Segmented Shield for Auditory Coil RF Link Stability
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Solution Overview
Problem
Cochlear implants face inefficiencies in RF link due to magnetic flux interference from external magnets, leading to sensitive coil-tuned frequencies and reduced power transfer efficiency, which is exacerbated by the use of ferrite shields that add weight and affect tuning frequencies.
Innovation Solution
A shaped shield material is placed between the external coil and sound processing hardware to minimize adverse magnetic flux effects, optimizing coil coupling and reducing the impact of magnet strength variations on tuned frequencies by increasing the inner diameter of the shield, thereby maintaining efficient RF links across different magnet strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a ferrite shield is installed between the external coil and speech processing hardware to improve RF link efficiency, then RF link efficiency is improved, but the coil-tuned frequency becomes unacceptably sensitive to magnetic flux from the external magnet
Solution Approach 1:
The shield is divided into two separate components: an inner shield and an outer shield, positioned at different distances from the external coil. This segmentation allows each shield to perform its function independently, with the inner shield providing frequency stability and the outer shield providing RF shielding, thereby resolving the contradiction between RF link efficiency and frequency stability.
Solution Approach 2:
A non-magnetic material spacer is introduced as an intermediary between the external coil and the ferrite shields. This spacer positions the shields at optimal distances to provide RF shielding while minimizing their impact on the coil-tuned frequency, thus maintaining both RF link efficiency and frequency stability.
2Loss of energy
If a shield of ferrite or other magnetic material is installed to improve RF link efficiency, then power transfer efficiency is improved, but the shield adds weight to the external portion
Solution Approach 1:
The shield system uses different materials with different magnetic properties in different locations: the inner shield is positioned closer to the coil where magnetic shielding is most critical for frequency stability, while the outer shield provides additional RF protection. This local differentiation optimizes shielding effectiveness while minimizing overall weight compared to a single thick shield.
Solution Approach 2:
The shield system combines different materials with complementary properties: ferrite material for magnetic shielding and non-magnetic spacer materials for positioning and structural support. This composite approach achieves effective RF shielding and frequency stability while distributing the weight and minimizing the total mass of the shielding system.
3Object-affected harmful factors
If a ferrite shield is used to block magnetic flux, then magnetic flux interference is reduced, but the shield affects the tuning frequencies of the coil
Solution Approach 1:
The shield is segmented into inner and outer portions positioned at different distances from the external coil. The inner shield is optimized for blocking magnetic flux interference, while the outer shield provides additional protection. This segmentation allows the system to achieve effective magnetic shielding while maintaining tuning frequency accuracy through proper spatial arrangement.
Solution Approach 2:
A non-magnetic material spacer serves as an intermediary element that positions the ferrite shields at optimal distances from the external coil. This spacer ensures that the shields provide sufficient magnetic flux blocking while minimizing their impact on the coil's tuning frequency, thus maintaining both interference protection and frequency accuracy.
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 enhances the coil quality factor, reduces the sensitivity of tuned frequencies to magnet strength changes, and maintains efficient RF link performance, extending battery life and improving data integrity across varying skin flap thicknesses.
Implementation Method 1
A shaped shield material can be placed between the external coil and the sound processing hardware to improve efficiency and effectiveness with the implanted coil, and minimize adverse effects caused by the magnet
Implementation Method 2
The external portion of the auditory prosthesis includes a magnet and is powered by an on-board battery and sends signals via a coil. An implanted coil receives the signals
Data Source
AI summary
Systems and apparatuses are used to transmit data between external and internal portions of auditory prostheses or other medical devices. The external portion of the auditory prosthesis includes a magnet and an implanted coil that provides stimulation to the device recipient. A shaped shield material can be placed between the external coil and the sound processing hardware to improve efficiency and effectiveness between the external coil and implanted coil. Adverse effects on tuning frequencies can be reduced by disposing the shield material away from the magnet.