Polymeric stent polishing method and apparatus

• US 20070023974A1
• Filed: 07/29/2005
• Published: 02/01/2007
• Est. Priority Date: 07/29/2005
• Status: Active Grant

• Current Assignee: Advanced Cardiovascular Systems Incorporated
• Original Assignee: Advanced Cardiovascular Systems Incorporated
• Inventors: Wu, Patrick
• Granted Patent: US 7,658,880 B2
• Time in Patent Office: Days
• US Class Current: 264/491
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2/91 made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
• CPC Class Codes: B29C 59/00 Surface shaping of articles, e.g. embossing; Apparatus therefor in-mould printing B29C37/0025; by using liquids B29C71/0009; by using gases without chemical reaction B29C71/009; for decorating in general B44; abrasive blasting B24C; chemical aspects C08J7/00
• CPC Class Codes: B29C 71/02 Thermal after-treatment B29C71/0063 and B29C71/0072 take precedence
• CPC Class Codes: B29C 71/04 by wave energy or particle radiation , e.g. for curing or vulcanising preformed articles during moulding, e.g. in a mould B29C35/08
• CPC Class Codes: B29L 2031/7532 Artificial members, protheses

Abstract

A method and apparatus for simultaneously polishing the inner and outer surfaces of an unpolished polymeric stent using a heat process. The unpolished stent can be mounted, for example, on a “spiral-mandrel,” a tubular helical structure with gaps in between a series of coils of the structure. Heat from a heat source can then applied to the spiral-mandrel at a range between the glass transition temperature and melting temperature of the polymer of the stent.

Claims

1. A method of polishing a polymeric stent, comprising:

directing heat into an interior space of an unpolished polymeric stent and against a luminal surface of the stent to thereby polish the luminal surface.

2. The method of claim 1, wherein the heat is radiation heat.

3. The method of claim 1, wherein the heat is convection heat.

4. The method of claim 1, wherein the heat is hot gas.

5. The method of claim 1, wherein the directing includes directing the heat from the exterior of the stent through at least one interstitial gap in the wall of the stent and thereby to the interior space.

6. The method of claim 1, wherein the directing includes directing the heat axially into the interior space of the stent.

7. The method of claim 1, further comprising before the directing, mounting the unpolished stent on a mandrel.

8. The method of claim 7, wherein the mandrel is a spiral mandrel, and the directing includes directing the heat between adjacent spaced coils of the spiral mandrel.

9. The method of claim 8, further comprising forming the spiral mandrel by wrapping a wire in a coiled manner around a mandrel and then separating the mandrel and the coiled wire.

10. The method of claim 7, wherein the mandrel is a tube having wall openings, and the directing includes directing the heat into the tube and out through the openings and against the luminal surface.

11. The method of claim 7, wherein the mandrel includes interconnected spaced rings and openings defined between the rings, the mounting includes mounting the unpolished stent on the rings, and the directing includes directing the heat into the mandrel and out through the openings and against the luminal surface.

12. The method of claim 1, wherein the temperature of a polymer of the stent is increased to equal to or greater than a glass transition temperature and less than a melting temperature of the polymer.

13. The method of claim 1, wherein the temperature of a polymer of the stent is increased to equal to or less than a melting temperature of the polymer.

14. The method of claim 1, wherein the heat is at a temperature equal to or greater than a glass transition temperature of a polymer of the stent.

15. The method of claim 1, wherein the heat is at a temperature equal to or greater a melting temperature of a polymer of the stent.

16. The method of claim 1, wherein the heat is from a heater coil, radio frequency heater or gas blower.

17. The method of claim 1, wherein the heat is from an element capable of being inserted into a hollow longitudinal bore of the stent.

18. The method of claim 1, wherein the directing includes the luminal surface being subjected to the heat for three to eight seconds at a selected temperature of about 40°

C. to about 175°

C.

19. The method of claim 1, wherein the heat polishes an abluminal surface of the stent.

20. The method of claim 1, wherein the directing is at a heating station, and further comprises conveying the unpolished stent by the station.

21. The method of claim 20, wherein the conveying includes the stent being stopped during the directing at the heating station.

22. The method of claim 1, wherein the heat is from a heater which radially encircles the stent.

23. The method of claim 1, wherein the directing includes radially directing heat from multiple spaced sources encircling the stent.

24. The method of claim 1, further comprising mounting the stent on a cylindrical braided device, and the directing includes directing the heat through gaps of the wall of the braided device.

25. The method of claim 1, additionally including rotating the stent during the application of heat.

26. The method of claim 25, additionally including rotating the stent during the polishing process, wherein the application of heat is terminated before the rotation of the stent and wherein the rotation of the stent is terminated prior to application of the heat.

27. A method of polishing a polymeric stent, comprising:

mounting a stent made from a material including a polymer onto a structure having a series of gaps; and

after the mounting, subjecting the stent to heat from a heat source so as to modify a surface morphometry of at least a section of the stent from an angular configuration to a non-angular configuration.

28. The method of claim 27, wherein the structure includes a tubular coiled wire, a tubular braided structure, a porous sheath, a porous hypotube or a series of interconnecting cylindrical rings.

29. The method of claim 27, wherein the structure is made from a material including a heat conductive material.

30. The method of claim 27, wherein the structure comprises a metallic material.

31. The method of claim 27, wherein the structure is made from a non-heat conductive material.

32. The method of claim 27, wherein the heat is at a temperature equal to or greater than a glass transition temperature of a polymer of the stent.

33. The method of claim 27, wherein the heat is at a temperature equal to or greater than a melting temperature of a polymer of the stent.

34. The method of claim 27, wherein the temperature of the polymer is increased to greater than or equal to a glass transition temperature of the polymer.

35. The method of claim 27, wherein the temperature of the polymer is increased to less than or equal to the melting temperature of the polymer.

36. The method of claim 27, wherein the heat source is positioned external to the structure.

37. The method of claim 27, wherein the heat source is positioned internal to the structure.

38. The method of claim 27, wherein the heat source encircles the stent.

39. A method of polishing a luminal surface of a polymeric stent, comprising:

mounting an unpolished polymeric stent on and around a cylindrical surface and in direct thermal contact therewith; and

heating the cylindrical surface to thereby heat and polish the luminal surface of the stent mounted thereon.

40. The method of claim 39, wherein the cylindrical surface is a heat conducting tube which is mounted on a heating element, and the heating includes heating the heating element to thereby heat the heat conducting tube, which in turn heat polishes the luminal surface.