WO2025049992A1

WO2025049992A1 - Actuatable ultrasound transducer and imaging techniques

Info

Publication number: WO2025049992A1
Application number: PCT/US2024/044792
Authority: WO
Inventors: Vignesh MANDALAPA BHOOPATHY; Joshua Michael ADLER; Richard Rhodes
Original assignee: Veran Medical Technologies Inc
Current assignee: Veran Medical Technologies Inc
Priority date: 2023-08-31
Filing date: 2024-08-30
Publication date: 2025-03-06
Anticipated expiration: 2026-02-28

Abstract

A disclosed ultrasound imaging device can include an actuated transducer that can be shifted into apposition with patient tissue. An example device comprises a distal housing containing an ultrasound transducer and an actuation mechanism. In an example, actuation mechanism is configured to transition from a non-actuated state, where the transducer is flush with the housing, to an actuated state where the transducer protrudes outward to contact intraluminal tissue. Various actuation mechanisms are disclosed, including piezoelectric actuators, inflatable actuators, and mechanical actuators. Methods for using the device involve inserting it into a lumen, advancing to a target tissue, actuating the mechanism to achieve transducer apposition, and generating ultrasound images. The actuation can be controlled based on analysis of the ultrasound output to optimize image quality. Actuation of the actuation mechanism can move the transducer or a distal end of the ultrasound imaging device.

Description

ACTUATABLE ULTRASOUND TRANSDUCER AND IMAGING TECHNIQUES

PRIORITY CLAIM

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 63/579,903, filed on August 31, 2023 and U.S. Provisional Patent Application Serial No. 63/614,978, filed on December 27, 2023.

FIELD OF THE INVENTION

[0002] The present disclosure relates to an ultrasound device, and more particularly but without limitation, to an ultrasound device having a transducer element that is actuatable to achieve apposition to intraluminal tissue.

BACKGROUND

[0003] Existing endobronchial ultrasound (EBUS) transbronchial needle aspiration (TBNA) sampling devices are not designed to sample nodules located deep in the peripheral area of the lungs which are only accessible via very distal and narrow airways. Rather, such existing EBUS TBNA sampling devices are designed for use in the more shallow and large diameter airways within which a clinician may freely advance or retract the sampling device to align the needle trajectory. Then, a saline filled balloon which encompasses the ultrasound transducer is used to achieve apposition between the transducer and tissue.

[0004] The following is a link to a YouTube™ video providing an overview of a typical EBUS TBNA procedure, which is provided for reference only -

August 2024). The next link references a video demonstrating, among other things, how an EBUS TBNA device uses a saline filled balloon tip -

CLINICAL OR USER NEED:

[0005] Intraluminal ultrasound (US) imaging facilitates real-time imaging of anatomical structures that lie beyond the luminal wall. For example, endobronchial ultrasound (EBUS) devices enable physicians to obtain a realtime image stream of a tissue structure of interest such as a Solitary Pulmonary Nodule (SPN) that is located adjacent to a patient’s airway. Obtaining a high- quality US image requires US energy to propagate from a transducer element into the patient’s tissue at least as deep as the tissue structure of interest, which reflects a portion of the US energy back to the transducer element. The transducer element generates signals based on the reflected portion of US energy and these signals are used to generate an image of the tissue structure of interest. [0006] Air gaps residing between the US transducer and the tissue structure of interest may create an unwanted sonographic barrier, due to air having an extremely low acoustic impedance relative to body tissues. This “impedance mismatch” results in US waves which strike a tissue-air surface being mostly reflected back. This severely limits penetration of the US waves into the tissue beyond a lumen wall and can result in a poor or even non-existent image of the tissue structure of interest.

[0007] Existing EBUS biopsy systems are deployed in large airways where there is ample room to manipulate the location of the sampling device. Once the sampling device is located adjacent to the target nodule, a balloon enshrouding the US transducer is filled with saline to remove airgaps and achieve ultrasonic contact.

[0008] Development of smaller diameter EBUS sampling devices may not utilize a saline filled balloon but instead will rely on the relative size of the outer diameter (OD) of the sampling device with respect to the inner diameter (ID) of the airway to achieve apposition. For example, a sampling device that has a 1.9 mm OD may be advanced into a portion of an airway that has a 1.85 mm ID, and this will in theory cause the airway wall to slightly stretch around the sampling device with no airgaps between the US transducer and the airway wall. In practice however, a target nodule may be located in an airway that is slightly larger than the OD of the sampling device which may lead to difficulties in achieving suitable apposition. As airways typically taper or narrow towards the terminal / distal end, target nodules being located at portions of an airway that are slightly larger than a sampling device OD will surely be a frequent occurrence.

[0009] Within the context of the document, apposition refers to the appropriate level of direct contact (e.g., air-gapless contact) and pressure needed for ultrasound (US) energy to propagate from and back to the US transducer. At the frequencies typically used for US sampling procedures, any amount of airgap results in a high impedance mismatch and ultimately a total loss of image beyond such airgaps. Accordingly, apposition can be interpreted to mean putting at least a portion of the emitting surface of the transducer in direct physical contact with adjacent tissue, unless otherwise indicated within the context of the specific device or technique discussed.

SUMMARY:

[0010] The subject matter discussed herein has been developed to address certain potential problems with extending EBUS tissue sampling devices into narrower passages (e.g., deep lung passages). Next generation EBUS sampling devices for use deep in the lung periphery may need to rely on direct apposition of the ultrasound transducer to the airway wall (i.e., no balloon to achieve ultrasound contact). Thus, next generation EBUS sampling devices will face new and unique challenges with respect to maintaining suitable apposition between the ultrasound transducer and the airway wall so as to produce an image. This is particularly true in devices that may lack steering capabilities to position distal ends directly adjacent the tissue wall (e.g., sub-2mm devices which are extended from working channels of traditional bronchoscopes). The smaller diameter devices are necessary to extending to regions of the lungs and similar anatomy for sampling tissue but may limit some capabilities typical for EBUS devices.

[0011] The present disclosure provides an ultrasound device having a transducer element that is actuatable to achieve apposition to intraluminal tissue. A problem being addressed by the actuatable transducer element includes eliminating air gaps residing between the US transducer and tissue that cause an impedance mismatch, which can severely limit penetration of the US waves into the tissue beyond a lumen wall and results in a poor or even non-existent image of the tissue structure of interest.

[0012] The technical solution provided by the present disclosure involves an ultrasound device having a transducer element that is actuatable (e.g., moveable) to achieve apposition to intraluminal tissue. In a relaxed (non-actuated) state, the ultrasound transducer element may be substantially flush with an outer profile of the sampling device distal tip body or housing. In a second (actuated) state, the transducer element is actuated (moved) upwards into direct contact with the airway wall. As a result, the airgap has been removed and a clear ultrasound image is produced by the system.

[0013] In one embodiment, the ultrasound device has an ultrasound transducer element such as a pMUT (i.e., piezoelectric micromachined ultrasound transducer) or poly-cMUT (i.e., polymer-based capacitive micromachined ultrasound transducer) integrated into a distal tip. Such ultrasound transducer elements may be configured to produce a linear ultrasound image. In some embodiments, the ultrasound transducer may be a radial type transducer which generates a radial ultrasound image. In a relaxed (nonactuated) state, the ultrasound transducer element may be substantially flush with an outer profile of the sampling device distal tip body or housing.

[0014] In a relaxed / non-actuated configuration, there may be an airgap between the ultrasound transducer and the airway wall (e.g., due to the airway inner diameter being greater than the sampling device outer diameter). This airgap results in a high impedance mismatch that essentially makes imaging the tissue beyond the airway wall impractical.

[0015] In an actuated configuration (second state), the transducer element is actuated upwards (e.g., away from the tip body or housing) into direct contact with the airway wall. As a result, the airgap is removed, and a clear ultrasound image is produced by the system.

