Measuring temperature change in an electronic biomedical implant

1. A method comprising:

receiving a signal transmitted by an implantable electronic device, wherein a transmission frequency of the received signal corresponds to an output frequency associated with a non-crystal oscillator included in the implantable electronic device;

comparing the transmission frequency of the received signal with an initial value to detect a frequency shift; and

determining a change in temperature of the implantable electronic device based on the detected frequency shift.

2. The method of claim 1 , wherein the received signal comprises an unmodulated signal.

3. The method of claim 1 , wherein the initial value comprises a transmission frequency of a signal transmitted by the implantable electronic device prior to a charging operation.

4. The method of claim 1 , wherein the received signal comprises a modulated signal including data representing a status of the implantable electronic device.

5. The method of claim 4 , further comprising:

determining a voltage change of a rechargeable power source included in the implantable electronic device based on the data representing the status of the implantable electronic device; and

factoring out of the detected frequency shift a component corresponding to the voltage change.

6. The method of claim 1 , further comprising:

factoring out of the detected frequency shift a component corresponding to aging of the implantable electronic device.

7. The method of claim 1 , further comprising:

adjusting a charging field based on the determined change in temperature.

8. The method of claim 1 , further comprising:

storing the transmission frequency of the received signal as the initial value before initiating a charging operation.

9. The method of claim 1 , further comprising:

determining the transmission frequency of the received signal by one or more of measuring pulse-width, determining a time interval between successive rising edges, and counting a number of pulses received within a time period.

10. A system for determining a change in temperature of an implantable electronic device, the system comprising:

an implantable electronic device configured to transmit a signal, wherein a transmission frequency of the transmitted signal corresponds to an output frequency associated with a non-crystal oscillator included in the implantable electronic device; and

an external controller including processor electronics configured to perform operations comprising:

receiving the transmitted signal;

comparing the transmission frequency of the transmitted signal with an initial value to detect a frequency shift; and

determining a change in temperature of the implantable electronic device based on the detected frequency shift.

11. The system of claim 10 , wherein the implantable electronic device and the external controller are inductively coupled through an electromagnetic field.

12. The system of claim 11 , wherein the processor electronics included in the external controller are further configured to perform operations comprising:

adjusting a strength of the electromagnetic field based on the determined change in temperature.

13. The system of claim 10 , wherein the transmitted signal comprises an unmodulated signal.

14. The system of claim 10 , wherein the initial value comprises a transmission frequency of a signal transmitted by the implantable electronic device prior to a charging operation.

15. The system of claim 10 , wherein the processor electronics included in the external controller are further configured to perform operations comprising:

factoring out of the detected frequency shift a component corresponding to one or more of (i) aging of the implantable electronic device and (ii) a voltage change in a rechargeable power source included in the implantable electronic device.

16. The system of claim 10 , wherein the output frequency associated with the non-crystal oscillator comprises a center frequency of the non-crystal oscillator.

17. The system of claim 10 , wherein the processor electronics included in the external controller are further configured to perform operations comprising:

storing the transmission frequency of the transmitted signal as the initial value before initiating a charging operation.

18. The system of claim 10 , wherein the processor electronics included in the external controller are further configured to perform operations comprising:

determining the transmission frequency of the transmitted signal by one or more of measuring pulse-width, determining a time interval between successive rising edges, and counting a number of pulses received within a time period.

19. The system of claim 10 , wherein the non-crystal oscillator comprises one of a ring-oscillator and a resistor-capacitor oscillator.

20. A method comprising:

providing power to a non-crystal oscillator associated with an implantable electronic device;

detecting an output frequency associated with the non-crystal oscillator;

comparing the detected output frequency with a stored output frequency value associated with the non-crystal oscillator to detect an output frequency shift; and

determining a change in temperature of the implantable electronic device based on the detected output frequency shift.

21. The method of claim 20 , further comprising:

adjusting a field strength associated with a charging field based on the determined change in temperature.

22. The method of claim 20 , further comprising:

factoring out of the detected output frequency shift a component that corresponds to one or more of (i) aging of the implantable electronic device and (ii) a change in a rechargeable power source voltage associated with the implantable electronic device.

23. The method of claim 20 , wherein the output frequency associated with the non-crystal oscillator comprises a center frequency.