MICROFABRICATED CATHETER DEVICES WITH HIGH AXIAL STRENGTH

Abstract

The present invention relates to microfabricated intravascular devices configured for high axial strength while maintaining effective flexural flexibility. A tube element includes a series of circumferentially extending rings connected to each other by a series of axially extending beams. Transverse cuts separate and define the rings. A series of axial cuts align with the beams and extend partially from the beams into adjacent rings, such that the beam length is partially nested within the axial length of adjacent rings. This increases the functional length of the beams to provide flexural flexibility while the ring structure remains sufficient to provide effective axial stiffness.

Description

Guide wires and catheters are frequently used in the medical field to perform delicate procedures deep within the body's vasculature. Typically, a catheter is inserted into a patient's femoral, radial, carotid, or jugular vessel and navigated through the patient's vasculature to the heart, brain, or other target anatomy. Often, a guide wire is first directed to the target anatomy, and then one or more catheters are passed over the guide wire and directed to the desired location. Once in place, the catheter can be used to aspirate clots or other occlusions, or to deliver drugs, stents, embolic devices, radiopaque dyes, or other devices or substances to treat the patient. In many applications, such catheters must be guided through the twists and turns of vascular pathways to reach the target anatomy. Ideally, these catheters include design features that allow for efficient navigation through such convoluted paths. For example, a catheter must be flexible enough to navigate the curves of the vasculature, but it must also be able to provide sufficient thrust capacity (i.e., the ability to transmit axial forces from the proximal to the distal portions) and torque capacity (i.e., the ability to transmit torque from the proximal to the distal portions). If a catheter lacks sufficient axial stiffness, for example, it can be difficult for the operator to advance the catheter through the vasculature. That is, the axial forces applied at the proximal end by the operator can cause the catheter to compress axially and form an accordion shape instead of being effectively transmitted to the distal end. Designing the catheter with greater axial stiffness can alleviate this problem. However, increasing the catheter's axial stiffness can lead to other problems that interfere with its effectiveness. For example, increasing the catheter's axial stiffness typically also increases its flexural stiffness, which can be detrimental if insufficient flexural flexibility remains in the device. Consequently, there is a constant need for catheter devices with features that are designed to allow effective axial rigidity without unduly altering necessary characteristics such as the device's flexibility and torsional capacity. Brief Description of the Invention This description describes microfabricated intravascular devices that are configured for high axial strength while maintaining effective flexural flexibility. In one embodiment, a tube element includes a series of circumferentially extending rings connected to each other by a series of axially extending beams. A plurality of cross-cuts separate and define the rings. The cross-cuts are arranged between adjacent rings and extend in a direction transverse to the longitudinal axis of the tube element, but not so far as to completely cut the tube element, thus leaving beams positioned between the rings. In some configurations, at least some of the cross-sections are wedge-shaped. For example, one or more cross-sections may be narrower near the corresponding beams and then widen as they extend circumferentially away from the corresponding beams. In some embodiments, a series of axial cuts are aligned with the beams and extend from the beams partially into the adjacent rings, so that the beam length partially fits within the axial length of the adjacent rings. This increases the functional length of the beams to provide flexural flexibility while the ring structure remains sufficient to provide effective axial stiffness. In some configurations, at least some of the axial cuts are wedge-shaped. For example, one or more axial cuts may be wider at one edge of the adjacent ring and then narrower as they extend along the axial direction into the interior of the adjacent ring. This brief description of the invention is provided to introduce a selection of concepts in a simplified form, which are described further in the detailed description. This brief description of the invention is not intended to identify key features or essential characteristics of the claimed related subject matter, nor is it intended to be used as an indication of the scope of the claimed related subject matter. Brief Description of the Figures Several aims, functions, features, and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken together with the accompanying figures and appended claims, all of which form part of this description. In the figures, similar reference numbers may be used to designate corresponding or similar parts in the various figures, and the various elements depicted are not necessarily drawn to scale. Figure 1 illustrates an example catheter device nofienn / eznz / E / YiAi that can be modified with the cutting pattern described herein to provide a catheter having high axial strength; Figure 2A is a detailed view of a microfabricated distal section of a catheter having a conventional two-beam cut pattern; Figures 2B and 2C are detailed views of microfabricated distal