MRI-safe implant magnet with angular magnetization
A magnetic arrangement is described for an implantable system for a recipient patient. An implantable coil housing contains a signal coil for transcutaneous communication of an implant communication signal. Freely rotatable within the coil housing is a cylindrical implant magnet for transcutaneous magnetic interaction with a corresponding external attachment magnet. The implant magnet has a central cylinder axis of symmetry, and a magnetization direction along a magnetic axis angled away from the axis of symmetry at a non-zero angle less than 45 degrees.
1. A magnetic arrangement for an implantable system for a recipient patient, the arrangement comprising:
an implantable coil housing containing a signal coil for transcutaneous communication of an implant communication signal;
a cylindrical implant magnet freely rotatable within the coil housing for transcutaneous magnetic interaction with a corresponding external attachment magnet, the implant magnet having:
i. a central cylinder axis of symmetry, and
ii. a magnetization direction along a magnetic axis angled away from the axis of symmetry at a non-zero angle less than 45 degrees.
2. An arrangement according to claim 1 , wherein the magnetic axis is angled away from the axis of symmetry at an angle of more than 10 degrees.
3. An arrangement according to claim 2 , wherein the magnetic axis is angled away from the axis of symmetry at an angle of less than 30 degrees.
4. An arrangement according to claim 1 , wherein the magnetic axis is angled away from the axis of symmetry at an angle of 20 degrees.
5. An arrangement according to claim 1 , further comprising:
a lubrication coating covering at least a portion of the implant magnet and reducing rotational friction between the implant magnet and the coil housing.
6. An arrangement according to claim 1 , wherein the implantable system is a cochlear implant system.
7. An arrangement according to claim 1 , wherein the implantable system is a middle ear implant system.
8. An arrangement according to claim 1 , wherein the implantable system is a vestibular implant system.