Porous membranes for medical implants and methods of manufacture

• US 20060175727A1
• Filed: 12/19/2005
• Published: 08/10/2006
• Est. Priority Date: 09/28/2001
• Status: Active Grant

• Current Assignee: Abbott Laboratories Limited (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Laboratories Limited (Abbott Laboratories Incorporated)
• Inventors: Huesler, Erhard J., Zucker, Arik, Fierens, Joost J., Nicaise, Philippe, Marcoux, Eric
• Granted Patent: US 7,815,763 B2
• Time in Patent Office: Days
• US Class Current: 264/172.190
• CPC Class Codes: A61F 2/01 Filters implantable into blood vessels
• 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: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/91508 the meander having a difference in amplitude along the band
• CPC Class Codes: A61F 2002/91533 characterised by the phase between adjacent bands
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: B29C 2948/92571 Position, e.g. linear or angular
• CPC Class Codes: B29C 2948/9258 Velocity
• CPC Class Codes: B29C 2948/9259 Angular velocity
• CPC Class Codes: B29C 2948/926 Flow or feed rate
• CPC Class Codes: B29C 2948/92609 Dimensions
• CPC Class Codes: B29C 2948/92628 Width or height
• CPC Class Codes: B29C 2948/92695 Viscosity; Melt flow index [MFI]; Molecular weight
• CPC Class Codes: B29C 2948/92904 Die; Nozzle zone
• CPC Class Codes: B29C 48/0012 combined with shaping by internal pressure generated in the material, e.g. foaming
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/151 Coating hollow articles
• CPC Class Codes: B29C 48/92 Measuring, controlling or regulating
• CPC Class Codes: B29K 2023/06 PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/12 : PP, i.e. polypropylene
• CPC Class Codes: B29K 2027/18 : PTFE, i.e. polytetrafluorethene , e.g. ePTFE, i.e. expanded polytetrafluorethene
• CPC Class Codes: B29K 2067/00 : Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2071/00 : Use of polyethers , e.g. PEEK, i.e. polyether-etherketone or PEK, i.e. polyetherketone or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2075/00 : Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2077/00 : Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2105/04 : cellular or porous
• CPC Class Codes: B29K 2105/108 : arranged in parallel planes and crossing at substantial angles B29K2105/206 takes precedence
• CPC Class Codes: B29L 2031/7532 : Artificial members, protheses
• CPC Class Codes: B29L 2031/755 : Membranes, diaphragms
• CPC Class Codes: D04H 3/07 : otherwise than in a plane, e.g. in a tubular way
• CPC Class Codes: Y10T 428/24273 : including aperture
• CPC Class Codes: Y10T 428/24298 : Noncircular aperture [e.g., slit, diamond, rectangular, etc.]
• CPC Class Codes: Y10T 428/24306 : Diamond or hexagonal

Abstract

The present invention involves porous polymer membranes, suitable for use in medical implants, having controlled pore sizes, pore densities and mechanical properties. Methods of manufacturing such porous membranes are described in which a continuous fiber of polymer is extruded through a reciprocating extrusion head and deposited onto a substrate in a predetermined pattern. When cured, the polymeric material forms a stable, porous membrane suitable for a variety of applications, including reducing emboli release during and after stent delivery, and providing a source for release of bioactive substances to a vessel or organ and surrounding tissue.

Claims

1. A method of making a porous membrane for use in medical implants comprising:

extruding a continuous fiber-forming biocompatible polymeric material through a reciprocating extrusion head to form an elongated fiber;

depositing the fiber onto a substrate in traces having a predetermined pattern and a trace width of 5 to 500 micrometers, adjacent traces being spaced apart a distance of between 0 and 500 micrometers, the fiber having a predetermined viscous creep characteristic that enables the adjacent traces to bond to each other at predetermined contact points; and

curing the biocompatible material on the substrate to provide a stable, porous membrane.

2. The method of claim 1 wherein depositing the fiber comprises depositing the fiber so that less than five adjacent traces of the fiber overlap or cross.

3. The method of claim 1 wherein depositing the fiber comprises depositing the fiber so that adjacent traces of the fiber do not overlap or cross.

4. The method of claim 3 wherein depositing the fiber comprises depositing the fiber so that adjacent traces of the fiber contact each other only at bond areas to define a row of pores.

5. The method of claim 1 wherein depositing the fiber comprises depositing the fiber with a high unevaporated solvent content so that adjacent traces of the fiber bond to each other.

6. The method of claim 1 further comprising providing a substrate, wherein the substrate comprises a vascular implant.

7. The method of claim 6 further comprising providing a medical implant comprising a stent.

8. The method of claim 1 wherein extruding a continuous fiber-forming biocompatible polymeric material comprises co-extruding a polymeric sheath surrounding a solid core filament.

9. The method of claim 1 wherein extruding a continuous fiber-forming biocompatible polymeric material comprises co-extruding a first polymeric sheath surrounding a second polymeric core filament.

10. The method of claim 1 further comprising removing the porous membrane from the substrate and affixing the porous membrane to a surface of a medical implant.

11. Apparatus for making a porous membrane for use in medical implants, the apparatus comprising:

an extrusion head having an outlet for extruding a fiber comprising a biocompatible polymer;

a substrate;

a numerically-controlled positioning system configured to move the extrusion head relative to the substrate, the positioning system providing four degrees of freedom of movement of the extrusion head relative to the substrate; and

a computer coupled to control operation of the extrusion head and the positioning system.

12. The apparatus of claim 11 wherein a first degree of freedom comprises translational motion of the extrusion head relative to a longitudinal axis of the substrate.

13. The apparatus of claim 11 wherein a second degree of freedom comprises rotational motion of the extrusion head relative to a longitudinal axis of the substrate.

14. The apparatus of claim 11 wherein a third degree of freedom comprises varying a radial distance between the extrusion head and the substrate.

15. The apparatus of claim 11 wherein a fourth degree of freedom comprises rotating the extrusion head relative to a vertical axis of the extrusion head.

16. The apparatus of claim 11 further comprising programming that controls the positioning system to rotate the substrate only when the extrusion head is stationary near a proximal or distal end of the substrate.

17. The apparatus of claim 11 further comprising programming that controls the positioning system to rotate the substrate in alternating directions when the extrusion head is disposed stationary at locations between a proximal end and a distal end of the substrate.

18. The apparatus of claim 11 further comprising programming the controls the positioning system to vary two or more degrees of freedom simultaneously.

19. The apparatus of claim 11 wherein the extrusion head is configured to extrude a fiber comprising a first polymer sheath co-extruded surrounding a core filament.

20. The apparatus of claim 11 wherein the extrusion head is configured to co-linearly extrude multiple fibers.