Method of manufacturing a stent

A stent, an intermediate article in the manufacture of a stent, and a method of forming a stent from a workpiece are disclosed. A portion of the wall thickness of a workpiece may be removed, demarcating the structural framework of a stent from the remainder of the workpiece material during a cutting process. In some embodiments, a residuum layer of material remaining after a cutting process may have a recessed surface in relation to a first surface of the structural framework of the stent formed in the workpiece. In some embodiments, a plurality of kerf channels may be cut in a workpiece to demarcate a structural framework of a stent from waste material of the workpiece. In some embodiments, a series of perforations may, at least in part, demarcate the structural framework of a stent from the remainder of the workpiece material. The waste material and/or residuum material may be removed from the structural framework of a stent during a post-cutting process.

TECHNICAL FIELD

This invention generally relates to stents and methods of making a stent from a workpiece for placement within a body lumen or interior space of a body during a medical procedure.

BACKGROUND

Stents are expandable endoprosthetic devices adapted to be placed in a body lumen in order to maintain the patency of a body lumen by providing a flow pathway and/or structural support, for example. Stents are typically used in the treatment of atherosclerotic stenosis in blood vessels and the like to reinforce body vessels and to prevent restenosis following angioplasty in the vascular system. Additionally, stents may be used in the treatment of aneurysms, such as aortic aneurysms, by providing strength to a weakened vascular wall. They have also been implanted in other body lumens, such as urinary tracts and bile ducts. Stents are generally tubular structures that may be radially expandable between an unexpanded size and an expanded size greater than the unexpanded size. Therefore, a stent may be inserted through a body lumen in an unexpanded state and then expanded at a specific location within the lumen to an expanded state.

Stents, as well as other medical devices, are commonly intricately laser cut from a workpiece. The intricate nature of a stent is formed by removing large quantities of material from the workpiece, leaving a delicate structural framework of the stent. The structural framework may then be subjected to additional processes to generate a finished product. The intricate and delicate characteristics of the structural framework greatly reduce the dimensional and structural integrity of the stent, which may compromise subsequent manufacturing processes.

As the use of stents in a variety of medical procedures is gaining widespread acceptance, it is desirable to provide improved methods of manufacturing stents in order to increase efficiency, maintain structural integrity, and/or reduce dimensional inaccuracies. The disclosed stents and accompanying methods of manufacturing a stent may be deemed advantageous in view of the increased usage of stents during medical procedures.

SUMMARY

The invention is directed to stents for intraluminal placement and methods of manufacturing the same. An exemplary stent may be formed from a workpiece, such as a flat sheet or a tubular member.

Accordingly, one embodiment is an intermediate article in the manufacture of a stent, or stent perform, including a workpiece having a wall thickness. The workpiece may have a first surface and an opposing second surface. The first surface may include a raised surface defining a structural framework of a stent and a recessed surface defining a residuum layer of material of the workpiece. Thus, the structural framework may be distinguished from the residuum layer of material, yet the residuum layer of material may be connected to the structural framework. The residuum layer of material may provide structural and/or dimensional integrity to the structural framework of the stent during a manufacturing process. In some embodiments, the workpiece may include a plurality of kerf channels and/or perforations cut into the first surface of the workpiece.

A stent may be formed by providing a workpiece including a wall of material having a thickness defined between a first surface and a second surface. Material may be removed from the first surface of the workpiece such that only a portion of the wall thickness is removed, wherein the first surface of the workpiece has a raised portion defining a structural framework for a stent and a recessed portion defining a residuum layer of material remaining attached to the raised portion. In some embodiments, the workpiece may include a plurality of kerf channels and/or perforations cut into the first surface of the workpiece. The residuum layer of material may subsequently be removed from the structural framework of the stent during an additional manufacturing process.

