IES87501Y1 - Bonded stent assembly and method of manufacturing - Google Patents

Abstract

A method of attaching a fabric material to a stent comprising a metal alloy formed by a network of struts, comprises applying a polymer binder to at least some struts within a transverse section of the stent so as to encapsulate the at least some struts with the polymer binder at a polymer-binder thickness of not less than 1 micron and not greater than 40 microns, radially constraining the transverse section so as to reduce a diameter thereof by at least 50%, and, while the transverse section is radially constrained, engaging the fabric material with the at least some struts so as to bond the fabric material with the polymer binder on at least a respective portion of at least one major surface of the stent.

Description

BONDED STENT ASSEMBLY AND METHOD OF MANUFACTURING CROSS—REFERENCE TO RELATED APPLICATIONS This patent application claims priority to US. Provisional Patent Application No. 63/046,746 filed on July I, 2020.

FIELD OF THE INVENTION The present invention relates to medical stent devices and assemblies comprising metal stents and covering materials (including fabrics) attached thereto, along with methods for their manufacture and assembly. In particular, the present invention is suitable for use in medical applications as a sutureless stent graft.

BAC KG RO UN D A stent is a metal or polymer tube inserted into the lumen ofan anatomic vessel or duct to keep the passageway open. For example. stents may be used in the vascular system, urogenital tract and bile duct. as well as in a variety ofother applications in the body. Endovascular stents have become widely used for the treatment ofstenosis, strictures. and aneuiysms in various blood vessels. These devices are implanted within the vessel to open and/or reinforce collapsing or partially occluded sections ofthe vessel.

Stents are generally open ended and are radially expandable between a generally unexpanded insertion diameter and an expanded implantation diameter which is greater than the unexpanded insertion diameter. Stents are often flexible in configuration, which allows them to be inserted through and conform to tortuous pathways in the blood vessel. The stent is generally inserted in a radially compressed state and expanded either through a self-expanding mechanism. or through the use of balloon catheters.

It is also known to combine a stent and a graft to form a composite medical device. Grafts are tubular devices which may be formed ofa variety ofmaterial. including textile and non-textile fabric materials and other covering materials. Such a composite medical device provides additional support for blood flow through weakened sections ofa blood vessel. In endovascular applications. the use ofa stent/graft combination is becoming increasingly important because the combination not only effectively allows the passage of blood therethrough. but also ensures the implant will remain open and stable.

Existing stent grafts with full bonding can require high radial forces to compress the stent for insertion into a catheter. and this can be exacerbated by resistance forces, for example, to longitudinal extension when the stent is compressed.

In addition, stent grafts with full circumferential bonding can experience non-optimal or uncontrolled wrinkling ofthe graft fabric when the stent is compressed and/or have a higher likelihood of kinking or twisting that can ‘choke‘ the lumen ofthe stent- supported vessel. In addition. stent assemblies having fabric coverings attached when the stent is in an unconstrained, e.g., expanded, state can exhibit excessive fabric wrinkling when constrained to a reduced-diameter state.

SUMMARY A method is disclosed, according to embodiments, for attaching a fabric material to a stent comprising a metal alloy. the stent being formed by a network of struts and having two major surfaces. The method comprises: (a) applying a polymer binder to at least solnc struts within a transverse section ofthe stent so as to encapsulate the at least some struts with the polymer binder at a polymer-binder thickness ofnot less than 1 micron and not greater than 40 microns; (b) radially constraining the transverse section so as to reduce a diameter thereof by at least 50%; and (c) while the transverse section is radially constrained, engaging the fabric material with the at least some struts so as to bond the fabric material with the polymer binder on at least a respective portion of at least one major surface ofthe ste nt.

In some embodiments, the applying the polymer binder can include: (i) encapsulating, to a first binder thickness of no more than 10 micron, at least 80%, by length, ofthe combined lengths ofthe struts ofthe network within the transverse section, and (ii) selectively applying the polymer binder, to a second binder thickness that is at least twice the first binder thickness and no more than 40 microns, to at least some struts within the transverse section.

In some embodiments, the transverse section can be is in a fully—expanded state during the applying of the polymer binder.

In some embodiments, the method can additionally include, before the applying the polymer binder: applying a primer to at least some struts of the network within the transverse section to form a covalent bond with the at least some struts.

In some embodiments, it can be that the applying ofthe polymer binding includes extruding the polymer binder.

In some embodiments, it can be that the fabric material engaged to the at least some struts can have an unfolded length along a circumference ofthe transverse section that is no more than 20% greater than a circumference ofthe transverse section to which the fabric material is engaged.

In some embodiments, upon cessation of the radial constraining, the diameter ofthe transverse section can increase by at least 100%. In some embodiments, upon cessation ofthe radial constraining, the diameter ofthe transverse section can increase by at least 200%.

In some embodiments, it can be that (i) the selectively applying the polymer binder is at multiple binder—locations eircumfercntially—displaced along a circumference of the transverse section, (ii) the multiple binder—locations occupy, in aggregate, at least 5% and not more than 75% ofthe circumference, and/or (iii) the multiple binder-locations are spaced such that no location—location spacing is greater than one—third of the circumference.

In some embodiments, it can be that at the reduced circumference, a diameter ofthe stent is no more than 2 mm.

According to embodiments, a stent assembly comprises: (a) a stent formed by a network of struts, the stent having an internal surface and an external surface: and (b) a fabric material covering at least a transverse section of at least one of the internal surface and the external surface, and bonded to the stent by a polymer binder that mediates between the fabric material and at least some struts ofthe network of struts to bind therebetween. The stent assembly has a fully—expanded state in the absence of a radial constraint and a reduced-diameter state characterized by the stent being radially constrained to reduce a diameter ofthe stent by at least 50%; when the stent assembly is in the reduced-diameter state, the fabric material covering the transverse section has an unfolded length along a circumference of the transverse section that is no more than 20% greater than a circumference ofthe covered transverse section.

In some embodiments, it can be that the polymer binder (i) encapsulates at least 80%, by length, ofthe combined lengths ofthe struts ofthe network within the transverse section to a first binder thickness, and/or (ii) selectively has a second binder thickness that is at least to ice the first binder thickness at multiple binder— locations circumferentially-displaccd along a circumference ofthe transverse section and occupying in aggregate. at least 5% and not more than 75% ofthe circumference with no location-location spacing being greater than one-third ofthe circumference.

In some embodiments, it can be that the first binder thickness is not greater than 10 micron. In some embodiments, it can be that the second binder thickness is not greater than 40 microns.

In some embodiments, the stent assembly can additionally include a primer between at least some struts ofthe network within the transverse section and the polymer binder to form a covalent bond with the at least some struts.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described further, by way of example, with reference to the accompanying drawings, in which the dimensions of components and features shown in the figures are chosen for convenience and clarity of presentation and not necessarily to scale. In the drawings: Figs. 1A and 113 illustrate a stent characterized by n—sided cells, according to embodiments of the present invention.

Figs. 2A and 28 illustrate a stent characterized by undulating rings, according to embodiments ofthe present invention.

Figs. 3 and 4 illustrate stent designs with different types of intersection locations. according to embodiments ofthe present invention.

Fig. 5 shows a perspective view ofa stent coated with a polymer binder, according to embodiments ofthe present invention.

Fig. 6 shows a perspective view ofa stent assembly according to embodiments of the present invention.

