Method and apparatus for dynamic adjustment of recharge parameters

• US 8,362,742 B2
• Filed: 09/29/2008
• Issued: 01/29/2013
• Est. Priority Date: 10/26/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Kallmyer, Todd A.
• Primary Examiner(s): DIAO, M BAYE
• Application Number:
  US12/738,065
• Publication Number:
  US 20100219796A1
• Time in Patent Office: 1,583 Days
• Field of Search: 320/153, 320/108, 320/162, 607/29
• US Class Current: 320/108
• CPC Class Codes: A61N 1/37223 Circuits for electromagnetic coupling
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• 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
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge

Abstract

A recharging system and method for an implantable medical device includes: a secondary coil associated with the implantable medical device; an external power source including a primary coil and a modulation circuit operatively coupled to the primary coil, the modulation circuit being capable of driving the primary coil at a carrier frequency when the primary coil is in proximity to the secondary coil and of varying the carrier frequency in response to sensor data received from the implantable medical device; a first sensor associated with the implantable medical device and in communication with the modulation circuit, the first sensor capable of sensing a first condition indicating a need to adjust the carrier frequency during a charging process; and a second sensor associated with the implantable medical device and in communication with the modulation circuit, the second sensor capable of sensing a second condition which is affected by the carrier frequency.

Claims

1. A passive recharging system for an implantable medical device comprising:

a) a secondary coil associated with the implantable medical device;

b) an external power source including;

a primary coil; and

a modulation circuit operatively coupled to said primary coil, said modulation circuit being capable of driving said primary coil at a carrier frequency when said primary coil is in proximity to said secondary coil and of varying the carrier frequency in response to sensor data received from the implantable medical device;

c) a first sensor associated with the implantable medical device and in communication with the modulation circuit, the first sensor being capable of sensing a first condition indicating a need to adjust the carrier frequency during a charging process;

d) a second sensor associated with the implantable medical device and in communication with the modulation circuit, the second sensor being capable of sensing a second condition which is affected by the carrier frequency.

2. The charging system of claim 1 wherein the first sensor includes a voltage sensor capable of measuring voltage across the secondary coil and the first condition is a voltage threshold.

3. The charging system of claim 2 wherein the implantable medical device includes a telemetry unit which transmits sensor data from the implantable medical device to the external power source.

4. The charging system of claim 2 wherein the second sensor is a temperature sensor and the second condition is a temperature at the implantable medical device.

5. The charging system of claim 4 wherein modulation circuit includes a frequency generator and a processor which is configured to control the frequency generator so as to control the carrier frequency in response to data from the voltage sensor and the temperature sensor.

6. The charging system of claim 5 wherein the processor causes the frequency generator to increase carrier frequency if the voltage sensor senses a voltage lower than a predetermined voltage threshold value and the temperature sensor senses a temperature lower than a predetermined temperature threshold value.

7. The charging system of claim 6 wherein the temperature threshold value is a value defined by a government regulation.

8. A method for charging an implantable medical device comprising:

initiating a charging process by driving a primary coil of an external device at a carrier frequency, wherein the primary coil is in proximity to a secondary coil of an implantable medical device;

during the charging process, monitoring a first condition of the implantable medical device via a first implantable sensor, wherein the first implantable sensor is capable of sensing a first condition indicating a need to adjust the carrier frequency;

during the charging process, monitoring a second condition of the implantable medical device via a second implantable sensor, wherein the second implantable sensor is capable of sensing a second condition which is affected by the carrier frequency; and

adjusting the carrier frequency based on data obtained via the first and second implantable sensor only if the first condition meets a first predetermined criterion and the second condition meets a second predetermined criterion.

9. The method of claim 8 wherein the first condition is a voltage at a secondary coil within the implantable device;

and the first predetermined criterion is voltage being below a voltage threshold value.

10. The method of claim 8 wherein the second condition is a temperature at the implantable device;

and the second predetermined criterion is temperature being below a temperature threshold value.

11. The method of claim 9 wherein the second condition is a temperature at the implantable device;

and the second criterion is temperature being below a temperature threshold value.

12. The method of claim 11 wherein the step of adjusting carrier frequency includes increasing the carrier frequency.

13. The method of claim 12 wherein the steps of monitoring the first condition and monitoring the second condition are carried out continuously.

14. The method of claim 12 wherein the steps of monitoring the first condition and monitoring the second condition are carried out at predefined time increments.

15. The method of claim 11 wherein the step of monitoring the first condition includes measuring a voltage across a secondary coil in the implantable medical device, and further comprising the step of comparing the measured voltage to a threshold value for voltage.

16. The method of claim 15 wherein the step of monitoring the second condition includes measuring a temperature within the implantable medical device, and further comprising the step of comparing the measured temperature to a threshold value for temperature.

17. The method of claim 8 further comprising the step of sensing that the implantable medical device is in proximity to an external charger;

and wherein the step of initiating a charging process includes initiating a charging process in response to a determination of the implantable medical device being in proximity to the external charger.

18. The method of claim 9 wherein the voltage threshold value is a voltage level at which energy transfer efficiency is below a desired level.