DETAILED DESCRIPTION

Referring now to the drawings, and particularlyFIG. 1, illustrates an exemplary stent10within the scope of the invention. As discussed herein, the stent10may be formed from a workpiece. The workpiece may be a tubular member, a flat sheet, or the like. The stent10may be manufactured from a variety of materials. For example, the stent10may include a nickel-titanium alloy, such as a shape memory material commonly referred to as nitinol, which may provide the stent10with superelastic properties, psuedoeleastic properties, or linear elastic properties. Other suitable materials for the stent include, but are not limited to, stainless steels and their alloys, composites, platinum enhanced stainless steel, layered materials, niobium (Nb), zirconium (Zr), Nb—Zr alloys, tantalum (Ta), platinum (Pt), titanium (Ti), gold (Au), silver (Ag), magnesium (Mg), and alloys and compositions comprising the same. Polymers, polymer composites, and combinations and mixtures thereof, may also be used. The stent10may be treated or coated with an anti-thrombogenic agent, an anti-proliferative agent, an anti-inflammatory agent, or an anti-coagulant. Additionally or alternatively, the stent10may be treated or coated with a medication, such as a time-release drug. The stent10may also desirably have radiopaque characteristics for visualization on a fluoroscopy device, which may aid in proper placement of the stent10during a medical procedure. For example, the stent10may be doped with, plated with, or otherwise include a radiopaque material. Radiopaque materials are understood to be materials capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during a medical procedure. Some examples of radiopaque materials include, but are not limited to, gold (Au), platinum (Pt), palladium (Pd), tantalum (Ta), tungsten (W), plastic material loaded with radiopaque filler, and the like. The stent10may, alternatively or additionally, include MRI compatible materials and/or be coated with one or more MRI compatible coatings.

The stent10includes a structural framework20of a plurality of interconnected struts22defining a plurality of interstices or openings25located throughout the structural framework20between adjoining struts22. The pattern of the structural framework20may be chosen to provide desired properties to the stent10. For example, a chosen pattern may provide a desired amount of flexibility, expandability, and/or structural support.

As shown inFIG. 2, an alternate embodiment of a stent110may include a structural framework120of a plurality of undulating filaments122having alternating peaks123and valleys124. The plurality of undulating filaments122may be interconnected by a plurality of connectors126extending from one filament122to an adjacent filament122. The connectors126may extend longitudinally between adjacent filaments122or otherwise extend between adjacent filaments122. The connectors126may extend from a peak123of a first filament122to a valley124of an adjacent filament122, from a peak123of a first filament122to another peak123of an adjacent filament122, or from a valley124of a first filament122to another valley124of an adjacent filament122, for example. However, the connectors126may extend from any portion of a first filament122to an adjacent filament122. The filaments122and adjacent connectors126distinguish a plurality of interstices or openings125located throughout the structural framework120and bounded by adjacent filaments122.

A stent, such as the stent10illustrated inFIG. 1or the stent110illustrated inFIG. 2, may be manufactured from a workpiece. The workpiece may be a flat sheet or a tubular member, for example. Referring toFIG. 3, a workpiece50may be a flat sheet of material having a first surface52and a second surface54opposite the first surface52. The thickness T of material between the first surface52and the second surface54defines a wall56. In some embodiments, the wall56may be of a uniform thickness, and in other embodiments the thickness of the wall56may vary throughout the length of the workpiece. For example, an intermediate portion of the workpiece50may be a different thickness, for instance thinner, than first and second end portions positioned on either side of the intermediate portion. The workpiece50may have a first edge58and a second edge59opposite the first edge58. Each edge58,59may extend between the first surface52and the second surface54. Edges58,59of the workpiece50may be brought together and secured to form a tubular member during a manufacturing process.

The phantom lines15shown inFIG. 3illustrate an imaginary outline of the structural framework20of the stent10which may be manufactured from the workpiece50. The phantom lines15are for illustrative purposes, and may not actually be visible on the surface52of the workpiece50. The portion of the workpiece50located between the outline of the structural framework20for the stent10may be waste material60which may be removed from the structural framework20prior to providing the finished stent10. The waste material60corresponds to the openings25of the stent10shown inFIG. 1, interposed between adjacent struts22. Thus, the removal of the waste material60may provide the openings25interstitially located throughout the structural framework20.

