Method for fabricating soft tissue implants with microscopic surface roughness

• US 5,965,076 A
• Filed: 09/22/1997
• Issued: 10/12/1999
• Est. Priority Date: 09/22/1997
• Status: Expired due to Fees

• Current Assignee: National Aeronautics and Space Administration USA As Represented By The Administrator of The Administrator of The
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Rutledge, Sharon K., Banks, Bruce A.
• Primary Examiner(s): Timm, Catherine
• Assistant Examiner(s): MCDOWELL, SUZANNE E
• Application Number:
  US08/936,492
• Time in Patent Office: 750 Days
• Field of Search: 264/219, 264/447, 264/446, 156/276, 156/344, 427/551, 427/552, 427/180, 427/259, 427/264, 427/270, 427/133, 425/2
• US Class Current: 264/219
• CPC Class Codes: A61L 27/28 Materials for coating prostheses
• CPC Class Codes: B29C 33/3842 Manufacturing moulds, e.g. shaping the mould surface by machining
• CPC Class Codes: B29C 33/42 characterised by the shape of the moulding surface, e.g. ribs or grooves
• CPC Class Codes: Y10T 156/11 Methods of delaminating, per se; i.e. , separating at bonding face

Abstract

A method for fabricating soft tissue implants using a mold. The cavity surface of an initially untextured mold, made of an organic material such as epoxy, is given a thin film coating of material that has pinholes and is resistant to atomic particle bombardment. The mold cavity surface is then subjected to atomic particle bombardment, such as when placed in an isotropic atomic oxygen environment. Microscopic depressions in the mold cavity surface are created at the pinhole sites on the thin film coating. The thin film coating is removed and the mold is then used to cast the soft tissue implant. The thin film coating having pinholes may be created by chilling the mold below the dew point such that water vapor condenses upon it; distributing particles, that can partially dissolve and become attached to the mold cavity surface, onto the mold cavity surface; removing the layer of condensate, such as by evaporation; applying the thin film coating over the entire mold surface; and, finally removing the particles, such as by dissolving or brushing it off. Pinholes are created in the thin film coating at the sites previously occupied by the particles.

Claims

1. A method for fabricating soft tissue implants having doubly curved or irregularly shaped surfaces, and having surface roughness from a mold made from an organic material, comprising the steps of:

(a) coating a mold cavity surface of the mold with a thin film coating of material, which is resistant to atomic particle bombardment, and forming pinholes within said coating;

(b) subjecting the mold cavity surface to atomic particle bombardment so that depressions are created in the mold cavity surface at the pinhole sites on the thin film coating;

(c) removing the thin film coating from the mold cavity surface; and

(d) creating an implant by using the mold to cast the implant.

2. A method as in claim 1, wherein said step (a) comprises the steps of:

(a1) creating a controlled layer of fluid on the mold cavity surface;

(a2) distributing particles, capable of being attached to the mold cavity surface by being partially dissolved by the fluid, onto the layer of fluid on the mold cavity surface;

(a3) removing the fluid from the mold cavity surface without removing the particles that are attached to the mold cavity surface;

(a4) applying a thin film coating, that is resistant to atomic particle bombardment, over the mold cavity surface; and

(a5) removing the particles from the surface of the mold cavity so that pinholes are created at the sites on the thin film coating where the particles had occupied.

3. A method as in claim 2, wherein said step (a1) is carried out with water vapor.

4. A method as in claim 2, wherein said step (a1) is carried out with an organic adhesive.

5. A method as in claim 2, wherein said step (a1) comprises the steps of:

chilling the mold cavity surface below the dew point; and

allowing a controlled layer of fluid to condense on the chilled mold cavity surface.

6. A method as in claim 2, wherein said step (a1) comprises the step of spraying a controlled layer of fluid onto the mold cavity surface.

7. A method as in claim 2, wherein said step (a1) comprises the step of brushing a controlled layer of fluid onto the mold cavity surface.

8. A method as in claim 2, wherein said step (a2) is carried out with particles of sodium chloride.

9. A method as in claim 2, wherein said step (a3) comprises the step of allowing the fluid to evaporate.

10. A method as in claim 2, wherein said step (a5) comprises the step of light brushing to remove the particles from the mold cavity surface.

