Implantable medical device with corrosion-resistant feedthrough assembly
A feedthrough assembly for an implantable medical device includes a housing, a solid insert, one or more conductive elements, a metal filler, and a non-corrosive sealant. The housing defines a central cavity through a height of the housing. The solid insert is disposed within the central cavity of the housing. The one or more conductive elements extend through one or more apertures defined within the solid insert and extend through the central cavity of the housing. The metal filler is disposed within a joint defined by an outer surface of the solid insert and an inner surface of the housing that defines the central cavity. The non-corrosive sealant coats a top surface of the metal filler to inhibit corrosion of the metal filler.
1 . A feedthrough assembly for an implantable medical device, the feedthrough assembly comprising:
a housing including an inner surface that defines a central cavity through the housing, wherein the housing has a stepped top side including a horizontal ridge surface and a raised lip that define a well, the horizontal ridge surface radially extending from the inner surface of the housing to the raised lip, the raised lip projecting from the horizontal ridge surface to a top surface of the raised lip at a top end of the housing, wherein a continuous angled inner surface of the raised lip extends to the top surface of the raised lip so a cross-sectional area of the well continuously increases along the continuous angled inner surface with increasing proximity to the top surface of the raised lip;
a solid insert disposed within the central cavity of the housing;
one or more conductive elements extending through one or more apertures defined within the solid insert and extending through the central cavity of the housing, the one or more conductive elements including one or more wires or one or more pins;
a metal filler disposed within a joint defined by an outer surface of the solid insert and the inner surface of the housing that defines the central cavity; and
a non-corrosive sealant that covers a top surface of the solid insert and coats the metal filler to inhibit corrosion of the metal filler, wherein the non-corrosive sealant at least partially fills the well to cover the top surface of the solid insert and coat the metal filler, and a perimeter of the non-corrosive sealant conforms to the angled inner surface.
2 . The feedthrough assembly of claim 1 , wherein the non-corrosive sealant is electrically insulative.
3 . The feedthrough assembly of claim 1 , wherein the non-corrosive sealant comprises one or more of alumina, parylene, polyurethane, silicone, or an epoxy material.
4 . The feedthrough assembly of claim 1 , wherein the housing comprises a metal material and the solid insert comprises a ceramic material.
5 . The feedthrough assembly of claim 1 , wherein the housing comprises titanium.
6 . The feedthrough assembly of claim 1 , wherein the housing has protrusions along an outer perimeter of the housing configured to a header of the implantable medical device, and the one or more conductive elements are configured to electrically connect to at least one of an antenna or a sensing electrode held in the header.
7 . The feedthrough assembly of claim 1 , wherein the central cavity of the housing is elongated along an axis, and the one or more conductive elements include multiple conductive elements arranged in a line along the axis.
8 . The feedthrough assembly of claim 1 , wherein the metal filler comprises gold.
9 . The feedthrough assembly of claim 1 , wherein the metal filler is also disposed within the one or more apertures between the one or more conductive elements and the solid insert to seal the one or more apertures, and the non-corrosive sealant coats the top surface of the metal filler within the one or more apertures.
10 . The feedthrough assembly of claim 1 , wherein the non-corrosive sealant fills the well and coats at least a portion of the top surface of the raised lip at the top end of the housing.
11 . The feedthrough assembly of claim 1 , wherein the perimeter of the non-corrosive sealant conforms to the continuous angled inner surface to funnel the non-corrosive sealant towards the metal filler.
12 . The feedthrough assembly of claim 1 , wherein the cross-sectional area of the well that continuously increases along the continuous angled inner surface is a horizontal cross-section.
