阅读说明：本技术 用于形成侵入式可部署装置的方法 (Method for forming an invasive deployable device ) 是由 爱德华·达克鲁兹 吉安多纳托·史泰龙 弗拉维安·达洛兹 于 2021-04-27 设计创作，主要内容包括：本发明提供了用于可部署导管的换能器的各种方法和系统。在一个示例中,用于形成换能器的方法包括：在处于平面构型时,将声学叠堆耦接到形状记忆材料,以形成换能器；以及使形状记忆材料暴露于卷曲刺激,以将换能器调节到弯曲构型。(Various methods and systems are provided for a transducer of a deployable catheter. In one example, a method for forming a transducer includes: coupling the acoustic stack to a shape memory material to form a transducer when in a planar configuration; and exposing the shape memory material to a curling stimulus to adjust the transducer to a curved configuration.)

1. A method for forming a transducer, the method comprising:

coupling an acoustic stack to a shape memory material to form the transducer when in a planar configuration; and

exposing the shape memory material to a curling stimulus to adjust the transducer to a curved configuration.

2. The method of claim 1, further comprising exposing the shape memory material to a straightening stimulus to transition the shape memory material from the curved configuration to the planar configuration prior to coupling the acoustic stack to the shape memory material.

3. The method of claim 2, wherein exposing the shape memory material to the straightening stimulus comprises exposing the shape memory material to at least one of a physical stimulus, a chemical stimulus, or a biological stimulus.

4. The method of claim 2, wherein exposing the shape memory material to the crimping stimulus comprises exposing the shape memory material to the crimping stimulus to activate crimping of the shape memory material after exposing the shape memory material to the straightening stimulus and in the planar configuration.

5. The method of claim 4, wherein exposing the shape memory material to the curling stimulus comprises exposing the shape memory material to a stimulus that is the same or a different type than the straightening stimulus.

6. The method of claim 5, wherein a threshold value of the straightening stimulus above which straightening of the shape memory material is activated is above a range of the straightening stimulus applied on the shape memory material when inserted into a patient during data acquisition by the transducer.

7. The method of claim 2, wherein transitioning the shape memory material from the bent configuration to the planar configuration comprises reducing a stiffness of the shape memory material to enable transitioning from the bent configuration to the planar configuration, and restoring the stiffness of the shape memory material when in the planar configuration, and wherein returning the shape memory material from the planar configuration to the bent configuration comprises reducing the stiffness of the shape memory material to enable crimping of the shape memory material, and restoring the stiffness of the shape memory material when in the bent configuration.

8. The method of claim 1, wherein coupling the acoustic stack to the shape memory material comprises laminating at least one of a backing material, a flex circuit, a piezoelectric crystal, and a matching layer to a surface of the shape memory material.

9. The method of claim 1, wherein forming the transducer comprises cutting a plurality of cuts into the transducer while the shape memory material is in the planar configuration.

10. The method of claim 1, wherein forming the transducer comprises forming one of a matching layer and a backing layer from the shape memory material.

11. A transducer for a deployable catheter, the transducer comprising:

an acoustic stack coupled to a shape memory polymer, the shape memory polymer configured to transition between a first configuration and a second configuration in response to one or more stimuli.

12. The transducer of claim 11, wherein the first configuration is any of a folded, convex, concave, spiral, and circular geometry, and wherein the second configuration is planar.

13. The transducer of claim 11, further comprising a plurality of cuts cut into the transducer, and wherein the plurality of cuts extend into a portion of the height of the transducer.

14. The transducer of claim 11, wherein the shape memory polymer is coupled to an outward facing surface of one of a backing layer and a matching layer of the transducer.

15. The transducer of claim 11, wherein the shape memory polymer is one of a backing layer or a matching layer of the transducer.

16. The transducer of claim 11, wherein the shape memory polymer is positioned between any layers of the transducer.

17. The transducer of claim 11, wherein the transducer is a radial transducer having a field of view of up to 360 °.

18. A method for manufacturing a transducer, the method comprising:

adjusting a Shape Memory Polymer (SMP) to a planar configuration;

laminating a transducer component to the SMP while in the planar configuration;

cutting the transducer assembly; and

adjusting the SMP to a curved configuration to form the transducer with a wide field of view.

19. The method of claim 18, wherein adjusting the SMP to the curved configuration comprises adjusting the transducer to any one of a circular, folded, helical, convex, and concave conformation.

20. The method of claim 18, wherein adjusting the SMP to the curved configuration comprises transitioning the transducer to a geometry having a radius of curvature that enables the transducer to be encased within a deployable catheter.

Background

Invasive devices may be used to obtain information about tissues, organs, and other anatomical regions, which may be difficult to collect via external scanning or imaging techniques. The invasive device may be a deployable catheter that may be inserted intravenously into a patient. In one example, the device may be used for intracardiac echocardiography (ICE) imaging, wherein the device is introduced into the heart via, for example, the aorta, inferior vena cava, or jugular vein. The apparatus may include a transducer probe having a wide field of view (FOV) that allows the probe to obtain images in a three-dimensional environment.

Disclosure of Invention

In one embodiment, a method for forming a transducer includes: coupling the acoustic stack to a shape memory material to form a transducer when in a planar configuration; and exposing the shape memory material to a curling stimulus to adjust the transducer to a curved configuration. The shape memory material may be exposed to a straightening stimulus prior to exposure to the crimping stimulus to transition the shape memory material to a planar configuration. Thus, the transducer can be manufactured while in a planar geometry, allowing for increased accuracy during manufacturing relative to manufacturing the transducer on a curved substrate. In this way, a radial transducer with a wide field of view for a deployable invasive device can be prepared efficiently at low cost.

