Medical electrode including an iridium oxide surface and methods of fabrication

• US 8,996,129 B2
• Filed: 01/31/2007
• Issued: 03/31/2015
• Est. Priority Date: 01/31/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Nygren, Lea A
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): GHAND, JENNIFER LEIGH-STEWAR
• Application Number:
  US11/669,512
• Publication Number:
  US 20080183260A1
• Time in Patent Office: 2,981 Days
• Field of Search: 600/372, 600/373, 600/377, 607/115, 607/116, 607/121, 607/122, 607/141
• US Class Current: 607/116
• CPC Class Codes: A61B 2562/125 characterised by the manufacture of electrodes
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/0565 Electrode heads
• CPC Class Codes: C23C 14/0036 Reactive sputtering
• CPC Class Codes: C23C 14/028 Physical treatment to alter the texture of the substrate surface, e.g. grinding, polishing
• CPC Class Codes: C23C 14/08 Oxides C23C14/10 takes precedence
• CPC Class Codes: C23C 14/085 of iron group metals
• CPC Class Codes: C23C 14/35 by application of a magnetic field, e.g. magnetron sputtering C23C14/3457 takes precedence

Abstract

An implantable medical electrode includes a substrate and an iridium oxide surface, which is formed by an iridium oxide film applied over a roughened surface of the substrate. The film is preferably applied via direct current magnetron sputtering in a sputtering atmosphere comprising argon and oxygen. A sputtering target power may be between approximately 80 watts and approximately 300 watts, and a total sputtering pressure may be between approximately 9 millitorr and approximately 20 millitorr. The iridium oxide film may have a thickness greater than or equal to approximately 15,000 angstroms and have a microstructure exhibiting a columnar growth pattern.

Claims

1. A method for fabricating an implantable medical electrode, the method comprising:

mechanically roughening a surface of a substrate; and

applying a film of iridium oxide over the roughened surface using direct current magnetron sputtering in a sputtering atmosphere comprising oxygen and argon, wherein a sputtering deposition rate is between approximately 100 angstroms/minute and approximately 2500 angstroms/minute, and wherein the film has a microstructure exhibiting a columnar growth pattern.

2. The method of claim 1, wherein mechanically roughening the surface comprises grit blasting with particles having approximately 50 micron diameters.

3. The method of claim 1, wherein a ratio of the oxygen to the argon in the sputtering atmosphere is greater than approximately 25%.

4. The method of claim 3, wherein the ratio is greater than approximately 50%.

5. The method of claim 4, wherein the ratio is approximately 75%.

6. The method of claim 1, wherein:

a sputtering target power is between approximately 80 watts and approximately 300 watts; and

a total sputtering pressure is between approximately 9 millitorr and approximately 20 millitorr.

7. The method of claim 6, wherein the sputtering pressure is approximately 15 millitorr.

8. The method of claim 6, wherein the sputtering target power is approximately 100 watts.

9. The method of claim 1, further comprising applying over the roughened surface of the substrate an interposing layer comprising a material enhancing adhesion of the iridium oxide film to the substrate.

10. The method of claim 9, wherein the material is selected from the group consisting of:

titanium, iridium, niobium and zirconium.

11. An implantable medical electrode comprising a substrate and an iridium oxide surface, the surface formed by applying a film of iridium oxide over a roughened surface of the substrate using direct current magnetron sputtering in which a sputtering atmosphere comprises oxygen and argon, and wherein the film has a microstructure exhibiting a columnar growth pattern.

12. The electrode of claim 11, wherein the substrate comprises a platinum iridium alloy.

13. The electrode of claim 11, wherein the substrate comprises titanium.

14. The electrode of claim 11, wherein a ratio of the oxygen to the argon in the sputtering atmosphere is greater than approximately 25%.

15. The electrode of claim 14, wherein the ratio is greater than approximately 50%.

16. The electrode of claim 15, wherein the ratio is approximately 75%.

17. The electrode of claim 11, wherein the roughened surface of the substrate comprises a material layer extending between the substrate and the iridium oxide film, the material layer comprising a material enhancing adhesion of the iridium oxide film to the substrate.

18. The electrode of claim 17, wherein the material is selected from the group consisting of titanium, iridium, niobium and zirconium.

19. The electrode of claim 11, wherein a sputtering target power is between approximately 80 watts and approximately 300 watts, and a total sputtering pressure is between approximately 9 millitorr and approximately 20 millitorr.

20. The electrode of claim 19, wherein the sputtering pressure is approximately millitorr.

21. The electrode of claim 19, wherein the sputtering target power is approximately 100 watts.

22. The electrode of claim 11, wherein a sputtering deposition rate is between approximately 100 angstroms/minute and approximately 2500 angstroms/minute.

23. An implantable medical electrode, comprising:

a substrate including a mechanically roughened surface; and

a direct current magnetron sputtered iridium oxide film extending over the surface, the film having a thickness greater than or equal to approximately 15,000 angstroms and a microstructure exhibiting a columnar growth pattern.

24. The electrode of claim 23, wherein the thickness of the film is greater than approximately 20,000 angstroms.

25. The electrode of claim 23, wherein the roughened surface of the substrate comprises a material layer extending between the substrate and the iridium oxide film, the material layer comprising a material enhancing adhesion of the iridium oxide film to the substrate.

26. The electrode of claim 25, wherein the material is selected from the group consisting of:

titanium, iridium, niobium and zirconium.

27. The electrode of claim 25, wherein the thickness of the iridium oxide film is greater than or equal to approximately 20,000 angstroms.