Rotatable Cochlear Implant Magnets for MRI Torque Stability
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Solution Overview
Problem
Conventional cochlear implants are susceptible to demagnetization and torque-induced dislocation during MRI procedures due to misalignment of magnetic fields, and existing solutions such as freely rotatable ball magnets or diametrically magnetized disk-shaped magnets are either ineffective or increase the size and weight of the headpiece, leading to suboptimal magnetic retention forces.
Innovation Solution
A cochlear implant system featuring a rotatable magnet apparatus with a case, a magnet frame, and elongate diametrically magnetized magnets that can align with both the external magnet and the MRI field, maintaining a strong magnetic attraction while preventing demagnetization and torque-induced issues, without increasing the headpiece size or weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional disk-shaped magnets with axial magnetic dipoles are used in cochlear implants, then the magnetic retention force is sufficient for headpiece positioning, but the magnets are demagnetized or subjected to torque-induced dislocation during MRI procedures
Solution Approach 1:
The patent employs freely rotatable ball magnets instead of fixed disk-shaped magnets. The ball magnets can rotate dynamically to align with the MRI magnetic field direction, allowing the magnetic field orientation to change from perpendicular to parallel with the MRI field, thereby eliminating torque and preventing dislocation while maintaining retention force through magnetic attraction
2Reliability
If freely rotatable ball magnets are used to align with MRI field, then torque-induced dislocation is prevented, but the magnetic retention force becomes insufficient for proper headpiece mounting
Solution Approach 1:
The patent combines multiple freely rotatable ball magnets within a single implantable magnet apparatus housing. By merging several ball magnets into one integrated unit, the collective magnetic force is sufficient for both headpiece retention and MRI compatibility, while each individual ball magnet maintains its rotational freedom to align with the MRI field
3Force
If the strength of the magnet is increased to improve retention force, then headpiece positioning is improved, but the torque on the magnet during MRI increases causing dislocation
Solution Approach 1:
The patent uses freely rotatable ball magnets that can dynamically adjust their orientation in response to the MRI magnetic field. This dynamic rotation capability allows the magnets to reduce torque exposure during MRI procedures by aligning with the field, while still providing sufficient retention force through their magnetic attraction to the headpiece magnet
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system ensures stable magnetic retention forces, preventing demagnetization and torque-induced dislocation during MRI procedures, and maintains proper alignment of the headpiece with the cochlear implant, enhancing patient safety and comfort.
Implementation Method 1
elongate diametrically magnetized magnets that can align with both the external magnet and the MRI field, maintaining a strong magnetic attraction while preventing demagnetization and torque-induced issues
Implementation Method 2
The magnitude of the retention force between the headpiece magnet and implant magnet is an important aspect of an ICS system. If the force is too low, the headpiece will not remain in place on the head during typical activities.
Data Source
AI summary
A cochlear implant including a cochlear lead, an antenna, a stimulation processor, and a magnet apparatus, associated with the antenna, including a case defining a central axis, a magnet frame within the case and rotatable about the central axis of the case, and a plurality of elongate diametrically magnetized magnets that are located in the magnet frame, the magnets defining a longitudinal axis and a N-S direction and being freely rotatable about the longitudinal axis relative to the magnet frame.