Cochlear Implant Magnet Apparatus MRI Torque Reduction
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Solution Overview
Problem
Conventional cochlear implant magnet systems are not compatible with strong MRI magnetic fields, leading to demagnetization, torque-induced dislocation, and discomfort, and existing MRI-compatible systems require excessive magnetic material to maintain attraction force and alignment.
Innovation Solution
A magnet apparatus with a case and rotatable frame containing only two elongate diametrically magnetized magnets, separated by a fixed distance, which reduces magnetic attraction and torque while maintaining alignment with an axially magnetized headpiece magnet, using less magnetic material and minimizing MRI artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional axially magnetized magnets are used in cochlear implants, then the magnets can maintain stable positioning with the headpiece, but they are not compatible with MRI systems and must be surgically removed and replaced
Solution Approach 1:
The patent changes the magnetization direction parameter from axial to diametric, and reduces the number of magnets from three or more to exactly two, creating an MRI-compatible configuration that maintains positioning stability while enabling MRI compatibility
2Adaptability or versatility
If diametrically magnetized disk-shaped magnets are used, then the magnets can rotate to align with MRI fields, but they experience excessive torque that may dislodge or reverse the magnet and cause discomfort
Solution Approach 1:
The patent segments the magnetic field generation into exactly two separate diametrically magnetized magnets instead of using a single magnet or three or more magnets, which reduces the total magnetic moment and consequently reduces the torque experienced in MRI fields while maintaining alignment capability
Solution Approach 2:
The patent uses exactly two magnets which is sufficient for MRI compatibility and torque reduction, avoiding the excessive magnetic material that would be present with three or more magnets, thereby achieving the minimum necessary magnetic field interaction for MRI safety
3Adaptability or versatility
If three or more elongate diametrically magnetized magnets are used, then the magnets can align with 3D MRI magnetic fields with low torque, but the amount of magnetic material increases the attraction force between magnets and headpiece magnet
Solution Approach 1:
The patent extracts one or more magnets from the three-or-more magnet configuration, reducing to exactly two magnets, which maintains sufficient MRI field alignment capability while reducing the total magnetic material and consequently reducing the magnetic attraction force to the headpiece
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 solution reduces the amount of magnetic material and torque associated with MRI fields, maintains magnetic attraction, and decreases MRI artifacts, making the system more efficient and cost-effective while ensuring compatibility with higher field MRI systems.
Implementation Method 1
a dominant magnetic field, such as the MRI magnetic field, that is misaligned by at least 30° or more from the N-S direction of the magnet may demagnetize the magnet or generate an amount of torque on the magnet
Implementation Method 2
three or more elongate diametrically magnetized magnets that are located in the frame in close proximity to one another and that are rotatable about their respective longitudinal axis relative to the frame
Implementation Method 3
the magnets to align with three-dimensional (3D) MRI magnetic fields, regardless of field direction, which results in very low amounts of torque on the magnets
Data Source
AI summary
A system including a cochlear implant with a cochlear lead including a plurality of electrodes, an antenna, a stimulation processor operably connected to the antenna and to the cochlear lead, and a magnet apparatus, adjacent to the antenna, including a case defining a central axis, a frame within the case and rotatable relative to the case about the central axis of the case, and only two elongate diametrically magnetized magnets that are located in the frame, that are separated from one another by a fixed non-zero distance, that each define a longitudinal axis and a N-S direction, and that are rotatable about the longitudinal axis relative to the frame, and an external device including an axially magnetized disk-shaped positioning magnet and an antenna adjacent to the axially magnetized disk-shaped positioning magnet.