sections of catheters that have three-beam and one-beam cutting patterns, respectively; Figures 3A and 3B schematically illustrate how the microfabricated catheter sections can be compressed and form an accordion under an axial load; Figure 4 illustrates a section of a microfabricated catheter that has relatively thick annular elements to improve axial stiffness, but which concentrates bending forces in the axial beam elements; and Figures 5A and 5B illustrate an example microfabricated catheter section with a shear pattern that provides effective axial stiffness without excessively increasing flexural stiffness and thus provides a high ratio of axial stiffness to flexural stiffness. Detailed Description of the Invention Introduction Figure 1 illustrates an example of a conventional catheter device 10 that can be enhanced by incorporating the unique high thrust resistance cutting patterns described below. The catheter device 10 includes a proximal section 40 and a distal section 50. A radiopaque marker 16 can be located near the distal end. A hub and / or port 42 can be located at the proximal end. Due to the particular benefits of high thrust resistance designs in catheter applications, most of the examples described herein will refer to catheter devices. However, it is understood that, in some modalities, the same features can be applied to other microfabricated components of other intravascular devices, such as guidewires. At least part of the distal section 50 is microfabricated with one or more shear patterns designed to enhance the device's effectiveness. Traditionally, these shear patterns have focused on increasing the device's flexural flexibility while maintaining good torsional capacity. However, as described below, improved shear patterns have now been designed that increase the device's flexural flexibility while optimizing thrust capacity (i.e., optimizing axial stiffness). Although the improved cutting patterns sacrifice some of the torsional capacity of conventional cutting patterns, the enhanced pushing capacity of the nofienn / eznz / E / YiAi device and the improved axial stiffness-to-flexural stiffness ratios provide more effective overall functionality, particularly in applications where axial stiffness is likely to be more important than torsional capacity, such as in many catheter applications. For example, unlike guidewires, catheters lack a solid core and therefore inherently lack good axial stiffness. Since catheters are often guided over guidewires, the guidewires can be used to sub-select vessels and reach the anatomical target. Therefore, pushing capacity is often more important than torsional capacity in catheters. The length of the catheter can vary depending on the needs of a particular application, but will typically be within a range of approximately 125 cm to 175 cm. The microfabricated portion will likely vary depending on the needs of the particular application, but will typically be approximately 50 to 90 cm long. The more distal sections (e.g., the most distal section measures between 10 and 30 cm) typically have a higher degree of microfabrication to make them more flexible. As with the catheter length, the catheter diameter can vary depending on the application. Examples might range from approximately 2 F to 10 F, although sizes outside this range may also be used when appropriate (e.g., outside of typical neurological and coronary applications).Aspiration catheters for use in neurovascular procedures are an exemplary application for the high thrust force devices described herein. The microfabricated section of catheter 10 includes a plurality of cuts extending transversely to the longitudinal axis of the catheter to form rings and beams. The rings are the circumferentially extending, ring-shaped structures, and the beams are the axially extending, uncut sections of tubing that connect adjacent rings. The sections of catheter 10 can be defined herein according to the number of beams arranged between each pair of successive rings. Figures 2A–2C illustrate conventional microfabricated configurations to describe general characteristics and define general terms. The enhanced characteristics, described later, can be applied to any of the conventional configurations shown in Figures 2A–2C. Figure 2A, for example, depicts a conventional two-beam section 15 of a microfabricated tube element. The two-beam section includes a series of successive rings 14 and a series of beams 12 that span between and connect the rings. As shown, each pair of adjacent rings is connected by two beams 12. Figure 2B illustrates a three-beam section 20 in which three of the beams 22 are arranged between each set of adjacent rings 24. Figure 2C illustrates a beam section 30 in which a single beam 32 spans between and connects each pair of adjacent rings 34. Although most of the examples described herein will refer to the two-beam configuration, it is understood that the same characteristics can be applied to other configurations having one-beam or three-beam configurations, or even configurations with a different number of beams between each set of adjacent rings. Figures 3A and 3B schematically illustrate how microfabricated catheter sections can compress and accordion-like form under axial load. Figure 3A shows a side view of a conventional two-beam section (as in Figure 2A) with beams 12 and rings 14. Figure 3B shows that when an axial load (i.e., a thrust) is applied, rings 14 can flex slightly and absorb some of the axial load instead of transferring it entirely to more distal sections of the device. This reduces the device's thrust capacity and makes it more difficult for the operator to track the catheter over a guidewire and / or