Method for fabrication of low-polarization implantable stimulation electrode

Abstract

A method for fabricating an implantable medical electrode includes roughening the electrode substrate, applying an adhesion layer, and depositing a valve metal oxide coating over the adhesion layer under conditions optimized to minimize electrode impedance and post-pulse polarization. The electrode substrate may be a variety of electrode metals or alloys including titanium, platinum, platinum-iridium, or niobium. The adhesion layer may be formed of titanium or zirconium. The valve metal oxide coating is a ruthenium oxide coating sputtered onto the adhesion layer under controlled target power, sputtering pressure, and sputter gas ratio setting optimized to minimize electrode impedance and post-pulse polarization.

1 . A method for fabricating an implantable electrode, comprising:
 roughening a surface of the electrode;   cleaning the roughened electrode surface; and   depositing a valve metal oxide coating over the roughened electrode surface.   
   
   
       2 . The method of  claim 1  wherein roughening the surface of the electrode comprises mechanical roughening of the electrode surface. 
   
   
       3 . The method of  claim 2  wherein the mechanical roughening of the electrode surface comprises grit blasting. 
   
   
       4 . The method of  claim 3  wherein the grit blasting is performed using an alumina oxide media. 
   
   
       5 . The method of  claim 1  wherein the cleaning of the roughened electrode surface comprises ultrasonic cleaning. 
   
   
       6 . The method of  claim 1  wherein the valve metal oxide includes ruthenium oxide. 
   
   
       7 . The method of  claim 1  wherein depositing the valve metal comprises sputtering the valve metal onto the cleaned and roughened electrode surface using sputtering process parameters optimized to minimize post-pulse polarization 
   
   
       8 . The method of  claim 7  wherein the sputtering process parameters, optimized to minimize post-pulse polarization, include a target power. 
   
   
       9 . The method of  claim 7  wherein the target power is about 300 Watts. 
   
   
       10 . The method of  claim 7  wherein the sputtering parameters optimized to minimize post-pulse polarization include a sputtering pressure. 
   
   
       11 . The method of  claim 7  wherein the sputtering parameters optimized to minimize post-pulse polarization include a sputtering gas ratio. 
   
   
       12 . The method of  claim 1  further comprising applying an adhesion layer to the roughened and cleaned electrode surface prior to depositing the valve metal oxide layer. 
   
   
       13 . The method of  claim 11  wherein the adhesion layer comprises a metal selected from the group of titanium and zirconium. 
   
   
       14 . The method of  claim 1  further comprising ion-etching the roughened electrode surface prior to depositing the valve metal oxide layer. 
   
   
       15 - 20 . (canceled) 
   
   
       21 . The method of  claim 1 , wherein the valve metal oxide coating comprises a metal oxide that comprises a metal selected from the group consisting of titanium, vanadium, zirconium, niobium, molybdenum, tantalum, iridium, platinum, and tungsten. 
   
   
       22 . A method for fabricating an implantable medical electrode, the method comprising:
 mechanically roughening a surface of the substrate; and   applying a coating of a valve metal oxide over the roughened surface using sputtering in a sputtering atmosphere comprising oxygen and argon.   
   
   
       23 . The method of  claim 22 , wherein the valve metal oxide coating comprises a metal oxide that comprises a metal selected from the group consisting of ruthenium, titanium, vanadium, zirconium, niobium, molybdenum, tantalum, iridium, platinum, and tungsten. 
   
   
       24 . The method of  claim 22  wherein the mechanical roughening of the electrode surface comprises grit blasting. 
   
   
       25 . The method of  claim 22  further comprising applying an adhesion layer to the roughened substrate surface prior to applying the valve metal oxide layer. 
   
   
       26 . The method of  claim 22  further comprising ion-etching the roughened electrode surface prior to applying the valve metal oxide layer.