Alternatively, a stent, such as the stent10illustrated inFIG. 1or the stent110illustrated inFIG. 2, may be manufactured from a workpiece comprising a tubular member as shown inFIG. 4. The workpiece150may have a first, outer surface152and a second, inner surface154defining an annular wall156therebetween. The wall156may have a material thickness T between the first surface152and the second surface154. In some embodiments, the wall156may be of a uniform thickness, and in other embodiments the thickness of the wall156may vary throughout the length of the workpiece. For example, an intermediate portion of the workpiece150may be a different thickness, such as thinner, than first and second end portions positioned on either side of the intermediate portion.

The phantom lines115shown inFIG. 4illustrate an imaginary outline of the structural framework120of the stent110which may be manufactured from the workpiece150. The phantom lines115are for illustrative purposes, and may not actually be visible on the surface152of the workpiece150. The portions of the workpiece150interstitially located between the outline of the structural framework120for the stent110may be waste material160which will be removed from the structural framework120prior to providing the finished stent110. The waste material160corresponds to the openings125of the stent110shown inFIG. 2, interposed between the filaments122. Thus, removal of the waste material160may provide the openings125throughout the structural framework120.

The structural framework of a stent, such as the stent10or the stent110, may be formed from a workpiece. The pattern of the structural framework20may be cut into the workpiece50by a laser cutting device controlled by a computer automated system, for example a computer numerically controlled (CNC) machine. Such a laser cutting device may be able to replicate a very intricate and precise pattern of the stent10. The laser may be a YAG laser, a CO2laser, an RF laser, a UV laser, an IR laser, a diode laser, etc., or any combination thereof. The laser may travel through a fluid jet, such as a water jet or other fluid medium. A laser beam, for example, or a laser beam traveling through a fluid jet may be directed at the workpiece50. The workpiece50may be translated and/or rotated relative to the position of the laser, or vise versa, in order to cut the desired pattern of the structural framework20. A fluid jet may be used to flush dross from the workpiece50, provide cooling to the cutting zone, and/or ensure against physical or thermal defects to the workpiece50during the cutting process. Additionally, the cutting depth of a laser, such as a fluid-guided laser, may be precisely controlled. Thus, the laser may be controlled to remove only a portion of the wall thickness T of the workpiece50. The speed and/or power of the laser may be selected to control the cutting depth of the laser. Each pass of the laser may remove a designated thickness of the workpiece50. Additional passes could be used to reach a predetermined cut depth at select locations greater than the cut depth at other locations, and/or additional passes may be used to cut completely through the wall thickness T of the workpiece50at select locations while only cutting partially through the wall thickness T of the workpiece50at other locations. Alternatively or additionally, the speed and/or power of the laser may be increased/decreased during the laser cutting process to vary the cutting depth of the laser. One such laser cutting process is disclosed in U.S. Pat. No. 6,696,666 entitled Tubular Cutting Process and System, which is herein incorporated by reference in its entirety. Other cutting techniques may include optical etching, chemical etching, electron beam ablation, material deposition, as well as other laser ablation techniques.

FIG. 5illustrates the workpiece50including kerf channels75cut in the first surface52of the workpiece50. The kerf channels75may outline the structural framework20of the stent10in the workpiece50. A plurality of kerf channels75may form a plurality of closed pathways demarcating the structural framework20of the stent10from the waste material60of the workpiece50. The kerf channels75may extend through only a portion of the thickness T of the wall56of the workpiece50. The kerf channels75extending partially through the wall56of the workpiece50may have opposing edges, which, in some embodiments, may be parallel, and a bottom surface. Therefore, the second surface54of the workpiece50may remain substantially intact throughout the cutting process forming the kerf channels75. In some embodiments, the second surface54may be uninterrupted by cuts or breaks during the cutting process of the kerf channels75, thus preserving the structural and/or dimensional integrity of the workpiece50. The kerf channels75may bound or otherwise define the extents of the waste material60of the workpiece50.