[0016] In one embodiment, the transducer element is affixed to the distal tip body of the sampling device by way of a pair of opposing piezoelectric actuation beams. The piezoelectric actuation beams may be thin film actuators comprising a piezoelectric film on a surface of an actuator plate. Activation of the piezoelectric film generates tensile stress or compressive stress at the surface, thereby inducing a bending moment that causes the actuator plate to undergo longitudinal curvature. The amount of bending moment can be proportional to the voltage applied to the piezoelectric actuation beam. Accordingly, varying the applied voltage can vary the degree of actuation-translating to distance of actuation and/or force of actuation.

[0017] Additionally, embodiments are also discussed that utilize various expansion methods to shift the ultrasound transducer into apposition with the target tissue.

[0018] The summary included here is not intended to be limiting or include discussion of all the details surrounding the various disclosed embodiments. Further details of each embodiment are discussed below in reference to the various figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The disclosure will be described in conjunction with the following drawings in which like reference numerals designate like elements and wherein: [0020] FIGS. 1A-1C are diagrams illustrating an actuatable ultrasound device, in accordance with an example embodiment.

[0021] FIGS. 2A-2B are diagrams illustrating an actuatable ultrasound device, in accordance with an example embodiment.

[0022] FIGS. 3A-3B are diagrams illustrating alternative actuation beam configurations in accordance with example embodiments.

[0023] FIGS. 4A-4D are diagrams illustrating an actuatable ultrasound device using a single piezoelectric actuator, in accordance with an example embodiment.

[0024] FIGS. 5A-5D are diagrams illustrating an actuatable ultrasound device using an expandable actuator, in accordance with an example embodiment.

[0025] FIGS. 6A-6D are diagrams illustrating an actuatable ultrasound device using a bias member actuator, in accordance with an example embodiment. [0026] FIGS. 7A-7B are diagrams illustrating an actuatable ultrasound device using a spring wire actuator, in accordance with an example embodiment.

[0027] FIGS. 8A-8B are diagrams illustrating an actuatable ultrasound device using a flexible stylet actuator, in accordance with an example embodiment.

[0028] FIG. 9 is a block diagram illustrating an example sampling device that incorporates an actuation mechanism.

[0029] FIG. 10 is a flowchart illustrating an example technique to operate an actuatable ultrasound device in accordance with example embodiments.

[0030] FIG. 11 illustrates a block diagram of an example machine upon which any one or more of the techniques discussed herein may perform in accordance with at least one example of this disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The following detailed description is of the best presently contemplated modes of carrying out the disclosed techniques. This description is not to be taken in a limiting sense but is made merely for the purpose of illustrating general principles of embodiments disclosed herein.

[0032] An ultrasound device having a transducer element that is actuatable to achieve apposition to intraluminal tissue is discussed throughout the specification. Various embodiments of the ultrasound devices discussed herein form a portion of an endobronchial ultrasound (EBUS) device, which are elongate devices designed to obtain tissue samples from deep within luminal structures within the body. The EBUS devices, while flexible by nature are considered to have a longitudinal axis that runs the length of the device. When discussed herein, the longitudinal axis of an ultrasound device is an axis running the length of at least the distal portion of the device that includes the sampling mechanism as well as the ultrasound transducer.

[0033] Regarding the ultrasound transducer, the ultrasound device has an ultrasound transducer element such as a pMUT or poly-cMUT integrated into a distal tip of an elongated medical instrument, such as an EBUS sampling device. In a relaxed (non-actuated) state, the ultrasound transducer element may be substantially flush with an outer profile of the sampling device distal tip body or housing. The actuation mechanisms discussed herein include devices to actuate (e.g., move) the emission surface of the ultrasound transducer relative to the housing as well as mechanisms that actuate an element opposing the ultrasound transducer to shift the entire distal end of the medical device against a tissue wall. The purpose of each actuation mechanism is to achieve apposition of the ultrasound transducer with the tissue wall. Apposition is achieved by shifting the emission surface of the ultrasound transducer into contact with the tissue (airway) wall. In some examples, the emission surface of the transducer may be embedded within an ultrasound gel other similar ultrasound conductive material in which case the purpose of the actuation mechanisms is to shift the ultrasound conductive material into contact with the tissue or airway wall.

[0034] In some examples discussed below, piezoelectric actuators are discussed for use within certain actuation mechanisms. The piezoelectric actuators utilize beams or similar structures that include a piezoelectric film. In general, piezoelectric films are thin sheets of material that generate an electrical charge when mechanically stressed or distorted. They exhibit the piezoelectric effect, which is the ability to convert mechanical energy into electrical energy and vice versa. Piezoelectric films can be made from materials such as polyvinylidene fluoride (PVDF), lead zirconate titanate (PZT), and zinc oxide (ZnO). Applying mechanical stress or distortion causes charge separation in the molecular structure of the film, generating an electrical voltage. This is known as the direct piezoelectric effect. Conversely, applying an electric field causes a change in the molecular structure of the film, resulting in mechanical deformation. This is known as the converse piezoelectric effect and is the principal behind the piezoelectric actuators discussed herein. Benefits of piezoelectric films include high piezoelectric coefficients, mechanical flexibility, lightweight, ease of integration into devices, and low cost manufacturing. In summary, piezoelectric films leverage the piezoelectric effect to interconvert mechanical and electrical energy. Their unique properties make them useful for a variety of applications.

[0035] As introduced above, the converse piezoelectric effect refers to the ability of a piezoelectric material to undergo mechanical deformation when an external electric field is applied. At the molecular level, piezoelectric materials have a crystalline structure that lacks central symmetry. This allows the molecular dipoles to align in response to an applied electric field. When a voltage is applied across the material, the dipoles will align according to the electric field direction. This alignment causes a net change in dipole moments per unit volume, resulting in strain along the poling axis. The amount of strain (deformation) is proportional to the strength of the applied electric field. Higher voltages induce greater structural deformation as more dipoles become aligned. Strain levels can vary widely depending on the piezoelectric coefficients of the material. Piezoelectric ceramics experience modest strains, while piezoelectric polymers can exhibit strains over 10 times higher. The induced strain is reversible - when the electric field is removed, the dipoles return to their original random orientation and the material regains its initial shape. Due to this deformation mechanism, applying an AC voltage leads to oscillating strains and vibrations in the material. This allows piezoelectrics to function as actuators or transducers. In summary, the converse piezoelectric effect enables electric signals to control the mechanical deformation and motion of a material through its influence on the molecular dipole structure. This electromechanical coupling is the bias for the piezoelectric actuators discussed herein to operate in response to applied electrical fields.

[0036] More specifically, piezoelectric actuators discussed herein can include structures produced along the following principals. The active element within an actuator is a piezoelectric material that deforms under an applied electric field, such as a piezoelectric ceramic or polymer. Electrodes are attached to the top and bottom surfaces of the piezoelectric material to apply the electric field and induce dipole alignment. Common electrode materials are silver, nickel, or conductive polymers. The electrodes are connected to an external power source, typically a high voltage amplifier. In the sampling devices discussed herein, the voltage source operating the ultrasound transducer and/or other portions of the sampling device can be utilized. The piezoelectric element is attached or bonded to a passive mechanical structure. This could be a cantilever, diaphragm, stack, bimorph, or other mechanical design. When activated, the deformation of the piezoelectric element is transferred to the larger mechanical structure to do work. The passive structure provides mechanical support, and its elasticity determines the achievable displacement and force generation. Piezoelectric actuators are simple, compact, and high precision. Strain amplification mechanisms can be incorporated to increase the range of motion. In summary, a piezoelectric actuator can consist of a polarized piezoelectric element sandwiched between electrodes and coupled to an elastic mechanical structure. When energized, the induced strains generate the actuation motions.

