阅读说明：本技术 用于形状改变侵入式可部署装置的方法和系统 (Methods and systems for shape-changing invasive deployable devices ) 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 2021-04-29 设计创作，主要内容包括：本发明提供了用于可部署侵入式装置的各种方法和系统。在一个示例中,可部署侵入式装置具有换能器,该换能器具有由至少一种形状记忆材料连接的多个换能器阵列,该至少一种形状记忆材料被构造成响应于一种或多种刺激而使换能器在第一折叠形状和第二展开形状之间转变。当处于第二展开形状时,换能器的有效区域相对于第一折叠形状增加。(Various methods and systems for deployable invasive devices are provided. In one example, a deployable invasive device has a transducer having a plurality of transducer arrays connected by at least one shape memory material configured to transition the transducer between a first collapsed shape and a second expanded shape in response to one or more stimuli. When in the second unfolded shape, the active area of the transducer is increased relative to the first folded shape.)

1. A deployable invasive device comprising:

a transducer having a plurality of transducer arrays connected by at least one shape memory material configured to transition the transducer between a first folded shape and a second unfolded shape in response to one or more stimuli;

wherein in the second expanded shape, the plurality of transducer arrays are arranged adjacent to each other without any other transducer components positioned in a region between each of the plurality of transducer arrays, the region defined by an inner edge of the plurality of transducer arrays and an edge of the plurality of transducer arrays perpendicular to an azimuthal direction, and an active area of the transducer is increased relative to the first folded shape.

2. The deployable invasive device of claim 1, wherein the at least one shape memory material is a two-way shape memory polymer.

3. The deployable invasive device of claim 1, wherein the at least one shape memory material is positioned along one side of the transducer along the azimuthal direction and extends between edges of each transducer array of the plurality of transducer arrays that are perpendicular to the azimuthal direction.

4. The deployable invasive device of claim 3, wherein the at least one shape memory material is coupled to the edge of each of the plurality of transducer arrays at planar segments of the at least one shape memory material, and wherein the planar segments are spaced apart from each other by a central segment of the at least one shape memory material.

5. The deployable invasive device of claim 4, wherein the central segment of the at least one shape memory material is not coupled to the plurality of transducer arrays, and wherein the central segment of the at least one shape memory material is configured to transition between a buckled geometry when the transducer is in the first folded shape and a less buckled geometry when the transducer is in the second unfolded shape.

6. The deployable invasive device of claim 1, wherein the plurality of transducer arrays comprises a first transducer array and a second transducer array, each of the first transducer array and the second transducer array coupled to the at least one shape memory material at a same side of the transducer along an edge perpendicular to the azimuthal direction.

7. The deployable invasive device of claim 1, wherein the plurality of transducer arrays includes a first transducer array, a second transducer array, and a third transducer array, the second transducer array is positioned between the first transducer array and the third transducer array, and wherein the at least one shape memory material comprises a first shape memory material and a second shape memory material, the first shape memory material is coupled to edges of the first transducer array and the second transducer array perpendicular to the azimuthal direction at a first side of the transducer, the second shape memory material is coupled to edges of the second transducer array and the third transducer array perpendicular to the azimuthal direction at a second side of the transducer, the second side opposite the first side.

8. The deployable invasive device of claim 1, wherein at least one transducer array pivots in a first rotational direction relative to an adjacent transducer array when the transducer transitions from the first folded shape to the second unfolded shape, and wherein the at least one transducer array is coplanar with the adjacent transducer array in the second unfolded shape than in the first folded shape.

9. The deployable invasive device of claim 8, wherein the at least one transducer array pivots in a second rotational direction opposite the first rotational direction when the at least one transducer transitions from the second unfolded shape to the first folded shape, and wherein the at least one transducer array is aligned and parallel with the adjacent transducer along a vertical axis of the transducer in the first folded shape.

10. A transducer for an imaging catheter, the transducer comprising:

two or more transducer arrays connected by a Shape Memory Polymer (SMP), the SMP configured to undergo one or more shape transitions to adjust an active area of the transducer, the active area comprising cumulative surface areas of the two or more transducer arrays facing in the same direction and a distance between each of the two or more transducer arrays.

11. The transducer of claim 10, wherein the one or more shape transitions comprise bending of the SMP into a curved shape and straightening of the SMP into a planar geometry.

12. The transducer of claim 11, wherein the transducer is adjusted to a folded configuration when the SMP is bent into the curved shape and is adjusted to an unfolded configuration when the SMP is straightened into the planar geometry, and wherein the active area of the transducer is larger in the unfolded configuration than in the folded configuration.

13. The transducer of claim 12, wherein the active area is increased by a factor of at least 1.5 in the deployed configuration relative to the folded configuration of the transducer.

14. The transducer of claim 10, wherein the one or more shape transitions comprise a contraction and expansion of the SMP at least in a region of the SMP extending between the two or more transducer arrays, and wherein the contraction and expansion occur along a height aperture of the transducer.

15. The transducer of claim 13, wherein the contraction and expansion of the SMP is triggered by exposure of the SMP to one or more stimuli when the effective area of the transducer is increased.

16. The transducer of claim 10, wherein the SMP is positioned as a segment coupled to and extending between inner edges of the two or more transducer arrays.

17. The transducer of claim 10, wherein the SMP is configured as one of a common matching layer or a common backing layer that spans the entire transducer and forms the two or more transducer arrays.

18. The transducer of claim 10, wherein each of the one or more shape transitions is induced by a different stimulus, and the different stimulus comprises any of a chemical stimulus, a physical stimulus, and a biological stimulus.

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

two or more transducer arrays connected by a Shape Memory Polymer (SMP), the SMP configured to contract and expand along an elevation hole and/or an azimuth hole of the transducer in a region of the SMP extending between each of the two or more transducer arrays.

20. The transducer of claim 19, wherein a cumulative width of the SMP is less than a threshold percentage of the elevation holes and/or the azimuth holes of the transducer when the SMP is tightened.

Technical Field

Embodiments of the subject matter disclosed herein relate to deployable catheters.

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 device may include an ultrasound probe having a hole size consistent with dimensions that enable the device to fit through an artery or vein. Thus, the resolution and penetration of the ultrasound probe may be determined by the maximum allowable diameter of the invasive device.

Disclosure of Invention

In one embodiment, a deployable invasive device comprises: a transducer having a plurality of transducer arrays connected by at least one shape memory material configured to transition the transducer between a first folded shape and a second unfolded shape in response to one or more stimuli, wherein in the second unfolded shape the plurality of transducer arrays are arranged adjacent to each other without any other transducer components positioned in a region between each of the plurality of transducer arrays, the region defined by an inner edge of the plurality of transducer arrays and an edge of the plurality of transducer arrays perpendicular to an azimuthal direction, and an active area of the transducer is increased relative to the first folded shape. The transducer size can thus be reduced to allow the transducer to pass through an intravenous pathway, and increased when needed to obtain high resolution data at increased acquisition speeds.

