Implantable capacitive pressure sensor system and method

• US 20060247539A1
• Filed: 04/28/2005
• Published: 11/02/2006
• Est. Priority Date: 04/28/2005
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Schugt, Michael A., Miesel, Keith A., Bonde, Eric H., Burdon, Jeremy W.
• Granted Patent: US 8,118,748 B2
• Time in Patent Office: Days
• US Class Current: 600/486
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/15192 Resurf arrangement of the internal vias

Abstract

Embodiments of the invention provide systems and methods for an implantable capacitive pressure sensor. Some embodiments of the invention include a capacitive pressure sensor capsule comprising a substrate, a conductive plate functionally coupled to the substrate, a conductive diaphragm spaced from the conductive plate and functionally coupled to the substrate, a lid hermetically sealed against the substrate, and pressure sensing circuitry disposed within a volume generally defined by the lid and the substrate. Embodiments of the invention also include a lead provided with an implantable pressure sensor capsule and a method of manufacturing a capacitive pressure sensor capsule.

Claims

1. An implantable capacitive pressure sensor capsule comprising:

a substrate;

a conductive plate functionally coupled to a first surface of the substrate;

a conductive diaphragm spaced from the conductive plate and functionally coupled to the first surface of the substrate;

a lid hermetically sealed against a second surface of the substrate opposite the first surface; and

pressure sensing circuitry disposed within a volume generally defined by the lid and the second surface of the substrate, wherein the pressure sensing circuitry is electrically coupled to the conductive plate.

2. A sensor capsule according to claim 1, wherein the substrate comprises a substantially monolithic substrate formed from at least one layer of ceramic.

3. A sensor capsule according to claim 2, wherein each layer of the ceramic includes a via to provide electrical communication between the conductive plate and pressure sensing circuitry.

4. A sensor capsule according to claim 3, wherein the via in each layer of ceramic is at least partially offset from the via of the adjacent layer.

5. A sensor capsule according to claim 1, wherein the conductive plate and the diaphragm independently comprise a metal selected from the group consisting of gold, silver, copper, titanium, niobium, platinum, and combinations or alloys thereof.

6. A sensor capsule according to claim 1, wherein the diaphragm is functionally coupled to the substrate by one of brazing, reactive metal brazing, diffusion bonding, and eutectic joint formation.

7. A sensor capsule according to claim 1, wherein the diaphragm is spaced from the conductive plate by an interlayer.

8. A sensor capsule according to claim 1, wherein the diaphragm is spaced from the conductive plate by a cavity formed in the substrate.

9. A sensor capsule according to claim 1, wherein the diaphragm directly contacts bodily fluid.

10. A lead provided with an implantable pressure sensor capsule comprising:

an elongated lead body having a window; and

an implantable pressure sensor capsule integrated in the lead body, the pressure sensor capsule including;

a substrate;

a conductive plate operatively connected to a first surface of the substrate;

a conductive diaphragm spaced from the conductive plate and functionally coupled to the first surface of the substrate;

a lid hermetically sealed against a second surface of the substrate opposite the first surface; and

pressure sensing circuitry disposed within a volume generally defined by the lid and the second surface of the substrate, wherein the pressure sensing circuitry is electrically coupled to the conductive plate, and further wherein at least a portion of the conductive diaphragm is located in the window of the lead body where it is directly exposed to bodily fluids when the lead body is implanted in a body.

11. A lead according to claim 10, wherein the substrate comprises a substantially monolithic substrate formed from at least one layer of ceramic.

12. A lead according to claim 11, wherein each layer of the ceramic includes a via to provide electrical communication between the conductive plate and pressure sensing circuitry.

13. A lead according to claim 12, wherein the via in each layer of ceramic is at least partially offset from the via of the adjacent layer.

14. A lead according to claim 10, wherein the conductive plate comprises a cofired thick-film metallization over a via.

15. A lead according to claim 10, wherein the conductive plate comprises a thin-film deposition over a via.

16. A lead according to claim 10, wherein the diaphragm is spaced from the conductive plate by an interlayer.

17. A method of manufacturing an implantable capacitive pressure sensor capsule comprising:

providing a wafer of a substrate and a conductive plate functionally coupled to a first surface of the substrate;

spacing a conductive diaphragm from the conductive plate;

functionally coupling the diaphragm to the first surface of the substrate;

electrically connecting pressure sensing circuitry to the conductive plate and the conductive diaphragm;

hermetically sealing a lid against a second surface of the substrate opposite the first surface to enclose the pressure sensing circuitry; and

dicing the wafer to produce individual capacitive pressure sensor capsules.

18. A method according to claim 17, wherein the diaphragm is functionally coupled to the substrate by one of brazing and diffusion bonding.

19. A method according to claim 17, wherein the diaphragm is spaced from the conductive plate by providing an interlayer between the diaphragm and the conductive plate.

20. A method according to claim 17, wherein the diaphragm is spaced from the conductive plate by forming a cavity in the substrate.