[0037] FIGS. 1A-1C are diagrams illustrating an actuatable ultrasound device, in accordance with an example embodiment. In this example, the sampling device 100 can include a housing 105, an ultrasound transducer 110, and an actuation mechanism 125. In this example, the actuation mechanism 125 includes two opposing piezoelectric actuation beams 130. The axis A included in FIG. 1 A is consider the longitudinal axis of sampling device 100 (also referred to as ultrasound device). All of the sampling/ultrasound devices discussed herein include a similar longitudinal axis.

[0038] The example sampling device 100 is in a relaxed / non-actuated configuration in FIG. 1A in which the field-of-view (FOV), such as FOV 150, is illustrated as hatched lines (extending in a cone shape away from the transducer element) - the FOV 150 in FIG. 1A is indicating a null image. This null image is the result of an airgap between the ultrasound transducer and the airway wall. Specifically, as shown in FIG. 1 A below, the airway wall tapers / narrows from proximal to distal regions (i.e., left to right as shown), and the airway wall is not in direct contact with the transducer along any portion of the transducer area.

This airgap results in a high impedance mismatch that essentially makes imaging the tissue beyond the airway wall impractical. Note, the discussion of the device disclosed is presented with respect to airway passages within a lung. However, similar techniques are applicable to a wide range of vessel and passageway imagine within the human body.

[0039] In FIG. IB, the ultrasound transducer has been actuated upwards (relative to the illustrated housing 105 of device) into direct contact with the airway wall (e.g., tissue wall 120). In other words, the actuation of the ultrasound transducer 110 is perpendicular to the longitudinal axis. As a result, the airgap has been removed and a clear ultrasound image is produced by the system (e.g., sampling device 100). In the illustrated embodiment, the ultrasound transducer 110 is affixed to the distal tip body of the sampling device 100 by way of a pair of opposing piezoelectric actuation beams, collectively referred to as piezoelectric beams 130.

[0040] The piezoelectric actuation beams 130 may be thin film actuators comprising a piezoelectric film on a surface of an actuator plate. Activation of the piezoelectric film generates tensile stress or compressive stress at the surface, thereby inducing a bending moment that causes the actuator plate to undergo longitudinal curvature. For additional background on thin film actuators see U.S. Patent 11,489, 461B2, which uses such actuators in a different application. The description of U.S. Patent 11,489,461 is hereby incorporated by reference in its entirety.

[0041] FIG. 1 A is a diagram illustrating an actuatable ultrasound device in a relaxed (non-actuated) state. In this example, the sampling device 100 includes a housing 105, an ultrasound transducer 110, and an actuation mechanism 125. The actuation mechanism 125 includes two opposing piezoelectric actuation beams 130 (referred to more generally as actuation beams 130). In this example, the ultrasound transducer 110 may be substantially flush with an outer profile of the sampling device distal tip body or housing 105 prior to actuation. In this relaxed / non-actuated configuration, there is an airgap between the ultrasound transducer 110 and the airway/tissue wall 120 (generally referred to as airway wall 120). This airgap results in a high impedance mismatch that essentially makes imaging the tissue beyond the airway wall 120 impractical. Within FIG.

1 A, the actuation beams 130 are in a relaxed, non-actuated, state. In this example, the non-actuated state of the actuation beams 130 is flat, flush with the mounting surface under the ultrasound transducer 110.

[0042] FIG. IB is a diagram illustrating the sampling device 100 in the actuated configuration. In the actuated state, the ultrasound transducer 110 has been actuated upwards (e.g., towards the airway wall 120) and into direct contact with the upper airway wall 120. As a result, the airgap has been removed and a clear ultrasound image can be produced by the system (as illustrated by a simulated ultrasound image being produced).

[0043] In one embodiment, the ultrasound transducer 110 is affixed to the distal tip of the housing 105 of the sampling device 100 by way of a pair of opposing piezoelectric actuation beams 130. The piezoelectric actuation beams 130 may be thin film actuators comprising a piezoelectric film on a surface of an actuator plate. Activation of the piezoelectric film generates tensile stress or compressive stress at the surface, thereby inducing a bending moment that causes the actuator plate to undergo longitudinal curvature. FIG. 1C is a diagram illustrating a detailed view of the distal end of housing 105 and actuation mechanism 125. In this example, the actuation beams 130 include an actuator plate 132 and piezoelectric film 134. The actuation beams 130 are anchored to the housing 105 via anchor end 138 and are coupled to the ultrasound transducer 110 via actuation end 136. In this example, an electrical voltage is applied to the actuation beams 130 via anchor end 138. The actuation end 136 can include a force sensor to provide force feedback to a control system regulating the supplied voltage. As illustrated in FIG. 1C, different voltages (e.g., voltage 140 and voltage 142) can be applied to each of the pair of opposing piezoelectric actuation beams 130 to angle the ultrasound transducer 110 to better align the transducer with the airway wall 120.

[0044] The embodiment illustrated in FIG. IB also includes a sampling needle 170 that is defected out of a side exit port 160 by a ramp 165 leading to the exit port 160. The ramp 165 can be formed within the lumen extending the length of the device for delivery of the sampling needle 170. As illustrated in FIG. IB, once apposition is achieved, the ultrasound transducer 110 can produce an image within the FOV 150 that includes sampling needle 170 entering a target tissue for sampling.

[0045] FIGS. 2A-2B are diagrams illustrating an alternative actuation mechanism design for an actuatable ultrasound device, in accordance with an example embodiment. FIG. 2A is a diagram illustrating a distal tip of housing 205 of the ultrasound device including an alternative actuation mechanism (actuation mechanism 225) in a non-actuated state in accordance with example embodiments. Within this example embodiment, the actuation mechanism 225 operates to extend (actuate) a portion of the housing opposite the US transducer to simplify manufacturing and operation of the device. The housing actuator 240 is illustrated in FIG. 2A in a relaxed or non-actuated state, where the housing actuator 240 remains flush with the surrounding portions of distal tip of housing 205. A benefit of this configuration is that wiring for the transducer 210 does not need to be movable upon actuation, which simplifies the manufacture, operation, and maintenance of the device. All of the variations in actuation beam configuration and operation techniques discussed above in reference to sampling device 100 are similarly applicable to sampling device 200 and housing actuator 240.

[0046] FIG. 2B is a diagram illustrating sampling device 200 including actuation mechanism 225 in an actuated state in accordance with example embodiments. FIG. 2B illustrates how the actuation mechanism 225 displaces the housing actuator 240 to achieve apposition of the transducer 210 to intraluminal tissue (e.g., airway wall 120). The housing actuator 240 includes two actuation beams 230 in a configuration similar to that illustrated and discussed in reference to FIGS. 1 A-1C but reversed to operate on a portion of the distal tip of housing 205 instead of the transducer 210. Accordingly, the actuation mechanism 225 is designed to shift the position of the entire distal portion of sampling device 200, including ultrasound transducer 210. As shown in FIG. 2B, the housing actuator 240 is extended (actuated) out of the housing 205 into contact the airway wall 120 opposite the transducer 210 and shift the transducer 210 into contact with the opposite section of airway wall 120 to achieve apposition with the airway wall 120 (intraluminal tissue).

[0047] FIGS. 3A and 3B illustrate alternative actuation beam configurations in accordance with example embodiments. Within this illustration, the actuation beams can be opposing beams with pivot or fixed points in the middle under the transducer, or parallel beams with pivot/fixed points staggered along a length of the distal tip. The actuation beams are discussed above in terms of piezoelectric film, but other implementations are within the scope of the present disclosure. For example, shape memory materials, such as nitinol, could be used in combination with a mechanism to trigger the shape memory transformation. Alternatively, other methods of manipulating the transducer could be implemented.