Figs. 7A and 7B are schematic cross-sectional illustrations ofbonding a fabric to a stent by having a polymer binder enter pores in the fabric. according to embodiments of the present invention; Fig. 8 shows a flowchart ofa method for attaching a fabric material to a stent comprising a metal alloy, according to embodiments ofthe present invention.

Figs. 9A and 9B illustrate a stent assembly characterized by stent-assembly segments, according to embodiments ofthe present invention.

Figs. 10A and 108 are schematic illustrations of intersecting struts coated with a polymer binder. according to embodiments ofthe present invention.

Fig. l 1 shows a flowchart ofa method for producing a radially compressible stent assembly comprising longitudinally displaced stent—assembly segments with different respective radial strengths, according to embodiments ofthe present invention.

Figs. 12A and 128 are schematic cross—sectional illustrations ofbinder wings provided to facilitate bonding ofa fabric to a stent. according to embodiments of the present invention.

Fig. 13 shows a flowchart ofa method for producing a stent assembly comprising a metal stent formed by a network of struts and having an internal major surface and an external major surface. according to embodiments ofthe present invention.

Fig. 14 illustrates the painting ofa binder onto a stent with fabric engaged therewith, according to embodiments of the present invention.

Figs. 15A and 158 illustrate examples of stent designs in which a fabric material can be attached to portions of stents. according to embodiments ofthe present invention.

Figs. 16A — 16E illustrate examples ofdifferent shapes and designs ofstents incorporating embodiments ofthe present invention.

Fig. 17A shows. schematically. a stent with multiple binder locations disposed circumferentially around a transverse section ofthe stent. according to embodiments ofthe present invention.

Fig. 178 shows a detail of Fig. 17A.

Fig. 18 shows, schematically. a fabric graft selectively bonded to the stent of Fig. 17A. according to embodiments ofthe present invention.

Fig. 20A shows, schematically, a stent with multiple binder locations disposed circumferentially around each ofa plurality oftransverse sections ofthe stent, according to embodiments ofthe present invention.

Fig. 20/\ shows. schematically. a stent with multiple binder locations disposed circumferentially around each ofa plurality of transverse sections ofthe stent, according to embodiments ofthe present invention.

Fig. 20B shows a detail of Fig. 20A.

Fig. 21 shows. schematically. a stent with multiple binder locations disposed circumferentially around each ofa plurality of transverse sections ofthe stent. according to embodiments ofthe present invention.

Fig. 22 shows. schematically. a stent with multiple binder locations disposed circum ferentially around each ofa plurality oftransverse sections ofthe stent with a staggered pattern ofselective bonding, according to embodiments ofthe present invention.

Figs. 23A and 238 show. schematically, a cutaway cross-section ofa selectively-bonded stent graft according to embodiments ofthe present invention. respectfully, before and after the application ofcompressive radial force.

Fig. 24 shows a graph oI‘experimental results of measuring loading force on stents manufactured according to embodiments of the present invention as a function ofselective bonding percentage.

Fig. 25 shows a flowchart ofa method of attaching a fabric material to a stent formed by a network ofstruts using selective bonding according to embodiments of the present invention.

Figs. 26A. 268, 26C, and 26D show respective schematic cross—sections of various examples ofstruts coated with a primer. encapsulated with a polymer binder to a first thickness, and coated with the polymer binder to a second thickness, according to embodiments ofthe present invention.

Figs. 27A and 278 show flowcharts of method steps for attaching a covering material to a stent formed by a network of struts. according to embodiments of the present invention.

Figs. 28A and 288 show flowcharts of method steps for attaching a fabric material to a metal-alloy stent formed by a network of struts, according to embodiments ofthe present invention.

Figs. 29A, 298, 29C, 29D. 29E. 29F, and 296 schematically illustrate stages and/or method steps for attaching a fabric material to a metal—alloy stent formed by a network ofstruts. according to embodiments of the present invention.

DETAILED DESCRIPTION OF Tl lE ILLUSTRATED EMBODIMENTS The invention is herein described. by way of example only. with reference to the accompanying drawings. With specific reference now to the drawings in detail. it is stressed that the particulars shown are by way oI‘example and for purposes of illustrative discussion ofthe preferred embodiments ofthe present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description ofthe principles and conceptual aspects ofthe invention. In this regard, no attempt is made to show structural details ofthe invention in more detail than is necessary for a fundamental understanding ofthe invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Throughout the drawings, like-referenced characters are generally used to designate like elements.

Subscripted reference numbers (e.g., 101) or letter—modified reference numbers (e.g., a) are used to designate multiple separate appearances ofelements in a single drawing, e.g. 101 is a single appearance (out ofa plurality of appearances) ofelement , and 100a is a single appearance (out ofa plurality ofappearances) ofelement 100.

For convenience, in the context ofthe description herein, various terms are presented here. To the extent that definitions are provided, explicitly or implicitly, here or elsewhere in this application, such definitions are understood to be consistent with the usage ofthe defined terms by those ofskill in the pertinent art(s).

Furthermore, such definitions are to be construed in the broadest possible sense consistent with such usage.

The term ‘stent assembly" as used herein means an assembly ofa medical stent and a fabric cover, sleeve or attachment, attached to the struts ofthe stent. A stent assembly can be what is commonly called a stent graft. A stent assembly can additionally include materials used in the assembly. such as, for example, primers. coatings, binders and polymers or elastomers.

The term ‘bonding’ can be used to mean a process ofjoining using any one or more of: applying an adhesive binder, e.g., by painting it onto a surface ofa stent strut; applying heat; and applying pressure. The bonding can be carried out by applying a binder to a strut and then engaging the fabric, or by engaging the fabric and then applying the binder. Either approach can be practiced in any of the embodiments disclosed herein. In some cases, the bonding or adhesion is chemical in nature, e.g., when the binder and fabric comprise materials which form adhesive chemical bonds thcrcbctwecn. In some cases. the bonding or adhesion is mechanical in nature, e.g., when a mechanical interlock is achieved. such as when a binder enters the pores ofa porous fabric. In some cases, the bonding or adhesion can achieve a combination of chemical and mechanical adhesion. All of these cases can be implemented in accordance with any ofthe embodiments disclosed herein.

The terms ‘eovcring material" and ‘fabric material’ (‘fabric) are used interchangeably throughout this disclosure and in the claims appended thereto except where fabric is modified by ‘woven’ or 'porous’ and the like". In another words. a covering material, or. equivalently. can include. and not exhaustively a fabric material. whether woven or not. or a non-fabric material, such as an elastomcric material. or any permeable or impermeable deployed as a covering material (or ‘graft’) for a stent.

In some embodiments. a stent assembly comprises a stent and a porous fabric material. In other embodiments. a stent assembly comprises a stent and a non-porous fabric. which can be liquid-impermeable. The fabric/covering material can be in the form ofa sheet or a sleeve, e.g.. a cylinder.

First Discussion of Embodiments A first example ofa stent is shown in Figs. IA and 18. The stent 101 is formed by a network ofstruts 102. The stent 101 has an internal surface 151 and an external surface 152. As seen. each ofthe surfaces 151. 152 comprises surfaces of struts 102. and open spaces 108 between the struts 102. The network ofstruts 102 can comprise a plurality ofstrut segments 110 defined by intersection locations 112. The area ofeithcr surface 151. 152 of the stent 102 can be thought of as comprising a plurality of stent-area portions.