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 a first cross-sectional view of an exemplary imaging catheter tip that may be included in the deployable catheter of fig. 2.

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

FIG. 5 is a first illustration showing the two-way shape memory effect of a transducer incorporating a shape memory material.

FIG. 6A shows a first example of a transducer in a folded configuration mated with a shape memory material.

Fig. 6B shows a first example of the transducer of fig. 6A in a deployed configuration.

FIG. 7A illustrates a second example of a transducer in a folded configuration mated with a shape memory material.

Fig. 7B shows a second example of the transducer of fig. 7A in a deployed configuration.

FIG. 8A illustrates a perspective view of a third example of a transducer in a folded configuration mated with a shape memory material.

FIG. 8B shows an end view of a third example of the transducer of FIG. 8A.

Fig. 8C shows a perspective view of a third example of the transducer of fig. 8A in a transformed configuration.

Fig. 8D shows a perspective view of a third example of the transducer of fig. 8A in an expanded configuration.

FIG. 9A illustrates a perspective view of a fourth example of a transducer in a folded configuration mated with a shape memory material.

FIG. 9B shows an end view of a fourth example of the transducer of FIG. 9A.

Fig. 9C shows a perspective view of a fourth example of the transducer of fig. 9A in a transformed configuration.

Fig. 9D shows a perspective view of a fourth example of the transducer of fig. 9A in an expanded configuration.

Fig. 10 shows a fifth example of a transducer adapted with a shape memory material forming the acoustic layer of the transducer.

Fig. 11 shows a sixth example of a transducer adapted with a shape memory material forming the acoustic layer of the transducer.

FIG. 12 is a diagram illustrating a shape transition mode variation of a shape memory material implemented in a transducer.

Fig. 1-4 and 6A-9D are drawn approximately to scale, although other relative dimensions may also be used.

Detailed Description

The following description relates to various embodiments of deployable invasive devices. The deployable invasive device may be a deployable catheter in an imaging system and configured 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 fig. 3 shows the internal components of the deployable catheter in a first cross-sectional view of the deployable catheter. A second cross-sectional view of the deployable catheter is shown in schematic form in fig. 4. The transformation between a first shape and a second shape of a transducer fitted with a shape memory material, which may be included in a deployable catheter, is shown in fig. 5. Examples of transducers incorporating shape memory materials in multiple locations relative to the active area of the transducer with the transducer in different configurations are shown in fig. 6A-11. For example, as shown in fig. 6A-7B, the shape memory material may be disposed between the transducer array, as shown in fig. 8A-9D, outside the active area, or as shown in fig. 10-11, may be disposed as an acoustic layer incorporated into the transducer. An additional pattern of shape transformation of the shape memory material is shown in fig. 12, which includes a contraction of the shape memory material along at least one dimension.

Fig. 1-12 illustrate example 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 one another may, at least in one example, abut or be adjacent to one another, respectively. For example, components disposed in coplanar contact with each other may be referred to as coplanar contact. 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 other elements is positioned vertically above the other elements. 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 shown as intersecting one another may 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 ultrasound imaging may be used to obtain real-time data about a patient's tissues, organs, blood flow, etc. However, it may be difficult to obtain high resolution data of the lumen of tissues and organs via external scanning of the patient. In such cases, a deployable catheter equipped with a probe may be intravenously inserted into a patient and guided to a target site. The deployable catheter may be advanced through a narrow passageway (such as a vein or artery) and thus may have a similar diameter. However, the narrow diameter of the deployable catheter may limit the size of the probe, which in turn may constrain the quality of data and acquisition speed provided by the probe. For example, when the probe is an ultrasound probe, the resolution and penetration of the ultrasound probe may be determined by the size of the transducer of the probe. To improve the quality of the images generated by the ultrasound probe, a larger transducer than can be enclosed within the housing of the deployable catheter may be required.

In one example, the above-described problems may be at least partially addressed by incorporating a shape memory material into a deployable catheter. The shape memory material may be a Shape Memory Polymer (SMP) configured to alternate between at least two different shapes. With the SMP coupled to the transducer, the footprint of the transducer of the deployable catheter may be selectively increased or decreased. The shape changing behavior of the SMP allows the transducer to have, for example, a first shape with a first set of dimensions within the deployable catheter housing such that the transducer array can be easily inserted into a patient. In response to exposure to the stimulus, the SMP may adjust to a second shape having a second set of dimensions that increases the size of the transducer.

The SMP can be coupled to the transducer via more than one configuration, allowing flexibility in the design of the transducer to accommodate the available packaging space and enhance the performance of the transducer. For example, the positioning of the SMP relative to the active area of the transducer may be varied and/or the SMP may be configured to change shape via more than one mode. In this way, the imaging probe may be in a conformation within the patient that is more conducive to intravenous passage, and then enlarged when deployed in the targeted anatomical region to obtain high resolution data. By using SMP to induce shape transformation, the cost of a deployable catheter can be kept low while allowing a wide range of deformation.

Turning now to fig. 1, a block diagram of an exemplary system 10 for medical imaging is shown. It should be appreciated that while described herein as an ultrasound imaging system, the 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 be used as an invasive probe. Reference numeral 16 designates a portion of the imaging catheter 14 which is 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 comprise one or more transducer arrays, each transducer array comprising 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. 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, for example, by a transmitter. In some examples, the piezoelectric element may be a single crystal having a crystal axis, such 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 transducers, but may all be coupled to a common layer positioned below or above the transducer elements with respect 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 signal generated by the transducer element 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 placement of the transducer 304 of the imaging catheter within the interior cavity 414 of the housing 302 is indicated by the dashed rectangle. The maximum height aperture 418 of the transducer 304 may be determined based on the inner diameter 410 of the housing 302, and the height 420 of the transducer 304 may be configured to fit between the lobes 412 of the housing 302. In one example, the height aperture 418 may be a maximum of 2.5mm and the height 420 may be a maximum of 1 mm.

As described above, the dimensions of the transducer 304 may be determined by the inner diameter 410, thickness 406, and outer diameter 408 of the housing 302, which in turn may be determined based on the insertion of the imaging catheter into a particular region of the patient's anatomy. Constraints imposed on the size of the transducer 304 and the diameter 422 of the catheter cable 310 may affect the resolution, penetration, and fabrication of the transducer 304. Each of resolution, penetration, and ease of manufacture may be enhanced by increasing the size of the transducer 304, but the geometry, and thus performance, of the transducer 304 is limited by the size of the catheter housing 302 so that the deployable catheter travels intravenously through the patient.

In one example, the transducer may be magnified when deployed at the target site by adapting 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, lower cost of SMP may be desirable for applications in disposable deployable catheters.

