Implantable medical device & electrical stimulation device with magnetic shield

• US 20050113888A1
• Filed: 11/29/2004
• Published: 05/26/2005
• Est. Priority Date: 06/16/2000
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Jimenez, Oscar, Kast, John E., Echarri, Guillermo, Riekels, James E., Schommer, Mark E.
• Granted Patent: US 7,945,334 B2
• Time in Patent Office: Days
• US Class Current: 607/61
• CPC Class Codes: A61N 1/3787 from an external energy source

Abstract

A rechargeable implantable medical device with a magnetic shield placed on the distal side of a secondary recharging coil to improve charging efficiency is disclosed. The rechargeable implantable medical device can be a wide variety of medical devices such as neuro stimulators, drug delivery pumps, pacemakers, defibrillators, diagnostic recorders, cochlear implants. The implantable medical device has a secondary recharging coil carried over a magnetic shield and coupled to electronics and a rechargable power source carried inside the housing. The electronics are configured to perform a medical therapy. Additionally a method for enhancing electromagnetic coupling during recharging of an implantable medical device is disclosed, and a method for reducing temperature rise during recharging of an implantable medical device is disclosed.

Claims

1. An implantable medical device, comprising:

a housing having an interior cavity;

electronics carried in the housing interior cavity and configured to perform a medical therapy;

a rechargeable power source;

a secondary charging coil, having an axis, operatively coupled to the electronics and the rechargeable power source; and

a magnetic shield being approximately perpendicular to the axis of the secondary charging coil and being located between the charging coil and the electronics.

2. The implantable medical device as in claim 1 wherein the magnetic shield improves recharging efficiency by improving electromagnetic coupling between the secondary charging coil and a primary charging coil.

3. The implantable medical device as in claim 2 wherein the magnetic shield improves the recharging efficiency by increasing flux lines that couple with the charging coil from the primary charging coil.

4. The implantable medical device as in claim 2 wherein the magnetic shield improves the electromagnetic coupling to greater than 10 percent coupling efficiency at about one centimeter.

5. The implantable medical device as in claim 1 wherein recharging efficiency is improved by decreasing flux lines emanating from a primary coil that couple with the housing.

6. The implantable medical device as in claim 5 wherein the magnetic shield provides improved recharging efficiency through reduced eddy currents in the housing.

7. The implantable medical device as in claim 6 wherein the magnetic shield provides reduced medical device temperature rise during recharging of the power source through reduced currents in the housing.

8. The implantable medical device as in claim 7 wherein the implantable medical device temperature rise during recharging is less than two degrees Celsius.

9. The implantable medical device as in claim 1 wherein the magnetic shield is a material with high magnetic permeability.

10. The implantable medical device as in claim 9 wherein the magnetic shield is selected from the group consisting of:

amorphous metal film, amorphous metal wire, and magnetic alloy.

11. The implantable medical device as in claim 1 wherein the magnetic shield has eddy cuts to reduce eddy current flow through the magnetic shield.

12. The implantable medical device as in claim 1 wherein the magnetic shield has a central opening.

13. The implantable medical device as in claim 1, wherein the magnetic shield comprises a first magnetic shield and a second magnetic shield and a first insulator placed between the first magnetic shield and the second magnetic shield.

14. The implantable medical device as in claim 13, wherein the magnetic shield further comprises a third magnetic shield and a second insulator placed between the second magnetic shield and the third magnetic shield.

15. The implantable medical device as in claim 14 wherein the first insulator and a second insulator are selected from the group consisting of:

plastic, mylar, and tape.

16. The implantable medical device as in claim 1 wherein the secondary charging coil is carried on the proximal face of the housing and the magnetic shield is placed between the charging coil and the proximal face of the housing.

17. The implantable medical device as in claim 1 wherein the secondary charging coil is an external secondary charging coil is located remotely away from the housing.

18. The implantable medical device as in claim 1 wherein the charging coil is located in the housing interior cavity.

19. The implantable medical device as in claim 1 wherein the housing is an electric conductor.

20. The implantable medical device as in claim 19 wherein the housing is selected from the group consisting of:

titanium, ceramic, and epoxy.

21. The implantable medical device as in claim 1 wherein the medical device is selected from the group consisting of:

neuro stimulators, pacemakers, defibrillators, drug delivery pumps, diagnostic recorders, and cochlear implants.

32. The implantable electrical stimulation device as in claim 1 wherein the charging coil is located in the housing interior cavity.

33. The implantable electrical stimulation device as in claim 1 wherein the housing is an electric conductor.

34. The implantable electrical stimulation device as in claim 19 wherein the housing is selected from the group consisting of:

titanium, ceramic, and epoxy.

22. An implantable electrical stimulation device, comprising:

a housing having an interior cavity;

electronics carried in the housing interior cavity and configured to perform a medical therapy;

an electrical lead operatively coupled to the electronics;

a rechargeable power source;

a secondary charging coil, having an axis, operatively coupled to the electronics and the rechargeable power source; and

a magnetic shield being approximately perpendicular to the axis of the secondary charging coil and being located between the charging coil and the electronics.

23. The implantable electrical stimulation device as in claim 22 wherein the magnetic shield is a material with high magnetic permeability.

24. The implantable electrical stimulation device as in claim 23 wherein the magnetic shield is selected from the group consisting of:

amorphous metal film, amorphous metal wire, and magnetic alloy.

25. The implantable electrical stimulation device as in claim 22 wherein the magnetic shield has eddy cuts to reduce eddy current flow through the magnetic shield.

26. The implantable electrical stimulation device as in claim 22 wherein the magnetic shield has a central opening.

27. The implantable electrical stimulation device as in claim 22, wherein the magnetic shield comprises a first magnetic shield and a second magnetic shield and a first insulator placed between the first magnetic shield and the second magnetic shield.

28. The implantable electrical stimulation device as in claim 27, wherein the magnetic shield further comprises a third magnetic shield and a second insulator placed between the second magnetic shield and the third magnetic shield.

29. The implantable electrical stimulation device as in claim 28 wherein the first insulator and a second insulator are selected from the group consisting of:

plastic, mylar, and tape.

30. The implantable electrical stimulation device as in claim 22 wherein the secondary charging coil is carried on the proximal face of the housing and the magnetic shield is placed between the charging coil and the proximal face of the housing.

31. The implantable electrical stimulation device as in claim 22 wherein the secondary charging coil is an external secondary charging coil is located remotely away from the housing.