NOVEL CAPACITIVE ELEMENTS AND FILTERED FEEDTHROUGH ELEMENTS FOR IMPLANTABLE MEDICAL DEVICES

• US 20090079518A1
• Filed: 07/31/2008
• Published: 03/26/2009
• Est. Priority Date: 09/25/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: IYER, Rajesh V.
• Granted Patent: US 8,059,386 B2
• Time in Patent Office: Days
• US Class Current: 333/182
• CPC Class Codes: A61N 1/3754 Feedthroughs
• CPC Class Codes: H01G 4/35 Feed-through capacitors or anti-noise capacitors
• CPC Class Codes: H03H 1/0007 of radio frequency interference filters
• CPC Class Codes: H03H 2001/0042 Wound, ring or feed-through type capacitor

Abstract

A capacitive element for an implantable medical device feedthrough element includes a bore, to receive a feedthrough member, or pin of the filtered feedthrough element, an external surface extending laterally outward from a first opening of the bore, and a recessed area formed in the external surface and extending about an outer perimeter thereof. The recessed area may provide a location on which to apply a conductive material to form a joint that electrically couples the capacitive element to a ferrule of the filtered feedthrough element.

Claims

1. A filtered feedthrough assembly for an implantable medical device, the assembly comprising:

a ferrule;

a feedthrough member extending through the ferrule;

a capacitive element located within the ferrule and surrounding the feedthrough member, the capacitive element including a first bore being formed by a non-conductive surface extending about a first portion of the member, a second bore being formed by a surface extending about a second portion of the member and being overlaid with at least one layer of a conductive material, and at least one electrode plate extending away from the second bore and being electrically coupled to the at least one layer of the conductive material; and

a conductive material extending between the second portion of the feedthrough member and the overlaid surface forming the second bore in order to electrically couple the member to the at least one electrode plate,

wherein a maximum gap between the first portion of the feedthrough member and the surface forming the first bore being less than a minimum gap between the second portion of the feedthrough member and the overlaid surface forming the second bore.

2. The filtered feedthrough assembly of claim 1, wherein the maximum gap between the first portion of the feedthrough member and the surface forming the first bore being no greater than approximately 0.002 inch.

3. The filtered feedthrough assembly of claim 1, wherein the minimum gap between the second portion of the feedthrough member and the overlaid surface forming the second bore being greater than approximately 0.002 inch.

4. The filtered feedthrough assembly of claim 1, wherein a diameter of the second bore being greater than a diameter of the first bore and the capacitive element further includes a third bore being formed by a surface tapering from the diameter of the second bore to the diameter of the first bore.

5. The filtered feedthrough assembly of claim 4, wherein the surface forming the third bore being overlaid with the at least one layer of the conductive material.

6. The filtered feedthrough assembly of claim 1, wherein the at least one layer of the conductive material comprises a first layer directly coupled to the at least one electrode plate and a second layer overlaying the first layer.

7. The filtered feedthrough assembly of claim 6, wherein the second layer comprises a noble metal.

8. The filtered feedthrough assembly of claim 1, wherein:

the ferrule includes an internal shelf; and

the capacitive element further includes an external surface extending laterally outward from an opening of the first bore, the external surface abutting the internal shelf of the ferrule.

9. The filtered feedthrough assembly of claim 1, further comprising:

an insulator element located within the ferrule, and surrounding the feedthrough member; and

an air gap,

wherein the capacitive element further includes an external surface that extends laterally outward from an opening of the first bore and faces toward the insulator element; and

the air gap being located between the external surface of the capacitive element and the insulator element.

10. The filtered feedthrough assembly of claim 1, wherein the capacitive element further includes an external surface extending laterally outward from an opening of the second bore, the external surface including a recessed area extending about an outer perimeter thereof and being adjacent to the ferrule.

11. The filtered feedthrough assembly of claim 10, wherein the recessed area of the external surface of the capacitive element being overlaid with at least one layer of a conductive material.

12. The filtered feedthrough assembly of claim 1, wherein the ferrule includes an edge, and the edge of the ferrule includes a recessed area extending about an inner perimeter thereof, adjacent to the capacitive element.

13. The filtered feedthrough assembly of claim 1, wherein the feedthrough member comprises a single pin extending through the first and second bores of the capacitive element.

14. The filtered feedthrough assembly of claim 1, wherein the feedthrough member comprises a first pin including the first portion of the feedthrough member, a second pin including the second portion of the feedthrough member, and a solder joint coupling the first pin to the second pin.