guide the catheter to the desired anatomical target. One way to increase the axial stiffness of the device is simply to increase the length of the rings along the axial direction (this dimension is sometimes also called the thickness, axial length, or width of the rings). Figure 4 illustrates a modality with a greater axial length of the rings 64. While increasing the axial length of the rings 64 can increase the axial stiffness of the device, there is a practical limit to how much the axial length of the rings 64 can be increased. For example, if the axial length of the rings 64 is increased too much relative to the size of the beams 62, excessive bending stresses will be concentrated in the beams 62. At some point, the device will not be able to bend sufficiently without plastic deformation occurring in the beams 62. Simply increasing the ring size until the desired axial stiffness is achieved is therefore not a practical option. Microfabricated sections with high thrust resistance Figures 5A and 5B illustrate one modality of a high-thrust shear pattern that can be applied to a tube element and used in a catheter device, such as the device shown in Figure 1. The shear pattern provides effective axial stiffness while still maintaining good bending flexibility. Furthermore, unlike simply expanding the thickness of the rings, the illustrated configuration allows for relatively high axial stiffness without excessively concentrating stresses on the beams. Figure 5A shows an example tube element 100 (for example, a distal section of a catheter), and Figure 5B shows the same shear pattern if the tube element 100 were cut in half along its longitudinal axis and uncoiled to lie flat. As shown, the elongated tube element 100 includes a series of circumferentially extending rings 114 connected to each other by a series of axially extending beams 112. The rings 114 have a length L in the axial direction. This dimension may sometimes be referred to as ring width, axial length, or ring thickness, but it is usually referred to herein as length (or, more specifically, axial length) for the purpose of consistency, as it is the dimension parallel to the longitudinal axis of the tube element 100. With respect to the beams 112, beam length 112 will be used herein to refer to the dimension along the axial direction, while beam width or thickness will be used herein to refer to the dimension along the circumference of the tube element 100. The rings 114 are separated by cross-sections 118 that each extend in a direction transverse to the longitudinal axis of the tube element 100, but do not extend completely through the tube element 100. Therefore, the tube element 100 is somewhat similar to the conventional configurations illustrated in Figures 2A. 2C. The illustrated tube element 100 represents a two-beam section because it includes two beams 112 between each pair of adjacent rings 114. However, as explained above, other modalities may include configurations with a different number of beams between each pair of adjacent rings (e.g., one-beam or three-beam configurations). However, unlike the conventional configurations shown in Figures 2A-2C, the illustrated modality also includes a series of axial cuts 116 aligned with the beams 112. Each axial cut 116 begins along an edge of a corresponding beam 112 and extends partially into the adjacent ring 114 in a substantially axial direction, so that the corresponding beam 112 is partially nested within the axial length of the adjacent beam 112. The beams 112 of the embodiment illustrated in Figures 5A and 5B are each associated with axial cuts 116 extending into each of the adjacent rings 114, representing a preferred embodiment. However, other embodiments may include fewer axial cuts 116. For example, some embodiments may have beams that are associated only with axial cuts extending into one of the two adjacent rings (e.g., only the proximal adjacent ring or only the distal adjacent ring, but not both). In another embodiment, the tube element 100 may have some beams 112 that are associated with axial cuts 116 while other beams 112 are not associated with axial cuts 116. Because part of beam 112 is nested within the axial length of ring 114, the result is a more flexible beam structure per unit length of tube element 100 compared to the same structure without the axial cuts 116. In other words, the illustrated cut pattern provides additional functional length to the beams 112 and thus greater bending flexibility to the device, while allowing the rings 114 to be relatively thick (i.e., to have a relatively long axial length) along most of the device's circumference. Therefore, the overall structure is able to provide good axial stiffness without excessively increasing bending stiffness, resulting in devices with a favorable axial stiffness-to-bending stiffness ratio. As shown in Figures 5A and 5B, the cross-sections 118 can be wedge-shaped. The wedge-shaped cuts 118 advantageously provide additional clearance, allowing the device to bend along the inside of a curve. Similarly, for modalities that fill the device voids with a polymeric material, as discussed later, the wedge-shaped cuts 118 provide additional space for the polymer to be compressed into a curve. For example, at a given axial position of the tube element 100, the cross-sections 118 may be narrower near the beams 112 and then widen as they move away from the beams 112. Starting from one of the beams 112 and extending around the circumference, the cross-sections 118 may widen to a vertex 119 and then begin to narrow again as they continue to extend toward the opposite beam 112. As shown, the vertex 119 may be located equidistant from the two beams 