[0048] In certain examples, any of the piezoelectric actuation beams, such as actuation beams 130/230, can utilize a shape memory alloy in combination with a piezoelectric film to enhance the actuation generated by any given voltage applied to the piezoelectric film.

[0049] FIGS. 4A-4D are diagrams illustrating an actuatable ultrasound device using a single piezoelectric actuator, in accordance with an example embodiment. In this example, the sampling device 400 can include a housing 405 with an ultrasound transducer 410 adjacent a distal end. The ultrasound transducer 410 can generate a FOV 450 for imaging tissue and sample targets. Opposite the ultrasound transducer 410 is an actuation mechanism 425 that includes a piezoelectric actuator. FIGS. 4 A and 4B illustrate sampling device 400 with the actuation mechanism 425 in a relaxed or non-actuated state.

[0050] FIGS. 4C and 4D illustrate sampling device 400 with the actuation mechanism 425 is an actuated state. In this example, the actuation mechanism 425 expands in a direction opposite the ultrasound transducer 410 to shift the ultrasound transducer 410 into apposition with the airway wall 120. As with some of the other example sampling device, the actuation mechanism 425 operates via converse piezoelectric principals to expand a portion of the housing 405 against a portion of the airway wall 120 opposite the ultrasound transducer 410. FIG. 4D provides a cross-sectional view to assist in illustrating the operation of actuation mechanism 425.

[0051] In an example, the actuation mechanism 425 can include a stacked piezoelectric actuator. A stacked piezoelectric actuator can consist of multiple layers of thin piezoelectric disks or beams stacked together and bonded with adhesive. The poling direction of the material alternate, so that when a voltage is applied, some layers expand while others contract. This causes the stack to lengthen or shorten depending on the polarity of the applied voltage. Electrode layers are interleaved between the piezoelectric layers to apply the electric field and collect charges. The stack can be preloaded with a bolt or compressive force to prevent tensile cracking during actuation. Displacements can be proportional to the number of layers in the stack. More layers allow larger motions from the same applied voltage. Stacked actuators can produce high forces and large displacements from a compact package. In summary, stacked piezoelectric actuators amplify displacements by combining multiple active layers. The compact, monolithic structure can provide high performance actuation with fast response times.

[0052] FIGS. 5A-5D are diagrams illustrating an actuatable ultrasound device using an expandable or inflatable actuator, in accordance with an example embodiment. In this example, the sampling device 500 can include a distal housing 505 containing an ultrasound transducer 510 and an actuation mechanism 525. In this example, the actuation mechanism 525 is an expandable or inflatable structure designed to engage a portion of the airway wall 120 opposite the ultrasound transducer 510 to achieve or enhance apposition with the airway wall 120 to improve imaging of potential target tissue. In this example, the expandable actuation mechanism 525 can be a hollow elastomeric structure connected to a feed tube 540. A control mechanism, not shown, can be connected to the feed tube 540 to introduce air, saline, or some other human compatible substance into the expandable actuation mechanism 525. For example, a simple syringe filled with saline can be coupled to the feed tube 540 to control expansion of the actuation mechanism 525. In an example, the graduations on the syringe can be calibrated to an expansion distance for the actuation mechanism 525. Limiting the volume of fluid/air in the syringe can be used to limit the amount of actuation. FIGS. 5C and 5D illustrate an example expanded actuation mechanism 525. Actuation of the actuation mechanism 525 can be achieved through any mechanism to deliver a pressurized fluid or gas to the expandable structure.

[0053] FIGS. 6A-6D are diagrams illustrating an actuatable ultrasound device using a bias member actuator, in accordance with an example embodiment. In this example, the sampling device 600 includes a distal housing 605 containing an ultrasound transducer 610 and an actuation mechanism 625. The actuation mechanism 625 can include an actuation member 630, a bias member 635, and an actuation control wire 642 routed through an actuation lumen to a control reel 644. The bias member 635 can be a coil spring, a shape memory structure, or similar spring/bias structure. In this example, the bias member 635 is a circular ring of shape memory alloy or elastomeric material that is compressed by the control wire 642. The control reel 644 is an example mechanism to apply a tension on the control wire 642-other tension mechanisms are within the scope of this embodiment. In an example, the control reel 644 can be coupled to a knob within a handle (user interface) for the sampling device 600.

[0054] As illustrated in FIGS. 6C and 6D, the tension on the control wire 642 can be released to cause the bias member 635 to expand and actuate the actuation member 630 into contact with the airway wall 120. In an example, the control knob for the control reel 644 can be calibrated to indicate an amount of actuation of the actuation mechanism 625. As in the other embodiments discussed herein, the purpose of the actuation mechanism 625 is to shift the distal housing 605 and more importantly the ultrasound transducer 610 into apposition with the airway wall 120 to improve imaging of tissue beyond the airway wall 120.

[0055] FIGS. 7A-7B are diagrams illustrating an actuatable ultrasound device using a spring wire actuator, in accordance with an example embodiment. In this example, the sampling device 700 includes a spring wire actuator 725 coupled to an ultrasound transducer 710 and an actuation member 730. The spring wire actuator 725 is used to extend the ultrasound transducer 710 and the actuation member 730 out of a distal end of housing 705 of the sampling device 700. The actuation mechanism (spring wire actuator 725) also includes a control tube 727 that houses the control extension 739 that allows for manipulation of the control wires 737, 735. The control wires 737, 735 can be pre-bent spring wire formed from a shape memory alloy such as nitinol. The control tube 727 can be used to assist in controlling the positioning of the ultrasound transducer 710 and actuation member 730 as they are extended out of a distal end of the be housing 705. As the control wires 735, 737 are extended, the control tube 727 can be retracted to allow the pre-bent wires to return more easily to a bent shape and direct the ultrasound transducer 710 and actuation member 730 against opposite portions of the airway wall 120. The resulting impact of actuation of the actuation mechanism (spring wire actuator 725) is enhanced apposition of the ultrasound transducer 710 with the airway wall 120.

[0056] FIGS. 8A-8B are diagrams illustrating an actuatable ultrasound device using a flexible stylet actuator, in accordance with an example embodiment. In this example, the sampling device 800 can include a distal housing containing an ultrasound transducer 810 and an actuation mechanism 825. The actuation mechanism 825 can include an actuation member 830 coupled to a flexible stylet 837 routed through a control lumen 835. The control lumen 835 can route the flexible stylet 837 to a handle or user interface element to allow for manipulation of the actuation mechanism 825. The user interface element can include a lever or similar mechanism. The flexible stylet 837 can be operated in a manner similar to a sampling needled extended through the sampling device 800. To actuate the actuation mechanism 825, the flexible stylet 837 can be pushed through the control lumen 835 to extend the actuation member 830 away from the distal housing 805. The actuation member 830 can be a movable section of the distal housing 805 that when retracted conforms with the shape of the distal housing 805. Upon extension, the actuation member 830 can engage with the airway wall 120 to shift the distal housing 805 and the ultrasound transducer 810 against an opposite portion of the airway wall 120 to enable apposition of the ultrasound transducer 810 with the tissue. Good apposition with the airway wall 120 produces a FOV 850 with good visualization of tissue beyond the airway wall 120. Once the target tissue has been located and sampled, the actuation mechanism 825 can retract the actuation member 830 by pulling the flexible stylet proximally through the control lumen 835.

[0057] FIG. 9 is a block diagram illustrating an example sampling device that incorporates an actuation mechanism. In this example, the sampling device 900 can include a tissue sampling mechanism 905, an ultrasound transducer 910, a user interface 915, an actuation mechanism 920, and a control system 930. The sampling mechanism 905 can include a flexible needle routed through a sampling lumen with an offset mechanism to direct the needle out of the sampling device at an angle to the longitudinal axis. Other sampling mechanisms known in the art could also be integrated into the device discussed herein.

