Cochlear Implant Magnet Clip for MRI Torque Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing implantable medical devices with magnet arrangements face challenges during Magnetic Resonance Imaging (MRI) due to torque and demagnetization issues, leading to potential tissue damage and imaging artifacts, and often restrict or limit MRI usage to lower field strengths.
Innovation Solution
An implantable medical device design featuring a u-shaped magnet clip that slides over the coil case, allowing for easy removal and replacement of the implant magnet with a magnetic field direction parallel to the lateral surface, using biocompatible materials like PEEK or FEP, and a magnet receptacle with an angled side wall for improved sliding and fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional implant magnet with perpendicular magnetic axis is used, then the magnet can effectively hold the external transmitter housing in place, but the magnet experiences torque and demagnetization during MRI, causing displacement, tissue damage, and imaging artifacts
Solution Approach 1:
The magnet is pre-oriented with its magnetic axis parallel to the skin surface (perpendicular to the conventional orientation) so that during MRI, the magnetic field interaction produces minimal torque and demagnetization. This preliminary positioning counteracts the harmful MRI effects before they occur.
Solution Approach 2:
The magnetic axis orientation parameter is changed from perpendicular to the skin (conventional) to parallel to the skin surface. This parameter change fundamentally alters how the magnet interacts with MRI fields, reducing torque and demagnetization while maintaining holding force through the magnet receptacle design.
2Object-affected harmful factors
If a stiffening ring is added around the magnet to resist torques, then the magnet can be held more securely during MRI, but the device complexity and surgical procedure difficulty increase
Solution Approach 1:
The stiffening ring is extracted from the implantable portion and placed only in the external transmitter housing. This external ring provides torque resistance during MRI without adding complexity to the implanted device or requiring additional surgical steps for magnet retention.
Solution Approach 2:
The magnet receptacle acts as an intermediary mechanism between the magnet and the external housing. It provides a secure mounting path that guides and constrains the magnet, eliminating the need for complex internal stiffening structures within the implant itself.
3Ease of operation
If a magnet mounting path is provided for easy magnet exchange, then the magnet can be quickly replaced after MRI, but the device complexity increases with additional structural components
Solution Approach 1:
The magnet receptacle is pre-configured with a mounting path and guide structures during manufacturing. This preliminary preparation allows the magnet to be easily exchanged by simply sliding it along the predetermined path, eliminating the need for complex removal and reinstallation procedures.
Solution Approach 2:
The magnet is nested within the coil case and secured through the magnet receptacle structure. This nested arrangement allows the magnet to be held securely during normal operation while providing a clear extraction path for easy removal and replacement when needed.
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
Enables safe MRI compatibility with minimal surgical incision and easy magnet exchange, reducing tissue risk and imaging artifacts, while maintaining secure magnet positioning.
Implementation Method 1
cooperating attachment magnets located in the implant and the external part to magnetically hold the external part in place over the implant
Implementation Method 2
held in place by interaction between the internal magnetic field lines and the external magnetic field lines
Implementation Method 3
the strong static magnetic field from the MRI creates a torque on the internal magnet, which may displace the internal magnet or the whole implant housing out of proper position
Implementation Method 4
Interactions occur between the implant magnet and the applied external magnetic field for the MRI
Data Source
AI summary
An implantable medical device includes an implantable coil case that contains a communications coil. A magnet receptacle is located within the coil case at the radial center and has a magnet opening in one of the lateral surface or the medial surface of the coil case. A magnet fitting groove is recessed into one of the lateral or medial surface of the coil case and extends from the magnet opening to the outer circumference of the coil case. A u-shaped implant magnet clip has parallel clip legs that are connected at a closed end of the u-shape, and an implant magnet is attached to one of the clip legs. The coil case and the magnet clip are configured to cooperate for a portion of the coil case to fit between the clip legs and the implant magnet to slide through the magnet fitting groove and fit through the magnet opening into the magnet receptacle.