Polymer fiber tubular structure having kinking resistance

• US 20040096532A1
• Filed: 09/17/2003
• Published: 05/20/2004
• Est. Priority Date: 12/19/2000
• Status: Active Grant

• Current Assignee: Nicast Ltd.
• Original Assignee: Nicast Ltd.
• Inventors: Bar, Eli, Dubson, Alexander
• Granted Patent: US 7,276,271 B2
• Time in Patent Office: Days
• US Class Current: 425/115
• CPC Class Codes: A61F 2/06 Blood vessels
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• 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: A61F 2002/072 Encapsulated stents, e.g. wire or whole stent embedded in lining
• CPC Class Codes: A61F 2210/0076 multilayered, e.g. laminated structures
• CPC Class Codes: A61F 2250/0023 differing in porosity
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61L 27/507 for artificial blood vessels apparatus for applying cells on a blood vessel prosthesis A61F2/062
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: B29C 67/20 for porous or cellular articles, e.g. of foam plastics, coarse-pored chemical aspects of working up macro-molecular substances to porous or cellular articles C08J9/00
• CPC Class Codes: D01D 5/0007 Electro-spinning non-woven fabrics produced by electro-spinning D04H1/728
• CPC Class Codes: D01D 5/0069 characterised by the spinning section, e.g. capillary tube, protrusion or pin
• CPC Class Codes: D01D 5/0092 characterised by the electrical field, e.g. combined with a magnetic fields, using biased or alternating fields
• CPC Class Codes: D01D 5/18 by means of rotating spinnerets
• CPC Class Codes: D04H 1/728 by electro-spinning electro-spinning methods and apparatus D01D5/0007
• CPC Class Codes: D04H 3/07 otherwise than in a plane, e.g. in a tubular way
• CPC Class Codes: D04H 3/16 with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion
• CPC Class Codes: Y10T 428/13 Hollow or container type article [e.g., tube, vase, etc.]
• CPC Class Codes: Y10T 428/1372 Randomly noninterengaged or randomly contacting fibers, filaments, particles, or flakes
• CPC Class Codes: Y10T 428/139 : Open-ended, self-supporting conduit, cylinder, or tube-type article
• CPC Class Codes: Y10T 428/1393 : Multilayer [continuous layer]
• CPC Class Codes: Y10T 442/614 : Strand or fiber material specified as having microdimensions [i.e., microfiber]

Abstract

An apparatus for forming a tubular structure from a liquefied polymer, the apparatus comprising: (a) a dispenser for dispensing the liquefied polymer; (b) a precipitation electrode being at a first potential relative to the dispenser, the precipitation electrode being designed and constructed for generating a polymeric shell thereupon; and (c) a mechanism for increasing a local density of the polymeric shell in a plurality of predetermined sub-regions of the polymeric shell, thereby to provide a tubular structure having an alternating density in a longitudinal direction.

Claims

1. An apparatus for forming a tubular structure from a liquefied polymer, the apparatus comprising:

(a) a dispenser for dispensing the liquefied polymer;

(b) a precipitation electrode being at a first potential relative to said dispenser, said precipitation electrode being designed and constructed for generating a polymeric shell thereupon; and

(c) a mechanism for increasing a local density of said polymeric shell in a plurality of predetermined sub-regions of said polymeric shell, thereby to provide a tubular structure having an alternating density in a longitudinal direction.

2. The apparatus of claim 1, wherein said mechanism for increasing said local density comprises a pressing mechanism.

3. The apparatus of claim 1, wherein said mechanism for increasing said local density comprises a plurality of rollers spaced apart from one another.

4. The apparatus of claim 1, wherein said mechanism for increasing said local density comprises a spiral pattern.

5. The apparatus of claim 1, wherein said mechanism for increasing said local density comprises a rigid irregular pattern.

6. The apparatus of claim 1, wherein said precipitation electrode comprises at least one rotating mandrel.

7. The apparatus of claim 1, wherein said dispenser is operable to move along said precipitation electrode.

8. The apparatus of claim 1, wherein said dispenser comprises a mechanism for forming a jet of the liquefied polymer.

9. The apparatus of claim 8, wherein said mechanism for forming a jet of the liquefied polymer includes a dispensing electrode.

10. The apparatus of claim 1, further comprising a reservoir for holding the liquefied polymer.

11. The apparatus of claim 1, further comprising a subsidiary electrode being at a second potential relative to said dispenser, and being for modifying an electric field generated between said precipitation electrode and said dispenser.

12. The apparatus of claim 11, wherein said subsidiary electrode serves for reducing non-uniformities in said electric field.

13. The apparatus of claim 11, wherein said subsidiary electrode serves for controlling fiber orientation of the tubular structure formed upon said precipitation electrode.

14. The apparatus of claim 11, wherein said subsidiary electrode is of a shape selected from the group consisting of a plane, a cylinder, a torus and a wire.

15. The apparatus of claim 11, wherein said subsidiary electrode is operative to move along said precipitation electrode.

16. The apparatus of claim 11, wherein said subsidiary electrode is tilted at angle with respect to said precipitation electrode.

17. The apparatus of claim 1, further comprising a mechanism for intertwining at least a portion of a plurality of polymer fibers dispensed by said dispenser, so as to provide at least one polymer fiber bundle moving in a direction of said precipitation electrode.

18. The apparatus of claim 17, wherein said mechanism for intertwining at least a portion of said plurality of polymer fibers comprises a system of electrodes, being laterally displaced from said dispenser, being at a third potential relative to said dispenser and capable of providing an electric field having at least one rotating component around a first axis defined between said dispenser and said precipitation electrode.

