Conductive composite electrode material

Abstract

A medical electrical lead and body implantable electrode suitable for a variety of medical applications are disclosed. In general, the electrode includes a composite material having particles of pseudo-capacitive material, such as iridium oxide, dispersed within a polymer matrix including a polyelectrolyte. The polymer matrix can also include a conductive polymer doped with an excess of the polyelectrolyte. The composite may used to form the electrode itself or an electrode coating. The presence of a pseudo-capacitive material within the composite may increase the charge-storage capacity of the electrode and may allow for safe deliveries of charge densities within an electrochemical window suitable for pacing a patient's heart.

1 . An implantable medical device comprising:
 an electrode comprising a polymer matrix including a conductive polymer doped with an excess of a negatively-charged polyelectrolyte and pseudo-capacitive, transition metal oxide particles dispersed throughout the polymer matrix.   
     
     
         2 . The implantable medical device of  claim 1 , wherein the electrode includes a conductive base material and wherein a coating including the polymer matrix is disposed over at least a portion of the conductive base material. 
     
     
         3 . The implantable medical device of  claim 1 , wherein the conductive polymer is selected from the group consisting of polypyrrole, polyaniline, polyacetylene, polythiophene, polyethylenedioxythiophene, poly (p-phenyl vinylene), and mixtures thereof. 
     
     
         4 . The implantable medical device of  claim 1 , wherein the conductive polymer comprises polyethylenedioxythiophene. 
     
     
         5 . The implantable medical device of  claim 1 , wherein the negatively-charged polyelectrolyte is selected from the group consisting of polystyrene sulfonate, polyglutamic acid, NAFION®, and mixtures thereof. 
     
     
         6 . The implantable medical device of  claim 1 , wherein the negatively-charged polyelectrolyte comprises polystyrene sulfonate. 
     
     
         7 . The implantable medical device of  claim 1 , wherein the pseudo-capacitive, transition metal oxide particles are selected from the group consisting of iridium oxide particles, ruthenium oxide particles, rhodium oxide particles, osmium oxide particles, titanium oxide particles, and combinations thereof. 
     
     
         8 . The implantable medical device of  claim 1 , wherein the pseudo-capacitive, transition metal oxide particles comprise iridium oxide particles. 
     
     
         9 . The implantable medical device of  claim 1 , wherein the pseudo-capacitive particles, transition metal oxide particles are present in a sufficient amount such that an electrode potential of the electrode is maintained within an electrochemical window suitable for pacing a heart. 
     
     
         10 . The implantable medical device of  claim 1 , wherein the conductive polymer comprises polypyrrole and the negatively-charged polyelectrolyte comprises polyglutamic acid. 
     
     
         11 . The implantable medical device of  claim 1 , wherein the conductive polymer comprises polyethylenedioxythiophene and the negatively-charged polyelectrolyte comprises polystyrene sulfonate.