Magnetic-interference-free surgical prostheses

Abstract

Interference-free coil systems are coil systems having at least two coils which are identical in terms of inductance. These coils are arranged such that their magnetic fields are antiparallel to one another. Consequently, induced voltages within the coils are substantially eliminated when the coils are exposed to a homogeneous electromagnetic field. If exposed to an nonhomogeneous electromagnetic field, however, a net voltage is induced and enables the extraction of data and power. Reed switch configurations in the implantable prostheses protect against induced voltages caused by the radio frequency field generated by an MR imager when the reed switches are mounted parallel to the plane of a receiver. Reed switch configuration may be used to disconnect, de-tune, or short circuit a receiver. For example, they may be used to disconnect the receiver diodes. Some magnet configurations reduce torque caused by an external magnetic field and prevent demagnetization when disposed within, outside, or partially within an implantable prosthesis. Magnets which align with the external magnetic field also reduce the torque caused by the field and prevent demagnetization.

Dependencies are inferred from the claim text.