In the embodiment illustrated in Figs. 1A and 18. the stent—area portions comprise 4-sided cells 120 each comprising 4 strut segments (e.g.. 1101. 1102. 1103. ) defined by 4 intersection locations (e.g.. 112A, 1121;. 112(', 1121)). More generally. the stent-area portions. in embodiments. can comprise n—sided cells each comprising n strut segments defined by n intersection locations. where n is an integer equal to at least 3 and at most 6. In various embodiments. the cells can have either regular polygon shapes or irregular shapes. Strut segments 110 can be mostly straight or curved in accordance with a stent design. /\ stent 101 can have at least I. at least . at least 20. at least 50. at least 100 or more such n-sided cells. The n-sided cells can make up one or more regions ofthe surfaces 151, 152 ofa stent 101, or can account for the entire stent surface.

Referring now to Figs. 2A and 28, another example of stent design is shown where the network ofstruts 102 is characterized by undulating rings 130 of strut segments 102 defined by bends 113. Bends 113 are another form ofintersection locations like the intersection locations 112 of Fig. IB, in that they mark where strut segments 102 intersect. As mentioned earlier, the stent 101 can be thought of as comprising a plurality of stcnt-area portions. in the embodiment illustrated in Figs. 2A and 28, the stent-area portions comprise undulating rings 130 (e.g., 1301, 1302, 1303).

A stent 101 can have at least I, at least 5. at least 10, at least 20, or more such undulating rings 130. The undulating rings 130 can make up one or more regions of the surfaces 151, 152 ofa stcnt 101, or can account for the entire stcnt surface.

Figs. 3 and 4 illustrate additional examples ol‘stents 101 characterized by n— sided cells 120, wherein the intersection locations 112 are different from those shown, for example, in Figs. IA and 18. In Fig. 3, the intersection locations 112 comprise overlapping hooks. In Fig. 4, the 4-sided cells 120 are laterally compressed and the constituent strut segments are somewhat curved; the corresponding intersection locations 112 are located where two such adjacent ‘curves’ touch each other. In spite of having a different form than the earlier examples of n-sided cells 120 and intersection locations 112. the actual design is not material to the invention, and any suitable strut design can be used. Similarly, the undulating rings 130 of Figs. 2A and can be, in embodiments, less regular and/or can have more complex shapes.

Fig. 5 shows a View ofa stent 101 coated with a polymer to form a polymer binder layer 104, according to an embodiment. Generally. the medical stent or stent is a tiny tube, comprising a plurality or network ol‘struts 102 configured to form a mesh like structure. The width of the strut 102 is typically between l—2 mm, although it can be narrower or wider according to specific stent designs. The term ‘width’ as used herein when applied to the strut of a stent refers to a measure ofthe strut’s "footprint" on the surface of the stent. According to the present invention. surfaces of the struts 102 ofthe stent 101 can be coated with a polymer binder. In embodiments, the binder layer 104 can comprise a elastomer, e.g., a thermoplastic elastomer, chosen for its thermoplastic and elastomeric properties. Examples ofsuitable thermoplastic elastomers include styrenie block eopolymers, thermoplastic polyolefinelastomers, thermoplastic vulcanizates. thermoplastic polyurethanes. thermoplastic copolyesters, and thermoplastic polyamides.

We now refer to Fig. 6 which shows a stent assembly 101 comprising a stent with struts 102 coated with a polymer binder 104 and paitly covered by a fabric material 106. In one embodiment, the fabric material 106 is attached to struts 102 of by means ofa solvent bonding technique. In another embodiment, the fabric material is attached to the struts 102 by means of heat and pressure application. In some embodiments, the fabric material 106 is fabricated from any desired fiber material used in the industry for stent sleeves. covers and grafts. such as, but not limited to. electro spun fibers, expanded polytetrafluoroethylene (EPTFE), Polyethylene tercphthalatc (PET or PETE) or thermoplastic polyurethane (TPU) film. The fabric material 106 can be manufactured by means ofany known manufacturing technology, but not limited to woven, non-woven. knitting or electrospinning techniques.

In some embodiments, a porous fabric material can be deployed to cover at least a portion of at least one ofthe internal surface 151 and the external surface 152, and bonded to the metal stent 101 by a polymer binder 104 that mediates between the struts 102 and the fabric material 106 to bind thercbetween.

As seen in Fig. 6. in some embodiments, the fabric material 106 covers, at least 60%, by length, ofthe combined lengths ofthe struts 102 of the network within a first surface region ofthe stent. and therefore at least 60%, by length, ofthe combined lengths ofthe struts 102 ofthe network within a first surface region ofthe stent is coated with the polymer binder 104. In other embodiments, at least 70%, at least 80%, or least 90% of the combined lengths of the struts 102 can be coated with the polymer binder 104.

As is illustrated schematically in Figs. 7A and 78, it can be desirable for the polymer binder 104 to enter pores 107 in fabric 106 as a way ofmaking the binding/bonding between fabric 106 and more effective. Returning to Fig. 6, the polymer binder 104 is applied (or expands/flows/is squeezed by pressure) close to the struts 102 so as to enter pores 107 in the fabric 106 and is not to be found far from the struts 102. In embodiments, for a given region (or multiple regions) comprising one or more stent-area portions, at least 70% or at least 80% ofthe area of the fabric material that is "close to struts 102" is rendered non-porous (meaning at least 90% non- porous) by a presence of the polymer binder 104 within pores 107 of the fabric material 106. "Close to struts 102" can be interpreted as with 0.5 mm, or within 1.0 mm, or with 2.0 mm. where the distance is measured laterally from lateral edges of the struts 102. Similarly, in those region(s), at least 70% or at least 80% ofthe area the fabric 106 in of portions ofthe fabric material that is "far from struts 102" is characterized by pores 107 that are free (meaning at least 90% free) of the polymer binder 104. "Far from struts 102" can be interpreted as at least 1 mm, at least 2 mm, or at least 3 mm displaced laterally from the lateral edges of struts 102.

It should be noted that any ofthe foregoing criteria (e.g., with respect to at least 70% or at least 80% ofthe area ofthe fabric material 106 that is "close to struts " being rendered non-porous. or with respect to at least 70% or at least 80% ofthe area the fabric 106 in ofportions ofthe fabric material that is "far from struts 102" being characterized by pores 107 that are free of the polymer binder 104) can be applied globally for all stent-areas (e.g., n-sided cells 110 and/or undulating rings ) in a region ofthe stent or even over the entire stent. but can also be applied at the individual stent-area (n-sided cell 110 and/or undulating ring 130) level. such that in some embodiments the criteria are applied within each individual one of the stent— areas.

According to some embodiments, the thickness ofthe polymer binder 104 is not less than 1 micron and not greater than 70 microns. In some embodiments, the thickness ofthe polymer binder 104 is not less than 5 microns and not greater than 40 microns.

In embodiments. the struts 102 are encapsulated with the polymer 104 and the fabric material 106 is attached thereto by the application of heat and pressure. In some embodiments. the fabric 106 is engaged (i.e., brought in contact) with the bare metal strut 102 and the polymer binder 104 is then applied so as to bind therebetween. In some embodiments, the polymer 104 is melted and flows into a plurality of pores 107 characteristics of the fabric 106 enabling a strong bond between the fabric material and struts 102. In some embodiments. the melting point of fabric 106 is greater than the melting point ofthe polymer by at least 100C.