19. The apparatus of claim 18, wherein said system of electrodes includes at least one rotating electrode, operable to rotate around said first axis.

20. The apparatus of claim 19, wherein said dispenser and said at least one rotating electrode are operative to independently move along said precipitation electrode.

21. The apparatus of claim 19, wherein said dispenser and said at least one rotating electrode are operative to synchronically move along said precipitation electrode.

22. A method of forming a tubular structure from a liquefied polymer, the method comprising:

(a) via electrospinning, dispensing the liquefied polymer from a dispenser in a direction of a precipitation electrode, hence forming polymeric shell; and

(b) increasing a local density of said polymeric shell in a plurality of predetermined sub-regions of said polymeric shell, thereby providing a tubular structure having an alternating density in a longitudinal direction.

23. The method of claim 22, further comprising independently repeating said steps (a) and (b) at least once.

24. The method of claim 22, wherein said increasing said local density is done by applying pressure onto said predetermined sub-regions of said polymeric shell.

25. The method of claim 22, wherein said increasing said local density is done by pressing a plurality of rollers, spaced apart from one another, onto said polymeric shell.

26. The method of claim 22, wherein said increasing said local density is done by pressing a spiral pattern onto said polymeric shell.

27. The method of claim 22, wherein said increasing said local density is done by pressing a rigid irregular pattern onto said polymeric shell.

28. The method of claim 22, further comprising mixing the liquefied polymer with a charge control agent prior to said step of dispensing.

29. The method of claim 28, wherein said dispenser being at a first potential relative to said precipitation electrode.

30. The method of claim 22, wherein said dispenser comprises a mechanism for forming a jet of the liquefied polymer.

31. The method of claim 30, wherein said mechanism for forming a jet of the liquefied polymer includes a dispensing electrode.

32. The method of claim 22, further comprising reducing non-uniformities in an electric field generated between said precipitation electrode and said dispenser.

33. The method of claim 32, wherein said reducing non-uniformities in said electric field is done by positioning a subsidiary electrode, being at a second potential relative to said precipitation electrode, close to said precipitation electrode.

34. The method of claim 22, further comprising controlling fiber orientation of the tubular structure formed upon said precipitation electrode.

35. The method of claim 34, wherein said controlling fiber orientation is done by positioning a subsidiary electrode, being at a second potential relative to said precipitation electrode, close to said precipitation electrode.

36. The method of claim 33, wherein said subsidiary electrode is of a shape selected from the group consisting of a plane, a cylinder, a torus and a wire.

37. The method of claim 35, wherein said subsidiary electrode is of a shape selected from the group consisting of a plane, a cylinder, a torus and a wire.

38. The method of claim 33, further comprising moving said subsidiary electrode along said precipitation electrode.

39. The method of claim 35, further comprising moving said subsidiary electrode along said precipitation electrode.

40. The method of claim 33, further comprising tilting said subsidiary electrode at angle with respect to said precipitation electrode.

41. The method of claim 35, further comprising tilting said subsidiary electrode at angle with respect to said precipitation electrode.

42. The method of claim 22, further comprising entangling at least a portion of a plurality of polymer fibers dispensed by said dispenser, so as to provide at least one polymer fiber bundle moving in a direction of said precipitation electrode.

43. The method of claim 41, wherein said step of entangling comprises providing an electric field having at least one rotating component around a first axis defined between said precipitation electrode and said dispenser.

44. The method of claim 43, wherein said providing an electric field having at least one rotating component, is done by providing a system of electrodes, being laterally displaced from said dispenser, being at a third potential relative to said precipitation electrode and operable to provide a time-dependent electric field.

45. The method of claim 43, wherein said providing an electric field having at least one rotating component, is done by providing at least one rotating electrode, being laterally displaced from said dispenser, being at a third potential relative to said precipitation electrode and operable to rotate around said first axis.

46. The method of claim 45, further comprising independently moving said dispenser and said at least one rotating electrode along said precipitation electrode.

47. The method of claim 45, further comprising synchronically moving said dispenser and said at least one rotating electrode along said precipitation electrode.

48. A tubular structure, comprising at least one layer of electrospun polymer fibers, each layer having a predetermined porosity and an alternating density in a longitudinal direction of the tubular structure.

49. The tubular structure of claim 48, sized and having properties so as to serve as a vascular prosthesis.

50. The tubular structure of claim 48, wherein said electrospun polymer fibers are biocompatible.

51. The tubular structure of claim 48, wherein said electrospun polymer fibers are selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

52. The tubular structure of claim 48, wherein at least one of said at least one layer includes at least one drug incorporated therein, for delivery of said at least one drug into a body vasculature during or after implantation of the tubular structure within said body vasculature.

53. The tubular structure of claim 52, wherein said electrospun polymer fibers are a combination of a biodegradable polymer and a biostable polymer.

54. A vascular prosthesis, comprising at least one layer of electrospun polymer fibers, each layer having a predetermined porosity and an alternating density in a longitudinal direction of the vascular prosthesis.

55. The vascular prosthesis of claim 54, wherein said electrospun polymer fibers are biocompatible.

56. The vascular prosthesis of claim 54, wherein said electrospun polymer fibers are selected from the group consisting of polyethylene terephtalat fibers and polyurethane fibers.

57. The vascular prosthesis of claim 54, wherein at least one of said at least one layer includes at least one drug incorporated therein, for delivery of said at least one drug into a body vasculature during or after implantation of the vascular prosthesis within said body vasculature.

58. The vascular prosthesis of claim 57, wherein said electrospun polymer fibers are a combination of a biodegradable polymer and a biostable polymer.