The depth of the kerf channels75may be precisely controlled using a laser, such as a fluid-guided laser, as discussed above. For example, the speed and/or power of the laser may influence the depth of the kerf channels75. Cutting limited depth kerf channels75distinguishes the structural framework20of the stent10from the waste material60of the workpiece50, while maintaining the integrity of the workpiece50throughout the cutting process, as well as subsequent handling/processing of the stent10. In some embodiments, by not cutting completely through the wall56of the workpiece50, the workpiece50may be completely supported along the second surface54during the cutting process. In other words, the second surface54may be laid flat on a support surface such that the two surfaces contact and oppose one another. Therefore, the potential for the workpiece50to deflect or shift may be greatly diminished. Thus, cycle times may be shortened and/or toolpaths may be optimized due at least in part to the sustained structural and/or dimensional integrity of the workpiece50. Additionally, since the kerf channel75does not extend to the second surface54, dross will be prevented from accumulating on the second surface54during a cutting process.

FIG. 6illustrates the workpiece150including a plurality of kerf channels175cut in the first, outer surface152of the workpiece150. A plurality of kerf channels175may form a plurality of closed pathways demarcating the structural framework120of the stent110from waste material160of the workpiece150. The kerf channels175, similar to the kerf channels75, may extend through only a portion of the thickness of the wall156of the workpiece150. Thus, the kerf channels175extending partially through the wall156of the workpiece150may have opposing edges, which, in some embodiments, may be parallel, and a bottom surface. Therefore, the second surface154may remain substantially intact throughout the cutting process forming the kerf channels175. In some embodiments, the second surface154may be uninterrupted by cuts or breaks during the cutting process of the kerf channels175, thus preserving the structural and/or dimensional integrity of the workpiece150. The depth of the kerf channels175may be precisely controlled using a laser, such as a fluid-guided laser, as discussed above. For example, the speed and/or power of the laser may influence the depth of the kerf channels175. Cutting limited depth kerf channels175distinguishes the structural framework120of the stent110from the waste material160of the workpiece150, while maintaining the integrity of the workpiece150throughout the cutting process, as well as subsequent handling/processing of the stent110. The kerf channels175may bound or otherwise define the extents of the waste material160of the workpiece150.

FIG. 7is an enlarged view of the kerf channels75cut in the workpiece50. It is noted that althoughFIG. 7illustrates a flat workpiece as shown inFIG. 5, the discussion that follows is likewise relevant to kerf channels cut in a tubular workpiece such as shown inFIG. 6. The kerf channels75may generally follow the phantom lines15as shown inFIG. 3to form an outline of the structural framework20of a stent. The kerf channels75may have a first edge76, an opposing second edge77, and a bottom surface78. The kerf channels75differentiate the structural framework20of the stent10from the waste material60, without completely separating the waste material60from the structural framework20. A residuum layer of material65may be located between the bottom surface78of the kerf channel75and the second surface54of the workpiece50. The residuum layer of material65has a reduced thickness less than the thickness of the workpiece50. The residuum material65maintains a connection between the structural framework20and the waste material60. This waste material60may not be completely removed from the structural framework20during the cutting process, but may be removed during a subsequent process. The residuum material65is uncut workpiece material remaining after the cutting process forming the kerf channels75. The residuum layer of material65may be integrally connected with the waste material60and the structural framework20. Thus, the residuum layer65connects or bridges the waste material60to the framework20. The residuum material65provides support to the workpiece50throughout the duration of the cutting process, as well as after the cutting process is completed. Thus, the structural and/or dimensional integrity of the structural framework20may be retained.