13 . A method of producing a feedthrough assembly, the method comprising:
installing a solid insert within a central cavity of a housing, the central cavity extending through the housing and defined by an inner surface of the housing, wherein the housing has a stepped top side including a horizontal ridge surface and a raised lip that define a well, the horizontal ridge surface radially extending from the inner surface of the housing to the raised lip, the raised lip projecting from the horizontal ridge surface to a top surface of the raised lip at a top end of the housing, wherein a continuous angled inner surface of the raised lip extends to the top surface of the raised lip so a cross-sectional area of the well continuously increases along the continuous angled inner surface with increasing proximity to the top surface of the raised lip;
installing one or more conductive elements through one or more apertures defined within the solid insert, the one or more conductive elements including one or more wires or one or more pins;
depositing a metal filler within a joint defined by an outer surface of the solid insert and the inner surface of the housing that defines the central cavity; and
forming a cover layer that covers a top surface of the solid insert and coats the metal filler, the cover layer composed of a non-corrosive sealant to inhibit corrosion of the metal filler, wherein forming the cover layer comprises at least partially filling the well with the non-corrosive sealant when in a flowable state so a perimeter of the non-corrosive sealant conforms to the angled inner surface.
14 . The method of claim 13 , wherein the cover layer is formed via one of chemical vapor deposition, physical vapor deposition, injection molding, precision fluid dispensing, or casting.
15 . The method of claim 13 , wherein the non-corrosive sealant comprises one or more of alumina, parylene, polyurethane, silicone, or an epoxy material, the solid insert comprises a ceramic material, and the housing comprises a metal material.
16 . The method of claim 13 , wherein forming the cover layer comprises filling the well with the non-corrosive sealant so that the non-corrosive sealant coats at least a portion of the top surface of the raised lip at the top end of the housing.
17 . An implantable medical device comprising:
a header that comprises a header body, an antenna, and a sensing electrode, the antenna and the sensing electrode both disposed within the header body; and
a feedthrough assembly mounted to a mounting end of the header body, the feedthrough assembly comprising:
a housing including an inner surface that defines a central cavity through the housing, wherein the housing has a stepped top side including a horizontal ridge surface and a raised lip that define a well, the horizontal ridge surface radially extending from the inner surface of the housing to the raised lip, the raised lip projecting from the horizontal ridge surface to a top surface of the raised lip at a top end of the housing, wherein a continuous angled inner surface of the raised lip extends to the top surface of the raised lip so a cross-sectional area of the well continuously increases along the continuous angled inner surface with increasing proximity to the top surface of the raised lip;
a solid insert disposed within the central cavity of the housing;
conductive elements extending through apertures defined within the solid insert and extending through the central cavity of the housing, the conductive elements including one or more of wires or pins, wherein a first conductive element of the conductive elements is electrically connected to the antenna and a second conductive element of the conductive elements is electrically connected to the sensing electrode;
a metal filler disposed within the apertures between the corresponding conductive elements and the solid insert to seal the apertures; and
a non-corrosive sealant that fills the well and covers at least a portion of the top surface of the raised lip at the top end of the housing, the non-corrosive sealant forming a cover layer that covers a top surface of the solid insert and coats the metal filler to inhibit corrosion of the metal filler,
wherein the header body couples to the housing of the feedthrough assembly and envelops the non-corrosive sealant.
18 . The implantable medical device of claim 17 , further comprising a case that encloses a battery and an electronics module within an internal cavity of the case, wherein the feedthrough assembly is disposed between the header and the case, and the conductive elements of the feedthrough assembly project into the internal cavity and electrically connect to the battery and the electronics module, and the feedthrough assembly maintains hermeticity of the case.
19 . The implantable medical device of claim 17 , wherein the metal filler is also disposed within a joint defined by an outer surface of the solid insert and the inner surface of the housing that defines the central cavity, and the non-corrosive sealant within the well covers the metal filler that is within the joint.
20 . The implantable medical device of claim 17 , wherein the continuous angled inner surface forms a lead-in surface to funnel the non-corrosive sealant towards the horizontal ridge surface, the metal filler, and the solid insert.
21 . The implantable medical device of claim 17 , wherein a perimeter edge of the non-corrosive sealant is defined by an inner surface of the raised lip extending from the horizontal ridge surface.