Elastomeric Magnet Management for MRI-Compatible Cochlear Implants

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Solution Overview

Problem

Existing hearing prostheses, such as cochlear implants, face challenges in managing magnet rotation and alignment within the body when subjected to external magnetic fields, which can affect device functionality and compatibility with MRI scans.

Innovation Solution

The implantable medical device incorporates a magnet and a body structure that moves apart upon initial rotation under an externally generated magnetic field, limiting further rotation and maintaining alignment through the use of slidable components and an elastomeric housing with a slit, thereby resisting rotation and ensuring proper magnet positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the magnet is allowed to rotate freely in the implantable device, then the device can be simpler in structure, but the magnet may rotate excessively under external magnetic fields causing misalignment and reduced reliability

Engineering Contradiction:

ImprovestructureVSAvoidmagnet alignment

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent employs an elastomeric body that acts as a flexible containment structure for the magnet. This elastomeric material allows controlled movement and rotation of the magnet while maintaining overall structural integrity and preventing excessive rotation under external magnetic fields such as those during MRI scans.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent modifies the physical properties of the containment structure by using an elastomeric body with specific mechanical properties. The elastomeric material's flexibility and elasticity parameters are chosen to allow initial rotation for proper alignment while resisting further excessive rotation, thus controlling the magnet's movement characteristics.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If structural components are added to limit magnet rotation, then magnet alignment is improved, but the device complexity increases

Engineering Contradiction:

Improvemagnet alignmentVSAvoidstructural components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the magnet containment function with the elastomeric body structure itself. Rather than adding separate rigid constraint mechanisms, the elastomeric body integrates both the containment and the rotational control functions into a single unified structure, reducing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent implements a dynamic solution where the elastomeric body allows the magnet to rotate initially for proper alignment under external magnetic fields, then naturally limits further rotation through its material properties. This dynamic behavior replaces the need for complex mechanical stoppers or rigid constraints.

Inventive Principle:

Principle #15Dynamics

3Stability of the object's composition

If the magnet is constrained to prevent rotation, then alignment stability is improved, but the device cannot adapt to external magnetic fields during MRI scans

Engineering Contradiction:

Improvemagnet alignmentVSAvoidMRI compatibility

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The elastomeric body is pre-configured to allow a specific range of rotation for initial magnet alignment before implantation. This preliminary design enables the magnet to achieve proper orientation while the elastomeric material's inherent properties subsequently prevent excessive rotation during MRI procedures, balancing adaptability and stability.

Inventive Principle:

Principle #10Preliminary action

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

This design enhances the stability and compatibility of hearing prostheses, such as cochlear implants, by limiting excessive magnet rotation and maintaining alignment, ensuring reliable operation and compatibility with MRI scans.

Implementation Method 1

an externally generated magnetic field that imparts a torque onto the magnet apparatus

Methodology Applied

Scientific EffectMagnetic torque: Torque

Implementation Method 2

The implantable medical device resists rotation of the magnet apparatus relative to the body in at least one plane when subjected to an externally generated magnetic field that imparts a torque onto the magnet apparatus

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12383739B2Magnet management MRI compatibility

Publication Date: 2025.08.12 COCHLEAR LIMITED

AI summary

An implantable medical device, including a magnet and a body encompassing the magnet, wherein the implantable medical device includes structural components in the body configured to move away from one another upon initial rotation of the magnet relative to the body when the magnet is subjected to an externally generated magnetic field, thereby limiting rotation of the magnet beyond the initial rotation.