It should be appreciated that the brief description above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

Drawings

The invention will be better understood by reading the following description of non-limiting embodiments with reference to the attached drawings, in which:

FIG. 1 shows a block diagram of an exemplary imaging system including a deployable catheter.

Fig. 2 illustrates the deployable catheter of fig. 1 in more detail, including an exemplary imaging catheter tip and transducer for use with the system shown in fig. 1.

Fig. 3 illustrates internal components of an exemplary imaging catheter tip that may be included in the deployable catheter of fig. 2.

Fig. 4 is a schematic illustration of a cross-sectional view of the deployable catheter of fig. 2.

Fig. 5 is a first diagram illustrating a process for manufacturing a radial transducer that is fitted with a shape memory material and configured to be implemented in a deployable catheter.

Fig. 6 shows a first example of how a transducer adapted to a shape memory material may be cut.

Fig. 7 shows a second example of how a transducer adapted to a shape memory material may be cut.

FIG. 8 illustrates a first arrangement of transducer layers adapted with a shape memory material.

FIG. 9 illustrates a second arrangement of transducer layers adapted with a shape memory material.

FIG. 10 illustrates a third arrangement of transducer layers adapted with a shape memory material.

FIG. 11 shows an example of a convex radial transducer adapted with a shape memory material.

FIG. 12 shows an example of a concave radial transducer adapted with a shape memory material.

Fig. 13 is a second diagram illustrating the transducer being adapted with the SMP being transitioned to an alternative configuration.

FIG. 14 is an example of a method for fabricating a radial transducer adapted with an SMP.

FIG. 15 shows a third example of how a transducer adapted with a shape memory material may be cut.

Detailed Description

The following description relates to various embodiments of deployable invasive devices, such as deployable catheters. Deployable catheters may be included in imaging systems to be inserted into a patient to obtain information about internal tissues and organs. An example of an imaging system equipped with a deployable catheter is shown in fig. 1. A side view of the deployable catheter is depicted in fig. 2, and the internal components of the deployable catheter are shown in fig. 3. A cross-sectional view of a deployable catheter is shown in schematic form in fig. 4. The deployable catheter may include a radial transducer adapted with a shape memory material. The shape memory material may enable the transducer to transition between a first shape and a second shape during a manufacturing process in which the transducer is manufactured, as shown in fig. 5. In fig. 14, the manufacturing process is further described in an example of a method for forming a radial transducer. The manufacturing process may include cutting (e.g., dicing) the transducer, wherein the cutting may be precisely controlled by adjusting the transducer to a planar configuration through the shape memory material. Examples of how the transducer may be cut are shown in fig. 6 and 7, and are further shown in fig. 15, along with an alternative positioning of the shape memory material. Incorporating shape memory materials into the transducer may also allow for varying the positioning of the shape memory material within the acoustic stack of the transducer, as shown in fig. 8-10. The radial transducers may be implemented as 360 ° field of view (FOV) transducers, but may have alternative configurations in other examples, such as convex transducers as shown in fig. 11 and convex transducers as shown in fig. 12. The manufacturing process may also be applied to non-radial transducers that utilize shape memory materials to adjust the footprint of the transducer, as shown in the second diagram in FIG. 13.

Fig. 1-13 and 15 show exemplary configurations with relative positioning of various components. In at least one example, such elements may be referred to as being in direct contact or directly coupled to each other, if shown as being in direct contact or directly coupled, respectively. Similarly, elements that abut or are adjacent to each other may, at least in one example, abut or be adjacent to each other, respectively. For example, components disposed in coplanar contact with each other may be referred to as coplanar contacts. As another example, in at least one example, elements that are positioned spaced apart from one another and have only space therebetween without other components may be referenced as so described. As another example, elements shown as being above/below one another, on opposite sides of one another, or between left/right sides of one another may be so described with reference to one another. Further, as shown, in at least one example, a topmost element or point of an element can be referred to as a "top" of a component, and a bottommost element or point of an element can be referred to as a "bottom" of the component. As used herein, top/bottom, upper/lower, above/below may be with respect to the vertical axis of the figure, and may be used to describe the positioning of elements in the figure with respect to each other. Thus, in one example, an element shown as being above another element is positioned vertically above the other element. As another example, the shapes of elements shown in the figures may be referred to as having these shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, etc.). Further, in at least one example, elements that are shown as intersecting one another can be referred to as intersecting elements or intersecting one another. Additionally, in one example, an element shown as being within another element or shown as being outside another element may be referred to as being so described.

Medical imaging techniques such as endoscopic ultrasound imaging may be used to obtain real-time data about a patient's tissues, organs, blood flow, and the like. However, it may be difficult to obtain high resolution images such as the lumen of tissues and organs that provide a complete view of a three dimensional environment by using a transducer probe with a linear array. In such cases, a deployable catheter equipped with a radial transducer probe may be inserted into a patient and guided to a target site. The radial transducer probe may have a field of view (FOV) of up to 360 °, providing full visualization of the target anatomical region that can be easily interpreted by the operator. The radial transducer probe may include a curved configuration of one or more transducer arrays of the probe. The curved configuration may include one or more transducer arrays having a non-planar geometry (e.g., bent, semi-circular, spiral, concave, convex, folded, etc.).

The deployable catheter may have a small diameter to allow the catheter to pass intravenously through the patient. Thus, the outer diameter of the radial transducer probe may be no greater than the desired outer diameter of the deployable catheter. However, manufacturing transducers with small radii of curvature may require cumbersome tooling and complex manipulation of transducer components. Furthermore, controlling the thickness of the adhesive used to laminate the component to the curved substrate can be challenging. Thus, the manufacturing process can be expensive and time consuming.