TABLE 1 physical Properties of shape memory polymers

In one example, the SMP can have two-way shape memory, such that the SMP can be tuned between the 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 return to a permanent shape in response to a second stimulus. The first and second stimuli may be of the same or different type, 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 bi-directional 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 an external force.

For example, the transformation of the transducer 502 between a first shape and a second shape is shown in the first diagram 500 in FIG. 5. The transducer 502 includes a first transducer array 504 and a second transducer array 506, wherein the second transducer array 506 is aligned with the first transducer array 504 and spaced apart from the first transducer array 504 along the z-axis. In other words, the transducer 502 has a generally planar shape, wherein the first transducer array 504 and the second transducer array 506 are coplanar with one another along a common plane (e.g., an x-z plane). A first step 501 of the first diagram 500 depicts the SMP 508 coupled to the backing layer 510 of each of the first transducer array 504 and the second transducer array 506. An SMP 508, configured as a two-way memory SMP, is disposed between the transducer array along the z-axis, and may be fixedly attached to an edge of the backing layer 510 and disposed coplanar with the backing layer 510. For example, the backing layer 510 and the SMP 508 disposed therebetween may form a continuous planar unit. The transducer elements 512 are laminated to the backing layer 510 of the first transducer array 504 and the second transducer array 506.

In some examples, the SMP 508 may form a continuous layer completely across the transducer 502. For example, the SMP 508 may be an acoustic layer of the transducer 502, such as a matching layer or backing layer. By incorporating the SMP 508 as an acoustic layer, the assembly and number of components of the transducer may be simplified without adversely affecting the reduction in the size of the transducer footprint. The implementation of SMP as the acoustic layer of the transducer is discussed further below with reference to fig. 10-11.

The transducer 502 is exposed to a first temperature T₁And at a second step 503, the SMP 508 responds to T₁But changes shape. The SMP 508 may be bent into a semi-circular shape such that the second transducer array 506 pivots substantially through 180 degrees in a first rotational direction (e.g., clockwise) as indicated by arrow 520. As described herein, bendThe curvature may be any transformation of a planar structure to a non-planar conformation. Thus, various deformations of the structure from a configuration aligned with a plane may be considered bends.

When the SMP 508 is flexed, the transducer 502 may thus also be flexed. While the SMP can be bent through a range of angles, bending of the SMP causes two regions of the transducer 502 to become stacked above and substantially parallel to each other is referred to herein as folding. In some examples, the SMP may not be bent to the extent that the transducer is folded. However, the folding of the transducer may provide the most compact conformation of the transducer to enable the deployable catheter to pass through the intravenous channel.

Due to the folding of the transducer 502, the second transducer array 506 is positioned below the first transducer array 504 in a folded shape with respect to the y-axis. When the transducer 502 is viewed along the y-axis, the overall surface area of the transducer elements 512 (including the transducer elements 512 of both the first transducer array 504 and the second transducer array 506) is reduced at the second step 503 as compared to the first step 501.

The transducer 502 is exposed to a second temperature T₂And in response SMP 508 reverts to the planar geometry of first step 501 at third step 505 of first diagram 500. The second transducer array 506 is pivoted substantially through 180 degrees in a second rotational direction (e.g., counterclockwise) opposite the first rotational direction. Second temperature T₂Can be above or below T₁The temperature of (2). The transducer 502 is again subjected to T₁The SMP 508 is actuated to bend, folding the transducer 502 such that the second transducer array 506 pivots 180 degrees at the fourth step 507.

As described above, the transducer 502 may be enclosed within a housing (such as the housing 302 of fig. 3 and 4) at the end of a deployable catheter. To accommodate the expansion of the transducer 502 to a planar geometry, the housing may be formed of a flexible, resilient material that stretches and deforms as the transducer 502 changes shape. For example, the deployable catheter may be a balloon catheter and the housing at the end of the catheter may be an inflatable balloon. The balloon may be formed of a material such as polyester, polyurethane, silicone, or the like, and may be inflated by filling the balloon with a fluid or gas. Prior to adjusting the transducer 502 to the planar geometry, the balloon may be inflated to allow the transducer 502 to transition unimpeded. The balloon may be deflated by venting gas or venting fluid while adjusting the transducer 502 to the folded configuration.

The steps shown in the first diagram 500 may be repeated multiple times. For example, transducer 502 of FIG. 5 may be initially exposed to T prior to insertion of an imaging catheter adapted for transducer 502 into a patient₁To fold and reduce the size of the transducer 502. The folded transducer 502 may be fitted within the housing of an imaging catheter and inserted intravenously into a patient. When the transducer 502 reaches a target site in a patient, the array may be subjected to T₂To deploy and amplify the transducers 502. As the transducers 502 expand and increase in size, an image may be obtained. For example, unfolding the transducer 502 may increase the height aperture of the transducer 502.

When the scan is complete, the transducer 502 may be exposed to T again₁Causing the transducer 502 to fold and decrease in size. The imaging catheter may then be withdrawn from the site and removed from the patient or deployed to another site for imaging within the patient. Thus, the shape and size of the transducer 502 may be adjusted multiple times between the planar configuration and the folded configuration during an imaging session.

It should be understood that the configuration of the transducer 502 shown in FIG. 5 is a non-limiting example of a shape between which the transducer may transition. Other examples may include the transducer 502 being in a non-planar geometry (such as a slightly bent or curved shape) at the first step 501, becoming more bent or curved at the second step 503, and alternating between a less bent/curved shape and a more bent/curved shape when exposed to one or more stimuli. Additionally, the transducer 502 may be folded such that the first transducer array 504 and the second transducer array 506 are not parallel to each other. In other examples, the first transducer array 504 and the second transducer array 506 may be different sizes.

Further, when the SMPs 508 form a segment across the entire layer of the transducer 502 rather than between the backing layers 510 of the first transducer array 504 and the second transducer array 506, the SMPs 508 may be adapted to change shape only in the regions between the transducer arrays. In one example, the SMP 508 may be capable of changing shape via more than one type of transition. For example, the SMP 508 may bend when exposed to one type of stimulus and contract when exposed to another type of stimulus. In another example, the SMP 508 may include more than one type of shape memory material. For example, the SMP 508 may be formed from a first type of material configured to bend and a second type of material configured to contract. Other variations in shape transformation, material combinations, and positioning of the SMP 508 within the transducer have been contemplated.

While a temperature change is described as a stimulus for inducing a change in shape of the SMP of the first diagram 500 of fig. 5, it should be understood that the first diagram 500 is a non-limiting example of how deformation of the SMP may be triggered. Other types of stimuli such as humidity, pH, UV light, etc. can be used to induce mechanical changes in the SMP. More than one type of stimulus can be applied to the SMP to achieve similar or different shape modifications. Further, the deformation of the SMP can include other shape changes besides bending. For example, the SMP can be crimped into a core configuration or contracted in at least one dimension. The details of the mechanical deformation are described further below.