[0058] The user interface 915 can include a handle with control mechanism and/or ports to manipulate the tissue sampling mechanism 905 as well as the actuation mechanism 920. In some example, the control system 930 can be fully integrated within the user interface 915, such as in examples that utilize fully mechanical control of the tissue sampling mechanism 905 and the actuation mechanism 920. The actuation mechanism 920 can be any of the mechanisms discussed in reference to FIGS. 1 A-8B above.

[0059] In some examples, the control system 930 can optionally include a processor 932, a memory device 934, and a feedback circuit 936. In these examples, the control system 930 can be configured to process data from the ultrasound transducer 910 and provide feedback to the actuation mechanism 920 (in particular when the actuation mechanism 920 is one of the piezoelectric actuator-based actuation mechanism or other electronically controlled mechanism). In an example, the control system 930 can monitor the imaging output from the ultrasound transducer 910 and provide control feedback via the feedback circuit 936 to the actuation mechanism 920 to control actuation to achieve apposition of the ultrasound transducer 910. Where the actuation mechanism 920 includes a piezoelectric actuator, the feedback circuit 936 is configured to output voltages tailored to control actuation of the piezoelectric actuator.

[0060] FIG. 10 is a flowchart illustrating an example technique to operate an actuatable ultrasound device in accordance with example embodiments. In this example, the technique 1000 is discussed in view of the sampling device 900 discussed above. In this example, the technique 1000 includes operations such as inserting a sampling device into a lumen at 1002, advancing the sampling device at 1004, monitoring output from an ultrasound transducer at 1006, determine image quality at 1008, actuating an actuation mechanism at 1010, and confirming apposition with an intraluminal tissue at 1012.

[0061] In this example, the technique 1000 begins with insertion of the sampling device 900 into a lumen, such as an airway or similar lumen. At 1002, the technique 1000 continues with the sampling device 900 being advanced to a target tissue location within the lumen. At 1006, the technique 1000 continues with the control system 930 monitoring output from the ultrasound transducer 910. In another example, the output from the ultrasound transducer 910 can be monitored by the practitioner to evaluate whether there is apposition between the intraluminal tissue and the ultrasound transducer. In this example, the technique 1000 continues at 1008 with the control system 930 determining image quality generated by the ultrasound transducer 910. At 1008, the control system 930 can evaluate whether any tissue features are distinguishable within in the ultrasound image to make the determination of image quality. In an example, the control system 930 can analyzing transducer receive data prior to beamforming (e.g., creating an image). A baseline of the receive signal for each individual element in the transducer can be saved when the transducer is in the air (e.g., no apposition). Within the monitoring loop (e.g., operations 1006 to 1010), the control system 930 can compare the baseline receive signal for each element to the baseline. If the compared received signal is within a specific threshold/range of the baseline (air measurement) in terms of ringdown pulse length and amplitude the evaluated element is considered to be in air (e.g., no apposition). The control system 930 determines, at 1008, the number of elements in apposition (e.g., above the threshold or range in comparison to baseline). In an alternative example, the control system 930 can utilize an apposition baseline for each element for comparison, where the apposition baseline is taken with the transducer in water or another acoustically friendly media.

[0062] Performing the analysis at 1008 on the receive signal on an element by element basis can provide beneficial detail regarding which elements are not achieving apposition and can subsequently be used within operation 1010 to inform actuation to achieve greater apposition. For example, if the first 15 elements on one side of the transducer are not achieving apposition but the rest of the elements are, the corresponding side of the transducer can be actuated until apposition is achieved. Knowledge of element by element apposition can assist the system in avoiding injury from over actuating the wrong part of the transducer. [0063] At 1008, the control system 930 alternatively can utilize various image processing techniques to evaluate ultrasound metrics such as contrast levels, reverberation, echo intensity, and near field quality. Here are some additional details on image processing algorithms that could be executed within the control system 930 for evaluating ultrasound transducer 910 apposition. Reverberation artifact detection - Algorithms can identify reverberation bands by analyzing echo intensity variations across image lines. The presence and frequency of bands provides a quantitative apposition measure. Some techniques use Fourier transforms or statistical methods to detect the periodic intensity patterns. Echo signal analysis - The echo intensity from well-coupled tissue will follow a predictable decay pattern as depth increases. Algorithms fit echo data to models of expected intensity decay. Significant deviations indicate poor apposition resulting in multiple reflections and intensity loss. Speckle pattern assessment - Speckle patterns change in poorly coupled regions. Algorithms can evaluate speckle size, brightness, and uniformity and compare to norms for well-coupled images. Abnormal speckle patterns suggest apposition issues. Near field metrics - The near field region is divided into sub-regions and analyzed for image quality metrics like brightness, contrast, resolution, and artifact presence. Each sub-region is scored and combined into an overall apposition measure. Machine learning approaches - Models can be trained on labeled ultrasound images to recognize features predictive of good vs poor apposition. Neural networks, support vector machines, and other ML techniques have been applied. Hybrid methods - Combinations of the above techniques have been developed into single algorithms that provide an overall apposition score based on multiple image features and quality metrics. In general, these algorithms leverage automated, quantitative image analysis to objectively evaluate apposition.

[0064] At 1010, the technique 1000 continues with the control system 930 activating the actuation mechanism based on a determination of poor (low) image quality - e.g., poor apposition. The objective evaluation of apposition can be leveraged to control the actuation mechanism 920 when the scoring indicates that apposition can be improved. The technique 1000 can loop between monitoring the transducer output at 1006, evaluating the image output at 1008 and actuating the actuation mechanism at 1010 to achieve apposition between the ultrasound transducer and the intraluminal tissue. If the evaluation performed at 1008 indicates good (high) image quality, the technique 1012 can complete with confirmation of apposition between the ultrasound transducer 910 and the intraluminal tissue.

[0065] While the technical solution has been described in detail with reference to disclosed embodiments, various modifications within the scope of the disclosure will be apparent to those of ordinary skill in this technological field. It is to be appreciated that features described with respect to one embodiment typically may be applied to other embodiments.

[0066] FIG. 11 illustrates a block diagram of an example machine 1100 upon which any one or more of the techniques (processes) discussed herein may perform in accordance with some embodiments. In alternative embodiments, the machine 1100 may operate as a standalone device and/or may be connected (e.g., networked) to other machines. In a networked deployment, the machine 1100 may operate in the capacity of a server machine, a client machine, or both in server-client network environments. In an example, the machine 1100 may act as a peer machine in peer-to-peer (P2P) (or other distributed) network environment. The machine 1100 may be a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile telephone, a web appliance, a network router, switch or bridge, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term "machine" shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as cloud computing, software as a service (SaaS), other computer cluster configurations. [0067] Machine (e.g., computer system) 1100 may include a hardware processor 1102 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory 1104 and a static memory 1106, some or all of which may communicate with each other via an interlink (e.g., bus) 1108. The machine 1100 may further include a display unit 1110, an alphanumeric input device 1112 (e.g., a keyboard), and a user interface (UI) navigation device 1114 (e.g., a mouse). In an example, the display unit 1110, input device 1112 and UI navigation device 1114 may be a touch screen display. The machine 1100 may additionally include a storage device (e.g., drive unit) 1116, a signal generation device 1118 (e.g., a speaker), a network interface device 1120, and one or more sensors 1121, such as a global positioning system (GPS) sensor, compass, accelerometer, or other sensor. The machine 1100 may include an output controller 1128, such as a serial (e.g., Universal Serial Bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate and/or control one or more peripheral devices (e.g., a printer, card reader, etc.). [0068] The storage device 1116 may include a machine readable medium 1122 on which is stored one or more sets of data structures or instructions 1124 (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The instructions 1124 may also reside, completely or at least partially, within the main memory 1104, within static memory 1106, or within the hardware processor 1102 during execution thereof by the machine 1100. In an example, one or any combination of the hardware processor 1102, the main memory 1104, the static memory 1106, or the storage device 1116 may constitute machine readable media.

