Reducing effect of magnetic and electromagnetic fields on an implant's magnet and/or electronics

Abstract

An implantable magnet that can freely turn in response to an external magnetic field, thus avoiding torque and demagnetization on the implantable magnet. The implantable magnet can be combined with an electric switching function depending on the orientation of an external magnetic field, thus protecting an implanted coil and/or implant electronics against induction of over-voltage or performing an electric switching function for other various purposes. The magnetic switch may further include, for example, a first switching contact and a second switching contact. A magnetically soft body that includes an electrically conductive surface is shiftable between a first position where the body is in simultaneous contact with the first and second switching contacts, and a second position where the body is out of contact with at least one of the first and second switching contacts. The body and the implantable magnet are positioned such that the body is shifted to one of the first position and the second position as a function of the external magnetic field resulting in a magnetic force between the magnet and the magnetically soft body.

What is claimed is: 
     
       1. A cochlear implant system comprising:
 an external portion adapted for placement on the external skin of a user, the external portion including a first coil;   an implantable portion including a second coil, the first coil and the second coil for transcutaneous transmission of a signal via electromagnetic coupling; and   a magnet held by a housing such that the magnet is without axial movement and is freely turnable in any direction, the magnet for maintaining a position of the external portion relative to the implantable portion so as to promote electromagnetic coupling between the first coil and the second coil.   
     
     
       2. The cochlear implant system according to  claim 1 , wherein the implantable portion includes a stimulator module for producing for the auditory system of a user an electrical stimulation signal representative of an acoustic signal. 
     
     
       3. The cochlear implant system according to  claim 1 , wherein the magnet is capable of aligning with an external magnetic field. 
     
     
       4. The cochlear implant system according to  claim 1 , further including a lubricant between the housing the magnet. 
     
     
       5. The cochlear implant system according to  claim 1 , wherein the magnet is prevented from rattling against the housing. 
     
     
       6. The cochlear implant system according to  claim 1 , wherein the housing includes a magnetically soft material at least partially surrounding the magnet. 
     
     
       7. The cochlear implant system according to  claim 1 , wherein the housing includes a material selected from the group of materials consisting of titanium, nonmagnetic stainless steel, and ceramic. 
     
     
       8. The cochlear implant system according to  claim 1 , wherein one of the housing and the magnet includes a Teflon surface. 
     
     
       9. The cochlear implant system according to  claim 1 , wherein the magnet is a spherical magnet. 
     
     
       10. The cochlear implant system according to  claim 1 , wherein the magnet is coated at least partially with a conductive surface. 
     
     
       11. The cochlear implant system according to  claim 1 , wherein the signal is one of a data signal and a power signal. 
     
     
       12. A cochlear implant system comprising:
 a first housing;   a first coil associated with the first housing;   a magnet held by the first housing such that the magnet is without axial movement and is freely turnable without bias, such that the at least one magnet is capable of aligning with an external magnetic field.   a second housing;   a second coil associated with the second housing, the first coil and the second coil for transmission of a signal via electromagnetic coupling; and   a second magnet held by the second housing, the first magnet and the second magnet for maintaining a position of the first housing relative to the second housing via magnetic attraction, so as to promote electromagnetic coupling between the first coil and the second coil.   
     
     
       13. The cochlear implant system according to  claim 12 , wherein the first housing includes a Teflon surface. 
     
     
       14. The cochlear implant system according to  claim 12 , wherein the first magnet is a spherical magnet. 
     
     
       15. The cochlear implant system according to  claim 12 , wherein the first magnet is capable of turning in response to the external magnetic field. 
     
     
       16. The cochlear implant according to  claim 12 , further including a lubricant placed between the first magnet and the first housing. 
     
     
       17. The implant system according to  claim 12 , wherein the magnet is coated at least partially with a conductive surface. 
     
     
       18. The implant system according to  claim 12 , wherein the signal is one of a data signal and a power signal. 
     
     
       19. A hearing implant system comprising:
 an external portion for placement on the skin of a user and including:
 i. a transmitting coil for transcutaneous transmission of a communication signal, and 
 ii. an external holding magnet within the transmitting coil; 
   an implantable portion including an implant housing containing:
 i. a receiving coil for transcutaneous reception of the communication signal from the transmitting coil, and 
 ii. at least one elongated implant holding magnet having a longitudinal rotation axis and adapted to be freely turnable within the implant housing around the longitudinal rotation axis in response to an external magnetic field, the at least one elongated implant holding magnet having a magnetization direction normal to the longitudinal rotation axis; 
   wherein the implant holding magnet and the external holding magnet magnetically cooperate to maintain the external portion in a fixed position on the skin relative to the implantable portion so as to promote electromagnetic coupling between the transmitting coil and the receiving coil.   
     
     
       20. The cochlear implant system according to claim 19, wherein the at least one elongated implant holding magnet is a single implant holding magnet. 
     
     
       21. The cochlear implant system according to claim 19, wherein the at least one elongated implant holding magnet is a plurality of implant holding magnets. 
     
     
       22. The cochlear implant system according to claim 19, wherein the implant housing further contains a magnetically soft material partially surrounding the implant holding magnet. 
     
     
       23. A hearing implant system comprising:
 an external portion for placement on the skin of a user and including:
 i. a transmitting coil for transcutaneous transmission of a communication signal, and 
 ii. an external holding magnet within the transmitting coil; 
   an implantable portion including an implant housing containing:
 i. a receiving coil for transcutaneous reception of the communication signal from the transmitting coil, and 
 ii. at least one elongated implant holding magnet having a longitudinal rotation axis and adapted to be freely turnable within the implant housing around the longitudinal rotation axis in response to an external magnetic field; 
 iii. wherein the implant holding magnet and the external holding magnet magnetically cooperate to maintain the external portion in a fixed position on the skin relative to the implantable portion so as to promote electromagnetic coupling between the transmitting coil and the receiving coil, 
   wherein the implant housing further contains a magnetically soft material partially surrounding the implant holding magnet.   
     
     
       24. The cochlear implant system according to claim 23, wherein the at least one elongated implant holding magnet is a single implant holding magnet. 
     
     
       25. The cochlear implant system according to claim 23, wherein the at least one elongated implant holding magnet is a plurality of implant holding magnets.