Efficient external charger for an implantable medical device optimized for fast charging and constrained by an implant power dissipation limit

• US 9,867,995 B2
• Filed: 06/03/2016
• Issued: 01/16/2018
• Est. Priority Date: 10/08/2009
• 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
• Primary Examiner(s): VOORHEES, CATHERINE M
• Application Number:
  US15/172,856
• Publication Number:
  US 20160279427A1
• Time in Patent Office: 592 Days
• CPC Class Codes: A61N 1/3605 Implantable neurostimulators for stimulating central or peripheral nerve system
• CPC Class Codes: A61N 1/37205 Microstimulators, e.g. implantable through a cannula
• CPC Class Codes: A61N 1/37217 characterised by the communication link, e.g. acoustic or tactile
• CPC Class Codes: A61N 1/3787 from an external energy source

Abstract

An external charger for a battery in an implantable medical device and charging techniques are disclosed. Simulation data is used to model the power dissipation of the charging circuitry in the implant at varying levels of implant power. A power dissipation limit constrains the charging circuitry from producing an inordinate amount of heat to the tissue surrounding the implant, and duty cycles of a charging field are determined so as not to exceed that limit. A maximum simulated average battery current determines the optimal (i.e., quickest) battery charging current, and at least an optimal value for a parameter indicative of that current is determined and stored in the external charger. During charging, the actual value for that parameter is determined, and the intensity and/or duty cycle of the charging field are adjusted to ensure that charging is as fast as possible, while still not exceeding the power dissipation limit.

Claims

1. An external charger configured to charge a battery in an implantable medical device, comprising:

a coil configured to generate a magnetic charging field, the magnetic charging field configured to charge a battery in the implantable medical device during a charging session; and

controller circuitry configured to adjust;

(1) an intensity of the magnetic charging field, and (2) a duty cycle of the magnetic charging field, during the charging session in accordance with a parameter indicative of a coupling between the external charger and the implantable medical device during the charging session,

wherein the controller circuitry is configured to adjust the intensity to cause the parameter to approach an optimal value for the parameter, wherein the optimal value for the parameter comprises a value at which an average of a battery charging current of the battery during the charging session is maximized.

2. The external charger of claim 1, wherein the parameter is indicative of the battery charging current of the battery during the charging session.

3. The external charger of claim 1, wherein the parameter is indicative of heating in the implantable medical device during the charging session.

4. The external charger of claim 1, further comprising receiver circuitry configured to receive the parameter via telemetry from the implantable medical device.

5. The external charger of claim 4, wherein the receiver circuitry is configured to receive the parameter during an off period of the duty cycle.

6. The external charger of claim 4, wherein the parameter comprises a voltage across charging circuitry serially coupled to the battery in the implantable medical device.

7. The external charger of claim 1, further comprising a memory, wherein the memory comprises possible values for the parameter and a duty cycle associated with each possible value, wherein each duty cycle in the memory is determined in accordance with a power dissipation limit for the implantable medical device.

8. The external charger of claim 7, wherein the controller circuitry is configured to adjust the duty cycle using the parameter and the duty cycles in the memory.

9. The external charger of claim 7, wherein the possible values for the parameter correspond to different battery charging currents of the battery, and wherein the duty cycle associated with each possible value is determined so as not to exceed a power dissipation limit in the implantable medical device.

10. The external charger of claim 1, wherein controller circuitry is further configured to adjust the intensity and duty cycle in accordance with a voltage of the battery.

11. The external charger of claim 1, wherein the parameter varies during the charging session, and wherein the controller circuitry is configured to adjust the intensity and duty cycle of the magnetic charging field periodically during the charging session in accordance with a current value of the parameter at each period.

12. An external charger configured to charge a battery in an implantable medical device, comprising:

a memory in which is stored data comprising;

a plurality of first relationships each associating (i) a parameter indicative of a coupling between the external charger and the implantable medical device when charging the battery in the implantable medical device, with (ii) a duty cycle for the external charger, wherein the duty cycles of the first relationships ensure that a power dissipation limit for the implantable medical device is not exceeded when charging the battery in the implantable medical device; and

a first optimal value of the parameters of the first relationships in the external charger, wherein the first optimal value is indicative of a maximum battery charging current of the battery in the implantable medical device; and

a microcontroller configured to store the data in the memory.

13. The external charger of claim 12, further comprising a transmitter for broadcasting a magnetic charging field to the implantable medical device, and a receiver for receiving a value of the parameter from the implantable medical device.

14. The external charger of claim 13, wherein the microcontroller is in communication with the memory, the transmitter, and the receiver.

15. The external charger of claim 13, wherein the transmitter controls a duty cycle and intensity of the magnetic charging field.

16. The external charger of claim 12, wherein the memory further stores:

a plurality of second relationships each associating (i) a parameter indicative of the coupling between the external charger and the implantable medical device when charging the battery in the implantable medical device, with (ii) a duty cycle for the external charger, wherein the duty cycles of the second relationships ensure that the power dissipation limit is not exceeded when charging the battery in the implantable medical device; and

a second optimal value of the parameters of the second relationships in the external charger, wherein the second optimal value is indicative of a maximum battery charging current.

17. The external charger of claim 16, wherein the plurality of first relationships and first optimal value correspond to a first voltage of the battery, and wherein the plurality of second relationships and second optimal value correspond to a second voltage of the battery.