Cochlear Implant Magnet Assembly for MRI Alignment and Retention

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Solution Overview

Problem

Conventional cochlear implants are not MRI-compatible due to misalignment and demagnetization issues with existing magnet assemblies, leading to surgical removal and reinsertion, and face challenges with weak magnetic attraction forces due to thick skin flaps.

Innovation Solution

A magnet assembly with a case, rotatable frame, and three elongate magnets, including a non-rotatable magnet between two rotatable magnets, enhances magnetic alignment and attraction, allowing optimal alignment with MRI fields and reducing torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a diametrically magnetized disk-shaped magnet is used in conventional cochlear implants, then the magnet can be positioned within the implant housing, but the magnet experiences demagnetization or excessive torque when misaligned with MRI magnetic fields by 30° or more, leading to potential dislodgement or implant dislocation

Engineering Contradiction:

Improvemagnet stability during MRIVSAvoidtorque and demagnetization from misaligned MRI fields

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The single disk-shaped magnet is segmented into multiple elongate diametrically magnetized magnets arranged in a specific configuration. This segmentation allows each magnet to experience reduced torque individually while collectively providing stable positioning, with at least one magnet being rotatable to align with the external magnet during MRI procedures

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The magnet assembly incorporates rotatable magnets that can dynamically adjust their orientation in response to external magnetic fields. During MRI, the rotatable magnet aligns with the external magnet's field, minimizing torque and preventing dislodgement, while maintaining functional positioning when the external field is absent

Inventive Principle:

Principle #15Dynamics

2Reliability

If the skin flap thickness is increased (3 mm to 11 mm or more), then there is greater tissue coverage and protection, but the magnetic attraction force between the external magnet and implant magnet becomes weaker, reducing retention

Engineering Contradiction:

Improvemagnetic retention forceVSAvoidskin flap thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

Multiple elongate magnets are combined in an array configuration within the implant housing, creating a composite magnetic field that collectively overcomes the attenuation effect of thick skin flaps. The combined magnetic force from multiple magnets provides sufficient attraction force to maintain reliable retention despite increased tissue thickness

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If axially magnetized disk-shaped magnets are used in conventional cochlear implants, then the magnets can be easily manufactured and positioned, but the magnets are not compatible with MRI systems and must be surgically removed and reinserted

Engineering Contradiction:

Improvemagnet fabricationVSAvoidMRI compatibility

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Instead of using axially magnetized magnets that are simple to manufacture but incompatible with MRI, the invention inverts the magnetization approach by using diametrically magnetized magnets. These magnets are configured to be MRI-compatible through their specific magnetic orientation and rotatable design, while still providing effective magnetic retention functionality

Inventive Principle:

Principle #13The other way round (Inversion)

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

Improves magnetic retention and alignment, minimizing torque and friction, ensuring stable operation during MRI procedures without surgical intervention.

Implementation Method 1

allows 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

Methodology Applied

Scientific EffectMagnetic alignment: Magnetism

Implementation Method 2

The skin and subcutaneous tissue that separates the headpiece magnet and implant magnet is sometimes referred to as the 'skin flap,' which is frequently 3 mm to 11 mm thick, and is sometimes thicker

Methodology Applied

Scientific EffectMagnetic attraction: Magnetism

Data Source

PatentUS20260077195A1Cochlear implants having MRI-compatible magnet assemblies and associated systems and methods

Publication Date: 2026.03.19 ADVANCED BIONICS LLC

AI summary

A magnet assembly including a case defining a central axis, a magnet frame within the case and rotatable about the central axis of the case, and first, second and third elongate magnets that are located within the frame, with the third elongate magnet located between the first and second elongate magnets, and that each define a longitudinal axis and a N-S direction that is perpendicular to the longitudinal axis. The first and third elongate magnets may be separated from one another by a first fixed non-zero distance that is perpendicular to at least one of their longitudinal axes, the second and third elongate magnets may be separated from one another by a second fixed non-zero distance that is perpendicular to at least one of their longitudinal axes, at least one of the elongate magnets is rotatable about its longitudinal axis relative to the frame, and at least one of the elongate magnets is not rotatable about its longitudinal axis relative to the frame.