The flowchart in Fig. 8 illustrates a method for attaching a fabric material 106 to a stent 101 comprising a metal alloy, where the stent 101 is formed by a network of struts 102 and having an external surface 151 and an internal surface 152. The method comprises: Step SO] engaging a porous fabric material 106 with at least some ofthe surfaces ofthe struts 102; and Step S02 applying a polymer binder 104 so as to bond the porous fabric material 106 with said at least some ofthe surfaces of the struts 102. The applying is such that: (i) at least 90%, by length, of the combined lengths of the struts of the network within a first surface region of the stent, are bonded to the porous fabric material by polymer binder, (ii) at least 70%. by area, of the fabric material disposed (A) within each one ofone or more stent-area portions within a second surface region ofthe stent and (B) no more than 2 mm from a nearest respective strut. is rendered non-porous by a presence of the polymer binder within pores of the fabric material, (iii) at least 70%. by area, ofportions ofthe fabric material (A) disposed within each one of said one or more stent-area portions and within said second surface region and (B) distanced at least 3 mm from a nearest respective strut, is characterized by pores that are free ofthe polymer binder, and (iv) the thickness ofthc polymer binder is not less than 1 micron and not greater than 70 microns.

In some embodiments, the fabric 106 can receive surface treatment, additionally or alternatively to the surface treatment ofstruts 102, so as to improve the bonding of the fabric with the struts.

Second Discussion of Embodiments Precise application of polymer binder to struts can be desirable because it facilitates control ofphysical parameters ofa stent or stent assembly. such as. for example, radial strength (also called radial resistance). In embodiments, radial strength (a measure of stiffness ofa segment of a stent can be a function ofthe lateral thickness ofthe polymer binder coating at or adjacent to intersection locations of struts, assuming all else (material, strut thickness) is held constant.

With precise control ofradial strength. it is possible to deploy a stent with different radial strengths in different segments. Referring now to Figs. 9A and 9B (similar to Figs. 2A and 28, except that in Figs. 9A and 9B the undulating rings 130 ofthe earlier figures are used to embody stent segments 131). in an embodiment. stent segment 1312 can have a radial strength that is higher (e.g.. at least 20% higher. at least 50% higher, or at least 80% higher) than stent segments 1311 and 1313, depending on the thickness ofa polymer binding (not shown in Figs. 2A and 28) applied at or adjacent to intersection locations 112. Such segments are obviously not limited to stents characterized by the undulating rings of Figs. 2A and 2B and can alternatively or additionally include stent surface regions characterized by n-sided cells. The term "adjacent" is used to mean within an "adjacent range" where the polymer binder 104 ofone strut 102 intersects with the polymer binder 104 ofanother strut 102 at an intersection location 112. as illustrated schematically Figs. 10A and .

In Figs. IOA and 108. it can be seen that the polymer binder 104 can be applied with different lateral thicknesses depending. inter alia, on the desired radial strength, i.e.. although the figures accompanying this specification are not draw n to scale, the thickness of polymer binder 104 in Fig. 10A has been deliberately and exaggeratcdly shown to be much thicker than in Fig. 108. It will be obvious to the skilled artisan that the illustration of Figs. 10/\ and 108 is equally applicable to a stent surface region where the intersection locations are characterized by bends (like those in Figs. 2A and 28). The term ‘lateral thickness" as used with respect to the polymer binder refers to the dimension ofthe binder on the strut as measured in a lateral direction. i.e., on and along the surface of the stent and is not a ‘thickncss’ which would be measured through the surface of the stent inwards our outwards.

In embodiments, a radially compressible covered stent assembly 100 comprises first and second stent-assembly segments 131 displaced from one another longitudinally, the stent assembly 100 has an external surface 152 and an internal surface 151. and the stent assembly comprises: (a) a radially compressible stent 101 formed by a network of struts 102, the network having a plurality ofinterseetion locations 112 at which intersections and/or bends define strut segments 110. each strut segment 110 having respective outward-facing and inward facing—surfaces which correspond to the external and internal surfaces ofthe stent assembly 152, 151. and two respective laterally—facing surfaces: (b) a polymer binder 104 applied to the struts so as to at least partially coat at least some ofthe strut segments 110 and at least some ofthe intersection locations 112; and a fabric 106 covering at least a portion of at least one ofthe internal surface 151 and the external surface 152 so as to be in contact with the polymer binder 104, where at least 80% ofsaid contact is characterized by the polymer binder 104 forming a bond between the fabric 106 and a strut segment 110 or intersection location 112 at the respective point of contact. First and second stent-assembly segments 131 are at least partially coated with the polymer binder 104, the polymer binder 104 having respective first and second thicknesses on one or both laterally—facing surfaces ofat least some respective strut segments 110 at or adjacent to respective intersection locations 112, said first and second thicknesses being different from each other. The radial strength ofthe first stent-assembly segment 131 is greater than the radial strength ofthe second stent-assembly segment . In some embodiments. the thickness are different from each other by at least % and the radial strength ofthe segments 13] differs by at least 20%.

These embodiments can be beneficially combined with any ofthe other embodiments disclosed herein, e.g.. with respect to the network of struts being characterized by n- sided cells (as in Figs. 1A and 18), with respect to the network of struts being characterized by undulating rings (as in Figs. 2A and 28), or with respect to the stated ranges ofthickness ofthe polymer binder. In embodiments, the network of struts 102 can comprise a plurality ofstrut segments 110 defined by intersection locations 112, where an n-sided cell comprises n strut segments 110 defined by n intersection locations 112, where n is an integer equal to at least 3 and at most 6, and at least 70% or at least 80% ofthe surface area of the metal stent is characterized by n-sided cells.

In embodiments, the network of struts 102 includes a plurality of undulating rings 130 ofdeflned by bends. and at least 7000 ofthe surface area or at least 80% ofthe metal stent 101 is characterized by undulating rings 130. In embodiments, the thickness of the polymer binder 104 is not less than 1 micron and not greater than 70 microns.

The flowchart in Fig. l 1 illustrates a method for producing a radially compressible stent assembly 100 comprising longitudinally displaced stent-assembly segments 131 with different respective radial strengths, the stent assembly 100 comprising a radially compressible stent 101 formed by a network of struts 102, the network having a plurality of intersection locations 112 at which intersections and/or bends define strut segments 110, each strut segment 110 having respective outward—facing and inward facing—surfaces which correspond to the external and internal surfaces 152, 151 ofthe stent assembly, and two respective laterally-facing surfaces. The method comprises: Step Sll engaging a fabric material 106 with at least some ofthe surfaces of the struts 102; and Step SlZ applying a polymer binder 104 so as to bond the fabric material 106 with said at least some of the surfaces ofthe struts 102, the applying being such that the fabric 106 is thereby bonded to at least some ofthe strut segments 102 and some ofthe intersection locations 112. The applying includes applying a first coating thickness on one or both laterally-facing surfaces of at least some respective strut segments 110 at or adjacent to respective intersection locations 112 ofa first stent- assembly segment 131 and applying a second coating thickness on one or both laterally-facing surfaces of at least some respective strut segments 110 at or adjacent to respective intersection locations 112 ofa second stcnt—assembly segment 131; the respective stcnt-assembly segments 131 have different radial strengths that are a Third Discussion of Embodiments According to embodiments, it can be desirable to bond a non-porous fabric material to a stent, i.e., without the benefit of binder filling pores to improve the efficiency of bonding. For example, lateral ‘wings’ of binder material on either side of a stcnt strut can be provided so as to increase the area of binding contact between the polymer binder and the fabric. The wings are provided laterally. i.e., locally parallel to the surface of the stent without necessarily thickening the coating on the inward- facing or outward-facing surfaces ofthe struts.