11. A method as in claim 2, wherein said step (a5) comprises the step of fully dissolving the particles off the mold cavity surface.

12. A method as in claim 1, wherein said step (a) is carried out with a thin film coating of a metal or metal oxide.

13. A method as in claim 1, wherein said step (b) comprises the step of placing the mold in an isotropic atomic oxygen environment.

14. A method as in claim 1, wherein said step (d) further comprises the step of applying a thin parting agent to assist in the separation of the implant from the implant mold.

15. A mold for making soft tissue implants having doubly curved or irregularly shaped surfaces, and having a mold cavity surface treated in accordance with the method of

(a) coating the mold cavity surface with a thin film coating of material, which is resistant to atomic particle, bombardment and forming pinholes within said coating;

(b) subjecting the mold cavity surface to atomic particle bombardment so that depressions are created in the mold cavity surface at the pinhole sites on the thin film coating; and

(c) removing the thin film coating from the mold cavity surface.

16. A method for fabricating soft tissue implants having doubly curved or irregularly shaped surfaces, and having surface roughness from a mold made from an organic material, comprising the steps of:

(a) attaching particles to a mold cavity surface of the mold;

(b) coating the mold cavity surface with a thin film coating of material that is resistant to atomic particle bombardment;

(c) removing the particles from the coated mold cavity surface such that pinholes are created in the coating at the sites occupied by the particles;

(d) subjecting the mold cavity surface to atomic particle bombardment so that depressions are created in the mold cavity surface at the pinhole sites on the thin film coating;

(e) removing the thin film coating from the mold cavity surface; and

(f) creating an implant by using the mold to cast the implant.

17. A method as in claim 16, wherein said step (a) comprises the steps of:

(a1) creating a controlled layer of fluid on the mold cavity surface;

(a2) distributing particles, capable of being attached to the mold cavity surface by being partially dissolved by the fluid, onto the layer of fluid on the mold cavity surface; and

(a3) removing the fluid from the mold cavity surface without removing the particles that are attached to the mold cavity surface.

18. A method as in claim 17, wherein said step (a1) is carried out with water vapor.

19. A method as in claim 17, wherein said step (a1) is carried out with an organic adhesive.

20. A method as in claim 17, wherein said step (a1) comprises the steps of:

chilling the mold cavity surface below the dew point; and

allowing a controlled layer of fluid to condense on the chilled mold cavity surface.

21. A method as in claim 17, wherein said step (a1) comprises the step of spraying a controlled layer of fluid onto the mold cavity surface.

22. A method as in claim 17, wherein said step (a1) comprises the step of brushing a controlled layer of fluid onto the mold cavity surface.

23. A method as in claim 17, wherein said step (a2) is carried out with particles of sodium chloride.

24. A method as in claim 17, wherein said step (a3) comprises the step of allowing the fluid to evaporate.

25. A method as in claim 16, wherein said step (b) is carried out with a thin film coating of a metal or metal oxide.

26. A method as in claim 16, wherein said step (c) comprises the step of light brushing to remove the particles from the mold cavity surface.

27. A method as in claim 16, wherein said step (c) comprises the step of fully dissolving the particles off the mold cavity surface.

28. A method as in claim 16, wherein said step (d) comprises the step of placing the mold in an isotropic atomic oxygen environment.

29. A method as in claim 16, wherein said step (f) further comprises the step of applying a thin parting agent to assist in the separation of the implant from the implant mold.

30. A mold for making soft tissue implants having doubly curved or irregularly shaped surfaces, and having a mold cavity surface treated in accordance with the method of:

(a) attaching particles to the mold cavity surface;

(b) coating the mold cavity surface with a thin film coating of material that is resistant to atomic particle bombardment;

(c) removing the particles from the coated mold cavity surface such that pinholes are created in the coating at the sites occupied by the particles;

(d) subjecting the mold cavity surface to atomic particle bombardment so that depressions are created in the mold cavity surface at the pinhole sites on the thin film coating; and

(e) removing the thin film coating from the mold cavity surface.