FIG. 8is an enlarged view of an alternate embodiment which may employ kerf channels. A plurality of kerf channels275may be similarly formed in a workpiece250as discussed above. The kerf channels275may have a first side276, an opposing second side277, and a bottom surface278. In addition to cutting kerf channels275into the workpiece250, a series of perforations280may be cut into the workpiece250. As shown inFIG. 8, a series of perforations280may be cut through the residuum layer of material265between the bottom surface278of the kerf channel275and the second surface254of the workpiece250. The perforations280may be apertures such as holes, gaps, or slots cut through the residuum layer of material265. Additionally, the perforations may be circular, oval, square, rectangular, or any other shape. The perforations280may be uniformly spaced along a length of the kerf channel275, or the perforations280may be more closely spaced in select locations relative to spacing of the perforations280throughout another length of the kerf channel275. In some embodiments, the perforations280may be coextensive with the kerf channels275. Although the series of perforations280illustrated inFIG. 8are cut through the workpiece250in addition to the kerf channels275, in some embodiments a series of perforations280may be cut into the workpiece250instead of the kerf channels275. Thus, in some embodiments the perforations280may extend from the first surface252of the workpiece250to the second surface254of the workpiece250and may distinguish the structural framework220from the waste material260. The series of perforations280may generally follow the phantom lines15shown inFIG. 3in order to outline the structural framework220of the stent210in the workpiece250. For example, a series of perforations280may bound or otherwise define the extents of a piece of waste material260corresponding to an interstitial opening of a stent. The series of perforations280may extend through the wall256of the workpiece250, or the series of perforations280may extend only partially through the wall256of the workpiece250. The perforations280remove a portion of the material of the wall256of the workpiece250, yet the waste material260may remain connected to the structural framework220of the stent210. As shown inFIG. 8, the waste material260may remain connected to the structural framework220by a bridging material267located between neighboring perforations280. The bridging material267may be integral with the structural framework220and the waste material260. By maintaining a connection between the waste material260and the structural framework220of the stent210, the structural and/or dimensional integrity of the stent210may be maintained. The bridging material267may be removed from the workpiece250during a subsequent manufacturing process, thus separating the waste material260from the structural framework220of the stent210.

FIG. 9is an enlarged view of an alternate embodiment employing kerf channels. A plurality of kerf channels375may be similarly formed in a workpiece350as discussed above. In addition to cutting the kerf channels375into the workpiece350, material may be completely removed from the workpiece350at select locations. For instance, the cuts390may extend completely through the wall356to the second side354of the workpiece350. Through cuts390may be formed in the workpiece350at select locations. In some embodiments, the cuts390may be formed on either side of a link395. The link395may be a piece of material of the workpiece350extending between adjacent segments of the structural framework320of the stent310. In some embodiments, a plurality of links395may extend between adjacent portions of the stent310throughout the structural framework320. The link395may provide structural and/or dimensional integrity to the structural framework320. In some embodiments, the link395, or a portion thereof, may be removed during a subsequent manufacturing process. For example, the link395may be removed during a chemical-etching or electro-polishing process, or the link395may be mechanically cut or laser ablated, in order to remove the link395from the structural framework320. The link395may have one or more frangible regions, such as regions of reduced cross-sectional area or including score lines, in order to remove the link395from the structural framework320. Additional methods known in the art may be used to separate the link395from the structural framework320.

FIG. 10is an enlarged view of an alternate embodiment of a structural framework420formed in a workpiece450. A portion of the material of the workpiece450may be removed in order to demarcate the structural framework420of the stent410from a residuum layer of material465of the workpiece450. Thus, the structural framework420may have a raised surface452relative to a recessed surface453of the residuum layer of material465remaining. The second surface454of the workpiece450may remain substantially intact. In some embodiments, the second surface454may be uninterrupted by cuts or breaks. Thus, the residuum material465may connect adjacent portions of the structural framework420such that the structural and/or dimensional integrity of the structural framework420is maintained. The residuum material465may be removed during a subsequent manufacturing process. For example, the residuum layer of material465may be removed during a chemical-etching or electro-polishing process, or the residuum material465may be mechanically cut or laser ablated, in order to remove the residuum material465from the structural framework420. Other means of removing the residuum layer of material465may include dissolving, eroding, dissipating, melting, or otherwise eliminating the residuum material465. Additional methods known in the art may be used to remove the residuum material465from the structural framework420.

