed, with a factory-made external opening available for battery maintenance.

Operator's handle

[089] Conventional medical ultrasound imaging uses a plurality of probes to contact the patient's body. The shape of the probe is often optimized for the body parts to be imaged and multiple probes are used in current systems. Despite probes being optimized for specific body organ imaging, nearly 85% of ultrasound imaging sonographers experience work-related pain, 90% of whom have experienced work-related pain for more than half of their careers. One out of every five sonographers has a work-related injury that ends their career, and the average time in the profession before a sonographer begins to experience pain is five years, according to a pivotal study cited by the Society for Ultrasound Diagnostics (SDMS) in 2000 based on responses from 10,000 participants in the United States and Canada.

[090] In 2017, a new type of probe was introduced, a versatile ultrasound imaging tool that can visualize 13 organs of the body. New probes allow even more organs to be examined with a single probe. However, this increases the problem for sonographers, as the shape of a single probe cannot be optimized for a wide range of tasks, which increases the strain on sonographers' hands. The handheld ultrasonic imaging devices described herein, in accordance with some embodiments, reduce operator health problems associated with the use of general purpose imaging devices.

[091] As shown in FIG. 19, according to a specific embodiment, a handheld ultrasound imaging device comprises an ultrasound transducer module 43 and an operator-specific handle 45 attached to the body 44 of the imaging device, this portion conventionally interacting with the hand of the sonographer/operator. Modifying the imaging device body 44 to allow the insertion of an operator-customizable handle (e.g., by sliding and snapping the operator handle 45 onto the imaging device body 44) allows the use of a plurality of operator handles, each optimized for a particular task and a particular operator. According to such embodiments, further optimization of the operator's handle 45 to the operator's hand is possible, for this the 3D image of the operator's hand is sent to a 3D printing shop equipped with the appropriate optimization software. Moreover, according to such embodiments, personalization of the handle 45 of the operator is possible.

[092] According to such embodiments, an additional benefit of a separate operator handle is an increase in the allowed power dissipation in the imaging device, which is important for higher frame rates and 3D rendering. The operator's handle is optionally made of heat-insulating and heat-reflecting materials, which allows operation with the temperature of the electronics inside the shell, which is higher than the temperature of the surface that the operator's hand touches.

[093] While preferred embodiments of the present invention are shown and described in this document, those skilled in the art will appreciate that such embodiments are provided by way of example only. Specialists in this field of technology can now make various variations, changes and substitutions without deviating from the essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be applied in the practice of the invention.

Claims (45)