Examples ofwings are shown in Figs. 12A and 1213. In Fig. l2/\. wings 109 are formed laterally from strut 102 and extent the polymer coating 104 to both sides ofthe strut 102. In Fig. 128. the wings 109 are bonded with a corresponding area of the surface of the fabric 106.

In embodiments. a fabric 106 can cover all, part, or none ofone of the sur % coverage-value means that 50% ofthe area ofa surface is covered, and a 0% coverage-value means that a surface has no fabric cover at all.

In embodiments, a stent assembly 100 comprises: a metal stent 101 formed by a network of struts 102 and having an internal major surface 151 and an external major surface 152; a polymer binder coating 104, covering at least a portion of at least some ofthe struts 102, and having a thickness not less than 1 micron and not greater than 70 microns (in some embodiments 5-40 microns); and a fabric 106 at least partly covering at least one of the two major surfaces 151, 152 and bonded thereto by the binder coating 104, such that a first surface (i.e., internal or external surface 151 or ) has a coverage-value ofno less than 50%. and the second surface (i.e., the other ofthe two surfaces 151, 152) has a coverage-value of at most 50% ofthe coverage- value ofthe first surface. In an example, a first surface has a coverage-value ofover % and the second surface has a coverage-value of0%. In another example, a first surface has a coverage-value 0f50% and the second surface has a coverage value of %. Further, the binder coating 104 forms a pair of binder—coating wings 109 extending laterally in respective opposite directions from each ofa plurality ofthe binder-coated struts 102, and the bonding ofthe fabric 106 to the surface of the stent includes bonding the fabric 106 to at least part ofeach binder wing 109. In some embodiments, the coverage-value ofthe second surface is zero. In some embodiments, the fabric 106 can be a non-porous, liquid impermeable film.

The flowchart in Fig. 13 illustrates a method for producing a stent assembly comprising a metal stent 101 formed by a network of struts 102 and having an internal major surface 151 and an external major surface 152, and (ii) a liquid- impermeable fabric 106 at least partly covering a single one ofthe two major surfaces , 152. The method comprises: Step SZ] surface-treating at least some of the surfaces ofthe struts 102', Surface treatment are known in the art and can be mechanical (e.g., sandblasting, creating pits or str Step S22 engaging a non—porous fabric 106 to at least some ofthe surface— treated struts 102 on either the internal major surface 151 or the external major surface 152 ofthe metal stent 101; and Step $23 applying a polymer binder 104 to at least a portion of at least some ofthe surface-treated struts 102. wherein the applying includes (i) forming a pair of polymer binder wings 109 extending laterally in respective opposite directions from a binder—coated surface—treated strut 102, and (ii) bonding the fabric 106 to at least part ofeach binder wing 107. In some embodiments, the applying includes painting.

In some embodiments, the fabric 106 can receive surface treatment. additionally or alternatively to the surface treatment of struts 102, so as to improve the bonding of the fabric with the struts.

Fig. 14 shows a metal stent. with a fabric material 106 engaged on the external surface of the stent. The example shown in Fig. 14 is ofa stent with fabric only on the external surface. but it will obvious to the skilled practitioner that the teaching herein applies equally to a stent with fabric on the internal surface and to stents fabric on both major surfaces, i.e., internal and external. According to embodiments, a polymer binder 104 is applied to the struts 102. In some embodiments, the application is by painting the binder onto the struts, as indicated schematically by paintbrush 200. In some embodiments, sections of fabric 106 defined by cells (such as n—sided cells 110 of Fig. 18) can be ‘masked’ using masks 190 to prevent painting the fabric 106 with binder material. Masks can be attached to each other to allow masking ofa large portion (or all) ofa major surface ofthe stent.

General Discussion Figs. 15A and 158 illustrate examples for attaching the fabric material 106 to various stents and expanded frames according to embodiments. In an embodiment, some portion of the stent or frame 101 could be covered by polymer film or layer 104, some portion ofthe stent or frame 101 could be covered by fabric material 106, and further some portion of the stent or frame 101 could be open 108. i.e., not covered with any material.

Figs. 16A - 1613' illustrate e assembly 100 can be configured in any desirable shape, and is not limited to conical or cylindrical/tubular shapes.

Selective bondingr ln embodiments, it can be desirable to selectively bond the fabric 106 to the stent 101. A fabric (’i.e., any covering material) 106 can be selectively bonded to a stent 101 to form a stent graft/assembly 101. The term ‘selective bonding" is used to describe bonding, i.e., application ofa binder such as polymer—based binder 104 that is applied at selected locations on a stent 101. In a non—limiting example, selective bonding is used to reduce the radial forces required to compress a stent assembly 100. e.g., for loading into a catheter. In another non-limiting example, selective bonding is used to facilitate control of wrinkling ofa fabric cover 106 around the circumference ofa stent 101 when the stent 101 is compressed. In another non—limiting example, selective bonding is used to reduce the resistance force oflongitudinal expansion encountered when radially compressing a stent 101 and/or the resistance forces that lead to kinking and/or twisting ofa stent 101.

Referring now to lr‘igs. 17A and 178. a ring-like transverse section 300 ofa sten1101 encompasses a circumference ofthe stent 101. The transverse section 300 can be of any longitudinal length; for example, a transverse section can between 0.01 mm and 5 mm, or between 0.01 mm and 10 mm. The circumference of the transverse section 300 intersects, at least partially, a plurality of selectively-bonded binder locations 305. The locations 305 in Fig. l7/\ are spaced around the circumference of the transverse section 300 with a regular location-location spacing. As shown in the cutaway detail ofFig. 178, the location-location spacing between any two adjacent locations 305 along the circumference ofthe transverse section 300 is represented by lulu/RAIL", such that the transverse location-location spacing between locations 3051 and is LLnmw 1.3, the transverse location-location spacing between locations 3052 and 3053 is LL’I'R/M‘s 2.3, and the transverse location-location spacing between locations and 3052 is LL/yems 3.4. Regular location-location spacing me location-location spacings Hominy-71,2, LLy/nggg, and [AL/mm}; are all the same, or all fall within an allowed-variation range of 95%-100% ofthe length of the longest LLy/Hm ofa given transverse section 300, or within a length range of 95%-100% of the length ofthe longest LLneANV ofthe transverse section 300, or within a range of %-100% ofthe length of the longest LLyre/rvx‘ ofthe transverse section 300, or within a length range of 85%-100% ofthe length ofthe longest LLyre/ws ofthe transverse section 300, or within a length range of 80%-100% ofthe length ofthe longest LLy/elms of the transverse section 300, or Within a length range of75%-100% ofthe length ofthe longest LLr/Mw ofthe transverse section 300, or within a length range of 70%-100% of the length of the longest LLHMNS of the transverse section 300.

The number of binder locations 305 shown in Figs. 17A and 178 for the transverse section 300 is merely illustrative ofa non-limiting example, and there can be fewer or more locations 305 on the circumference of any given transverse section , for example from 3 to 24, or from 4 to 18, or from 5 to 12, or from 6 to 9, all ranges inclusive. A skilled artisan will understand that too few binder locations 300 could result in inadequate bonding, or too much ‘loose’ fabric when the stent 101 is compressed, or that too many binder locations 305 could result in not achieving other desired benefits of selective bonding such as, without limitation, reducing radial forces when compressing a stent 101 or reducing resistance force to longitudinal extension or contraction during compressing or expansion, respectively, ofa stent .