[0069] While the machine readable medium 1122 is illustrated as a single medium, the term "machine readable medium" may include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) configured to store the one or more instructions 1124. The term "machine readable medium" may include any medium that is capable of storing, encoding, or carrying instructions for execution by the machine 1100 and that cause the machine 1100 to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding, or carrying data structures used by or associated with such instructions. Non-limiting machine- readable medium examples may include solid-state memories, and optical and magnetic media. [0070] The instructions 1124 may further be transmitted or received over a communications network 1126 using a transmission medium via the network interface device 1120 utilizing any one of a number of transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone networks (e.g., cellular networks), Plain Old Telephone (POTS) networks, and wireless data networks (e.g., Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards known as Wi-Fi®, IEEE 802.16 family of standards known as WiMax®), IEEE 802.15.4 family of standards, peer-to-peer (P2P) networks, among others. In an example, the network interface device 1120 may include one or more physical jacks (e.g., Ethernet, coaxial, or phonejacks) or one or more antennas to connect to the communications network 1126. In an example, the network interface device 1120 may include a plurality of antennas to wirelessly communicate using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) techniques. The term “transmission medium” shall be taken to include any intangible medium that is capable of storing, encoding, or carrying instructions for execution by the machine 1100, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

[0071] Technique (method) examples described herein may be machine or computer-implemented at least in part. Some examples may include a computer- readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform methods as described in the above examples. An implementation of such methods may include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code may include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, in an example, the code may be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media may include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memories (RAMs), read only memories (ROMs), and the like.

EXAMPLES

[0072] The following are non-limiting examples of the devices and techniques discussed herein. The example expansion mechanisms can be used alone or in combination with other disclosed expansion mechanisms. The methods or techniques discussed can be performed using any of the disclosed expansion mechanisms, unless the example involves utilizing a particular aspect of a particular expansion mechanism.

[0073] Example 1 is an ultrasound imaging device including an actuated transducer. The actuated transducer comprises a transducer and an actuator configured to shift a position of the transducer relative to a distal portion of a housing of the ultrasound imaging device into apposition with tissue of a patient. [0074] Example 2 is an endobronchial ultrasound device. The device comprises a distal tip housing, a transducer element disposed within the distal tip housing, and one or more actuation beams coupled to the transducer element opposite an emission surface of the transducer element. The one or more actuation beams are configured to displace the transducer element out of the distal tip housing.

[0075] Example 3 is an ultrasound device. The device comprises a distal tip body and an ultrasound transducer element disposed within the distal tip body. In a non-actuated state, an outer surface of the ultrasound transducer element is flush with an outer profile of the distal tip body. The device further comprises one or more piezoelectric actuation beams coupled to the ultrasound transducer element. The one or more piezoelectric actuation beams are configured to actuate the ultrasound transducer element from the non-actuated state to an actuated state in which the ultrasound transducer element protrudes outward from the outer profile of the distal tip body. [0076] Example 4 includes the subject matter of Example 3, wherein in the non-actuated state, there is an airgap between the outer surface of the ultrasound transducer element and an intraluminal tissue surface. In the actuated state, the outer surface of the ultrasound transducer element is extended outward into contact with the intraluminal tissue surface to enhance acoustic transmission and resulting image quality.

[0077] Example 5 includes the subject matter of Examples 3 or 4, wherein the one or more piezoelectric actuation beams comprise a thin film actuator having a piezoelectric film disposed on a surface of an actuator plate.

[0078] Example 6 includes the subject matter of Example 5, wherein activation of the piezoelectric film generates one of tensile stress and compressive stress to induce bending of the actuator plate.

[0079] Example 7 includes the subject matter of any one of Examples 3 to 6, wherein the ultrasound transducer element comprises one of a pMUT and a poly- cMUT.

[0080] Example 8 includes the subject matter of any one of Examples 3 to 7, wherein the distal tip body houses a sampling needle configured to extract a tissue sample.

[0081] Example 9 includes the subject matter of any one of Examples 3 to 8, wherein the ultrasound device comprises an endobronchial ultrasound device configured for insertion into an airway.

[0082] Example 10 is a method for imaging an intraluminal tissue surface. The method comprises providing an ultrasound device including an ultrasound transducer element disposed with a distal end of the ultrasound device and an actuation mechanism including one or more piezoelectric actuation beams coupled to the ultrasound transducer element. The method further comprises inserting the distal end of the ultrasound device into a lumen, advancing the distal end within the lumen towards a target tissue, and actuating the one or more piezoelectric actuation beams within the actuation mechanism to move the ultrasound transducer element from a non-actuated state to an actuated state in which the ultrasound transducer element protrudes outward from an outer profile of the distal end and contacts an intraluminal tissue surface. The method also includes generating ultrasound images of the intraluminal tissue surface using signals from the ultrasound transducer element.

[0083] Example 11 includes the subject matter of Example 10, wherein providing the ultrasound device includes the actuation mechanism being in a non-actuated state where the ultrasound transducer element is flush with an outer profile of the distal end.

[0084] Example 12 includes the subject matter of Example 10 or 11, further comprising extracting a tissue sample from the intraluminal tissue surface using a sampling needle housed in the distal end.

[0085] Example 13 includes the subject matter of any one of Examples 10 to

12, wherein inserting the distal end of the ultrasound device into the lumen includes entering an airway passage.

[0086] Example 14 includes the subject matter of any one of Examples 10 to

13, wherein actuating the one or more piezoelectric actuation beams includes applying a voltage to a piezoelectric film.

[0087] Example 15 includes the subject matter of any one of Examples 10 to

14, wherein actuating the one or more piezoelectric actuation beams includes applying a first voltage to a first piezoelectric actuation beam and a second voltage to a second piezoelectric actuation beam.

[0088] Example 16 includes the subject matter of any one of Examples 10 to

15, wherein actuating the one or more piezoelectric actuation beams includes applying a gradually increasing voltage to the one or more piezoelectric actuation beams.

[0089] Example 17 includes the subject matter of Example 16, wherein applying the gradually increasing voltage is continued until an ultrasound image is produced by the ultrasound device indicating that the ultrasound transducer element is in contact with the intraluminal tissue surface.

[0090] Example 18 includes the subject matter of any one of Examples 10 to 17, wherein actuating the actuation mechanism includes monitoring a b-mode ultrasound image generated by the ultrasound device. [0091] Example 19 includes the subject matter of Example 18, wherein monitoring the b-mode ultrasound image includes analyzing image quality of the b-mode ultrasound image.

[0092] Example 20 includes the subject matter of Example 19, wherein the actuation of the actuation mechanism is controlled in part based on a result generated from analyzing the image quality.

[0093] Example 21 is an ultrasound device comprising a distal housing, an ultrasound transducer disposed within the distal housing, and an actuation mechanism disposed within the distal housing. The actuation mechanism is configured to transition from a non-actuated state to an actuated state to displace a portion of the distal housing to move the ultrasound transducer in a direction perpendicular to a longitudinal axis of the ultrasound device to achieve apposition with an intraluminal tissue.

[0094] Example 22 includes the subject matter of Example 21, wherein the actuation mechanism includes a plurality of piezoelectric actuators coupled to an actuation member forming an outer portion of the distal housing opposite the ultrasound transducer in the non-actuated state.

[0095] Example 23 includes the subject matter of Example 22, wherein each piezoelectric actuator of the plurality of piezoelectric actuators includes a composite beam structure formed by a piezoelectric layer and a passive mechanical structure.

[0096] Example 24 includes the subject matter of any one of Examples 22 to 23, wherein each piezoelectric actuator of the plurality of piezoelectric actuators forms a cantilevered beam including a piezoelectric element.

