Efficient External Charger for Charging a Plurality of Implantable Medical Devices

• US 20140200631A1
• Filed: 03/17/2014
• Published: 07/17/2014
• Est. Priority Date: 11/23/2009
• Status: Active Grant

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Inventors: Carbunaru, Rafael, Parramon, Jordi, Ozawa, Robert, Shi, Jess, Chen, Joey, Rahman, Md. Mizanur
• Granted Patent: US 9,339,659 B2
• Time in Patent Office: Days
• US Class Current: 607/61
• CPC Class Codes: A61N 1/37223 Circuits for electromagnetic coupling
• CPC Class Codes: A61N 1/37288 Communication to several implantable medical devices within one patient
• CPC Class Codes: A61N 1/3787 from an external energy source

Abstract

An external charger for a battery in an implantable medical device (implant), and technique for charging batteries in multiple implants using such improved external charger, is disclosed. During charging, values for a parameter measured in the implants are reported from the implants to the external charger. The external charger infers from the magnitudes of the parameters which of the implants has the highest (hot) and lowest (cold) coupling to the external charger. The intensity of the magnetic charging field is optimized for the cold implant to ensure that it is charged with a maximum (fastest) battery charging current. The duty cycle of the magnetic charging field is also optimized for the hot implant to ensure that it does not exceed a power dissipation limit. As a result, charging is optimized to be fast for all of the implants, while still safe from a tissue heating perspective.

Claims

1. A method for charging batteries in a plurality of implantable medical devices (IMDs), comprising:

(a) generating a magnetic charging field during a charging session using an external charger to simultaneously charge the batteries in the plurality of IMDs;

(b) determining at the external charger a first of the IMDs having a highest coupling to the external charger, and a second of the IMDs having a lowest coupling to the external charger; and

(c) adjusting the magnetic charging field during the charging session to maximize a speed of charging of the second IMD and to limit a power dissipation of the first IMD in accordance with a maximum power dissipation limit.

2. The method of claim 1, wherein adjusting the magnetic charging field to maximize the speed of charging of the second IMD comprises adjusting an intensity of the magnetic charging field, and wherein adjusting the magnetic charging field to limit the power dissipation of the first IMD comprises adjusting a duty cycle of the magnetic charging field.

3. The method of claim 2, wherein the external charger comprises a coil configured to generate the magnetic charging field, and wherein adjusting the intensity of the magnetic charging field comprises adjusting a current in the coil.

4. The method of claim 1, wherein determining the first and second IMDs comprises ignoring any of the plurality of IMDs whose battery is fully charged.

5. The method of claim 1, further comprising:

(d) repeating steps (b) and (c) periodically during the charging session.

6. The method of claim 1, wherein determining the first and second IMDs comprises assessing at least one parameter for each of the IMDs during the charging session.

7. The method of claim 6, wherein the at least one parameter for each IMD is indicative of a coupling between the external charger and that IMD.

8. The method of claim 7, wherein the magnetic charging field is adjusted in accordance with the at least one parameter for the first and second IMDs indicative of their coupling to the external charger.

9. The method of claim 8, wherein the magnetic charging field is further adjusted in accordance with a voltage of the battery in at least one of the first and second IMDs.

10. The method of claim 6, wherein the at least one parameter for each IMD is measured at that IMD, and wherein the at least one parameter is telemetered from each IMD to the external device during the charging session.

11. The method of claim 10, wherein the magnetic charging field is duty cycled, and wherein the at least one parameter for the IMDs are telemetered during one or more off periods in the duty cycle.

12. The method of claim 6, wherein the magnetic charging field induces a battery charging current in each IMD, and wherein the at least one parameter for each IMD is indicative of the battery charging current in that IMD.

13. The method of claim 12, wherein the at least one parameter comprises a voltage across circuitry in line with the battery charging current.

14. The method of claim 6, wherein determining the first and second IMDs comprises assessing a largest and smallest of the at least one parameter for each IMD.

15. The method of claim 6, wherein the external charger comprises data, and wherein the at least one parameter for the first and second IMDs are compared to the data to determine how to adjust the magnetic charging field.

16. The method of claim 15, wherein the data comprises an optimal value for the at least one parameter.

17. The method of claim 16, wherein the magnetic charging field is adjusted by adjusting an intensity of the magnetic charging field to bring the at least one parameter of the second IMD closer to the optimal value.

18. The method of claim 15, wherein the data relates the at least one parameter with a duty cycle that limits the power dissipation of the IMDs to the maximum power dissipation limit, and wherein the magnetic charging field is adjusted by adjusting a duty cycle of the magnetic charging field as determined from the data using the at least one parameter for the first IMD.

19. A method for charging batteries in a plurality of implantable medical devices (IMDs), comprising:

(a) generating a magnetic charging field during a charging session using an external charger to simultaneously charge the batteries in the plurality of IMDs;

(b) providing at the external charger at least one parameter indicative of a coupling between the external charger and each IMD during the charging session;

(c) determining a first of the parameters corresponding to a first of the IMDs having a highest coupling to the external charger, and a second of the parameters corresponding to a second of the IMDs having a lowest coupling to the external charger; and

(d) adjusting the magnetic charging field during the charging session at least in accordance with the first parameter and the second parameter.

20. The method of claim 19, wherein adjusting the magnetic charging field comprises adjusting an intensity and a duty cycle of the magnetic charging field.

21. The method of claim 20, wherein the external charger comprises a coil configured to generate the magnetic charging field, and wherein adjusting the intensity of the magnetic charging field comprises adjusting a current in the coil.

22. The method of claim 20, wherein the intensity is adjusted in accordance with the first parameter, and wherein the duty cycle is adjusted in accordance with the second parameter.

23. The method of claim 19, wherein determining the first and second parameters comprises ignoring the at least one parameter corresponding to any of the IMDs whose battery is fully charged.

24. The method of claim 19, further comprising:

(e) repeating steps (b) and (d) periodically during the charging session.

25. The method of claim 19, wherein the magnetic charging field is adjusted in accordance with the first parameter and the second parameter, and one or more of a battery voltage of the first IMD and the second IMD.

26. The method of claim 19, wherein the at least one parameter for each IMD is measured at that IMD, and wherein the at least one parameter is telemetered from each IMD to the external device during the charging session.

27. The method of claim 26, wherein the magnetic charging field is duty cycled, and wherein the at least one parameter for the IMDs are telemetered during one or more off periods in the duty cycle.

28. The method of claim 19, wherein the magnetic charging field induces a battery charging current in each IMD, and wherein the at least one parameter for each IMD is indicative of the battery charging current in that IMD.

29. The method of claim 28, wherein the at least one parameter comprises a voltage across circuitry in line with the battery charging current.

30. The method of claim 19, wherein determining the first and second parameters comprises assessing a largest and smallest of the at least one parameter for each IMD.

31. The method of claim 19, wherein the external charger comprises data, and wherein the first and second parameters are compared to the data to determine how to adjust the magnetic charging field.

32. The method of claim 31, wherein the data comprises an optimal value for the at least one parameter.

33. The method of claim 32, wherein the magnetic charging field is adjusted by adjusting an intensity of the magnetic charging field to bring the second parameter closer to the optimal value.

34. The method of claim 31, wherein the data relates the at least one parameter with a duty cycle that limits a power dissipation of the IMDs to a maximum power dissipation limit, and wherein the magnetic charging field is adjusted by adjusting a duty cycle of the magnetic charging field as determined from the data using the first parameter.