Even with some variations in the value oftransverse location-location spacing LLy/Hm, including minor variations, it can be useful to set a minimum value for transverse location-location spacing LL/ymsg. This minimum value of LLHMM can apply to any transverse sections 300 ofa given stent 101, or can vary with respect to different portions ofa given stent 101, as might be the case for a stent 101 with variable diameter(s).ln some embodiments, no LL/yemxs ofa given transverse section is greater than one-third o circumference ofthe transverse section 300. The foregoing minimum LLmrxs values can be combined with the allowed LL/mx’x variation—ranges discussed hereinabove, such that the statement "no [Jr/ms ofa given transverse section 300 is greater than one—third (for example) of the circumference of the transverse section 300" can be interpreted as "no [LIN/1x5 ofa given transverse section 300 is greater than one—third ofthe circumference ofthe transverse section 300 i5%, or i10%, or i15%, or i20%, or i25%, or i30%".

As shown in Fig. 18, fabric 106 can be bonded to the stent 101 by the selectively applied binder such that all, or at least 99%, or at least 95%, or at least %, or at least 85%, or at leas 80%, or at least 75%, of at least the circumference of at least the transverse section 300 is covered by the fabric 106. The stent assembly of Fig. 18 shows the fabric bonded on the external (outwards-facing) major surface ofthe stent 101, but this is merely for illustration and in other examples the fabric can be bonded to the internal (inwards-facing) major surface of the stent 101.

A binder location 305 can merely include a spot, e.g., ofa binder 104, or can include application ofa binder 104 in any shape and any size. In the example of Figs. l7A—I7B. each location 305 includes a ‘splotch’ ofbinder 104 having no regular shape. In some examples, a location 305 can include a polygonal, e.g., rectangular, application ofa binder 104 having an area of several square millimeters. In other examples, locations 305 can include specific shapes that are not polygonal.

Fig. 19 shows another example ofa stent 101 having a polymer applied at a number of locations 305 around a circumference ofa transverse section 300, for selective bonding ofa fabric to the stent 101. As can be seen in Fig. 19, the binder locations 305 can be elongated to any practical length which does overly not restrict the desired flexibility of the stent. [t can be desirable, in embodiments, to employ selective bonding in the longitudinal direction as well as the transverse direction, for example, to reduce the resistance to longitudinal extension/contraction of a stent when compressed/expanded (respectively). In such embodiments, rather than used elongated binder locations such as those shown in Fig. l9, it can be useful to apply the polymer binder 104 in multiple unconnected transverse-section "rings" 300, for example, so as to further reduce the force required to compress the final stent assembly 100 (since the force applied typically must overcome longitudinal resistance as well as direct radial forces).

Referring now to Figs. 20/\ and 208, multiple ring—like transverse sections 3001, 3002, ofa stent 101 are defined so that each encompasses a circumference ofthe stent along at least a portion ofa (longitudinal) length ofa stent 101. Each transverse section 300 at least partially, a respective plurality ofselectively—bonded binder locations 305 disposed circumferentially therearound. Three transverse sections 3001. , 3003 are shown for purposes of illustration but there can be any practical number oftransverse sections 300 along the length of the stent 101. The transverse sections 3001, 3002. 3003 can be contiguous or spaced—apart (as shown) but do not overlap. It should be understood that any or all of the features described in connection with the single transverse section 300 of Figs 17A and 178 (e.g., and not exhaustively: size, shape. spacing, etc.), can apply to each ofthe transverse sections . 3002, 3003.

As shown in the cutaway detail of Fig. 20B. binder locations 305 can be characterized not only by location-location spacing around the transverse circumference. i.e., LL’r/em‘s‘. but also by longitudinal location-location spacing LLum; along at least a portion ofthe length ofthe stent 101. Thus. the spacing between consecutive locations 305x and 3051' is LL/.().v(;7x.1t and the spacing between consecutive locations 305v and 3052 is LLmm 1:2.

Fig. 21 shows a second example (after Fig. 20) of multiple transverse sections , 3002,3003 ofa stent 101. In this example, the binder locations 305 are ‘staggered‘. In the non-limiting example of Fig. 20, three binder locations 305 are shown in each transverse section 300, although ofcourse there can be more than three. The selective-binding ‘pattern’ repeats every other transverse section. such that the ‘pattern' (positions ofbinder locations 305 around the circumference of the respective transverse section 300) oftransverse section 3001 is substantially the same as that of transverse section 3003, and the circumferentially—offset patter of transverse section 3002 is substantially the same as the ‘next’ transverse section (e.g., 3004). which isn’t show n because only 3 transverse sections 300 are shown in Fig. 21.

Repeating selective-bonding binder-location ‘patterns’ can alternatively repeat, for example, with every third transverse section. or with every fourth transverse section. etc., with the underlying principle remaining that the requirement to provide reliable bonding ofthe fabric to the stent is combined with a desire to reduce. to a practical extent. the force required to compress the stent graft (and expand it. ifthe stent is not a self-expanding stent).

Fig. 22 illustrates yet another example ofselective bonding. in which the polymer at each binder location 305 is applied so as to minimize the binder material in the "open’ areas ofthc stent 101 between the struts 102. While the embodiments disclosed herein can be applied with cithcr porous or non—porous fabrics 106, in the case of porous fabrics it can desirable to reduce or minimize the extent to which fabric pores are clogged by the binder 104. Thus, it can be desirable to apply the polymer in the binder locations 305 (as in the example ofFig. 22) such that not more than %, by area. ofthc fabric material disposed at each binder-location 305 and more than 0.5 mm from a nearest respective strut 102, is rendered non-porous by a presence ofthe polymer binder 104 within pores ofthe fabric material 102.

Figs. 23A and 23B schematically illustrate radial forces (also known as "loading force") applied to a stent assembly 100 for compression, c.g., for insertion into a delivery catheter. The forces shown in Fig. 23A are effective to compress the stent 101. and. as shown in Fig. 238, the selective bonded ofthe fabric 106 (Le. bonded at binder locations 305) reduces or minimizes wrinkling or bunching ofthe fabric 106 between the binder locations 305. To be clear, the terms 'loading force’ and "radial forces" are used herein interchangeably and for the purpose ofthis disclosure refer to the forces required for compressing a stent and/or the forces acting upon the lumen ofa subject by an expanding (self-expanding or balloon-expanded) stent. The skilled artisan will understand that that the schematic illustration of radial forces in Fig. 23A is a simplification made for ease ofpresentation. and that numerous forces are at play in the sheathing, loading or compression ofa stent, as well as in the in-site deployment and expansion. The forces can include, and not exhaustively, frictional and mechanical resistance forces during sheathing, loading and deploying; the resistance forces can include longitudinal resistance to extension and foreshortening or any change in length.

Experimental results The extent to which selective bonding is effective to reduce the radial forces (as a representation oftotal forces as discussed in the preceding paragraph) required to compress a stent graft was tested for a number of selectively—bonded stent assemblies. The results ofone illustrative experiment are shown in the graph ofFig. , which shows loading force. i.e.. applied radial force (on a relative scale). as a function of bonding percentage, i.e., the percentage ofthe circumference of each transverse section 300 occupied in aggregate by binder locations 305.

In a first set of measurements, effective loading force was reduced by at least % when the occupied fraction ofthe circumference was at least l0% and not more than 50%. In a second set of measurements, the effective loading force was reduced by at least 25% when the fraction of the circumference was at least 10% and not more than 50%. In a third set of measurements, the effective loading force was reduced by at least 30% when the fraction ofthe circumference was at least 5% and not more than %. In a fourth set of measurements. the effective loading force was reduced by at least 35% when the fraction ofthe circumference was at least 5% and not more 25%.