FIG. 11shows an enlarged view of an alternate embodiment of a structural framework520formed in a workpiece550. Similar to previously discussed embodiments, a plurality of kerf channels575may be cut into the first surface552of the workpiece550to demarcate a structural framework520of a stent510. The kerf channels575may extend only partially through the wall556of the workpiece550. In this embodiment, the residuum layer of material565may be a layer of material dissimilar from the material comprising the remainder of the workpiece forming the structural framework520of the stent510. For instance, the wall556of the workpiece550may be a laminated structure including a first layer of material582and a second layer of material584different from the first layer of material582. The structural framework520may comprise the first layer of material582and the residuum layer of material565may comprise the second layer of material584. One or more additional layers of material may be present in the wall556. For example, a tie layer may be located between the first layer of material582and the second layer of material584, affixing the first layer of material582to the second layer of material584. In some embodiments, the second layer of material584may be a sleeve or liner extending through a tubular workpiece and partially defining an annular wall556of the workpiece550. In some embodiments the first layer of material582may be secured to the second layer of material584by adhesive, bonding, welding, soldering, brazing, or the like.

The first layer of material582and the second layer of material584may be chosen for their individual, dissimilar laser energy absorbing properties. For instance, the material of the residuum layer565may not absorb laser energy or may absorb laser energy at a different level, frequency, wavelength, or degree than the material comprising the structural framework520. For example, the first layer of material582may readily absorb laser energy at a first wavelength and the second layer of material584may readily absorb laser energy at a second wavelength different from the first wavelength. The first layer of material582may not readily absorb laser energy or may reflect laser energy at the second wavelength, or may absorb laser energy at the second wavelength to a lesser extent. The second layer of material584may not readily absorb laser energy or may reflect laser energy at the first wavelength, or may absorb laser energy at the first wavelength to a lesser extent. In some embodiments, the first wavelength may be in the near-infrared region, about 750 nm to about 2,500 nm, or the mid-infrared region, about 2,500 nm to about 10 μm, and the second wavelength may be in the far-infrared region, about 10 μm to about 1 mm. In other embodiments, the first wavelength may be in the far-infrared region and the second wavelength may be in the near-infrared region or the mid-infrared region. In some embodiments, the material of the structural framework520may absorb laser energy and the residuum layer of material565may reflect laser energy.

For example, the first layer of material582may comprise a metal, a metal alloy, or other metallic material, which may readily absorb laser energy emitted from a YAG laser. YAG lasers commonly emit laser energy having a relatively short wavelength in the near-infrared region or the mid-infrared region, which may be in the range of about 1000 nm to about 3000 nm. For instance, an Nd:YAG laser commonly emits energy in the near-infrared region having a wavelength of about 1064 nm or about 1320 nm. An Er:YAG laser commonly emits energy in the mid-infrared region having a wavelength of about 2940 nm. A YAG laser may be unsuitable for readily cutting a polymeric material or other material not compatible with the emitted wavelength of the laser.

The second layer of material may comprise a polymer or other material, which may readily absorb laser energy emitted from a CO2laser. CO2lasers commonly emit laser energy having a relatively long wavelength in the far-infrared region, such as in the range of about 9,300 nm to about 10,600 nm. Emitted energy from a CO2layer may tend to be reflected off of most metallic surfaces. Thus, a CO2laser may be unsuitable for readily cutting a metallic material or other material not compatible with the emitted wavelength of the laser. In some embodiments, the first layer of material582may comprise a polymeric material and the second layer of material584may comprise a metallic material.

Therefore, laser energy emitted from a laser may be absorbed by the first layer of material582, but not be absorbed, be absorbed to a lesser extent, or be reflected by the second layer of material584. For instance, laser energy of a YAG laser may cut through a metallic material, but not cut through a polymeric material, or laser energy of a CO2laser may cut through a polymeric material, but not cut through a metallic material.

Laser energy directed at the workpiece550may be readily absorbed by the first layer of material582, thus cutting through the first layer of material582. However, the laser energy may not be readily absorbed, be absorbed to a lesser extent, or may be reflected by the second layer of material584. Thus, the second layer of material584may remain substantially uncut during the laser-cutting process. The second surface554of the workpiece550may be uninterrupted by cuts or breaks during the cutting process. As a result, the kerf channels575may be formed in the workpiece550. As noted above, the kerf channels575may extend completely through the first layer of material582, but may not extend through the second layer of material584. Therefore, the structural framework520of the stent may be cut from the first layer of material582, leaving a residuum layer of material565comprising the second layer of material584secured to the structural framework520.

