RECHARGE OF AN IMPLANTABLE DEVICE IN THE PRESENCE OF OTHER CONDUCTIVE OBJECTS

• US 20130289662A1
• Filed: 04/25/2012
• Published: 10/31/2013
• Est. Priority Date: 04/25/2012
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Olson, David P., Kallmyer, Todd A.
• Granted Patent: US 8,818,523 B2
• Time in Patent Office: Days
• US Class Current: 607/61
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment

Abstract

Techniques are disclosed for controlling the transcutaneously transfer of energy to an implantable medical device (IMD) that is in proximity to a conductive object that conducts current in the presence of an electromagnetic field. Various techniques are disclosed for estimating or determining the levels of heat dissipation associated with the object during the transfer of energy. If too much heat is being dissipated, the transfer of energy may be adjusted so that heating remains below acceptable levels.

Claims

1. A system, comprising:

a primary coil configured to transcutanously transfer energy to an implantable medical device (IMD) that is located in proximity to a conductive object; and

a circuit configured to control the transfer of energy based on an estimated amount of heat associated with the object during the transfer of energy.

2. The system of claim 1, wherein the circuit is configured to determine the amount of heat dissipated by the object and to control the transfer of energy based on the determined amount.

3. The system of claim 1, wherein the circuit is configured to vary a frequency at which the primary coil is driven to determine respective loading profiles of the system in the presence of the object and in the absence of the object and to control the transfer of energy based on the respective loading profiles.

4. The system of claim 3, wherein the circuit is configured to control the transfer of energy based on a peak-to-baseline ratio indicated by at least one of the respective loading profiles.

5. The system of claim 1, wherein the circuit is configured to control the transfer of energy based on at least one predetermined characteristic of the object.

6. The system of claim 1, wherein the circuit is configured to control the transfer of energy based on heating of the IMD.

7. The system of claim 1, wherein the circuit is configured to control the transfer of energy based on a change in a ratio of power delivered to a power source of the IMD and total heat dissipation within the system.

8. The system of claim 1, wherein the circuit is configured to control the transfer of energy based on a positional map containing associations, each association associating a relative position between the primary coil and a secondary coil of the IMD and an indication of a power level obtained when energy is transferred from the primary coil to the secondary coil when the primary coil is in the relative position with respect to the secondary coil.

9. The system of claim 8, wherein one or more relative positions between the primary coil and the secondary coil are selected based on the positional map for use in transferring energy from the primary coil to the secondary coil, and wherein feedback is provided to a user to guide the user in locating the primary coil in one of the relative positions with respect to the secondary coil.

10. The system of claim 1, further comprising an Implantable Medical Device (IMD) configured to perform at least one of providing a therapy and sensing a signal.

11. A method, comprising:

transcutanously transferring energy to an implantable medical device (IMD) that is located in proximity to a conductive object; and

controlling the transcutaneous transfer of energy based on an estimated amount of heat associated with the object during the transfer of the energy.

12. The method of claim 11, further comprising determining the amount of heat dissipated by the object and wherein controlling the transfer of energy comprises controlling the transfer of energy based on the determined amount of heat dissipated by the object.

13. The method of claim 11, further comprising varying a frequency at which the transfer of energy occurs to determine a loading profile and wherein controlling the transfer of energy comprises controlling the transfer of energy based on the loading profile.

14. The method of claim 13, further comprising determining a difference between a resonant frequency of the determined loading profile and a resonant frequency of a reference loading profile, and where controlling the transfer of energy comprises controlling the transfer of energy based on the difference.

15. The method of claim 11, further comprising determining a peak-to-baseline ratio for power delivery at a resonant frequency, and wherein controlling the transfer of energy comprises controlling the transfer of energy based on the peak-to-baseline ratio.

16. The method of claim 11, further comprising controlling the transfer of energy based on at least one predetermined characteristic of the object.

17. The method of claim 11, further comprising controlling the transfer of energy based on at least one of heat dissipated by the primary coil and heat dissipated by the IMD.

18. A system, comprising:

means for transcutanously transferring energy to an implantable medical device (IMD) that is located in proximity to a conductive object; and

means for controlling the transfer of energy to the IMD based on an estimated amount of heat associated with the object during the transfer of energy.

19. A non-transitory storage medium for storing instructions to cause a control circuit to perform a method, comprising:

transcutanously transferring energy to an implantable medical device (IMD) that is located in proximity to a conductive object; and

controlling the transfer of energy based on an estimated amount of heat associated with the object during the transfer of energy.

20. The storage medium of claim 19, wherein the method further comprises varying a frequency at which the transfer of energy occurs to determine a loading profile and wherein controlling the transfer of energy comprises controlling the transfer of energy based on a characteristic of the loading profile.

21. The storage medium of claim 20, wherein the method further comprises determining respective loading profiles in the presence and absence of the conductive object and controlling the transfer of energy based on a difference between the respective loading profiles.

22. The storage medium of claim 19, wherein the method further comprises controlling the transcutaneous transfer of energy based on a determined amount of heat dissipated by the object.

23. The storage medium of claim 22, wherein the method further comprises determining the amount of heat dissipated by the object based on an amount of power provided to a rechargeable power source of the IMD and an amount of heat dissipated by the IMD.

24. The storage medium of claim 19, wherein the method further comprises estimating the amount of heat associated with the object based on a difference between an amount of power delivered by a primary coil in the presence of the conductive object to achieve a predetermined level of power delivered to a rechargeable power source of the IMD as compared to an amount of power delivered by the primary coil in the absence of the conductive object to achieve the predetermined level of power delivered to the rechargeable power source.