In one example, the above-described problems may be at least partially addressed by incorporating a shape memory material into a transducer of a deployable catheter. The shape memory material may be a Shape Memory Polymer (SMP) configured to alternate between at least two different shapes. In this way, the SMP can be tuned to a conformation that simplifies manufacturing the transducer, and then returned to a geometry that allows the transducer to obtain high quality data when deployed in a patient.

Turning now to fig. 1, a block diagram of an exemplary system 10 for medical imaging is shown. It should be understood that while described herein as an ultrasound imaging system, system 10 is a non-limiting example of an imaging system that may utilize a deployable device to obtain medical images. Other examples may include incorporation of other types of invasive probes, such as endoscopes, laparoscopes, surgical probes, intracavity probes, and the like. The system 10 may be configured to facilitate acquisition of ultrasound image data from a patient 12 via an imaging catheter 14. For example, the imaging catheter 14 may be configured to acquire ultrasound image data representative of a region of interest within the patient 12, such as a cardiac or pulmonary region. In one example, the imaging catheter 14 may be configured to function as an invasive probe. Reference numeral 16 designates a portion of the imaging catheter 14 disposed within the body of the patient 12, such as for insertion into a vein. Reference numeral 18 designates a portion of the imaging catheter 14 depicted in more detail in fig. 2.

The system 10 may also include an ultrasound imaging system 20 operatively associated with the imaging catheter 14 and configured to facilitate acquisition of ultrasound image data. It should be noted that while the exemplary embodiments shown below are described in the context of a medical imaging system, such as an ultrasound imaging system, other imaging systems and applications are also contemplated (e.g., industrial applications such as non-destructive testing, borescopes, and other applications that may use ultrasound imaging within a confined space). In addition, the ultrasound imaging system 20 may be configured to display an image indicative of the current position of the imaging catheter tip within the patient 12. As shown in fig. 1, the ultrasound imaging system 20 may include a display area 22 and a user interface area 24. In some examples, the display area 22 of the ultrasound imaging system 20 may be configured to display a two-dimensional image or a three-dimensional image generated by the ultrasound imaging system 20 based on image data acquired via the imaging catheter 14. For example, the display area 22 may be a suitable CRT or LCD display on which the ultrasound images may be viewed. The user interface region 24 may include an operator interface device configured to assist an operator in identifying a region of interest to be imaged. The operator interface may include a keyboard, mouse, trackball, joystick, touch screen, or any other suitable interface device.

Fig. 2 shows an enlarged view of the portion 18 of the imaging catheter 14 shown in fig. 1. As shown in fig. 2, the imaging catheter 14 may include a tip 26 on the distal end of a flexible shaft 28. The catheter tip 26 may house a transducer and motor assembly. The transducer may include one or more transducer arrays, each transducer array including one or more transducer elements. The imaging catheter 14 may also include a handle 30 configured to facilitate manipulation of the flexible shaft 28 by an operator.

An example of the catheter tip 26 of fig. 2 is shown in fig. 3. A set of reference axes 301 indicating the y-axis, x-axis and z-axis are provided. Catheter tip 26 may have a housing 302 that surrounds a transducer 304, which may include at least one transducer array 306, a capacitor 308, and a catheter cable 310. In one example, the transducer 304 may be a radial transducer having a curved outer geometry. For example, the cross-section of the transducer taken along the x-y plane may be circular or semi-circular, or other curved configurations, such as helical, slightly curved, and the like. Other components not shown in fig. 3 may also be enclosed within the housing 302, such as, for example, a motor holder, a thermistor, and an optional lens. Further, in some examples, catheter tip 26 may include a system for filling the tip with a fluid (such as an acoustic coupling fluid).

The transducer array 306 has several layers stacked along the y-axis and extending along the x-z plane. One or more layers of the transducer array 306 may be layers of transducer elements 312. In one example, the transducer elements 312 may be piezoelectric elements, where each piezoelectric element may be a mass formed of a natural material (such as quartz) or a synthetic material (such as lead zirconate titanate) that deforms and vibrates when a voltage is applied by, for example, a transmitter. In some examples, the piezoelectric element may be a single crystal having a crystal axis, the piezoelectric elementsSuch as lithium niobate and PMN-PT (Pb (Mg)_1/3Nb_2/3)O₃–PbTiO₃). The vibration of the piezoelectric element generates an ultrasonic signal formed by ultrasonic waves emitted from the catheter tip 26. The piezoelectric element may also receive ultrasonic waves (such as ultrasonic waves reflected from a target object) and convert the ultrasonic waves into a voltage. The voltages may be transmitted to a receiver of the imaging system and processed into an image.

An acoustic matching layer 314 may be positioned over the transducer elements 312. The acoustic matching layer 314 may be a material positioned between the transducer elements 312 and a target object to be imaged. By disposing the acoustic matching layers 314 therebetween, the ultrasonic waves may first pass through the acoustic matching layers 314 and be emitted out of the acoustic matching layers 314 in phase, thereby reducing the likelihood of reflection at the target object. The acoustic matching layer 314 may shorten the pulse length of the ultrasound signal, thereby increasing the axial resolution of the signal.

The layer formed by the acoustic matching layer 314 and the transducer elements 312 may be cut along at least one of the y-x plane and the y-z plane to form individual acoustic stacks 316. Each of the acoustic stacks 316 may be electrically isolated from adjacent acoustic stacks 316, but may all be coupled to a common layer positioned below or above the transducer element 312 relative to the y-axis.