The residuum layer of material565, not severed during the cutting process, may provide structural and/or dimensional integrity to the workpiece550. Thus, the residuum layer of material565may provide support to the structural framework520during subsequent handling/processing of the stent. The residuum layer of material565may be removed from the structural framework520during a post-cutting process and prior to providing a finished stent. For example, the residuum layer of material565may be dissolved, dissipated, eroded, melted, mechanically separated, or otherwise removed from the structural framework520. Thus, the waste material560may be completely separated from the structural framework520of the workpiece550.

FIG. 12shows a stent10with the waste material60and the residuum material65removed. The waste material60(FIG. 7) and/or the residuum material65(FIG. 7) may be removed during one or more additional processes subsequent to cutting the kerf channels75in the workpiece50or otherwise removing material from the workpiece50to demarcate the structural framework20of the stent10. The waste material60and/or the residuum material65may be removed by chemical-etching (otherwise known as chemical milling, photo-etching, or photo-chemical machining), electro-polishing, milling, punching, laser ablation, mechanical cutting, fracturing, or the like.

The structural and/or dimensional integrity of the structural framework20of the stent10may be maintained throughout the cutting process, as well as post-cutting processes performed on the workpiece. For instance, after the structural framework20is demarcated from the waste material of a workpiece comprising a flat sheet, the sheet may be formed into a tubular configuration. For example, the first edge58and second edge59of the workpiece50(as shown inFIG. 3) may be adjoined to form a tubular member. In some embodiments, the edges58,59may be secured together. For example, the edges58,59may be secured by an adhesive, welding, soldering, brazing, bonding, mechanically coupling, crimping, swaging, or the like. Because the residuum material remains attached to the structural framework while forming the framework into a tubular member, the integrity of the stent is enhanced.

The workpiece may be subjected to additional or alternative post-cutting processes prior to completely removing the waste material from the structural framework of the stent. For example, the workpiece may undergo a cleaning process, a heat treating process, a forming process, an annealing process, a thermal setting process, a strength hardening process, or similar process. Handling and/or manipulating the workpiece may be improved due at least in part to the structural and/or dimensional integrity afforded by the residuum layer of material connected to the structural framework of the stent.

Any one of the previously described stent forming processes may include one or more further processing steps. For example, the structural framework may be expanded or contracted. For instance, the structural framework may be placed over a mandrel in order to expand the structural framework. Additionally, or alternatively, the structural framework may be compressed into a reduced size, such as into a delivery configuration. Additionally, the structural framework of the stent may be subjected to a cleaning process to remove dross or residue subsequent to a cutting process. For instance, an alcohol and/or water solution may be used to clean foreign material from the workpiece. A chemical-etching process may be used to remove waste material and/or other material from the workpiece to provide a surface with no sharp edges or burrs. An electro-polishing process may be used to remove waste material and/or other material to reduce the surface roughness of the workpiece and provide a stent having a substantially smooth outer surface. An electro-polishing process, or similar electrical process, may also be used to dissolve, dissipate, erode or otherwise separate selected portions of material from the structural framework of the stent. For example, an electro-polishing process may dissolve a percentage of the mass of the material forming the stent. By dimensioning portions of the workpiece relatively small compared to the interconnected segments of the structural framework of the stent, the undesired portions of material will completely dissolve, dissipate, erode or otherwise be separated from the structural framework of the stent without fully dissolving the interconnected segments during an electro-polishing process. An electrical current of a sufficient magnitude may be applied to the workpiece to separate the waste material from the structural framework of the stent. Additionally, a stent may be subjected to one or more heat treating processes in order to remove residual stresses and/or provide favorable characteristics to the stent, such as shape memory properties.

It is noted that although the disclosed processes and methods have been discussed regarding the formation of a stent, such processes and methods may also be utilized to form other stent configurations, as well as other medical devices such as guidewires, coil tips, balloon delivery components, filter mesh, filter devices, retrieval devices, and other medical devices.