In a fifth set of measurements, the effective loading force was reduced by at least 40% when the fraction ofthe circumference was at least 5% and not more 25%. For all of the experimental measurements, the multiple binder—locations occupied, in aggregate. at least 5% and not more than 75% ofthe respective circumference ofeach transverse section.

According to embodiments, a method is disclosed for attaching a fabric material to a stent formed by a network of struts. As illustrated in the flowchart of Fig. , the method comprises the following steps: Step SS] engaging a porous fabric material 106 with at least a transverse section ofa major surface (151 or 152) ofthe stent 101; Step $32 selectively bonding the porous fabric material 106 to at least some struts 102 by applying a polymer binder 104 at multiple binder—locations 305 circumferentially-displaced along a circumference ofthe transverse section 300, wherein the multiple binder-locations 305 occupy. in aggregate. at least 5% and not more than 75% ofthe circumference ofthe transverse section 300, and the multiple binder—locations 300 are spaced such that no location—location spacing LLy/mg is greater than one-third ofthe circumference ofthe transverse section 300.

We now refer to Figs. 26A, 26B, 26C and 26D. ln embodiments, a strut 102, e.g., ofa network ofstruts 102 making up a stent or a portion ofa stent 101, is surface-treated with a primer 97. The surface treatment with the primer 97 can include creating a covalent bond with the metallic or metal-allow strut 102. A suitable, non-limiting example ol‘surl‘ace treatment with a primer 97 is use ofa primer such as cobalt acetoacetonate or triphenyl phosphine to increase polymerization rate ofa cyanoacrylate adhesive Another example ofsurface treatment with a primer 97 is silanization, where the primer 97 includes a reactive silane compound such as an organofunctional alkoxysilane compound. Following application ofthe primer 97, the strut 102 is encapsulated with a polymer binder 104 according to any ofthe examples ol‘suitable polymer binders discussed hereinabove.

The encapsulation is to a first binder thickness which can be between 1 micron and 10 microns, between 5 microns and 10 microns, between I micron and 5 microns, or within any range between a minimum thickness of at least 1 micron and a maximum thickness ot‘no more than 10 microns (all ranges being inclusive). /\ second application ofpolymer binder 104, to a second binder thickness, can be used to selectively coat the strut 102 at multiple binder—locations 355 around the circumference of at least a transverse section 300 of the stent 101. Binder locations are illustrated in Figs. 17A, 178. 18, 19,20A, 208, 21, and 22, and discussed hereinabove.

The embodiments illustrated in Figs. 26A. 26B, 26C and 26D are specific examples of implementation of the embodiments and examples ofselectively applying a binder at binder locations 355 as illustrated in Figs. l7/\, I78, l8, 19, 20A, B, 21, and 22. The percentages ofcovcrage ofa circumference ofa transverse section, the location—location spacing In these implementation examples, surfaces of struts 102, at least within respective transverse sections 300, are surface—treated by application ofa binder 97, and encapsulated by application of the binder 104 to a first thickness. /\t the multiple binder—locations 355, the struts (already treated with the primer and encapsulated by the binder to a first thickness, are further selectively coated by application ofthe binder 104 to a second thickness. Thus, in such implementation examples, a strut 102 can be coated to the first binder thickness at least within one or more transverse sections 300. and selectively coated to the second binder thickness only at the binder-locations 355. The second binder application, i.e.. the application of the binder to the second thickness, can include encapsulation or. alternatively, coating of only a portion of the circumference.

Figs. 26A and 268 show cross-sections ofa strut 102 having a circular cross— scction. e.g.. at a binder—location 355. A primer 97 has been applied to the strut 102 around its circumference. Examples of surface treatment with a primer 97 is use ofa primer such as cobalt acetoacetonate or triphenyl phosphine to increase polymerization rate ofa cyanoacrylate adhesive. Another example ofa suitable primer is a primer comprising a silane compound so as to create a covalent bond with the strut 102 by silanization. 'l‘he strut 102 — with primer 97 is coated with a first application ofthe polymer binder 1041 and is encapsulated by the binder 1041 to a first thickness in any ofthe ranges disclosed hereinabove. A second application ofthe polymer binder 1042 is applied to a second thickness that is at least twice the thickness of the first binder application 1041 and which is in one of the ranges disclosed hereinabovc. [n the example ofl’ig. 26A. the second application ofthe polymer binder 1042 is applied to encapsulate the stent 102 at the binder-location 355.

In the example of Fig. 268. the second application ofthe polymer binder 1042 is applied to a portion of the circumference of the strut 102 to be bonded to the covering material 106.

Figs. 26C and 26D Show cross-sections ofa strut 102 having a prismatic cross- section, e.g.. at a binder-location 355. A primer 97 has been applied to the strut 102 around its circumference. The strut 102 — with primer 97 is coated with a first application ol'the polymer binder 1041 and is encapsulated by the binder 1041 to a first thickness in any ofthe ranges disclosed hereinabove. A second application ofthe polymer binder 1042 is applied to a second thickness that is at least twice the thickness ofthe first binder application 1041 and which is in one of the ranges disclosed hereinabovc. [n the example of l’ig. 26C, the second application ofthe polymer binder 1042 is applied to encapsulate the stent 102 at the binder-location 355.

In the example ofl-‘ig. 268. the second application ofthe polymer binder 1042 is applied to a portion of the periphery of the strut 102 to be bonded to the covering material 106.

A method is disclosed, according to embodiments. for attaching a covering material 106 to a stent 101 formed by a network of struts 102. As seen in the flowchart of Irig. 27A, the method comprises: Step S41 engaging a covering material 106, e.g., a fabric material, and/or an impermeable layer, and/or an impermeable elastomer and/or a non—woven Inaterial, with at least a transverse section 300 ofa major surface 151 or 152 of the stent 101; Step S42 applying a polymer binder 1041. to a first binder thickness, to encapsulate at least 80%, by length, of the combined lengths ofthe struts 102 within the transverse section 300. In embodiments, the first binder thickness is not greater than 10 micron.

Step S43 selectively applying the polymer binder 1042, to a second binder thickness at least twice the first binder thickness, at multiple binder-locations 305 circumferentially-displaeed along a circumference of the transverse section 300 and occupying in aggregate, at least 5% and not more than 75% ofthe circumference, or not more than 50% ofthe circumference, or not more than 30 ofthe circumference, with no transverse location-location spacing LLTRANS being greater than one-third of the circumference, or greater than one-quarter ofthe circumference, or greater than one-fifth ofthe circumference, or greater than one—sixth ofthe circumference. In embodiment, the second binder thickness is not greater than 40 microns.

In some embodiments, the method additionally comprises, as shown in the flowchart ofFig. 278: Step S44 applying a primer 97 to at least some struts 102 within the transverse section to form a covalent bond with the at least some struts 102.

In some embodiments, Steps S43 and S44 are carried out before Step S41. and Step S41 includes radially constraining the transverse section 300 (as illustrated in Fig. 29A) so as to reduce a diameter thereof by at least 50%, and (ii) engaging the fabric while the transverse section is radially constrained (as illustrated in Fig. 29F).

The fabric material 106 bonded to the at least some struts 102 can have an unfolded length along a circumference of the transverse section 300 that is no more than 20% greater than a circumference ofthe transverse section to 300 which the fabric material is engaged.