Circuitry 318 may be layered below transducer elements 312 with respect to the y-axis. In one example, the circuit can be at least one Application Specific Integrated Circuit (ASIC)318 in direct contact with each of the acoustic stacks 316. Each ASIC 318 may be coupled to one or more flexible circuits 317, which may extend continuously between the transducer array 306 and the catheter cable 310. The flex circuit 317 may be electrically coupled to the catheter cable 310 to enable transmission of electrical signals between the transducer array 306 and an imaging system (e.g., the imaging system 20 of fig. 1). The electrical signal may be tuned by the capacitor 308 during transmission.

The acoustic backing layer 320 can be disposed below the ASIC 318 with respect to the z-axis. In some examples, as shown in fig. 3, the backing layer 320 may be a continuous layer of material extending along the x-z plane. The backing layer 320 may be configured to absorb and attenuate backscattered waves from the transducer elements 312. The bandwidth and axial resolution of the acoustic signals produced by the transducer elements 312 may be increased by the backing layer 320.

As described above, the transducer 304, the capacitor 308, and the catheter cable 310 may be enclosed within the housing 302. Thus, the size (e.g., diameter or width) of the components may be determined by the inner diameter of the housing 302. The inner diameter of the housing 302 may, in turn, be determined by the outer diameter of the housing 302 and the desired thickness. The outer diameter of the housing 302 may be constrained by the region of the patient's body into which the imaging catheter is inserted. For example, the imaging catheter may be an intracardiac echocardiography (ICE) catheter for obtaining images of cardiac structures and blood flow within the heart of a patient.

The imaging catheter may be introduced into the heart through the aorta, inferior vena cava, or jugular vein. In some cases, the imaging catheter may be fed through regions of narrower diameter, such as the coronary sinus, tricuspid valve, and pulmonary artery. Thus, the outer diameter of the imaging catheter may be no greater than 10Fr or 3.33 mm. The outer diameter and corresponding inner diameter of the imaging catheter housing are shown in fig. 4 in cross-section 400 of housing 302 of catheter tip 26 taken along line a-a' shown in fig. 3.

As shown in fig. 4, an outer surface 402 of the housing 302 of the imaging catheter may be spaced apart from an inner surface 404 of the housing 302 by a thickness 406 of the housing 302. The thickness 406 of the housing 302 may be optimized to provide the housing 302 with a targeted degree of structural stability (e.g., resistance to deformation) that is balanced with flexibility (e.g., ability to bend when force is applied). In one example, the outer diameter 408 of the housing 302 may be 3.33mm, the thickness 406 may be 0.71mm, and the inner diameter 410 of the housing 302 may be 2.62 mm. In other examples, the outer diameter of the housing may be between 2mm-5mm, the thickness may be between 0.24mm-1mm, and the inner diameter may be between 1mm-4 mm. In other examples, the imaging catheter may have a variety of sizes depending on the application. For example, the endoscope may have an outer diameter of 10mm-12 mm. It is understood that the imaging catheter may have various diameters and sizes without departing from the scope of the present disclosure.

The inner surface 404 of the housing 302 may include a circular protrusion 412 that protrudes into an internal volume or cavity 414 of the housing 302. The lobes 412 may be semi-circular shaped lobes, each of which encloses a separate lumen 416 for receiving steering wires of an imaging catheter. The arrangement of the transducer 304 of the imaging catheter within the lumen 414 of the housing 302 is indicated by the dashed circle. The maximum outer diameter 418 of the transducer 304 may be determined based on the distance between the innermost points of the oppositely disposed lobes 412. Thus, the outer diameter 418 of the transducer 304 may be less than the inner diameter 410 of the housing 302. In some examples, the imaging catheter may not have a steering wire, and the lobe 412 may be omitted. In such cases, the outer diameter 418 of the transducer 304 may be similar to the inner diameter 410 of the housing 302.

The circular geometry of the transducer can cause difficulties during the manufacturing process. For example, laminating the acoustic layer in a circular conformation can result in uneven application of adhesive, which can adversely affect transducer performance. Cutting the acoustic stack in a circular conformation can result in low precision and/or demanding use of expensive and complex instruments. However, ease and efficiency of radial transducer fabrication can be achieved by configuring the transducer with a shape memory material. The shape memory material may be a Shape Memory Polymer (SMP) configured to mechanically respond to one or more stimuli. Examples of SMPs include linear block copolymers such as polyurethanes, polyethylene terephthalates, polyethylene oxides, and other thermoplastic polymers (such as polynorbornenes). In one example, the SMP may be a powder mixture of silicone and tungsten in an acrylic resin.

SMPs can be stimulated by physical stimuli (such as temperature, moisture, light, magnetic energy, electricity, etc.), chemical stimuli (such as chemicals, pH levels, etc.), and biological stimuli (such as the presence of glucose and enzymes). When applied to an imaging catheter, the transducer may incorporate an SMP such that the shape of the transducer can change upon exposure to at least one stimulus. SMPs can have physical properties as provided in table 1 below, which can provide more desirable properties than other types of shape memory materials, such as shape memory alloys. For example, the SMP can have a higher elastic deformability, lower cost, lower density, and greater biocompatibility and biodegradability. In particular, the lower cost of SMP may be desirable for applications in disposable deployable catheters.