112, although in other embodiments, one or more cross-sections 118 may be asymmetrical, and the vertex 119 need not be equidistant from each beam 112. The size and shape of the wedge-shaped cross-sections 118 can vary. In general, wider clearances provide greater allowance for tighter bending, but at the cost of reduced axial stiffness. Consequently, the wedge angle and / or clearance size can be increased for applications requiring greater bending flexibility, or decreased for applications requiring greater axial stiffness. Alternatively, the wedge angle and / or clearance can be increased for areas of the device requiring greater flexibility and decreased for areas requiring greater axial strength. As a non-limiting example, the wedge angle and / or clearance size can be increased in the more distal sections of the device relative to the more proximal sections.In some embodiments, at least in a distal section of the tube element 100, the size of the vertex space 119 (i.e., the widest part of the cross-section 118) may be from approximately 25% to approximately 100% of the length of the rings 114, or from approximately 35% to 75% of the length of the rings 114. In addition, or alternatively, the wedge angle may progressively increase or decrease between sections, so that there is a gradual change in the wedge angle from a first section to a second section. The angle A at which the wedge shape of the cross-sections 118 extends from the beam 112 can range from approximately 2 degrees to approximately 35 degrees, or from approximately 5 degrees to approximately 25 degrees, or from approximately 10 degrees to approximately 20 degrees. In other words, if an angle of 0 degrees represents a straight perpendicular cut, the wedge-shaped cuts 118 preferably have an angle greater than 0 degrees but less than 35 degrees, more typically less than 25 degrees or less than 20 degrees. In the illustrated embodiment, the cross-sections 118 form an angle in both axial directions (proximal and distal). That is, starting at a given beam 112 and moving in a circumferentially perpendicular direction around the tube element 100 toward another beam 112, the corresponding cross-section 118 forms an angle away from the perpendicular along the proximally adjacent ring 114 and the distally adjacent ring 114. Other embodiments may include cross-sections 118 that are only angled away from the perpendicular in one direction (i.e., only along the proximal adjacent ring or only along the distal adjacent ring). One or more axial cuts 116 may be wedge-shaped. As shown in Figures 5A and 5B, the axial cuts 116 may be somewhat wider where the cuts begin along the edge of the ring, and then narrow as they extend along the axial direction further into the adjacent ring. Similar to the wedge shape of the transverse cuts 118, the wedge shape of the axial cuts 116 may provide additional clearance that allows greater movement of the rings 114 relative to the beam 112, enabling the rings 114 to bend more effectively toward each other along the inside of a bend when the tube member 100 is bent.If a straight axial cut (parallel to the longitudinal axis) has a cutting angle of 0 degrees, the angle of axial cuts 116 can be greater than 0 degrees, but less than approximately 35 degrees, more typically less than approximately 25 degrees or less than approximately 20 degrees. At least for the distal sections of the tube element 100, the axial cuts 116 can extend into the adjacent rings 114 by a distance equal to approximately 25% to approximately 75%, or approximately 35% to approximately 65%, or approximately 45% to approximately 55% of the axial length of the rings 114. The greater the extension of the axial cuts 116 into the rings 114, the greater the added functional length of the associated beam 112. However, this occurs at the expense of part of the ring structure, and thus deeper axial cuts 116 reduce part of the ring 114 structure that otherwise contributes to axial stiffness, at least in the particular portion of the ring 114 that coincides with the axial cuts 116 and the beam 112.In some applications, the axial cuts 116 may extend further into the rings 114 to increase the length of the associated beam 112 and, therefore, the flexibility of the tubular element 100. In other applications, the axial cuts 116 may extend further into the ring 114 in one section of the device compared to another section. For example, the axial cuts 116 may increase or decrease near the distal or proximal ends of the device. Consequently, the beam length can also increase or decrease. This can result from the length of the axial cut 116, as explained above. Alternatively, or in addition, the beam length can vary independently of the axial cut 116 by increasing or decreasing the length of the portion of the beams 112 between the corresponding pair of rings 114. In some applications, one section of the tubular element 100 may have a longer beam length relative to another section to provide the device with differential flexibility in different parts. Finally, the beam length can vary progressively from a first section to a second section, such that the beam length gradually increases or decreases between the two sections. The beam width, or beam thickness, can also vary depending on the device application, the overall size of the device, and / or the device section. In some applications, one section of a device may have a relatively larger beam width than a second section. Furthermore, the beam width may vary progressively, so that the beam width of each beam 112 increases gradually from the first to the second section. The ring size may also vary according to the overall size of the device and / or the section