Implant Actuator Mass Segmentation to Mitigate Eddy Currents

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Solution Overview

Problem

Eddy currents generated by magnetic flux in implantable medical devices, such as transcutaneous bone conduction devices, degrade the RF coupling link efficiency and hinder the development of smaller form-factor devices with improved communication performance and battery life.

Innovation Solution

The use of a unitary mass with electrically isolated conductive sub-masses and insulating material mitigates eddy currents, allowing the vibrating mass to be positioned closer to the RF communication coil, enhancing communication efficiency and reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a unitary mass is used in the actuator, then the device structure is simpler and manufacturing is easier, but eddy currents are generated that degrade RF coupling link efficiency

Engineering Contradiction:

Improveactuator manufacturingVSAvoidRF coupling link efficiency

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The unitary mass is segmented into multiple electrically isolated conductive sub-masses arranged in a circular pattern. This segmentation breaks the continuous conductive path that would otherwise allow large eddy currents to form, thereby reducing eddy current losses and improving RF coupling link efficiency while maintaining manufacturing simplicity.

Inventive Principle:

Principle #1Segmentation

2Use of energy by moving object

If the vibrating mass is positioned closer to the RF communication coil, then communication efficiency is enhanced and power consumption is reduced, but eddy current interference increases

Engineering Contradiction:

Improvepower consumptionVSAvoideddy current interference

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The conductive mass is divided into multiple electrically isolated sub-masses that can be positioned close to the RF communication coil. The electrical isolation between sub-masses prevents the formation of large eddy current loops, allowing the mass to be placed closer to the coil for improved communication efficiency without excessive eddy current interference.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Electrically insulating material is introduced between the conductive sub-masses to act as an intermediary that prevents electrical contact and eddy current formation. This allows the sub-masses to be positioned close to the RF coil while the insulating material blocks the harmful eddy current paths.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Volume of moving object

If the device form-factor is reduced, then smaller implantable devices are achieved, but eddy current effects become more significant

Engineering Contradiction:

Improvedevice form-factorVSAvoideddy current losses

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

The mass is segmented into multiple small electrically isolated sub-masses, which allows the overall device form-factor to be reduced while preventing large eddy current loops. The segmented structure inherently limits eddy current paths to smaller regions, reducing energy losses even in compact configurations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sub-masses are arranged in a circular pattern, utilizing two-dimensional spatial distribution to achieve compact form-factor while maintaining electrical isolation. This dimensional arrangement allows close spacing of sub-masses without creating continuous eddy current paths, enabling small device size with reduced eddy current losses.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 configuration improves RF coupling link efficiency and enables a smaller form-factor device with better communication performance and extended battery life by minimizing eddy current interference.

Implementation Method 1

a first electrical current flowing within the first circuitry generates a magnetic flux configured to magnetically induce a second electrical current to flow within the second circuitry

Methodology Applied

Scientific EffectMagnetic induction: Electromagnetic Induction

Implementation Method 2

Eddy currents generated by magnetic flux in implantable medical devices

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Data Source

PatentUS12520089B2Medical implant actuator with mass configured to mitigate eddy currents

Publication Date: 2026.01.06 COCHLEAR LIMITED

AI summary

An apparatus includes a housing configured to be implanted beneath a portion of skin of a recipient and first circuitry within the housing. The first circuitry is configured to wirelessly communicate with second circuitry of an external device positioned on or above the portion of skin. The apparatus further includes an actuator within the housing and configured to be in mechanical communication with a portion of bone of the recipient. The actuator includes a unitary mass configured to undergo vibratory motion within the housing. The unitary mass includes a plurality of electrically conductive sub-masses in mechanical communication with one another and electrically isolated from one another.