[0097] Example 25 includes the subject matter of Example 24, wherein the piezoelectric element is configured to induce a compressive strain on the cantilevered beam upon application of a voltage.

[0098] Example 26 includes the subject matter of any one of Examples 21 to 25, wherein the actuation mechanism includes a piezoelectric actuator disposed within a portion of the distal housing opposite the ultrasound transducer. [0099] Example 27 includes the subject matter of Example 26, wherein an outer surface of the piezoelectric actuator conforms with the distal housing in the non-actuated state.

[00100] Example 28 includes the subject matter of Example 26, wherein the piezoelectric actuator is a stacked piezoelectric structure including a plurality of alternating layers of piezoelectric materials.

[00101] Example 29 includes the subject matter of Example 28, wherein upon application of a voltage, the stacked piezoelectric structure expands along an axis perpendicular to the longitudinal axis of the ultrasound device.

[00102] Example 30 includes the subject matter of any one of Examples 21 to 29, wherein the actuation mechanism includes an inflatable actuator disposed within a portion of the distal housing opposite the ultrasound transducer.

[00103] Example 31 includes the subject matter of Example 30, further comprising a control lumen configured to deliver a fluid or a gas to the inflatable actuator.

[00104] Example 32 includes the subject matter of Example 31, further comprising a syringe coupled to the control lumen to control fluid or gas delivery to the inflatable actuator.

[00105] Example 33 includes the subject matter of any one of Examples 30 to

32, wherein the inflatable actuator is configured to expand at least along an axis perpendicular to the longitudinal axis of the ultrasound device upon delivery of a pressurized fluid or gas.

[00106] Example 34 includes the subject matter of any one of Examples 21 to

33, wherein the actuation mechanism includes a bias member and control structure disposed within a portion of the distal housing opposite the ultrasound transducer.

[00107] Example 35 includes the subject matter of Example 34, wherein the bias member is selected from a group of bias members including a coil spring, a circular elastomer, and a shape memory alloy.

[00108] Example 36 includes the subject matter of any one of Examples 34 to 35, wherein the control structure includes a control wire configured to compress and release the bias member. [00109] Example 37 includes the subject matter of any one of Examples 34 to 36, wherein the actuation mechanism includes a control lumen extending through at least a portion of the ultrasound device to route the control structure to a user interface.

[00110] Example 38 includes the subject matter of Example 37, wherein the user interface includes a control knob coupled to a control reel to tension the control structure.

[00111] Example 39 includes the subject matter of any one of Examples 21 to 38, wherein the actuation mechanism includes a spring wire actuator coupled to the ultrasound transducer via a first control wire and to an actuation member via a second control wire.

[00112] Example 40 includes the subject matter of Example 39, wherein, upon actuation, the first control wire biases the ultrasound transducer in a first direction perpendicular to the longitudinal axis and the second control wire biases the actuation member in a second direction perpendicular to the longitudinal axis, wherein the first direction is opposite the second direction.

[00113] Example 41 includes the subject matter of any one of Examples 21 to 40, wherein the actuation mechanism includes a stylet actuator coupled to an actuation member.

[00114] Example 42 includes the subject matter of Example 41, wherein the actuation mechanism includes a control lumen to route a stylet of the stylet actuator from a user interface element to the actuation member.

[00115] Example 43 includes the subject matter of Example 42, wherein the actuation mechanism is transitioned from the non-actuated state to an actuated state by extension of the stylet through the control lumen.

[00116] Example 44 includes the subject matter of Example 43, wherein extension of the stylet results in movement of the actuation member in a direction perpendicular to the longitudinal axis.

[00117] Example 45 is a method for achieving apposition of an ultrasound transducer with an intraluminal tissue. The method comprises inserting a sampling device including the ultrasound transducer into a lumen, advancing the sampling device within the lumen to position the ultrasound transducer adjacent a target portion of the intraluminal tissue, and analyzing output from the ultrasound transducer to determine whether apposition of an emission surface of the ultrasound transducer and the intraluminal tissue surface has been achieved. Upon determining a lack of apposition, the method includes actuating an actuation mechanism within a housing at a distal end of the sampling device containing the ultrasound transducer, wherein actuating the actuation mechanism includes expanding an element of the housing to shift the ultrasound transducer towards the intraluminal tissue surface. The method further comprises analyzing output from the ultrasound transducer to confirm apposition between the emission surface and the intraluminal tissue surface.

[00118] Example 46 includes the subject matter of Example 45, wherein actuating the actuation mechanism includes applying a voltage to a piezoelectric actuator.

[00119] Example 47 includes the subject matter of Example 46, wherein applying a voltage to a piezoelectric actuator includes applying a first voltage to a first piezoelectric actuator and a second voltage to a second piezoelectric actuator.

[00120] Example 48 includes the subject matter of Example 47, wherein actuating the actuation mechanism includes angling the element of the housing by applying the first voltage greater than the second voltage.

[00121] Example 49 includes the subject matter of Example 46, wherein applying the voltage includes applying the voltage to a plurality of piezoelectric layers in a stacked piezoelectric actuator.

[00122] Example 50 includes the subject matter of Example 46, wherein analyzing the output from the ultrasound transducer includes monitoring the output during the actuating the actuation mechanism.

[00123] Example 51 includes the subject matter of Example 50, wherein monitoring the output includes providing feedback to a control circuit that regulates the voltage applied to the piezoelectric actuator.

[00124] Example 52 includes the subject matter of Example 51, wherein regulating the voltage applied includes ramping the voltage incrementally until the feedback indicates a quality image is being output from the ultrasound transducer.

Claims

CLAIMS What is claimed is:

1. An ultrasound imaging device including an actuated transducer comprising a transducer and an actuator configured to shift a position of the transducer relative to a distal portion of a housing of the ultrasound imaging device into apposition with tissue of a patient.

2. An endobronchial ultrasound device comprising: a distal tip housing; a transducer element disposed within the distal tip housing; and one or more actuation beams coupled to the transducer element opposite an emission surface of the transducer element, the one or more actuation beams configured to displace the transducer element out of the distal tip housing.

3. An ultrasound device, comprising: a distal tip body; an ultrasound transducer element disposed within the distal tip body, wherein in a non-actuated state an outer surface of the ultrasound transducer element is flush with an outer profile of the distal tip body; and one or more piezoelectric actuation beams coupled to the ultrasound transducer element, wherein the one or more piezoelectric actuation beams are configured to actuate the ultrasound transducer element from the non-actuated state to an actuated state in which the ultrasound transducer element protrudes outward from the outer profile of the distal tip body.

4. The ultrasound device of claim 3, wherein in the non-actuated state, there is an airgap between the outer surface of the ultrasound transducer element and an intraluminal tissue surface, and in the actuated state, the outer surface of the ultrasound transducer element is extended outward into contact with the intraluminal tissue surface to enhance acoustic transmission and resulting image quality.

5. The ultrasound device of claim 3, wherein the one or more piezoelectric actuation beams comprise a thin film actuator having a piezoelectric film disposed on a surface of an actuator plate.

6. The ultrasound device of claim 5, wherein activation of the piezoelectric film generates one of tensile stress and compressive stress to induce bending of the actuator plate.

7. The ultrasound device of claim 3, wherein the ultrasound transducer element comprises one of a pMUT and a poly-cMUT.

8. The ultrasound device of claim 3, wherein the distal tip body houses a sampling needle configured to extract a tissue sample.

9. The ultrasound device of claim 3, wherein the ultrasound device comprises an endobronchial ultrasound device configured for insertion into an airway.

