Magnetic field detector for implantable medical devices

A method comprising:

• obtaining a first signal sensed by a magnetic field strength sensor, wherein the first signal is representative of a strength of an external magnetic field imposed on the magnetic field strength sensor by the external magnetic field;
• obtaining a second signal sensed by a torque sensor, wherein the second signal is representative of a torque imposed on the torque sensor by the external magnetic field, the torque sensor being separate from the magnetic field strength sensor, the torque sensor including at least one force sensor that produces the second signal which varies in proportion to an amount of force produced by interaction of the external magnetic field with a magnetic moment of a coil within the torque sensor resulting in rotation of the coil;
• and
• controlling operation of an implantable medical device based on the first signal and the second signal by changing a mode of operation for transmitting a therapy via an implantable medical lead coupled to the implantable medical device when the first signal represents that the strength of the magnetic field exceeds a strength threshold and where the mode of operation chosen depends on whether the second signal represents that the external magnetic field is imposing torque on the torque sensor that exceeds a threshold torque value.

An implantable medical device comprising:

• a magnetic field strength sensor configured to output a first signal that varies as a function of the strength of an external magnetic field;
• a torque sensor configured to output a second signal that varies as a function of a torque imposed on the torque sensor by the external magnetic field, wherein the torque sensor is separate from the magnetic field strength sensor and wherein the torque sensor includes at least one force sensor that produces the second signal which varies in proportion to an amount of force produced by interaction of the external magnetic field with a magnetic moment occurring within the torque sensor;
• and
• a control module configured to control operation of the implantable medical device based on the first signal output of the magnetic field strength sensor and the second signal output of the torque sensor by changing a mode of operation for transmitting a therapy via an implantable medical lead coupled to the implantable medical device when the second signal represents that the external magnetic field is imposing torque on the torque sensor that exceeds a threshold torque value and when the first signal represents that the strength of the magnetic field exceeds a strength threshold.

A non-transitory computer-readable storage medium comprising instructions that, when executed by a processor, cause the processor to:

• obtain a first signal sensed by a maqnetic field strength sensor, wherein the first signal is representative of a strength of an external maqnetic field imposed on the magnetic field strength sensor by the external magnetic field;
• obtain a second signal from a torque sensor that varies as a function of a torque imposed on a torque sensor by an external magnetic field, the torque sensor being separate from the magnetic field strength sensor, where the torque sensor includes at least one force sensor that produces the second signal which varies in proportion to an amount of force produced by interaction of the external magnetic field with a magnetic moment occurring within the torque sensor;
• and
• control operation of an implantable medical device based on the first signal and the second signal by changing a mode of operation for transmitting a therapy provided by the implantable medical device via an implantable medical lead when the output first signal represents that the strength of the magnetic field exceeds a strength threshold and where the mode of operation chosen depends on whether the second signal represents that the external magnetic field is imposing torque on the torque sensor that exceeds a threshold torque value.