In some examples, as shown in fig. 5, the transducer of the deployable catheter may include two segments or two transducer arrays. Each transducer array may include one or more acoustic stacks, including matching layers, elements, and backing layers as described above with reference to fig. 2. An ASIC may be coupled to each transducer array. A first example of a transducer 602 incorporating SMP to enable modification of the active area of the transducer 602 is shown in fig. 6A and 6B. The transducer 602 is shown in a first, collapsed configuration 600 in fig. 6A and in a second, expanded configuration 650 in fig. 6B.

The transducer 602 has a first transducer array 604 and a second transducer array 606. The first transducer array 604 and the second transducer array 606 have similar dimensions, e.g., length, width, and thickness, and are each rectangular and longitudinally aligned with the x-axis, e.g., the length 608 of each transducer array is parallel to the x-axis. However, in other examples, the first transducer array 604 and the second transducer array 606 may have different dimensions from each other. For example, the first transducer array 604 may be wider and/or longer than the second transducer array 606. The SMPs 610 are arranged between the transducer arrays along the z-axis. In other words, as shown in fig. 6B, the first transducer array 604 is spaced apart from the second transducer array 606 by a width 612 of the SMP 610. A width 612 of the SMP 610 may be less than a width 614 of each of the first transducer array 604 and the second transducer array 606, while a length of the SMP 610 defined along the x-axis may be similar to the length 608 of the transducer array.

The SMP 610 may be connected to an inner edge of the backing layer 616 of each of the first transducer array 604 and the second transducer array 606. For example, the SMP 610 may directly contact and adhere to a longitudinally inner edge 618 of the backing layer 616 of the first transducer array 604, e.g., an edge of the backing layer 616 facing the second transducer array 606 and aligned with the x-axis, and directly contact and adhere to a longitudinally inner edge 620 of the backing layer 616 of the second transducer array 606, e.g., an edge of the backing layer 616 facing the first transducer array 604 and aligned with the x-axis. The thickness of the SMP 610 may be similar to the thickness of the backing layer 616 of each of the first transducer array 604 and the second transducer array 606, which is defined along the y-axis. A matching layer 622 is stacked over the backing layer 616 of each of the transducer arrays. Elements (e.g., piezoelectric elements) may be disposed between the matching layer 622 and the backing layer 616 (not shown in fig. 6A and 6B).

When in the first configuration 600 as shown in FIG. 6A, the SMP 610 is bent into a semi-circular shape. The second transducer array 606 is stacked directly above and aligned with the first transducer array 604 relative to the y-axis and is spaced apart from the first transducer array 604 such that the two transducer arrays remain parallel to the x-z plane. The transducers 602 are folded in fig. 6A such that each matching layer 622 of the transducer array faces outward and away from each other and the backing layers 616 of the transducer array face each other. The backing layers 616 can be spaced apart from one another by a distance 630 similar to the diameter of the semicircle formed by the SMP 610. However, in other examples, the transducers 602 may be folded in opposite directions such that the backing layers 616 of the transducer array face each other and the matching layers 622 face away from each other.

In the first configuration 600, the width 624 of the transducer 602 is reduced relative to the width 626 of the transducer 602 in the second configuration 650. The active area of the transducer 602 may be equal to the surface area of one of the first transducer array 604 or the second transducer array 606. In the second configuration 650, with the first transducer array 604 and the second transducer array 606 coplanar and juxtaposed to each other, the active area of the transducer 602 doubles relative to the first configuration 600 when the transducer arrays are similarly sized. Thus, when deployed into the second configuration 650, the height aperture of the transducer 602 may be doubled, thereby increasing the resolution and penetration of the transducer 602.

In another example, the transducer of the imaging probe may include more than two segments or transducer arrays. A second example of a transducer 702 is shown in a first, folded configuration 700 in fig. 7A and a second, unfolded configuration 750 in fig. 7B. The transducer 702 includes a first transducer array 704, a second transducer array 706, and a third transducer array 708. All three transducer arrays may have similar dimensions (e.g., length, width, and thickness) and geometry, and may be connected by a first SMP 710 and a second SMP 712. However, in other examples, the transducer arrays may all have different sizes from one another, or two of the three transducer arrays may be similar, and the remaining transducer arrays may have different sizes or shapes.

For example, in the second configuration 750 of fig. 7B, the transducers may be spaced apart from each other but coplanar and aligned along the x-axis and z-axis. The first transducer array 704 is spaced apart from the second transducer array 706 by a first SMP 710, and the second transducer array 706 is spaced apart from the third transducer array 708 by a second SMP 712. As described above for the first example of the transducer 602 of fig. 6A-6B, the SMP may be connected directly to the longitudinally inner edge of the transducer array along the backing layer 714 of each of the transducer arrays. The SMP may be coplanar and have a similar thickness to the backing layer 714 of the transducer array. The matching layer 716 of each of the transducer arrays is positioned above the backing layer 714 and aligned with each backing layer 714 along the y-axis. Thus, the matching layer 716 protrudes above the first SMP 710 and the second SMP 712 relative to the y-axis. The elements may be disposed between the mating layer 716 and the backing layer 714 (not shown in fig. 7A and 7B).

In the first configuration 700 of fig. 7A, the transducer 702 is folded into an S-shaped geometry when viewed along the x-axis. In the S-shaped geometry, the first SMP 710 is bent into a half circle, forming the right half of the circle. The first transducer array 704 may be pivoted relative to the second transducer array 706 through a first rotational direction such that the second transducer array 706 is stacked above the first transducer array 704 and aligned with the first transducer array relative to the y-axis. While the backing layer 714 of the second transducer array 706 and the backing layer 714 of the first transducer array 704 face each other without positioning other components of the transducer 702 therebetween, the backing layers 714 of the transducer arrays are spaced apart by a distance similar to the diameter of the semicircle formed by the first SMP 710.

The second SMP 712 is bent in the opposite direction from the first SMP 710 into a semi-circle forming the left half of the circle. The bending of the second SMP 712 causes the third transducer array 708 to be stacked above the second transducer array 706 along the y-axis. The third transducer array 708 is pivoted through a second rotational direction opposite the first rotational direction such that the third transducer array 708 is aligned with both the first transducer array 704 and the second transducer array 706 along the y-axis and the matching layer 716 of the third transducer array 708 faces the matching layer 716 of the second transducer array 706. The matching layers 716 of the second and third transducer arrays 706, 708 are separated by a gap that is less than the distance between the backing layer 714 of the second and first transducer arrays 704, 706.