of the device. nofienn / eznz / E / YiAi For example, in a distal section of tube element 100, the rings 114 may have a ring length-to-diameter ratio of approximately 0.25 to 0.8, or approximately 0.35 to 0.65, or approximately 0.4 to 0.6. In some applications, the entire device will use similar ring sizes, with each ring 114 having a similar axial length. Alternatively, in some applications, the ring size of one or more sections of the device will differ from that of one or more other sections, such that one or more sections of the device have greater axial strength relative to one or more other sections. In some embodiments, the axial length of the ring may vary progressively along the length of the device, so that the ring size gradually increases or decreases from one section to another. As shown, the beams 112 between each pair of adjacent rings 114 can be equally spaced circumferentially (for example, spaced 180 degrees apart in a two-beam configuration), although other embodiments may arrange the beams so that they are not equally spaced circumferentially. Beam assemblies 112 can also be rotationally offset from adjacent beam assemblies 112. For example, a beam assembly 112 between a given pair of adjacent rings can be rotationally offset from the beam assembly of a previous and / or subsequent pair of adjacent rings. In the embodiment illustrated, the rotational offset is 90 degrees. That is, a first pair of beams is provided in a first rotational position, then, as it moves along the tube element 100, the next pair of beams is offset from the first pair by 90 degrees. Other rotational offsets may be used. The rotational offset can be from approximately 5 degrees to approximately 90 degrees, for example. A rotational offset of less than 90 degrees provides a helical pattern that minimizes preferred bending axes in the tube element 100. Alternatively, other beneficial distributed beam arrangements may be used to avoid preferred bending axes. These are described in more detail in U.S. Patent Application Serial Number 16 / 616,139, entitled "Microfabricated Medical Device Having a Non-Helical Shear Arrangement," which is incorporated herein by reference in its entirety. The 100 tube element can be formed from any material or combination of materials suitable for intravascular application. Examples include polymeric materials, such as polyether ether ketone (PEEK), other polymers that can be formulated with a similar modulus of elasticity range, stainless steel, or superelastic materials, such as nitinol. The preferred embodiments nofienn / eznz / E / YiAi are formed from nitinol. As briefly mentioned above, a polymeric material can be added to the tube element 100 to fill the voids created by the transverse cuts 118 and the axial cuts 116, thus enabling the tube element 100 to be fluid-carrying. The polymeric material may comprise an elastomer, such as a polyether block amide, and / or another similar polymer. Another advantage of the described configurations compared to conventional ones relates to the relatively smaller open space along the outer surface of the 100 tube element. Because the improved cutting patterns allow for a greater axial length of the rings, less of the total outer surface area is occupied by voids. This means that, proportionally, a smaller portion of the device relies on the polymer material to maintain fluid-tight integrity under pressure, and therefore the device is less likely to fail when supplying fluids under pressure. Other embodiments may omit a polymeric material. For example, certain applications may not require the supply or aspiration of fluids, and it is feasible to use a device in which the spaces are not filled. Maintaining open spaces is beneficial in certain applications because adding polymer to the cross-sections and axial sections increases the flexural stiffness of the tube element 100. Other embodiments may use one or more coatings instead of a polymer filler material. For example, an inner coating may be disposed along an inner surface of the tube element 100, and / or an outer coating may be disposed along an outer surface of the tube element 100. In either case, the inner and outer coatings do not fill the voids of the tube element 100.Such modalities can advantageously keep the gaps in the transverse and axial cuts open and unobstructed, reducing the amount of bending resistance and thus allowing for less bending stiffness. It should be understood that the above features are primarily directed towards a distal section of the 100 tube element. Similar features can be used in more proximal sections. However, more proximal sections typically do not require the same flexural flexibility and, therefore, these sections can be tailored more towards thrust and / or torsional capacity and less towards flexural flexibility. Further modifications to proximal sections can be made by increasing the axial lengths of the rings, increasing the width of the beams, decreasing the size of the wedge-shaped spaces, decreasing the depth of the axial cuts, or increasing the number of beams between each pair of rings. Examples A useful metric for comparing intravascular devices is the ratio of axial stiffness to flexural stiffness. Axial stiffness and flexural stiffness (i.e., bending stiffness) are generally reported using different units. In the SI system, for example, axial stiffness is usually reported in units of force times distance (e.g., Newtons per meter), while flexural stiffness is usually reported in units of force times distance squared (e.g., Newtons per meter squared). When such units are used, a useful metric can be determined by comparing the ratio of axial stiffness to flexural stiffness of a