Medical electrode including an iridium oxide surface and methods of fabrication

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.

1 - 28 . (canceled) 
     
     
         29 . 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.   
     
     
         30 . The method of  claim 29 , wherein mechanically roughening the surface comprises grit blasting with particles having approximately 50 micron diameters. 
     
     
         31 . The method of  claim 29 , wherein a ratio of the oxygen to the argon in the sputtering atmosphere is greater than approximately 25%. 
     
     
         32 . The method of  claim 31 , wherein the ratio is greater than approximately 50%. 
     
     
         33 . The method of  claim 32 , wherein the ratio is approximately 75%. 
     
     
         34 . The method of  claim 29 , wherein a sputtering deposition rate is between approximately 100 angstroms/minute and approximately 2500 angstroms/minute. 
     
     
         35 . The method of  claim 29 , 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.   
     
     
         36 . The method of  claim 35 , wherein the sputtering pressure is approximately 15 millitorr. 
     
     
         37 . The method of  claim 35 , wherein the sputtering target power is approximately 100 watts. 
     
     
         38 . 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. 
     
     
         39 . The electrode of  claim 38 , wherein the substrate comprises a platinum iridium alloy. 
     
     
         40 . The electrode of  claim 38 , wherein the substrate comprises titanium. 
     
     
         41 . The electrode of  claim 38 , wherein a ratio of the oxygen to the argon in the sputtering atmosphere is greater than approximately 25%. 
     
     
         42 . The electrode of  claim 41 , wherein the ratio is greater than approximately 50%. 
     
     
         43 . The electrode of  claim 42 , wherein the ratio is approximately 75%. 
     
     
         44 . The electrode of  claim 38 , wherein the iridium oxide film has a thickness greater than or equal to approximately 15,000 angstroms. 
     
     
         45 . The electrode of  claim 44 , wherein the film thickness is greater than approximately 20,000 angstroms. 
     
     
         46 . The electrode of  claim 38 , 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. 
     
     
         47 . The electrode of  claim 46 , wherein the material is selected from the group consisting of: titanium, iridium, niobium and zirconium. 
     
     
         48 . The electrode of  claim 46 , wherein the iridium oxide film has a thickness greater than or equal to approximately 20,000 angstroms. 
     
     
         49 . The electrode of  claim 38 , 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. 
     
     
         50 . The electrode of  claim 49 , wherein the sputtering pressure is approximately 15 millitorr. 
     
     
         51 . The electrode of  claim 49 , wherein the sputtering target power is approximately 100 watts. 
     
     
         52 . An implantable medical electrode, comprising:
 a substrate including a mechanically roughened surface; and   a 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.   
     
     
         53 . The electrode of  claim 52 , wherein the thickness of the film is greater than approximately 20,000 angstroms. 
     
     
         54 . The electrode of  claim 52 , 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. 
     
     
         55 . The electrode of  claim 54 , wherein the material is selected from the group consisting of: titanium, iridium, niobium and zirconium. 
     
     
         56 . The electrode of  claim 54 , wherein the thickness of the iridium oxide film is greater than or equal to approximately 20,000 angstroms.