As shown in fig. 7A, the width 720 of the transducer 702 in the first configuration 700 may be narrower than the width 722 of the transducer 702 in the second configuration 750. Where the transducer arrays are of similar size, the effective area of the transducer 702, as determined by the total (e.g., cumulative) transducer array face area along the x-z plane facing the same direction, may increase, for example, by a factor of three, when the transducer 702 is adjusted from the first configuration 700 to the second configuration 750. Thus, when a transducer is formed of three transducer arrays (hereinafter 3-segment transducers) and the size of the deployed 3-segment transducer (e.g., the second configuration 750 of fig. 7B) is equal to the deployed transducer (hereinafter 2-segment transducer) having two transducer arrays (e.g., the second configuration 650 of fig. 6B), the transducer array of the 3-segment transducer may be narrower in width than the transducer array of the 2-segment transducer. When folded, a 3-segment transducer may have a smaller footprint than a 2-segment transducer and thus may be inserted through a narrower channel.

Alternatively, the transducer arrays of the 3-segment transducer and the 2-segment transducer may be similar in size. When folded, the two transducers may have similar footprints. However, when deployed and deployed at a target scan site, a 3-segment transducer may have a larger active area, allowing the 3-segment transducer to have greater resolution and penetration than a 2-segment transducer. Further, the first example and the second example of the transducer shown in fig. 6A to 7B are non-limiting examples. Other examples may include transducers having more than three segments, or transducers and transducer arrays having different geometries and dimensions than those shown. Thus, the transducers may be selected based on the desired footprint of the folded and/or unfolded transducers. For example, when the 3-segment transducer and the 2-segment transducer have similar footprints in the folded configuration, the 3-segment transducer may be used when the target imaging site has a larger volume than if the 2-segment transducer was used.

As shown in fig. 6A-7B, positioning the SMP between each transducer array of the transducer allows the size of the transducer to be varied along the height direction of the transducer. However, if the distance between the transducer arrays of the transducers is too large, the quality of the image generated by the transducers may be reduced. For example, to maintain the enhanced performance of the transducer provided by increasing the active area of the transducer, the distance between each transducer array of the transducer may cumulatively not exceed a threshold percentage, such as 5%, of the total effective height aperture of the transducer. Therefore, it is desirable to minimize the distance between the transducer arrays during data acquisition at the transducers. However, as shown in fig. 5, 6A, and 7A, the folding of the transducer along the azimuthal aperture may be a shape transition that provides the lowest complexity and ease of actuation. To facilitate efficient packaging of the transducers by folding, a total pitch of distances between the transducer arrays that is greater than a threshold percentage of the total active height aperture may be required.

In one example, the distance between the transducer array when the transducer is deployed may be reduced by positioning the SMP outside the active area of the transducer. Such an arrangement is referred to hereinafter as an external arrangement of the SMP. Repositioning the SMP outside the active area along the azimuthal aperture of the transducer may allow the transducer to be bent out of the transducer array, alleviating the need for a minimum distance between the transducer arrays to achieve sufficient bending of the SMP. A first example of a transducer 802 equipped with an externally arranged SMP is shown in fig. 8A to 8D. The transducer 802 is shown in a folded configuration in a perspective view 800 in fig. 8A and in an end view 830 in fig. 8B. The transducer 802 is further illustrated in fig. 8C in a perspective view 850 showing the transducer 802 in a transformed configuration, and in fig. 8D in a perspective view 870 of the transducer 802 in an expanded configuration.

As shown in fig. 8A, the transducer 802 includes a first transducer array 804, a second transducer array 806, and an SMP 808 positioned at one end of the first and second transducer arrays 804, 806 along an x-axis, which may also be the azimuthal direction of the transducer 802. The transducer arrays may be longitudinally aligned with the azimuth direction and parallel to each other. The first transducer array 804 and the second transducer array 806 are not directly coupled to each other, e.g., the transducer arrays may contact each other during shape transition, but not attached to each other at any point. Each of the transducer arrays has a matching layer 810 and a backing layer 812. As shown in fig. 8A, the first transducer array 804 and the second transducer array 806 may have a similar width 814 and a similar length 816, and may be longitudinally aligned with the x-axis and parallel to each other.

For example, as shown in fig. 8A, 8C, and 8D, the SMPs 808 are coupled to a first edge 818 of the backing layer 812 of each transducer array in the transducer array by an adhesive. However, in other examples, when the SMP has attenuation properties, such as when the SMP is configured as a matching layer, the SMP may be part of, e.g., integrated into, the transducer array. The first edge 818 is parallel to the z-axis and extends along the width 814 of each transducer array. As shown in fig. 8D, the thickness of the SMP 808 may be less than the thickness of each of the transducer arrays, which is defined along the y-axis, such that the matching layer 810 protrudes higher along the y-axis than the SMP 808. The central region 820 of the SMP 808 is not attached to the transducer array and is configured to bend as shown in fig. 8A, 8B, and 8C. The central region 820 is positioned between the planar regions 822 of the SMPs 808 that are not bent due to the coupling of the planar regions 822 to the first edge 818 of the backing layer 812 of each of the transducer arrays.

In the folded configuration shown in fig. 8A and 8B, the SMP 808 is bent such that the planar regions 822 are stacked on top of each other along the y-axis and the central region 820 forms a semicircle. The bending of the SMP 808 causes the first transducer array 804 to fold under the second transducer array 806 to become stacked under the second transducer array 806 along the y-axis. For example, the first transducer array 804 may be pivoted through 180 degrees in a first rotational direction (e.g., counterclockwise) as indicated by arrow 824 shown in fig. 8D relative to the deployed configuration. In some examples, the first transducer array 804 may be pivoted by any angle greater than 180 degrees, such as 190 degrees or 210 degrees, or less than 180 degrees. It should be appreciated that while pivoting of the first transducer array 804 is described, in other examples, the second transducer array 806 may be pivoted instead.

As shown in fig. 8B, when adjusted to the folded configuration, the backing layers 812 of the first transducer array 804 and the second transducer array 806 may face each other separated by a distance equal to a diameter 826 of a semicircle formed by the central region 820 of the SMP 808. In the folded configuration, the active area of the transducer 802 may be the total surface area of the transducer facing in one direction. Thus, the active area may be equal to the area of one of the transducer arrays.

In the folded configuration, the transducer 802 may have a sufficiently small footprint to fit within the outer housing of a deployable catheter for intravenous passage. Upon reaching the target imaging site, the transducer 802 may expand to the deployed configuration shown in fig. 8D. When the transducers 802 are deployed, the straightening of the SMP 808 causes the first transducer array 804 to rotate in a second rotational direction (e.g., clockwise) opposite to the direction indicated by arrow 824, thereby passing through the transitional configuration shown in fig. 8C. The first transducer array 804 and the second transducer array 806 are separated by a gap extending longitudinally between the transducer arrays until the transducers 802 are in the deployed configuration of fig. 8D.