micromachined structure with the ratio of axial stiffness to flexural stiffness of a homogeneous material (not micromachined but otherwise similar to the micromachined structure).For example, the ratio of axial stiffness to flexural stiffness of the micromachined structure can be divided by the ratio of axial stiffness to flexural stiffness of the homogeneous material to provide a useful comparative ratio illustrating how the micromachined structure compares to a reference homogeneous material. Such an overall ratio is dimensionless. This metric is referred to in the present relationship of nofienn / eznz / E / YiAi micromachined to homogeneous. A variety of catheter devices and materials were tested to measure the ratios of axial stiffness to flexural stiffness. Materials tested included homogeneous rubber tubing and plastic materials, including PEBAX® (a polyether block amide), polyurethane, and similar materials. Commercially available catheter devices formed with coiled and / or braided material sections were also tested. The ratio of micromachined to homogeneous material for commercially available catheters typically ranged from approximately 1 to 2.5. The highest micromachined-to-homogeneous ratios were found in certain commercial catheter products with coiled and / or braided sections and measured at approximately 3. In comparison, tube elements formed with a high thrust strength configuration, as shown in Figure 5A, were also tested. Nitinol-formed tube elements were the most preferred, although elements formed from other materials also performed well. The high thrust strength configuration provided micromachining-to-homogeneous ratios that were significantly higher than those of the common coil and / or braided arrangements. Tube elements with the high thrust strength configuration had micromachining-to-homogeneous ratios greater than 100, and in some cases, much greater than 3. Certain tests showed micromachining-to-homogeneous ratios of approximately 14. Some tests even showed micromachining-to-homogeneous ratios of up to 100 in distal sections of the tube with high degrees of microfabrication. Additional terms and definitions Although certain aspects of the present description have been described in detail, with reference to specific configurations, parameters, components, elements, etc., the descriptions are illustrative and should not be interpreted as limiting the scope of the claimed invention. Furthermore, it should be understood that for any given element or component of a described modality, any of the possible alternatives listed for that element or component may generally be used individually or in combination with each other, unless implicitly or explicitly stated otherwise. Furthermore, unless otherwise stated, numbers expressing quantities, constituents, distances, or other measurements used in the description and claims shall be understood to be optionally modified by the term "approximately" or its synonyms. When the terms "about," "approximately," "substantially," or similar terms are used in conjunction with a stated quantity, value, or condition, they may be understood to mean a quantity, value, or condition that deviates by less than 20%, less than 10%, less than 5%, or less than 1% from the stated quantity, value, or condition. At a minimum, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter shall be interpreted in light of the number of significant digits reported and by applying ordinary rounding techniques. All titles and subtitles used herein are for organizational purposes only and are not intended to limit the scope of the description or claims. It will also be noted that, as used in this description and the accompanying claims, the singular forms *un*, *una*, and *el* do not exclude plural referents, unless the context clearly indicates otherwise. Thus, for example, a modality that refers to a singular referent (e.g., gadget) may also include two or more such referents. It will also be appreciated that the modalities described herein may include properties and characteristics (e.g., ingredients, components, members, elements, parts, and / or portions) described in other modalities herein. Consequently, the various characteristics of a given modality may be combined and / or incorporated into other modalities in this description. Therefore, the description of certain characteristics relating to a specific modality in this description should not be interpreted as a limited application or inclusion of such characteristics to that specific modality. Rather, it will be appreciated that other modalities may also include such characteristics. Additional exemplary modalities The modalities in this description may include, but are not necessarily limited to, the characteristics listed in the following clauses: Mode 1: A microfabricated elongated tube element (i.e., device) for an intravascular device, the elongated tube element extending along a longitudinal axis and comprising: a plurality of circumferentially extending rings, each ring having an axial length; a plurality of cross-sections, each positioned between adjacent rings, each cross-section extending in a direction transverse to the longitudinal axis of the tube element; a plurality of axially extending beams, each extending from one ring to another to connect adjacent rings; and a plurality of axial cuts aligned with the beams, each axial cut extending partially into an adjacent ring in a substantially axial direction, such that a corresponding beam is nestled at least partially within the length of one or both adjacent rings connected by the corresponding beam. Mode 2: The device of Mode 1, where the cross-sections are wedge-shaped. Mode 3: The