Polymeric feed-thru for chronic implantable devices

Abstract

A method of making a feed-thru connector assembly includes inserting a conductor within an opening within a housing of a pulse generator and dispensing a sealant in a gap between the conductor and portions of the housing adjacent to the conductor that define the opening of the housing and curing the sealant to form a seal comprising a polyisobutylene cross-linked network.

We claim: 
     
         1 . An implantable system comprising:
 a pulse generator including a housing, electronics within the housing, and an opening;   a lead attached to the pulse generator;   a feed-thru connector assembly mounted on the pulse generator and positioned at least partially within the opening, the feed-thru connector assembly comprising:
 a conductor; and 
 a seal disposed within a gap between the conductor and portions of the housing adjacent to the conductor that define the opening of the housing, wherein the seal comprises a polyisobutylene cross-linked network. 
   
     
     
         2 . The implantable system of  claim 1 , wherein the conductor comprises one of titanium, platinum iridium (PtIr), palladium iridium (PdIr), stainless steel SS316, MP35N, silver and gold alloys, and mixtures thereof. 
     
     
         3 . The implantable system of  claim 1 , wherein at least a portion of a surface of the conductor includes a roughened surface. 
     
     
         4 . The implantable system of  claim 1 , wherein the tensile strength between the conductor and the seal is greater than 1,500 psi. 
     
     
         5 . The implantable system of  claim 1 , wherein the seal has a leak test rate less than about 4×10 −9  atm cc/sec (or Pa m 3 /s) when subjected to helium gas at a pressure of about 0.4 Pa. 
     
     
         6 . The implantable system of  claim 1 , wherein the dielectric strength of the seal is greater than 1000 volts per mil. 
     
     
         7 . The implantable system of  claim 1 , wherein the bulk resistivity of the seal is greater than 1×10 7  ohm-m. 
     
     
         8 . The implantable system of  claim 1 , wherein the surface resistivity of the seal is greater than 1×10 6  ohm-m. 
     
     
         9 . A feed-thru connector assembly positioned at least partially within an opening in a pulse generator housing, the feed-thru connector assembly comprising:
 a conductor disposed within the opening of the pulse generator housing; and   a seal disposed within a gap between the conductor and portions of the pulse generator housing adjacent to the conductor, wherein the seal comprises a polyisobutylene cross-linked network.   
     
     
         10 . The feed-thru connector assembly of  claim 9 , wherein the seal has a leak test rate less than about 4×10 −9  atm cc/sec (or Pa m 3 /s) when subjected to helium gas at a pressure of about 0.4 Pa. 
     
     
         11 . A method of making a feed-thru connector assembly for a pulse generator, the method comprising:
 inserting a conductor within an opening within a housing of the pulse generator, the conductor being coupled to electronics housed within the housing;   dispensing a sealant in a gap between the conductor and portions of the housing adjacent to the conductor that define the opening of the housing; and   curing the sealant to form a seal comprising a polyisobutylene cross-linked network, wherein the seal is adapted to create a hermetic seal for the feedback assembly portion.   
     
     
         12 . The method of  claim 11 , further comprising plasma treating at least a portion of the surface of the conductor that is bonded to the seal. 
     
     
         13 . The method of  claim 11 , further comprising priming at least a portion of the conductor with a primer comprising an epoxy functional silane or a methylene diphenyl diisocyanate (MDI). 
     
     
         14 . The method of  claim 11 , further comprising forming the polyisobutylene cross-linked network that comprises:
 reacting a telechelic polyisobutylene diol and a diisocyanate to form a diisocyanate derivative; and   reacting the diisocyanate derivative with a crosslinking initiator to form the polyisobutylene cross-linked network.   
     
     
         15 . The method of  claim 11 , wherein the diisocyanate is 4,4′-methylenephenyl diisocyanate (MDI) and the crosslinking initiator is pentaerythritol. 
     
     
         16 . The method of  claim 11 , further comprising forming the polyisobutylene cross-linked network that comprises:
 reacting a diisocyanate with a polyol or a polyamine to form a polyisocyanate; and   reacting the polyisocyanate with a telechelic polyisobutylene diol to form the polyisobutylene cross-linked network.   
     
     
         17 . The method of  claim 16 , wherein the diisocyanate comprises 4,4′-methylenephenyl diisocyanate (MDI) and the polyol comprises 1,1,2,2-Tetrakis(p-hydroxyphenyl)ethane. 
     
     
         18 . The method of  claim 11 , further comprising forming a polyisobutylene cross-linked network by reacting together:
 a telechelic polyisobutylene derivative;   a silane agent; and   a transition metal species.   
     
     
         19 . The method of  claim 18 , wherein the telechelic polyisobutylene derivative is a polyisobutylene dichloride or a polyisobutylene diallyl. 
     
     
         20 . The method of  claim 18 , wherein the silane agent has more than two reactive hydrosilane groups per molecule in the presence of a catalyst.