Cochlear Implant Magnet Assembly with Rotatable MRI Alignment
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Solution Overview
Problem
Conventional cochlear implants are not compatible with MRI systems, as existing MRI-compatible magnet apparatus experience significant torque and demagnetization issues due to misalignment with MRI magnetic fields, and there is a need to reduce magnetic material without compromising attraction force or increasing size.
Innovation Solution
A magnet apparatus with a case and frame, featuring two elongate diametrically magnetized magnets separated by a fixed distance, allowing them to rotate and align with both MRI and axially magnetized headpiece magnets, reducing torque and magnetic attraction while maintaining efficient alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional axially magnetized magnets are used in cochlear implants, then the magnet structure is simple and manufacturing is easy, but the magnets are not compatible with MRI systems and must be surgically removed and replaced
Solution Approach 1:
The magnet is divided into multiple segments (first magnet and second magnet) arranged in a specific configuration. This segmentation allows the implant to achieve MRI compatibility by reducing torque effects while maintaining the necessary magnetic attraction force for headpiece positioning.
Solution Approach 2:
Different regions of the magnet structure have different magnetic properties. The first and second magnets are positioned at specific locations within the implant housing, with their magnetic moments oriented perpendicular to the central axis, creating localized magnetic fields that collectively achieve both MRI compatibility and functional performance.
2Adaptability or versatility
If diametrically magnetized disk-shaped magnets are used, then MRI compatibility is improved, but significant torque and demagnetization issues occur when misaligned with MRI magnetic fields by 30° or more
Solution Approach 1:
The magnet configuration uses asymmetric arrangement of the first and second magnets relative to the central axis, with their magnetic moments oriented perpendicular to the axis. This asymmetric configuration reduces the dominant magnetic field interaction that causes torque and demagnetization in conventional diametrically magnetized magnets.
Solution Approach 2:
The magnet structure is designed to dynamically respond to external magnetic fields. The perpendicular orientation of magnetic moments allows the magnet system to better accommodate varying MRI field directions without experiencing excessive torque or demagnetization.
3Reliability
If multiple elongate diametrically magnetized magnets are used to achieve MRI compatibility, then torque is reduced, but the amount of magnetic material increases and manufacturing costs increase
Solution Approach 1:
The design extracts only the essential magnetic elements needed for functionality. By using just two magnets (first and second magnets) with perpendicular magnetic moment orientation, the design removes unnecessary magnetic material while maintaining sufficient magnetic attraction force for headpiece positioning and achieving MRI compatibility.
Solution Approach 2:
Instead of using three or more magnets as in conventional designs, the invention uses exactly two magnets - a partial configuration that provides sufficient magnetic function while reducing material quantity and manufacturing complexity.
4Adaptability or versatility
If the distance between magnets is increased to reduce attraction force, then MRI compatibility is improved, but the attraction force between headpiece and implant may be insufficient
Solution Approach 1:
The design optimizes the distance parameter between the first and second magnets to achieve the desired balance. By carefully controlling this distance, the system maintains sufficient magnetic attraction force for proper headpiece positioning while ensuring MRI compatibility through reduced torque effects.
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 torque and magnetic material, minimizing MRI artifacts and manufacturing costs while ensuring effective alignment and attraction force between magnets, facilitating MRI compatibility without increasing magnet size.
Implementation Method 1
two elongate diametrically magnetized magnets that are located in the frame, that each define a longitudinal axis and a N-S direction, that are rotatable about the longitudinal axis relative to the frame, and that are attracted to one another with an attraction force F1
Implementation Method 2
The magnets will rotate into alignment with the magnetic field of the axially magnetized headpiece magnet, which maximizes the magnetic attraction between the magnets
Implementation Method 3
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 that is sufficient to dislodge or reverse the magnet
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.