Table 1. Physical characteristics of shape memory polymers

In one example, the SMP can have two-way shape memory, such that the SMP can be tuned between two shapes without reprogramming or application of external forces. For example, the SMP may transition to a temporary shape in response to a first stimulus and revert to a permanent shape in response to a second stimulus. The first and second stimuli may be the same or different types of stimuli, for example, the first stimulus may be a high temperature and the second stimulus may be a low temperature, or the first stimulus may be a humidity level and the second stimulus may be a threshold temperature. The two-way shape memory behavior is neither mechanically nor structurally constrained, allowing the SMP to switch between a temporary shape and a permanent shape without the application of external forces. In this way, the SMP can be tuned to a conformation that is more conducive to assembly of the radial transducer, and returned to a radial geometry for deployment.

For example, the fabrication of a radial transducer is shown in fig. 14 in an example of a method 1400 for fabricating a transducer. Method 1400 may be implemented by one or more machines, such as a machine configured for cutting and/or grinding. The machine may include instructions stored in the memory that can be executed by the processes or to implement various steps. In detail, at least some of the method steps may be implemented as automated machine processes. However, in other examples, at least some of the steps may be performed in response to user input, or may be performed manually via a manufacturing person. The manufacturing process is further illustrated in a first diagram 500 in fig. 5.

At 1402, the method includes machining the SMP to a desired geometry. The SMP can be a circular configuration, which can be a permanent configuration of the SMP. For example, at a first step 501 of diagram 500 of fig. 5, the SMP502 is in a continuous circular configuration. The SMP502 may be a block of rigid two-way shape memory material provided as, for example, a tube having a thickness (e.g., the difference between the outer diameter and the inner diameter of the tube) between 200 μm and 5 mm. The tube may be cut into desired segments, for example, along the z-axis into segments that conform to the desired azimuthal aperture of the transducer. At a second step 503, the SMP502 is cut to form a gap 504 in the SMP502 such that the SMP502 is no longer continuous. The gap 504 may be, for example, between 20 μm to 40 μm wide.

Returning to fig. 14, at 1404 the method includes adjusting the SMP to a planar configuration. For example, as shown in FIG. 5, the SMP502 may be programmed to be exposed to a first stimulus S at the SMP502₁Then, the transition to the second temporary shape is made at a third step 505 of the diagram 500. First stimulus S₁Can be a straightening stimulus, e.g., causing the SMP502 to straighten, and can be a variety of stimuli, including humidity, temperature, UV light, and the like. In response to a first stimulus S₁The SMP502 may become planar, e.g., parallel and aligned with the x-z plane.

For example, the SMP502 is being exposed to a first stimulus S₁The transition behavior may include the SMP502 transitioning from a rigid material to a pliable material and automatically becoming flat once sufficiently pliable. Upon transitioning to the planar configuration shown at third step 505, the SMP502 may return to the initial stiffness. The SMP502 may be ground to a desired thickness, such as, for example, 700 μm, while in a planar configuration. In other examples, the thickness of the SMP502 may be between 200 μm to 5 mm. Grinding of the SMP502 may also adjust texture, e.g., roughness, of the surface of the SMP 502.

At 1406 of the method 1400 shown in fig. 14, the transducer can be assembled by coupling the acoustic stack to the SMP. For example, as shown at fourth step 507 in fig. 5, an acoustic stack 506 comprising a backing layer, a flexible printed circuit board, one or more piezoceramic layers, and a matching layer may be laminated to one face of the SMP 502. Laminating the acoustic stack 506 onto the SMP502 forms a transducer 508 that can be implemented in a deployable catheter.

At 1408 of fig. 14, the transducer is cut or diced. For example, as shown at fifth step 509 in fig. 5, the acoustic stack 506 is cut to form a plurality of cuts 510 extending through the acoustic stack 506 along the y-axis, the plurality of cuts dividing the acoustic stack 506 into individual transducer elements 512. The acoustic stack 506 may be cut by various techniques including, for example, scribing and breaking, mechanical sawing, or laser cutting. Variations of the cutting of the transducer to produce different cut configurations are described further below with reference to fig. 6-7 and 15. Thus, the transducer 508 may include at least one array of transducer elements 512.

Turning again to fig. 14, at 1410 the method includes returning the SMP to a radial (e.g., circular) configuration. The method then ends. For example, at the sixth step 511 of fig. 5, the transducer 508 is exposed to the second stimulus S₂. The second stimulus may be a curling stimulus, for example, causing the SMP to curl or bend. In response to a second stimulus S₂The SMP502 returns to a permanent circular configuration. The transducer elements 512 may be positioned along an outer surface of the SMP502 in a circular configuration, e.g., with the transducer elements 512 facing outward. Thus, when adjusted to the permanent configuration, the transducer 508 may have a 360 ° FOV.

SMP502 is exposed to a second stimulus S₂The transition behavior may include softening the SMP502 to become more flexible. Upon softening, the planar SMP502 may automatically curl and return to a circular configuration. In the circular configuration, the SMP502 may return to a rigid state.

Second stimulus S₂May be associated with the first stimulus S₁The same or different types. For example, the first stimulus S₁And a second stimulus S₂All can be temperature, wherein the first stimulus S₁Is higher than the second stimulus S₂The temperature of (2). Alternatively, as another example, the first stimulus S₁May be a temperature value above ambient temperature and the second stimulus S2 may be an elevated humidity level relative to ambient humidity. The stimulation threshold may be selected based on expected conditions when the deployable catheter is inserted into the patient. As an example, if based on temperature, the first stimulus S₁May be a temperature higher than the internal temperature of the patient to avoid transitioning the transducer to a planar configuration during deployment within the patient for data acquisition, such as imaging. As another example, a stimulus that the transducer will not be exposed to in the patient can be used to switch the SMP between geometries, such as UV light or chemical stimulus. At the other endIn an example, mechanical constraints can be used to maintain the shape of the SMP. The stimulus may be a type of physical stimulus that is easily controlled in the manufacturing environment, such as temperature, humidity, or UV light. However, the stimulus can be of various types, including chemical, biological, and physical stimuli.