As shown in fig. 8D, the transducer 802 is planar, e.g., coplanar with the x-z plane, and includes first and second transducer arrays 804 and 806 and an SMP 808. The central region 820 of the SMP 808 is coplanar with the planar region 822, thereby together forming a rectangular extension of the transducer 802 along the x-axis. The width 834 of the SMP 808 may be similar to the sum of the widths 814 of the transducer array, and the length 832 of the SMP 808 is less than the length 816 of the transducer array.

In the deployed configuration, the first transducer array 804 and the second transducer array 806 may be positioned very close to each other, e.g., the first transducer array 804 and the second transducer array 806 are contiguous without any other transducer components disposed in the spatial region between the transducer arrays. The area between the transducer arrays may be defined or bounded by the inner edges of the transducer arrays and the edges of the transducer arrays perpendicular to the azimuthal direction. The transducer arrays may be separated by a small gap or, in some examples, the inner edges of the backing layer 812 of each transducer array may contact when the transducers 802 are deployed. The active area of the transducer 802 may be doubled relative to the folded configuration, and the distance between the transducer arrays may be less than if the SMP were positioned between the transducer arrays. For example, the total distance between the transducer arrays may be less than 5% of the height aperture of the transducer 802.

By adapting the transducers of more than two transducer arrays, the active area of the transducers can be more than doubled. As shown in fig. 9A-9D, a second example of a transducer 902 equipped with two externally arranged SMPs may include a first transducer array 904, a second transducer array 906, and a third transducer array 908. The transducer arrays may be longitudinally aligned with an azimuthal direction (e.g., x-axis) and parallel to each other. The transducer 902 is shown in a folded configuration according to perspective view 900 in fig. 9A and according to end view 930 in fig. 9B. The transducer 902 is further illustrated in fig. 9C in a perspective view 950 showing the transducer 902 in a transformed configuration, and in fig. 9D in a perspective view 970 of the transducer 902 in an expanded configuration.

The transducer 902 may include a first SMP 910 positioned at a first end 912 of the transducer 902 and a second SMP 914 positioned at a second end 916 of the transducer 902. The first SMP 910 and the second SMP 914 may each be attached to two of the transducer arrays, and may be formed of the same or different materials. More specifically, a first SMP 910 is coupled to the first transducer array 904 and the second transducer array 906 at a first end 912, and a second SMP 914 is coupled to the second transducer array 906 and the third transducer array 908 at a second end 916. As shown in fig. 9A, each of the transducer arrays has a matching layer 918 and a backing layer 920, and may each have a similar width 922 and a similar length 924. The transducer arrays may each be longitudinally aligned with the x-axis. The thickness of each of the first SMP 910 and the second SMP 914, which may be similar to each other and less than the thickness of each of the transducer arrays, is defined along the y-axis such that the matching layer 918 protrudes higher along the y-axis than the SMPs in the deployed configuration of fig. 9D.

The second transducer array 906 is positioned between the first transducer array 904 and the third transducer array 908, and the transducer arrays are not directly coupled to each other. Instead, the transducer array is connected by a first SMP 910 and a second SMP 914, and the transition of the transducer 902 between the folded and unfolded configurations is guided by the SMPs. Each of the SMPs includes a central region 926 configured to flex and planar regions 928 disposed on opposite sides of the central region 926. The planar region 928 makes edge-sharing contact with the edge of the backing layer 920 of the transducer array and is fixedly coupled to the edge of the backing layer 920.

When adjusted to the folded configuration shown in fig. 9A and 9B: the first SMP 910 may be bent such that the first transducer array 904 pivots through, for example, 180 degrees in a first rotational direction relative to the deployed configuration of fig. 9D to become stacked below the second transducer array 906 along the y-axis. The second SMP 914 may be bent in a direction opposite the first SMP 910 such that the third transducer array 908 is pivoted through, for example, 180 degrees in a second rotational direction opposite the first rotational direction to become stacked over the second transducer array 906 along the y-axis. As described above, other examples may include the first transducer array 904 and the third transducer array 908 rotating through greater or less than 180 degrees. Further, in other examples, the transducers 902 may be folded in an inverted configuration, e.g., the first transducer array 904 above the second transducer array 906 and the third transducer array 908 below the second transducer array 906. As shown in fig. 9B, in the folded configuration, the stacked transducer arrays are aligned along the y-axis but spaced apart from each other.

End view 930 of FIG. 9B shows the S-shaped geometry of the transducer. The backing layers 920 of the first transducer array 904 and the second transducer array 906 face each other in the folded configuration, while the matching layers 918 of the second transducer array 906 and the third transducer array 908 face each other. The first transducer array 904 and the second transducer array 906 are spaced apart by a distance similar to the diameter 932 of the semi-circle formed by the first SMP 910. The second transducer array 906 and the third transducer array 908 are spaced apart by a distance that is less than the diameter of the semicircle formed by the second SMP 914. Thus, when the transducer 902 is in the folded configuration, the transducer arrays do not contact each other.

As the transducers transition from the folded to the unfolded configuration, the first SMP 910 may straighten, causing the first transducer array 904 to pivot through a second rotational direction as indicated by arrow 934 in fig. 9B. The second SMP 914 may also be straightened, thereby oscillating the third transducer array 908 in a first rotational direction as indicated by arrow 936 in fig. 9B. The transducers 902 may pass through a transition configuration shown in fig. 9C, where the transducer arrays are still spaced apart and not in contact with each other.

In the deployed configuration shown in fig. 9D, the first SMP 910 and the second SMP 914 become aligned with the x-z plane (e.g., flat). The SMPs form rectangular extensions along the x-axis at opposite sides of the transducer 902 and may be offset from each other along the x-axis. For example, the first SMP 910 has a width 972 similar to or slightly larger than the combined width 922 of the first transducer array 904 and the second transducer array 906, and is positioned at the first end 912 of the transducer 902. The second SMP 914 has a width 974 that is similar to or slightly larger than the combined width 922 of the second transducer array 906 and the third transducer array 908, and is positioned at the second end 916 of the transducer 902. The second SMP 914 is positioned higher than the first SMP 910 with respect to the z-axis.

In the deployed configuration, the transducer arrays are aligned along x, y, and z axes and are coplanar with one another along a common plane. The transducer arrays are depicted as being spaced apart from each other by a small gap that is less than the distance of the transducer arrays if the SMP is instead disposed between the transducer arrays. In some examples, the transducer arrays may be in edge-shared contact in the deployed configuration, e.g., inner edges of the transducer arrays are in contact with each other. As described above for the transducer 802 shown in fig. 8A-8D, when the transducer 902 is deployed, the first transducer array 904, the second transducer array 906, and the third transducer array 908 are adjacently disposed without any other transducer components disposed in the spatial regions between the transducer arrays. The area between the transducer arrays may be defined or bounded by the inner edges of the transducer arrays and the edges of the transducer arrays perpendicular to the azimuth direction.

