Segmented Cochlear Implant Magnet for MRI Torque Reduction

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Solution Overview

Problem

Conventional cochlear implants are not compatible with MRI systems due to magnetic field misalignment, leading to torque-induced magnet reorientation, skin stress, and pain, necessitating surgical magnet removal and replacement, and potential biofilm and bacterial ingress through the magnet aperture.

Innovation Solution

A cochlear implant design with a magnet apparatus comprising two partial disk-shaped magnet members embedded within a flexible housing without a magnet aperture, allowing the magnet to rotate within the housing to minimize skin stress and eliminate the need for surgical magnet removal, featuring a diameter-to-thickness ratio of 2.5 or less and a lubricious coating to reduce friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional cochlear implant with a single disk-shaped magnet is used, then the implant can be positioned over the antenna for communication, but the magnet experiences torque-induced reorientation during MRI procedures causing skin stress and pain

Engineering Contradiction:

ImproveMRI compatibilityVSAvoidskin stress and pain

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The single disk-shaped magnet is segmented into two partial disk-shaped magnet members with opposite polarities. This segmentation allows each magnet member to independently rotate in response to MRI magnetic fields, distributing the torque and preventing the severe skin stress and pain caused by rotation of a single large magnet.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The magnet members are designed to be able to rotate dynamically within the housing in response to external magnetic fields during MRI procedures. This dynamic adaptation allows the magnets to realign with the MRI field without causing harmful stress concentrations, making the implant MRI-compatible while minimizing patient discomfort.

Inventive Principle:

Principle #15Dynamics

2Ease of repair

If a magnet aperture is provided in the housing for magnet insertion and removal, then the magnet can be accessed for replacement, but the aperture allows biofilm and bacterial ingress

Engineering Contradiction:

Improvemagnet replacementVSAvoidbiofilm and bacterial ingress

Core Design Contradiction:

Ease of repairVSObject-affected harmful factors

Solution Approach 1:

The harmful feature (aperture) is completely removed from the housing design. The magnet is instead accessed through a minimally invasive percutaneous procedure that does not require a permanent opening in the housing, thereby eliminating the pathway for biofilm and bacterial ingress while still allowing magnet replacement when necessary.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The seal interface is designed as a temporary, disposable element that can be pierced or accessed percutaneously for magnet replacement, then sealed again. This approach prioritizes long-term infection prevention over repeated easy access, accepting that magnet replacement will require minor surgical intervention rather than simple user-accessible openings.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Stability of the object's composition

If the magnet diameter is large for stable positioning, then the magnet can maintain position over the antenna, but the magnet causes greater skin stress during MRI procedures

Engineering Contradiction:

Improvemagnet positioning stabilityVSAvoidskin stress during MRI

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The large disk-shaped magnet is divided into two smaller partial disk-shaped magnet members. Each smaller magnet experiences less torque during MRI procedures, reducing skin stress and pain, while the combined magnetic field strength and positioning capability of both magnets together maintains stable positioning over the antenna.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The magnet members are designed to rotate dynamically within the housing during MRI procedures to realign with external magnetic fields. This dynamic behavior reduces the effective torque transmitted to the skin, minimizing skin stress and pain while maintaining positioning stability through controlled rotation rather than rigid resistance.

Inventive Principle:

Principle #15Dynamics

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

Reduces skin stress and pain during MRI procedures by minimizing the distance change between the skin and bone, eliminating the need for surgical magnet removal and replacement, and preventing biofilm and bacterial ingress by eliminating the magnet aperture.

Implementation Method 1

allowing the magnet to rotate within the housing to minimize skin stress... during MRI procedures

Methodology Applied

Scientific EffectMagnetic field alignment: Magnetic Field

Implementation Method 2

featuring a diameter-to-thickness ratio of 2.5 or less and a lubricious coating to reduce friction

Methodology Applied

Scientific EffectFriction reduction: Lubrication

Data Source

PatentUS10646718B2Cochlear implants and magnets for use with same

Publication Date: 2020.05.12 ADVANCED BIONICS AG

AI summary

A cochlear implant including a cochlear lead, a housing, a magnet apparatus located within the flexible housing and including a first partial disk shaped magnet member and a second partial disk shaped magnet member spaced apart from the first partial disk shaped magnet member, an antenna within the housing, and a stimulation processor.