10. A method for imaging an intraluminal tissue surface, the method comprising: providing an ultrasound device including an ultrasound transducer element disposed with a distal end of the ultrasound device and an actuation mechanism including one or more piezoelectric actuation beams coupled to the ultrasound transducer element; inserting the distal end of the ultrasound device into a lumen; advancing the distal end within the lumen towards a target tissue; actuating the one or more piezoelectric actuation beams within the actuation mechanism to move the ultrasound transducer element from a nonactuated state to an actuated state in which the ultrasound transducer element protrudes outward from an outer profile of the distal end and contacts an intraluminal tissue surface; and generating ultrasound images of the intraluminal tissue surface using signals from the ultrasound transducer element.

11. The method of claim 10, wherein the providing the ultrasound device includes the actuation mechanism being in a non-actuated state where the ultrasound transducer element is flush with an outer profile of the distal end.

12. The method of claim 10, further comprising: extracting a tissue sample from the intraluminal tissue surface using a sampling needle housed in the distal end.

13. The method of claim 10, wherein the inserting the distal end of the ultrasound device into the lumen includes entering an airway passage.

14. The method of claim 10, wherein actuating the one or more piezoelectric actuation beams includes applying a voltage to a piezoelectric film.

15. The method of claim 10, wherein actuating the one or more piezoelectric actuation beams includes applying a first voltage to a first piezoelectric actuation beam and a second voltage to a second piezoelectric actuation beam.

16. The method of claim 10, wherein actuating the one or more piezoelectric actuation beams includes applying a gradually increasing voltage to the one or more piezoelectric actuation beams.

17. The method of claim 16, wherein the applying the gradually increasing voltage is continued until an ultrasound image is produced by the ultrasound device indicating that the ultrasound transducer element is in contact with the intraluminal tissue surface.

18. The method of claim 10, wherein actuating the actuation mechanism includes monitoring a b-mode ultrasound image generated by the ultrasound device.

19. The method of claim 18, wherein monitoring the b-mode ultrasound image includes analyzing image quality of the b-mode ultrasound image.

20. The method of claim 19, wherein the actuation of the actuation mechanism is controlled in part based on a result generated from the analyzing the image quality.

21. An ultrasound device, comprising: a distal housing; an ultrasound transducer disposed within the distal housing; and an actuation mechanism disposed within the distal housing, the actuation mechanism configured transition from a non-actuated state to an actuated state to displace a portion of the distal housing to move the ultrasound transducer in a direction perpendicular to a longitudinal axis of the ultrasound device to achieve apposition with an intraluminal tissue.

22. The ultrasound device of claim 21, wherein the actuation mechanism includes a plurality of piezoelectric actuators coupled to an actuation member forming an outer portion of the distal housing opposite the ultrasound transducer in the non-actuated state.

23. The ultrasound device of claim 22, wherein each piezoelectric actuator of the plurality of piezoelectric actuators includes a composite beam structure formed by a piezoelectric layer and a passive mechanical structure.

24. The ultrasound device of any one of claims 22 and 23, wherein each piezoelectric actuator of the plurality of piezoelectric actuators forms a cantilevered beam including a piezoelectric element.

25. The ultrasound device of claim 24, wherein the piezoelectric element is configured to induce a compressive strain on the cantilevered beam upon application of a voltage.

26. The ultrasound device of claim 21, wherein the actuation mechanism includes a piezoelectric actuator disposed within a portion of the distal housing opposite the ultrasound transducer.

27. The ultrasound device of claim 26, wherein an outer surface of the piezoelectric actuator conforms with the distal housing in the non-actuated state.

28. The ultrasound device of claim 26, wherein the piezoelectric actuator is a stacked piezoelectric structure including a plurality of alternating layers of piezoelectric materials.

29. The ultrasound device of claim 28, wherein upon application of a voltage, the stacked piezoelectric structure expands along an axis perpendicular to the longitudinal axis of the ultrasound device.

30. The ultrasound device of claim 21, the actuation mechanism includes an inflatable actuator disposed within a portion of the distal housing opposite the ultrasound transducer.

31. The ultrasound device of claim 30, further comprising a control lumen configured to deliver a fluid or a gas to the inflatable actuator.

32. The ultrasound device of claim 31, further comprising a syringe coupled to the control lumen to control fluid or gas delivery to the inflatable actuator.

33. The ultrasound device of any one of claims 30 to 32, wherein the inflatable actuator is configured to expand at least along an axis perpendicular to the longitudinal axis of the ultrasound device upon delivery of a pressurized fluid or gas.

34. The ultrasound device of claim 21, the actuation mechanism includes a bias member and control structure disposed within a portion of the distal housing opposite the ultrasound transducer.

35. The ultrasound device of claim 34, wherein the bias member is selected from a group of bias members including: a coil spring; a circular elastomer; and a shape memory alloy.

36. The ultrasound device of any one of claims 34 and 35, wherein the control structure includes a control wire configured to compress and release the bias member.

37. The ultrasound device of any one of claims 34 to 36, wherein the actuation mechanism includes a control lumen extending through at least a portion of the ultrasound device to route the control structure to a user interface.

38. The ultrasound device of claim 37, wherein the user interface includes a control knob coupled to a control reel to tension the control structure.

39. The ultrasound device of claim 21, the actuation mechanism includes a spring wire actuator coupled to the ultrasound transducer via a first control wire and to an actuation member via a second control wire.

40. The ultrasound device of claim 39, wherein, upon actuation, the first control wire biases the ultrasound transducer in a first direction perpendicular to the longitudinal axis and the second control wire biases the actuation member in a second direction perpendicular to the longitudinal axis, wherein the first direction is opposite the second direction.

41. The ultrasound device of claim 21, the actuation mechanism includes a stylet actuator coupled to an actuation member.

42. The ultrasound device of claim 41, wherein the actuation mechanism includes a control lumen to route a stylet of the stylet actuator from a user interface element to the actuation member.

43. The ultrasound device of claim 42, wherein the actuation mechanism is transitioned from the non-actuated state to an actuated state by extension of the stylet through the control lumen.

44. The ultrasound device of claim 43, wherein extension of the stylet results in movement of the actuation member in a direction perpendicular to the longitudinal axis.

45. A method for achieving apposition of an ultrasound transducer with an intraluminal tissue, the method comprising: inserting a sampling device including the ultrasound transducer into a lumen; advancing the sampling device within the lumen to position the ultrasound transducer adjacent a target portion of the intraluminal tissue; analyzing output from the ultrasound transducer to determine whether apposition of an emission surface of the ultrasound transducer and a surface of the intraluminal tissue has been achieved; upon determining a lack of apposition, actuating an actuation mechanism within a housing at a distal end of the sampling device containing the ultrasound transducer, wherein actuating the actuation mechanism includes expanding an element of the housing to shift the ultrasound transducer towards the surface of the intraluminal tissue; and analyzing output from the ultrasound transducer to confirm apposition between the emission surface and the surface of the intraluminal tissue.

46. The method of claim 45, wherein the actuating the actuation mechanism includes applying a voltage to a piezoelectric actuator.

47. The method of claim 46, wherein the applying a voltage to a piezoelectric actuator includes applying a first voltage to a first piezoelectric actuator and a second voltage to a second piezoelectric actuator.

48. The method of claim 47, wherein the actuating the actuation mechanism includes angling the element of the housing by applying the first voltage greater than the second voltage.

49. The method of claim 46, wherein applying the voltage includes applying the voltage to a plurality of piezoelectric layers in a stacked piezoelectric actuator.

50. The method of claim 46, wherein the analyzing the output from the ultrasound transducer includes monitoring the output during the actuating the actuation mechanism.

51. The method of claim 50, wherein the monitoring the output includes providing feedback to a control circuit that regulates the voltage applied to the piezoelectric actuator.

52. The method of claim 51, wherein regulating the voltage applied includes ramping the voltage incrementally until the feedback indicates a quality image is being output from the ultrasound transducer.