With similar dimensions of the transducer array, the active area of the transducer 902 may be tripled when the transducer 902 is unfolded relative to when the transducer is folded. By placing the SMPs outside of the active area, the transducer arrays are positioned closer together so the total distance between the transducer arrays can be less than 5% of the height aperture of the transducer. The external arrangement of the SMP may allow the distance between the transducer arrays to be reduced without introducing additional complexity to the shape transition of the SMP or the manufacturing process of the transducer. When the packaging space in the azimuthal direction of the transducer is not limited, the SMP can be arranged outside the active area of the transducer.

As shown in fig. 5-9D, the SMP may be attached to the backing layer of the transducer, for example, to a separate backing layer for each transducer array of the transducer. Alternatively, in some examples, the SMP may be similarly coupled to the matching layer of each transducer array. The material of the SMP can be selected to be physically compatible with the material of the backing layer to reduce the likelihood of separation between the SMP and the matching layer or backing layer during transition of the SMP between shapes. However, fabrication and material selection can be simplified by incorporating the SMP as the acoustic layer of the transducer. Thus, as shown in fig. 10-11, the SMP can form the backing layer or match of the transducer.

Fig. 10 shows a first example of a transducer 1000 with an SMP forming an acoustic layer. The transducer 1000 has a first transducer array 1002 and a second transducer array 1004 spaced apart from each other along the x-axis. The SMPs 1006 extend between the transducer arrays and across the entire width 1008 of the transducer 1000, forming a continuous backing layer across the transducer 1000. Thus, each transducer array is coupled to a common backing layer, and the remaining components of the acoustic stack of each transducer array, such as the matching layer 1010 and the elements 1012, may be laminated onto the SMP 1006. The transducer 1000 may be cut from the top of the matching layer 1010 through the element 1012 down to the top of the SMP 1006 with respect to the y-axis. When forming the backing layer of the transducer 1000, the SMP 1006 may include additives to provide the SMP 1006 attenuation characteristics. For example, the SMP 1006 may have an increased density and/or include silicone and tungsten as additives.

Alternatively, the SMP can form the matching layer of the transducer. A second example of a transducer 1100 is shown in fig. 11, where the SMP 1102 forms a continuous matching layer that extends completely across the width 1104 of the transducer 1100. The transducer 1100 has a first transducer array 1106 and a second transducer array 1108. The transducer arrays are spaced apart from each other along the x-axis with SMPs 1102 extending between the transducer arrays. Transducer 1100 can be cut from the bottom of the backing layer 1110, through element 1112, up to the bottom of the SMP 1102, relative to the y-axis. When forming the matching layers of the transducer 1100, the SMP 1102 can be formed from a matrix polymer.

By implementing the SMP as an acoustic layer of the transducer, rather than as a connection between the transducer arrays of the transducer, adhesion of the SMP to the backing layer (or matching layer) of the transducer array is eliminated. Therefore, less material and components are required to perform the manufacturing process, thereby reducing costs. In addition, the shape changing properties provided by the SMP are incorporated into the transducer without adding thickness to the transducer. The thickness and footprint of the transducer is maintained (e.g., not increased) while enhancing transducer gain.

As described above, whether the SMPs form segments between the transducer arrays as shown in fig. 6A-7B or form a continuous common acoustic layer of the transducer arrays as shown in fig. 10-11, the performance of a transducer having transducer arrays spaced apart by the SMPs extending between the transducer arrays may be impeded by separating the transducer arrays a distance from each other. Due to the limited packaging space along the azimuthal direction of the transducer, positioning of the SMP outside the active area can be eliminated. However, a minimum cumulative distance between the transducer arrays greater than a threshold amount (e.g., 5% of the height aperture) may be required to allow the SMP to bend and fold the transducer into a folded configuration. This problem may be addressed, at least in part, by configuring the SMP to change shape via more than one transition path. For example, the SMP may fold in response to a first stimulus and may contract in at least one dimension in response to a second stimulus.

SMPs can have large deformation capacities, for example up to 800%. By using an SMP adapted to contract in at least one dimension in response to a stimulus, the distance between the transducers can be reduced. For example, as shown in fig. 12 in a second illustration 1200, a transducer 1250 has a first transducer array 1202 and a second transducer array 1204 spaced apart from the first transducer array 1202 by an SMP 1206. The transducer 1250 is depicted in a first, collapsed configuration 1201, wherein the effective area of the transducer 1250 is reduced relative to a second, expanded configuration 1203.

Upon exposure to a first stimulus S₁Upon which the SMP 1206 transitions to a second configuration 1203. First stimulus S₁May be any of the above stimuli. The active area of the transducer 1250 (e.g., the total surface area of the transducer 1250 facing the same direction along the y-axis) is doubled relative to the first configuration 1201. The first transducer array 1202 is spaced apart from the second transducer array 1204 by an SMP 1206, which in the second configuration 1203 has a first width 1208 defined along an x-axis, which may also be the elevation direction of the transducer 1250.

The SMP 1206 may be exposed to a different stimulus S than the first stimulus₁Second stimulus S₂The second stimulus may actuate the SMP 1206 to contract along the x-axis. In one example, the first stimulus S₁May be temperature, and a second stimulus S₂May be humidity. In other examples, the first stimulus S₁And a second stimulus S₂Any combination of various chemical, physical and biological stimuli are possible. The contraction of the SMP 1206 in the elevation direction transitions the transducer 1250 to a third contracted configuration 1205. In the third configuration 1205, the SMP 1206 has a second width 1210 that is less than the first width 1208. Thus reducing the distance between the first transducer array 1202 and the second transducer array 1204. The transducer 1250 can be transitioned from the third configuration 1205 to the second configuration 1203 and from the second configuration 1203 to the first configuration 1201 by exposing the SMP 1206 to more than one stimulus. The SMP 1206 may be similarly applied to transducers having more than two transducer arrays, such as the transducer 902 of fig. 9A-9D.

To return the transducer 1250 to the first configuration 1201, the transducer 1250 may be exposed to a second stimulus S₂To expand the SMP 1206 along the x-axis. For example, if the second stimulus S₂At pH, the SMP 1206 may be subjected to a first, lower pH to induce contraction and a second, higher pH to facilitate swelling. The transducer 1250 may then be exposed to the first stimulus S₁To induce bending of the SMP 1206, thereby folding the transducer 1250. For example, if the first stimulus S₁Being humid, the transducer 1250 may be exposed to a lower humidity to actuate bending of the SMP 1206, and may be exposed to a higher humidity to trigger straightening of the SMP 1206.

The contraction and expansion of the SMP 1206 allows the spacing between the transducer arrays to be adjusted based on the response of the SMP 1206 to a stimulus. As shown in fig. 6A-7B, when the SMP 1206 is configured as a segment disposed between and coupled to the inner edge of the transducer array, the entire segment of the SMP may contract and expand. However, as shown in fig. 10-11, when the SMPs 1206 form a continuous common acoustic layer of transducers, the SMPs 1206 may be adapted to contract and expand only in regions extending between the transducer arrays (e.g., regions 1050 shown in fig. 10 and 11). Further, in some examples, the SMP 1206 may be configured to contract and expand in an azimuthal direction in addition to or instead of an elevational direction. By constraining the constricted and expanded regions, undesirable separation of the SMP from transducer components coupled to the SMP can be mitigated.