1. An ultrasonic transducer for a hand-held device for ultrasound imaging for therapeutic and diagnostic purposes, wherein the ultrasonic transducer comprises a transducer element, which includes an array of piezoelectric micromachined ultrasonic transducers (pMUTs), while the transducer element is integrated on an application-specific integrated circuit (ASIC), forming a transducer tile, and a cavity is formed under the transducer element to provide acoustic isolation of the transducer element from the ASIC. 2. An ultrasonic transducer according to claim 1, wherein the array comprises a plurality of transducer pixels. 3. An ultrasonic transducer according to claim 1, wherein the array contains 4096 or more transducer pixels. 4. Ultrasonic transducer according to claim 1, in which there is a gas, vapor, liquid or vacuum inside the cavity. 5. The ultrasonic transducer according to claim 1, wherein the integration of the transducer element and the ASIC is realized by an inverted chip/transducer chip to ASIC wafer (C2W), transducer chip to ASIC chip (C2C) or transducer wafer to ASIC wafer (W2W) direct connection. 6. The ultrasonic transducer of claim. 1, wherein the ASIC is integrated into a module containing connectors that allow connection to external signal processing electronics using wired connections to pads on the ASIC, or via through holes in silicon (TSV) directly to a high-density printed circuit board (PCB). 7. The ultrasonic transducer of claim 1, wherein the transducer tile is mounted on the transducer substrate. 8. An ultrasonic transducer according to claim 7, wherein the transducer tile is mounted on the transducer substrate via an acoustic absorber. 9. An ultrasonic transducer according to claim 7, wherein the transducer tile is mounted on the transducer substrate through a foamed porous metal material. 10. The ultrasonic transducer of claim 9, wherein the foamed porous metal material is filled with a solid. 11. The ultrasonic transducer of claim 10 wherein the solid contains a mixture of high acoustic impedance and low acoustic impedance powders to provide acoustic dispersion. 12. The ultrasonic transducer of claim 7, wherein the transducer substrate is mounted on a heatsink. 13. The ultrasonic transducer of claim 12, wherein the heatsink comprises a multilayer heatsink structure with alternating electrically conductive and insulating layers that both remove heat from the transducer tile and provide multiple independent electrical power connections. 14. The ultrasonic transducer of claim 12, wherein the heatsink provides resilient mounting to improve reliability against shock and vibration. 15. The ultrasonic transducer of claim 7, wherein the transducer substrate is attached to one or more high-density flexible circuits with a mounting pitch of less than 50 microns, allowing connection to external signal processing electronics. 16. An ultrasonic transducer according to claim 1, which further comprises a top-molded multilayer lens, wherein the multilayer lens comprises a plurality of layers containing at least a first layer and a second layer, wherein the acoustic impedance of the first layer is higher than that of the transducer element and lower than that of the second layer, and the acoustic impedance of the second layer is higher than that of the first layer and lower than that of the target being rendered; wherein the overmolded multilayer lens is optionally configured to focus the imaging beams. 17. The ultrasonic transducer of claim 16, wherein the plurality of layers have thicknesses that are multiples of 1/4 of the target wavelength or set of wavelengths. 18. The ultrasonic transducer of claim 16, wherein the first layer comprises a silicone-based material. 19. The ultrasonic transducer of claim 18, wherein the second layer comprises a silicone-based material and a higher density material added to increase the acoustic impedance of the second layer. 20. The ultrasonic transducer of claim 19, wherein the higher density material comprises rare earth doped amorphous alumina. 21. A handheld ultrasound imaging device for therapeutic and diagnostic purposes, wherein the handheld ultrasound imaging device comprises: a) body; b) an ultrasonic transducer module located within the housing and containing an array of capacitive micromachined ultrasonic transducers (cMUTs) or piezoelectric micromachined ultrasonic transducers (pMUTs), the ultrasonic transducer module being in contact with the first heat sink and associated with the first thermal zone; c) a plurality of receiver subsystems and transmitter subsystems located within the housing and integrated into a multilayer stack, the multilayer stack being in contact with a second heat sink and associated with a second thermal zone, the second heat sink being connected to the housing, the multilayer stack and the first heat sink so as to serve as a main structure providing an internal rigid structure for a handheld ultrasonic imaging instrument; d) an anisotropic thermal interface material configured to transfer heat from the first thermal zone to the second thermal zone, wherein the anisotropic thermal interface material reduces thermal coupling between the first heat sink and the second heat sink; And e) logic for actively monitoring the ultrasound procedure to control the heating of the ultrasonic transducer module within the transient heating range by adjusting the user available power to limit overheating. 22. The handheld ultrasonic imaging tool of claim 21, wherein the anisotropic thermal interface material comprises one or more heat pipes. 23. The handheld ultrasonic imaging instrument of claim 21, wherein the anisotropic thermally conductive material comprises one or more pyrographite sheets (PGL). 24. The handheld ultrasound imaging device of claim 21, configured to generate one or more of 2D, 3D, 4D, Doppler images with power consumption below 11 W peak and below 7 W average. 25. The handheld ultrasonic imaging tool of claim 21, further comprising an anisotropic thermal interface material that reduces thermal coupling between the first heatsink and the second heatsink. 26. The handheld ultrasonic imaging tool of claim 21, wherein the first heat sink comprises a phase change material. 27. The handheld ultrasonic imaging instrument of claim 26, wherein the phase change material comprises paraffin, a metal matrix, or a combination thereof. 28. The handheld ultrasonic imaging instrument of claim 21, wherein the housing comprises a first material having a high thermal conductivity and a second material having a low thermal conductivity, the housing facilitating heat transfer from the first thermal zone to the second thermal zone. 29. The handheld ultrasonic imaging tool of claim 21, which further comprises a frame configured to secure an ultrasonic transducer module located within the housing. 30. The handheld ultrasonic imaging instrument of claim 29, which further comprises a frame seal structure comprising a spring structure to generate a uniform force. 31. The handheld ultrasonic imaging tool of claim 21, which further comprises a flexible spacer between the ultrasonic transducer module and the housing to absorb force and improve drop resistance. 32. The handheld ultrasonic imaging instrument of claim 21, wherein the multilayer stack acts as a support structure to improve drop resistance. 33. The handheld ultrasonic imaging instrument of claim 21, wherein the housing provides access for battery replacement through a non-destructive cut-through window in the housing that can be ultrasonically sealed again after the battery has been replaced. 34. The handheld ultrasonic imaging instrument of claim 21, wherein the inner surface of the housing comprises a thermally insulating material that selectively insulates internal heat sources from the outer surface of the housing where it is gripped by the user. 35. The handheld ultrasonic imaging device of claim 21, wherein the inside surface of the housing includes a metallized thin film shield to shield the electronics within the housing from electromagnetic interference (EMI). 36. The handheld ultrasonic imaging device of claim 21, wherein the outer surface of the housing comprises a hydrophobic material. 37. The handheld ultrasonic imaging device of claim 21, which further comprises a detachable operator's handle. 38. The handheld ultrasonic imaging instrument of claim 37, wherein the handle of the operator is adapted to the hand of the particular operator. 39. The handheld ultrasonic imaging tool of claim 21, wherein the second heatsink comprises a phase change material. 40. The handheld ultrasonic imaging instrument of claim 39, wherein the phase change material comprises paraffin, a metal matrix, or a combination thereof.