device of Mode 2, wherein each cross-section is narrower near the corresponding beams and widens as it extends circumferentially away from the corresponding beams. Mode 4: The device of any of Modes 1-3, wherein the axial cuts are wedge-shaped. Mode 5: The Mode 4 device, wherein each axial cut is wider at one edge of the adjacent ring and narrows as it extends along the axial direction into the interior of the adjacent ring. Mode 6: The device of any of Modes 1-5, wherein the tube element has a two-beam configuration, such that two beams extend between each pair of adjacent rings and connect them. Mode 7: The Mode 7 device, wherein the pair of beams between each pair of adjacent rings are spaced circumferentially at approximately 180 degrees. Mode 8: The device of Mode 6 or Mode 7, wherein the two-beam configuration includes a rotational displacement, such that the beams between a given pair of adjacent rings are rotationally displaced from the beams of a previous and / or subsequent pair of adjacent rings. Mode 9: The device of Mode 8, where the rotational displacement is from approximately 5 degrees to approximately 90 degrees. Mode 10: The device of any of Embodiments 1-9, wherein the axial length of the ring becomes progressively shorter towards a distal end of the tube element. Mode 11: The device of any of Modes 1-10, wherein the beam thickness becomes progressively smaller towards a distal end of the tubular element. Mode 12: The device of any of Modes 1-11, wherein in the distal section of the tube element, the rings have a ring length to ring diameter ratio of approximately 0.25 to 0.8, or approximately 0.35 to 0.65, or approximately 0.4 to 0.6. Mode 13: The device of any of Modes 1-12, wherein the tubular element is made of nitinol. Mode 14: The device of any of Modes 1-13, wherein at least one section of the tube element has a homogeneous micromachined ratio nofienn / eznz / E / YiAi of at least approximately 3, or at least approximately 10, or at least approximately 20, or at least approximately 30, or at least approximately 40, or at least approximately 50, or at least approximately 60, or at least approximately 70, or at least approximately 80, or at least approximately 90. Mode 15: The device of any of Modes 1-14, wherein the tubular element is made of one or more polyether ether ketone (PEEK), stainless steel, or nitinol. Mode 16: The device of Mode 15, wherein the tubular element is made of nitinol. Mode 17: The device of any of Modes 1-16, further comprising a polymer applied to the tubular element to fill the transverse cuts and axial cuts. Mode 18: The device of any of Modes 1-16, which further comprises an inner and / or outer coating attached to the tubular element. Mode 19: The device of Mode 18, wherein the inner and / or outer covering does not fill the cross-sections or axial cuts. Mode 20: The device of any of the nofienn / eznz / E / YiAi Modalities 1-19, wherein the tube element is sized for use as an aspiration catheter in a neurovascular application. Modality 21: A microfabricated elongated tube element for an intravascular device, the elongated tube element extending along a longitudinal axis and comprising: a plurality of circumferentially extending rings, each ring having an axial length; a plurality of axially extending beams, each extending from one ring to another to connect adjacent rings; and a plurality of cross-cuts, each positioned between adjacent rings, each cross-cut extending in a direction transverse to the longitudinal axis of the tube element, wherein each cross-cut is narrower near a corresponding beam and widens as it extends circumferentially away from the corresponding beam. Mode 22: The tube element of Mode 21, wherein at least some of the cross-sections are wedge-shaped, and wherein at least some of the cross-sections are narrower near the corresponding beams and widen as they extend circumferentially away from the corresponding beams. Modality 23: An elongated tube element, microfabricated for an intravascular device, the elongated tube element extending along a longitudinal axis and comprising: a plurality of circumferentially extending rings, each ring having an axial length; a plurality of axially extending beams, each extending from one ring to another to connect adjacent rings; and a plurality of axial cuts aligned with the beams, each axial cut extending partially into an adjacent ring in a substantially axial direction, such that a corresponding beam is nestled at least partially within the length of one or both adjacent rings connected by the corresponding beam. Mode 24: The tube element of Mode 23, wherein at least some of the axial cuts are wedge-shaped, and wherein at least some of the axial cuts are wider at an edge of the adjacent ring and narrow as they extend along the axial direction in the adjacent ring. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A microfabricated elongated tube element for an intravascular device, the elongated tube element extending along a longitudinal axis and characterized in that it comprises: a plurality of circumferentially extending rings, each ring having an axial length; a plurality of transverse cuts, each positioned between adjacent rings, each transverse cut extending in a direction transverse to the longitudinal axis of the tube element; a plurality of axially extending beams, each extending from one ring to another to connect adjacent rings; and a plurality of axial cuts aligned with the beams, each axial cut extending partially into an adjacent ring in a substantially axial direction, such that a corresponding beam is at least partially nestled within the length of one or both adjacent rings connected by the corresponding beam.

