Intra-cochlear electrode with a partially detachable hydrophilic segment for deferred self-positioning

Abstract

A perimodiolar electrode for cochlear implantation includes an electrode carrier having a front end and a back end. The electrode carrier includes one or more contacts and a hydrophilic segment that swells after insertion in a cochlea and detaches at least in part from the carrier. In accordance with related embodiments, the hydrophilic segment may detach from the electrode carrier between the front end and the back end. The detached hydrophilic segment may surround the modiolus of a scala tympani of the cochlea or the inner wall of a scala tympani of the cochlea.

What is claimed is:  
     
         1 . A perimodiolar electrode for cochlear implantation comprising: 
 an electrode carrier having a front end and a back end, the carrier including one or more contacts and a hydrophilic segment that swells after insertion in a cochlea and detaches at least in part from the carrier.    
     
     
         2 . A perimodiolar electrode according to  claim 1 , wherein the hydrophilic segment detaches from the electrode carrier between the front end and the back end.  
     
     
         3 . A perimodiolar electrode according to  claim 1 , wherein the detached hydrophilic segment surrounds the modiolus of a scala tympani of the cochlea.  
     
     
         4 . A perimodiolar electrode according to  claim 1 , wherein the detached hydrophilic segment surrounds the inner wall of a scala tympani of the cochlea.  
     
     
         5 . A perimodiolar electrode according to  claim 1 , wherein the electrode carrier further comprises an elastomer.  
     
     
         6 . A perimodiolar electrode according to  claim 1 , wherein the hydrophilic segment comprises an elastomer and a metal-based catalyst.  
     
     
         7 . A perimodiolar electrode according to  claim 6 , wherein the elastomer is silicone rubber.  
     
     
         8 . A perimodiolar electrode according to  claim 6 , wherein the elastomer is polyurethane.  
     
     
         9 . A perimodiolar electrode according to  claim 6 , wherein the catalyst is platinum-based.  
     
     
         10 . A perimodiolar electrode according to  claim 1 , wherein the hydrophilic segment includes a hydrogel.  
     
     
         11 . A perimodiolar electrode according to  claim 1 , wherein the hydrophilic segment includes a hydrogel and an elastomer.  
     
     
         12 . A perimodiolar electrode according to  claim 11 , wherein the elastomer is silicone rubber.  
     
     
         13 . A method for forming a cochlear implant electrode, the method comprising: 
 preparing a hydrophilic segment;    placing the hydrophilic segment in a first section of an electrode mold;    placing electrical contacts in a second section of the electrode mold; and    injecting an elastomeric carrier into the mold.    
     
     
         14 . A method according to  claim 13 , wherein preparing a hydrophilic segment includes forming a hydrogel.  
     
     
         15 . A method according to  claim 13 , wherein preparing a hydrophilic segment includes a mixing a hydrogel and an elastomer.  
     
     
         16 . A method according to  claim 15 , wherein mixing a hydrogel and an elastomer includes mixing a hydrogel and liquid silicone rubber.  
     
     
         17 . A method according to  claim 13 , wherein preparing a hydrophilic segment includes mixing an elastomer and a metal-based catalyst.  
     
     
         18 . A method according to  claim 17 , wherein the mixing an elastomer and a metal-based catalyst includes mixing liquid silicone rubber and a platinum-based catalyst.  
     
     
         19 . A method for preparing a hydrophilic segment, the method comprising: 
 adding a metal-based catalyst to an elastomer;    mechanically mixing the metal-based catalyst and the elastomer to form a crossed linked product;    de-gasing the mixture;    curing the mixture in a segment mold;    immersing the mixture in a polymerization solution; and    suspending the mixture in a sealed glass reactor.    
     
     
         20 . A method according  claim 19 , further comprising: 
 raising the temperature to allow monomer, initiator, and cross-linker to react; and    removing the monomers and unreacted hompolymers by soxlet extraction in distilled water.