As described above, the cutting of the transducer separates the transducer into transducer elements. By enabling cutting of the transducer in a planar configuration, the cutting of the acoustic stack can be tuned to a desired cut depth. For example, as shown in fig. 6, a first example cut 600 of the transducer 508 of fig. 5 may include a plurality of cuts 510 extending through a portion of the height 602 of the acoustic stack 506 of the transducer 508.

The acoustic stack 506 may be formed from an acoustic layer, including a matching layer 604, one or more piezoelectric crystals 606, a flex circuit (hereinafter referred to as a flexure) 608, and a backing layer 610 from the top to the bottom of the acoustic stack 506 with respect to the y-axis. The acoustic layers can be similar to those described above with respect to fig. 3, and can be coupled to each other and to the SMP502 via conventional methods such as lamination in a stack, coating, and the like. In the first example cut 600, the depth 612 of each cut of the plurality of cuts 510 is less than the height 602 of the acoustic stack 506. More specifically, the depth 612 of the plurality of slits 510 extends from the top of the acoustic stack 506 into the backing layer 610, but does not completely penetrate the backing layer 610.

In contrast, in the second example cut 700 of the transducer 508, the plurality of cuts may have a depth 702 that is different than the depth 612 of the plurality of cuts 510 shown in fig. 6. The depth 702 of the plurality of cuts 510 of the second example of cutting 700 is greater than the height 602 of the acoustic stack 506. More specifically, a plurality of cuts 510 extend from the top of the acoustic stack 506 through the bottom of the backing layer 610 and into a portion of the thickness 704 of the SMP 502.

While the transducer 508 is depicted in fig. 5-7, where the SMP502 is coupled to and in coplanar contact with an outward facing surface (e.g., a bottom surface, relative to the y-axis) of the backing layer 610, in other examples, the SMP502 may be positioned at an opposite side of the transducer 508. For example, as shown in fig. 15, the SMP may alternatively be coupled to and in coplanar contact with an outward-facing (e.g., top) surface of the matching layer 604. In such cases, the plurality of cuts 510 may extend from the bottom surface of the backing layer 610 up through a portion of the height 1502 of the transducer 508.

By varying the depth of the plurality of cuts 510, acoustic layer sharing between transducer elements 512 may be controlled. For example, in the first cutting example 600 of fig. 6, the backing layer 610 remains a continuous common layer in electrical communication with each of the transducer elements 512. However, in the second cut example of fig. 7, each transducer element 512 is electrically isolated from each other by having the plurality of cuts 510 extend completely through the height 602 of the acoustic stack 506. Thus, the electrical configuration of the transducer can be adjusted by cutting of the transducer, and can be easily controlled when the transducer is in a planar, flat configuration. In contrast, cutting the transducer when it is in a circular configuration can result in cutting inaccuracies, thereby reducing transducer performance.

It should be understood that the example of the cutting of the transducer shown in fig. 6 and 7 is a non-limiting example. Other examples may include the difference in depth of the plurality of cuts from the depth shown, non-uniform depth between the plurality of cuts, and non-uniform spacing of the plurality of cuts.

The SMP can be implemented in the transducer as a structural component (e.g., as shown in fig. 5-7) that serves as a backing substrate to which the acoustic stack is coupled, thereby changing the shape of the transducer as the SMP transitions from one geometry to another. However, in some examples, the SMP may be positioned between the acoustic layers rather than as a termination layer, e.g., arranged along the top or bottom of the acoustic stack. Further, in other examples, the SMP may be configured to act as an acoustic layer for the transducer and actively participate in the operation of the transducer probe. Examples of transducers showing variations in placement and implementation of SMPs are shown in fig. 9-11. For simplicity, the transducer is not shown cut, but may be cut as shown in fig. 6-7 and 15 or in other configurations.

As shown in fig. 8, a first arrangement of the transducer 800, as an alternative to the arrangement shown in fig. 5-7, may include a matching layer 802, one or more piezoelectric crystals 804, flexures 806, SMP 808, and backing layer 810 from the top to the bottom of the transducer 800 with respect to the y-axis. The SMP 808 is arranged as a layer between the flexure 806 and the backing layer 810, such that the flexure 806 can be coupled to a top surface of the SMP 808 and the backing layer 810 can be coupled to a bottom surface of the SMP 808. In this configuration, the SMP 808 may be formed from a material that is transparent to the data transmission source. For example, in an ultrasound probe, the SMP 808 may be a material that is electrically conductive and does not affect the transmission of ultrasound waves. Thus, SMP 808 does not affect signal transmission and data acquisition. Further, other examples may include SMP 808 disposed between any layers of transducer 800 (e.g., between flexure 806 and one of piezoelectric crystals 804, between one of piezoelectric crystals 804 and matching layer 802). As another example, the backing layer 810 can be disposed between the one or more piezoelectric crystals 804 and the flexure 806, and the SMP 808 can be positioned below the flexure 806 and coupled directly to the flexure.

Alternatively, as shown in fig. 9, in a second arrangement of the transducer 900, the SMP 902 may be configured as the backing layer of the transducer 900. The SMP 902 may be in coplanar contact with the flexure 806 and coupled to the bottom surface of the flexure 806. When implemented as the backing layer of the transducer 900, the SMP 902 may be formed of a material tuned at the desired frequency to maximize attenuation. For example, a higher density load such as tungsten powder, epoxy powder, silicone powder, etc. can be added to the polymer matrix of the SMP 902 to increase the damping characteristics of the SMP material.