It should be understood that the above examples of shape transformation (e.g., bending and pinching) are non-limiting examples. Various other modes of shape change have been contemplated for use in deployable catheters. For example, SMPs can crimp, twist and/or expand in addition to bending and tightening. SMPs can be configured to change shape via more than one mode depending on the stimulus applied and the desired level of complexity.

In this way, the transducer for the deployable catheter can be easily passed intravenously through the patient and provide enhanced field of view, resolution, penetration, and image update rate for the image. The transducer arrays of the transducers may be connected to each other by the SMP, and the transducers may be transitioned between at least a first folded shape and a second unfolded shape as a result of the SMP's response to a stimulus. The active area of the transducer may be selectively increased to enhance the performance of the transducer. SMPs can be incorporated in the transducer via more than one configuration. For example, the SMP may be attached to the edge of the transducer array and extend between the transducer arrays. Alternatively, the SMP may form a continuous common acoustic layer of the transducer arrays and bend at the regions between the transducer arrays. To reduce the distance between the transducer arrays during data acquisition, the SMP can be configured to contract in at least one dimension. Furthermore, when packaging space is available along the azimuth aperture of the transducer, the SMP can be located outside the active area of the transducer, also resulting in a reduced distance between the transducer arrays. Thus, the transducer may be adjusted to a conformation that facilitates intravenous passage of the deployable catheter at low cost, increasing the data quality and data acquisition speed of the 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 that "comprise," "include," or "have" 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. 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 deployable invasive device comprising: a transducer having a plurality of transducer arrays connected by at least one shape memory material configured to transition the transducer between a first folded shape and a second unfolded shape in response to one or more stimuli, wherein in the second unfolded shape the plurality of transducer arrays are arranged adjacent to each other without any other transducer components positioned in a region between each of the plurality of transducer arrays, the region defined by an inner edge of the plurality of transducer arrays and an edge of the plurality of transducer arrays perpendicular to an azimuthal direction, and an active area of the transducer is increased relative to the first folded shape. In a first example of the system, the at least one shape memory material is a two-way shape memory polymer. In a second example of the system, optionally including the first example, at least one shape memory material is positioned along one side of the transducer in the azimuthal direction and extends between edges of each of the plurality of transducer arrays that are perpendicular to the azimuthal direction. In a third example of the system, optionally including the first and second examples, the at least one shape memory material is coupled to an edge of each transducer array of the plurality of transducer arrays at planar segments of the at least one shape memory material, and wherein the planar segments are spaced apart from each other by a central segment of the at least one shape memory material. In a fourth example of the system, optionally including the first through third examples, the central section of the at least one shape memory material is not coupled to the plurality of transducer arrays, and wherein the central section of the at least one shape memory material is configured to transition between a flexed geometry when the transducer is in the first folded shape and a less flexed geometry when the transducer is in the second unfolded shape. In a fifth example of the system, optionally including the first through fourth examples, the plurality of transducer arrays includes a first transducer array and a second transducer array, each of the first transducer array and the second transducer array coupled to the at least one shape memory material along an edge perpendicular to the azimuth direction at a same side of the transducer. In a sixth example of the system, optionally including the first through fifth examples, the plurality of transducer arrays includes a first transducer array, a second transducer array, and a third transducer array, the second transducer array positioned between the first transducer array and the third transducer array, and wherein the at least one shape memory material includes a first shape memory material coupled to edges of the first transducer array and the second transducer array perpendicular to the azimuthal direction at a first side of the transducer and a second shape memory material coupled to edges of the second transducer array and the third transducer array perpendicular to the azimuthal direction at a second side of the transducer, the second side opposite the first side. In a seventh example of the system, optionally including the first through sixth examples, at least one transducer array pivots in a first rotational direction relative to an adjacent transducer array when the transducer transitions from a first folded shape to a second unfolded shape, and wherein the at least one transducer array is coplanar with the adjacent transducer array in the second unfolded shape than in the first folded shape. In an eighth example of the system, optionally including the first through seventh examples, the at least one transducer array pivots in a second rotational direction opposite the first rotational direction when the at least one transducer transitions from the second unfolded shape to the first folded shape, and wherein the at least one transducer array is aligned and parallel with adjacent transducers along a vertical axis of the transducer in the first folded shape.

The present disclosure also provides support for a transducer for an imaging catheter, the transducer comprising: two or more transducer arrays connected by a Shape Memory Polymer (SMP) configured to undergo one or more shape transitions to adjust an active area of the transducer, the active area comprising an accumulated surface area of the two or more transducer arrays facing in a same direction and a distance between each of the two or more transducer arrays. In a first example of the system, the one or more shape transformations include bending the SMP into a curved shape and straightening the SMP into a planar geometry. In a second example of the system, optionally including the first example, the transducer is adjusted to a folded configuration when the SMP is bent into a curved shape and the transducer is adjusted to an unfolded configuration when the SMP is straightened into a planar geometry, and wherein an active area of the transducer is larger in the unfolded configuration than in the folded configuration. In a third example of the system, optionally including the first example and the second example, the active area is increased by at least a factor of 1.5 in the deployed configuration relative to the folded configuration of the transducer. In a fourth example of the system, optionally including the first through third examples, the one or more shape transitions comprise constrictions and expansions of the SMP at least in regions of the SMP that extend between the two or more transducer arrays, and wherein the constrictions and expansions occur along height holes of the transducers. In a fifth example of the system, optionally including the first through fourth examples, contraction and expansion of the SMP is triggered by exposure to one or more stimuli as the active area of the transducer increases. In a sixth example of the system, optionally including the first through fifth examples, the SMP is positioned as a segment coupled to and extending between inner edges of the two or more transducer arrays. In a seventh example of the system, optionally including the first through sixth examples, the SMP is configured as one of a common matching layer or a common backing layer that spans the entire transducer and forms two or more transducer arrays. In an eighth example of the system, optionally including the first through seventh examples, each of the one or more shape transitions is induced by a different stimulus, and the different stimulus comprises any one of a chemical stimulus, a physical stimulus, and a biological stimulus.

The present disclosure also provides support for a transducer for a deployable catheter, the transducer comprising: two or more transducer arrays connected by a Shape Memory Polymer (SMP), the SMP configured to contract and expand along an elevation hole and/or an azimuth hole of the transducer in a region of the SMP extending between each of the two or more transducer arrays. In a first example of the system, when the SMP is tightened, the cumulative width of the SMP is 5% or less of the height and/or azimuth aperture of the transducer.

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.