2. The tube element according to claim 1, characterized in that at least a portion 34 of the cross-sections are wedge-shaped.

3. The tube element according to claim 2, characterized in that at least some of the cross-sections are narrower near the corresponding beams and widen as they extend circumferentially away from the corresponding beams.

4. The tube element according to claim 1, characterized in that at least some of the axial cuts are wedge-shaped.

5. The tubular element according to claim 4, characterized in that at least some of the axial cuts are wider at one edge of the adjacent ring and narrow as they extend along the axial direction into the interior of the adjacent ring.

6. The tube element according to claim 1, characterized in that it has a two-beam configuration, such that there is a pair of beams between each pair of adjacent rings, and the pair of beams between each pair of adjacent rings are spaced circumferentially by approximately 180 degrees.

7. The tube element according to claim 6, characterized in that the two-beam configuration includes a rotational displacement, such that the beams between a given pair of adjacent rings are rotationally displaced from the beams of a prior and / or subsequent pair of adjacent rings.

8. The tube element according to claim 7, characterized in that the rotational displacement is from approximately 5 degrees to approximately 90 degrees.

9. The tube element according to claim 1, characterized in that the axial length of the ring decreases progressively towards a distal end of the tube element.

10. The tube element according to claim 1, characterized in that the thickness of the beam decreases progressively towards a distal end of the tube element.

11. The tube element according to claim 1, characterized in that in a distal section of the tube element, the rings have a ring length to ring diameter ratio of approximately 0.25 to 0.

8.

12. The tube element according to claim 1, characterized in that at least one section of the tube element has a micromachined-to-homogeneous ratio of at least approximately 3.

13. The tube element according to claim 1, characterized in that it is formed from one or more layers of polyether ether ketone (PEEK), stainless steel, or nitinol. nofienn / eznz / E / YiAi 14. The tube element according to claim 1, characterized in that it further comprises a polymer applied to the tube element to fill the transverse cuts and axial cuts.

15. The tube element according to claim 1, characterized in that it further comprises one or both of an inner coating or an outer coating.

16. The tube element according to claim 15, characterized in that the inner coating and the outer coating do not fill the transverse cuts or the axial cuts.

17. A microfabricated elongated tube element for an intravascular device, the elongated tube element extending along a longitudinal axis and characterized in that: a plurality of circumferentially extending rings, each ring having an axial length; a plurality of axially extending beams, each extending from one ring to another to connect adjacent rings; and a plurality of cross-cuts, each positioned between adjacent rings, each cross-cut extending in a direction transverse to the longitudinal axis of the tube element, wherein each cross-cut is narrower near a corresponding beam and widens as it extends circumferentially away from the corresponding beam.

18. The tubular element according to claim 17, characterized in that at least some of the cross-sections are wedge-shaped, and wherein at least some of the cross-sections are narrower near the corresponding beams and widen as they extend circumferentially away from the corresponding beams.

19. A microfabricated elongated tube element for an intravascular device, the elongated tube element extending along a longitudinal axis and characterized in that it comprises: a plurality of circumferentially extending rings, each ring having an axial length; a plurality of axially extending beams, each extending from one ring to another to connect adjacent rings; and a plurality of axial cuts aligned with the beams, each axial cut extending partially into an adjacent ring in a substantially axial direction, such that a corresponding beam is nestled at least partially within the length of one or both adjacent rings connected by the corresponding beam.

20. The tube element according to claim 19, characterized in that at least some of the axial cuts are wedge-shaped, and wherein at least some of the axial cuts are wider at an edge of the adjacent ring and narrow as they extend along the axial direction in the adjacent ring.

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