In a third arrangement of transducer 1000, illustrated in fig. 10, SMP1002 may be configured as a matching layer for transducer 1000. The SMP1002 may form a top layer of the transducer 1000 in coplanar contact with and coupled to a top surface of one of the piezoelectric crystals 804. When implemented as a matching layer for transducer 1000, the material of SMP1002 may already have acoustic impedance characteristics, but the acoustic impedance of SMP1002 can be tuned by adding higher density loads such as tungsten powder, epoxy powder, silicone powder, and the like.

By enabling the radial transducer to be assembled while in a planar configuration, the positioning of the SMP in the transducer can be adjusted according to the desired application. The positioning of the SMP can be changed without the need to use additional, more complex tools, and the SMP can be implemented as an acoustic layer, thereby reducing the number of layers in the transducer and simplifying manufacturing. High precision fabrication of the transducer is achieved in each configuration, thereby preserving the performance of the transducer.

As previously described, in one example, the radial transducer may have a 360 ° FOV that is desired for applications such as endoscopic ultrasound imaging, breast imaging, and the like. In addition, other constellations of radial transducers may be formed by the process described above with reference to fig. 5-10. For example, a radial transducer with less than 360 ° can be fabricated with SMP as a structural backing and/or as an acoustic layer to control the shape of the transducer during fabrication. The radial transducers may be convex or concave transducers as shown in fig. 11-12.

An example of a convex transducer 1100 is shown in fig. 11. The convex transducer 1100 has a semi-circular geometry, such as a half circle, and the direction of signal transmission is indicated by arrow 1102. However, if the SMP 1104 is used as a matching layer for the convex transducer 110, the signal transmission direction may be opposite to that indicated by arrow 1102. The SMP 1104 may form the innermost layer of the convex transducer 1100. In other words, SMP 1104 may be closer to central axis of rotation 1106 and further away from the scanned target (e.g., the target area from which data is to be collected) of convex transducer 1100 than acoustic stack 1108 of convex transducer 1100. The acoustic stack 1108 may form the outer layer of a convex transducer and provide a 180 ° FOV. Convex transducers may be implemented in, for example, endoscopes and laparoscopes.

One example of a concave transducer 1200 is depicted in fig. 12. The concave transducer 1200 also has a semi-circular geometry and the direction of signal transmission is indicated by arrow 1202. The SMP 1204 may form the outermost layer of the concave transducer 1200. In other words, the SMP 1204 may be farther from the central axis of rotation 1206 of the concave transducer 12001106 and farther from the scan target than the acoustic stack 1208 of the concave transducer 1200. The concave transducer 1200 may have a narrower focal FOV than the convex transducer 1100 of fig. 11 and may be used for applications such as High Intensity Focused Ultrasound (HIFU).

Other examples of radial transducers that incorporate SMP to tune the transducer to a planar configuration during manufacturing may include transducers that form various portions of a circle. For example, the radial transducers may form a quarter circle, a three quarter circle in either a concave configuration or a convex configuration. The radial transducer may have a FOV anywhere between 10 ° to 360 °.

The manufacturing process for radial transducers described herein may also be applied to the manufacture of non-radial transducers, such as linear array transducers. For example, the transducer may be configured with an SMP to adjust the size and shape of the transducer between a first conformation that is more conducive to intravenous passage of the transducer when implemented in a deployable catheter and a second conformation that increases the active area of the transducer to enhance performance of the transducer.

For example, the transformation of the transducer 1302 between a first shape 1301 and a second shape 1303 is shown in the illustration 1300 of FIG. 13, where the second shape 1303 may be a folded shape. The transducer 1302 includes a first transducer array 1304 and a second transducer array 1306 connected by SMPs 1308. The SMP1308 can be incorporated into the transducer 1302 in a variety of configurations. For example, the SMP1308 may be a segment of shape memory material that extends between the first transducer array 1304 and the second transducer array 1306 and is coupled to an inner edge of the transducer arrays. Alternatively, the SMP1308 may form an acoustic layer of the transducer 1302, such as a backing layer or matching layer. As another example, the SMPs 1308 may be attached to one side of the transducer 1302 along an edge of each of the transducer regions and positioned outside of an active area of the transducer 1302, where the active area is defined as a total surface area of the transducer array facing in the same direction.

Regardless of the positioning of the SMP1308, the SMP1308 can be adjusted to a planar configuration to enable assembly and cutting of the transducer 1302. For example, the SMP1308 can be provided as a tube in a permanent conformation, as shown in fig. 5, and can be cut according to the desired shape of the SMP 1308. For example, the tube can be cut in half such that the SMP1308 has a semi-circular configuration. The SMP1308 may be exposed to a first stimulus S₁As described above with reference to fig. 5, to adjust the SMP1308 to a planar configuration. In a planar configuration, the transducer 1302 can be assembled and cut, which can include coupling the SMP1308 to one or more components of the acoustic stack, such as to an edge of a backing layer or matching layer, and/or laminating the acoustic stack to the SMP1308, and so forth. The assembled transducer 1302 may be in a first shape 1301.

