How Cochlear Implants Use Free-Spinning Magnets to Survive MRI Scans

A cochlear implant design that uses a freely rotating internal magnet to prevent the device from being pulled or damaged by the strong magnetic fields of an MRI machine.

What it covers

This patent describes a cochlear implant system where the internal magnet is housed in a way that allows it to rotate freely in any direction without moving out of its designated spot. Because the magnet can spin, it aligns itself with the powerful magnetic fields of an MRI machine rather than resisting them. This prevents the magnet from experiencing high torque, which could otherwise damage the implant or cause pain to the patient. The system also includes a housing that keeps the magnet in place while allowing this rotation, ensuring the external and internal coils remain aligned for power and data transmission.

What it doesn't cover

• —Does not cover magnets that are fixed in place and cannot rotate freely.
• —Does not cover systems that rely on external mechanical clamps or non-magnetic fasteners to hold the device in place.
• —Does not cover the specific electronic signal processing algorithms used to convert sound into electrical stimulation.

The clever bit

Instead of trying to shield the magnet from the MRI's magnetic field, the inventors designed the housing to allow the magnet to pivot and align with the field, effectively neutralizing the torque that would otherwise cause mechanical damage.

Why it matters

Before this technology, patients with cochlear implants often faced significant risks or were completely barred from undergoing MRI scans due to the potential for the implant's magnet to be dislodged or demagnetized. This design allows patients to safely receive necessary medical imaging without needing surgery to remove the implant first, significantly improving the quality of life for those with hearing loss.

Real-world examples

• 1.MED-EL cochlear implant systems
• 2.MRI-compatible cochlear implant internal receivers