In some embodiments Step S41 includes engaging a first covering material with at least a transverse section 300 ofa first major surface 151 or 152, and engaging a second covering material 106, different from the first covering material , with at least a transverse section 300 ofa second major surface 152 or 151. /\ method is disclosed, according to embodiments, attaching a fabric material to a stent 101 comprising a metal alloy, e.g., a stainless steel or a nitinol, the stent being formed by a network of struts 102 and having two major surfaces 151, 152.

Performance ofsome ofthe method steps. and the results of performing some method steps, are shown schematically in Figs. 29A, 298, 29C, 29D, 29E. 29F and 296. As seen in the flowchart of Fig. 28A, the method comprises: Step S51 applying a polymer binder 104 to at least some struts 102 within a transverse section 300 of the stent 101 so as to encapsulate the them with the polymer binder 103 at a thickness of not less than 1 micron and not greater than 40 microns.

Step $52 radially constraining the transverse section 300 so as to reduce a diameter DIM‘(2.\‘s'/'/e,»1/.\'/;/) thereof by at least 50%.

Steps $51 and 852 can be performed in either order. As illustrated in Fig.

A, a stent 101 has a diameter DUNCONSTRAINEI) in an unconstrained state.

If Step S51 precedes Step 852: Fig. 29B shows, as per Step SS], application ofthe binder to the stent 101 as indicated schematically by paintbrush 200. In some embodiments, the application includes: - encapsulating the struts 102 of the stent 101, at least in transverse section , to a first binder thickness ofno more than 10 micron, over at least %, by length, ofthe combined lengths of the struts 102 within the transverse section 300, and - selectively applying the polymer binder (not show n), to a second binder thickness that is at least twice the first binder thickness and no more than microns, to at least some struts 102 within the transverse section 300. In some embodiments, the selectively applying the polymer binder is at multiple binder-locations circumferentially—displaced along a circumference of the transverse section. wherein the multiple binder— loeations occupy, in aggregate, at least 5% and not more than 60% ofthe circumference, and the multiple binder-locations are spaced such that no location-location spacing is greater than one-third ol‘the circumference.

Subsequently, in Step $52, the stent 101 is constrained. as shown schematically by constraining force 1120 in Fig. 29C, to have a diameter in a constrained state, or a reduced-diameter state, ochomva/NED, which is at least 50% less than unconstrained diameter DUM'(msm/IINED shown in Fig. 29A. The constraining can be done in any tool or mechanical set-up suitable for providing a radial constraining force around the circumference and maintaining it as needed.

If Step S52 precedes Step SS]: The stent101 is constrained, as shown schematically by constraining force in Fig. 29C. to have a diameter in a constrained state, or a reduced-diameter state, OFD(‘0NSTRAINED, Which is at least 50% less than unconstrained diameter DUNCOJV'STK4INEI) shown in Fig. 29A. The constraining can be done in any tool or mechanical set-up suitable for providing a radial constraining force around the circumference and maintaining it as needed.

Subsequently, as per Step 851 and as shown in Fig. 29D, application ofthe binder to the stent 101 as indicated schematically by paintbrush 200 while the stent is constrained. In some embodiments, the application includes: - encapsulating the struts 102 ofthe stent 101, at least in transverse section . to a first binder thickness of no more than 10 micron, over at least %. by length. ot‘the combined lengths ot‘the struts 102 within the transverse section 300, and - selectively applying the polymer binder (not shown), to a second binder thickness that is at least twice the first binder thickness and no more than microns, to at least some struts 102 within the transverse section 300. In some embodiments. the selectively applying the polymer binder is at multiple binder—locations circumferentially-displaced along a circumference ofthe transverse section. wherein the multiple binder— locations occupy, in aggregate, at least 5% and not more than 60% ofthe circumference, and the multiple binder—locations are spaced such that no location—location spacing is greater than one—third ofthe circumference.

Step 853 while the transverse section 300 is radially constrained, and as shown schematically in Figs. 29E and 29F, engaging the fabric material 106 with the at least some struts 200 so as to bond the fabric material 106 with the polymer binder on at least a respective portion of at least one major surface 151 or 152 of the stent 101 to form a stent assembly 100. In embodiments, the fabric material 106 engaged to the at least some struts 102 has an unfolded length along a circumference ofthe transverse section 300 that is no more than 20% greater than a circumference of the transverse section 300 to which the fabric material is engaged. In other words, no more than 20% excess fabric material is taken up in folds in the reduced-diameter state ofthe stent assembly 100.

In some embodiments, as shown in Fig. 28B, the method additionally comprises, before Step 851: Step SS4 applying a primer 97 to at least some struts 102 within the transverse section to form a covalent bond with the at least some struts 102. Application ofthe primer 97 between the at least some struts 102 within the transverse section 300 and the polymer binder can be effective to form a covalent bond vx ith the at least some struts 102.

We now refer to Fig. 29G. ln embodiments, the metal alloy of the struts 102 includes a shape-memory allow, and after cessation ofthe constraining of Steps 852 and S53, the force (indicated by arrow 1130) ofself—expansion causes the diameter of the transverse section 300 to increase by at least 100% to an expanded diameter DEXPANIHfl) Relative to the constrained diameter DCONSTRAINEI) ofthe reduced- diameter state. In some embodiments, the diameter ofthe transverse section 300 increases by at least 200%.

In any of the embodiments disclosed herein, applying the polymer binder 104 can include extruding the binder 104.

The features ofthe embodiments disclosed herein can be usefully combined in combinations not specifically disclosed, and such combinations fall within the scope ofthe present invention.

The word ‘selectively’ as used in this disclosure and in the claims appended hereto refers to selected binder-locations for application ofthe polymer binding in at least one or more transverse sections, including: (a) applying only the binder at the selected specific binder-locations, (b) applying the binder at the selected specific binder—locations over a primer applied to the struts, e.g., throughout the at least one or more transverse sections, for surface treatments of the struts, and (c) applying the binder to a second thickness over a first thickness applied, e.g., throughout the at least one or more transverse sections, and over a primer applied directly to the struts, for surface treatments ofthe struts.

In the description and claims ofthe present disclosure, each of the verbs, "comprise", "include" and "have", and conjugates thereof, are used to indicate that the object or objects ofthe verb are not necessarily a complete listing ol'members, components, elements or parts ofthe subject or subjects ofthe verb. As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a marking" or "at least one marking" may include a plurality of markings.

Claims (1)

CLAIMS .t\) A method of attaching a fabric material to a stent comprising a metal alloy, the stent being formed by a network of struts and having two major surfaces, the method comprising: a. applying a polymer binder to at least some struts within a transverse section of the stent so as to encapsulate the at least some struts with the polymer binder at a polymer-binder thickness of not less than 1 micron and not greater than 40 microns b. radially constraining the transverse section so as to reduce a diameter thereof by at least 50%; and c. while the transverse section is radially constrained, engaging the fabric material with the at least some struts so as to bond the fabric material with the polymer binder on at least a respective portion of at least one major surface of the stent. The method ol‘claim I, wherein the applying the polymer binder includes:

1. encapsulating, to a lirst binder thickness of no more than 10 micron, at least 80%, by length, ofthe combined lengths of the struts of the network within the transverse section, and ii. selectively applying the polymer binder, to a second binder thickness that is at least twice the first bindcr thickness and no more than 40 microns, to at least some struts within the transverse section. The method ofeither one ofclaims l or 2, additionally including, before the applying the polymer binder: applying a primer to at least some struts ofthe network within the transverse section to form a covalent bond with the at least some struts. The method of any one of claims 1 to 3, wherein upon cessation of the radial constraining, the diameter ofthe transverse section increases by at least 100%. A stent assembly comprising