When the transducer 1302 is assembled, the transducer 1302 may be exposed to a second stimulus S₂The second stimulus can be the same as the first stimulus S₁The same or different types. Exposure to the second stimulus may induce the SMP1308 to transform into a permanent semi-circular shape, which adjusts the transducer 1302 to a folded second shape 1303. In the second shape 1303, the active area of the transducer 1302 is reduced and the footprint of the transducer is reduced, thereby allowing the transducer 1302 to be inserted through a stenotic passageway, such as an artery or vein of a patient. When the transducer 1302 is deployed and reaches the target site, the transducer 1302 may be exposed to a first stimulus S₁To adjust the transducer 1302 to the first shape 1301 to increase the active area. In this way, the resolution, penetration, and data acquisition speed of the transducer 1302 may be improved.

It should be understood that the folded conformation of the transducer shown in fig. 13 is a non-limiting example of how the footprint of the transducer may be reduced. Other examples may include other shape variations than bending or folding. For example, the SMP can be crimped in at least one dimension into a roll core configuration and/or contracted.

In this way, the radial transducer can be manufactured with increased accuracy without the use of complex tools. The transducer may include an SMP incorporated as an inert layer or as an acoustic layer to adjust the geometry of the transducer in response to one or more stimuli. Thus, the transducer can be in a planar configuration during assembly of the transducer and return to a radial conformation when coupling of the acoustic stack to the SMP and cutting of the stack is complete. Thus, the yield of the manufacturing process can be increased while the arrangement of the transducers can be modified with high precision and consistency and at low cost.

The technical effect of adapting the radial transducer to the shape memory material is to simplify the high precision manufacturing of the radial transducer.

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments "comprising," "including," or "having" an element or a plurality of elements having a particular property may include additional such elements not having that property. The terms "including" and "in … are used as shorthand, language equivalents of the respective terms" comprising "and" wherein ". Furthermore, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements or a particular positional order on their objects.

The present disclosure also provides support for a method for forming a transducer, the method comprising: coupling the acoustic stack to a shape memory material to form a transducer when in a planar configuration; and exposing the shape memory material to a curling stimulus to adjust the transducer to a curved configuration. In a first example of the method, the method further comprises: prior to coupling the acoustic stack to the shape memory material, the shape memory material is exposed to a straightening stimulus to transition the shape memory material from a curved conformation to a planar configuration. In a second example of the method, optionally including the first example, exposing the shape memory material to a straightening stimulus comprises exposing the shape memory material to at least one of a physical stimulus, a chemical stimulus, or a biological stimulus. In a third example of the method, optionally including the first example and the second example, exposing the shape memory material to a curling stimulus includes exposing the shape memory material to a curling stimulus to activate curling of the shape memory material after exposing the shape memory material to a straightening stimulus and in the planar configuration. In a fourth example of the method, optionally including the first through third examples, exposing the shape memory material to a curling stimulus includes exposing the shape memory material to a stimulus that is the same or different type as the straightening stimulus. In a fifth example of the method, optionally including the first through fourth examples, a threshold of the straightening stimulus is above a range of straightening stimuli applied on the shape memory material when inserted into the patient during data acquisition by the transducer, above which threshold the straightening of the shape memory material is activated. In a sixth example of the method, optionally including the first through fifth examples, transitioning the shape memory material from the bent configuration to the planar configuration includes reducing a stiffness of the shape memory material to enable transitioning from the bent configuration to the planar configuration, and restoring the stiffness of the shape memory material when in the planar configuration, and wherein returning the shape memory material from the planar configuration to the bent configuration includes reducing the stiffness of the shape memory material to enable crimping of the shape memory material, and restoring the stiffness of the shape memory material when in the bent configuration. In a seventh example of the method, optionally including the first through sixth examples, coupling the acoustic stack to the shape memory material comprises laminating at least one of a backing material, a flexible circuit, a piezoelectric crystal, and a matching layer to a surface of the shape memory material. In an eighth example of the method, optionally including the first through seventh examples, forming the transducer comprises cutting a plurality of cuts into the transducer while the shape memory material is in the planar configuration. In a ninth example of the method, optionally including the first through eighth examples, forming the transducer comprises forming one of the matching layer and the backing layer from a shape memory material.

The present disclosure also provides support for a transducer for a deployable catheter, the transducer comprising: an acoustic stack coupled to a shape memory polymer configured to transition between a first configuration and a second configuration in response to one or more stimuli. In a first example of the system, the first configuration is any one of a folded, convex, concave, helical, and circular geometry, and wherein the second configuration is planar. In a second example of the system, optionally including the first example, the system further comprises: a plurality of cuts cut into the transducer, and wherein the plurality of cuts extend into a portion of the height of the transducer. In a third example of the system, optionally including the first and second examples, the shape memory polymer is coupled to an outward facing surface of one of a backing layer and a matching layer of the transducer. In a fourth example of the system, optionally including the first through third examples, the shape memory polymer is one of a backing layer or a matching layer of the transducer. In a fifth example of the system, optionally including the first through fourth examples, the shape memory polymer is positioned between any layers of the transducer. In a sixth example of the system, optionally including the first through fifth examples, the transducers are radial transducers having a field of view of up to 360 °.

The present disclosure also provides support for a method for manufacturing a transducer, the method comprising: adjusting a Shape Memory Polymer (SMP) to a non-radial configuration; laminating the transducer component to the SMP while in a non-radial configuration; cutting the transducer assembly; and adjusting the SMP to a radial configuration to form a transducer with a wide field of view. In a first example of the method, adjusting the SMP to a radial configuration comprises adjusting the transducer to any one of a circular, folded, spiral, convex, and concave conformation. In a second example of the method, optionally including the first example, adjusting the SMP to a radial configuration includes transitioning the transducer to a geometry having a radius of curvature that enables the transducer to be encased within the deployable catheter.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the relevant art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.