15. A capacitive element for an implantable medical device feedthrough assembly, the feedthrough assembly including a feedthrough member extending through a ferrule, and the capacitive element comprising:

a first bore formed, at least in part, by a non-conductive surface and having a diameter;

a second bore being formed by a surface being overlaid with at least one layer of a conductive material and having a diameter being greater than the diameter of the first bore;

and at least one electrode plate extending away from the second bore and being electrically coupled to the at least one layer of conductive material;

wherein the diameters of the first and second bores are sized to receive the feedthrough member of the feedthrough assembly.

16. The capacitive element of claim 15, further comprising a third bore being formed by a surface tapering from the diameter of the second bore to the diameter of the first bore.

17. The capacitive element of claim 16, wherein the surface forming the third bore being overlaid with the at least one layer of the conductive material.

18. The capacitive element of claim 15, wherein the at least one layer of the conductive material comprises a first layer directly coupled to the at least one electrode plate and a second layer overlaying the first layer.

19. The capacitive element of claim 18, wherein the second layer comprises a noble metal.

20. The capacitive element of claim 15, further comprising an external surface extending laterally outward from an opening of the second bore, the external surface including a recessed area extending about an outer perimeter thereof.

21. The capacitive element of claim 20, wherein the recessed area of the external surface being overlaid with a conductive material.

22. An implantable medical device comprising a housing and a filtered feedthrough assembly extending through a sidewall of the housing, the filtered feedthrough assembly comprising:

a ferrule;

a feedthrough member extending through the ferrule;

a capacitive element located within the ferrule and surrounding the feedthrough member, the capacitive element including a first bore being formed by a non-conductive surface extending about a first portion of the member, a second bore being formed by a surface extending about a second portion of the member and being overlaid with at least one layer of a conductive material, and at least one electrode plate extending away from the second bore and being electrically coupled to the at least one layer of the conductive material; and

a conductive material extending between the second portion of the feedthrough member and the overlaid surface forming the second bore in order to electrically couple the member to the at least one electrode plate,

wherein a maximum gap between the first portion of the feedthrough member and the surface forming the first bore being less than a minimum gap between the second portion of the feedthrough member and the overlaid surface forming the second bore.

23. The device of claim 22, wherein the maximum gap between the first portion of the feedthrough member and the surface forming the first bore of the capacitive element being no greater than approximately 0.002 inch.

24. The device of claim 22, wherein the minimum gap between the second portion of the feedthrough member and the overlaid surface forming the second bore of the capacitive element being greater than approximately 0.002 inch.

25. The device of claim 22, wherein a diameter of the second bore of the capacitive element being greater than a diameter of the first bore of the capacitive element, and the capacitive element further includes a third bore being formed by a surface tapering from the diameter of the second bore to the diameter of the first bore.

26. The device of claim 25, wherein the surface forming the third bore being overlaid with the at least one layer of the conductive material.

27. The device of claim 22, wherein the at least one layer of the conductive material comprises a first layer directly coupled to the at least one electrode plate of the capacitive element, and a second layer overlaying the first layer.

28. The device of claim 27, wherein the second layer comprises a noble metal.

29. The device of claim 22, wherein:

the ferrule includes an internal shelf; and

the capacitive element further includes an external surface extending laterally outward from an opening of the first bore, the external surface abutting the internal shelf of the ferrule.

30. The device of claim 22, wherein the feedthrough assembly further comprises:

an insulator element located within the ferrule, and surrounding the feedthrough member; and

an air gap,

wherein the capacitive element further includes an external surface that extends laterally outward from an opening of the first bore and faces toward the insulator element; and

the air gap being located between an external surface of the capacitive element and the insulator element.

31. The device of claim 22, wherein the capacitive element further includes an external surface extending laterally outward from an opening of the second bore, the external surface including a recessed area extending about an outer perimeter thereof and being adjacent to the ferrule.

32. The device of claim 31, wherein the recessed area of the external surface of the capacitive element being overlaid with at least one layer of a conductive material.

33. The device of claim 22, wherein the ferrule includes an edge, and the edge of the ferrule includes a recessed area extending about an inner perimeter thereof, adjacent to the capacitive element.

34. The device of claim 22, wherein the feedthrough member comprises a single pin extending through the first and second bores of the capacitive element.

35. The device of claim 22, wherein the feedthrough member comprises a first pin including the first portion of the feedthrough member, a second pin including the second portion of the feedthrough member, and a solder joint coupling the first pin to the second pin.