US Patent 7200504 Measuring temperature change in an electronic biomedical implant

The change in temperature of an implanted electronic device can be determined by providing power to one or more circuit elements included in the implanted electronic device, wherein the circuit elements comprise a non-crystal oscillator. A shift in the output frequency associated with the non-crystal oscillator can be detected, and the temperature change of the implanted electronic device can be determined based on the detected output frequency shift. One or more signals based on the output frequency associated with the non-crystal oscillator can be transmitted by the implanted electronic device. The transmitted signals can be received by an external device, which can detect the current output frequency associated with the non-crystal oscillator from the transmitted signals and compare the current output frequency with a previous output frequency to determine the output frequency shift associated with the non-crystal oscillator. The output frequency can, for example, be converted to a voltage measure.