Implantable Device Housing with Sealed Openings for Eddy Current Reduction
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Solution Overview
Problem
Implantable medical devices face challenges in efficiently receiving electromagnetic energy for recharging due to the generation of large eddy currents in conductive housing materials like titanium, which interfere with the magnetic field and reduce energy transfer efficiency.
Innovation Solution
The implementation of an implantable medical device with openings in its sidewall hermetically sealed by nonconductive materials and windows on its housing, which form high resistance tortuous paths for eddy current loops, reducing the intensity of interfering magnetic fields and improving recharge efficiency by allowing electromagnetic energy to be transmitted to charging coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the housing is made of conductive material like titanium, then the housing provides structural strength and biocompatibility, but large eddy currents are generated that interfere with the magnetic field and reduce energy transfer efficiency
Solution Approach 1:
The housing is segmented by introducing openings that break the continuous conductive path of the titanium housing. This segmentation creates high resistance tortuous paths for eddy currents, reducing their intensity while maintaining the structural integrity of the housing through strategic placement and sizing of the openings.
Solution Approach 2:
Nonconductive sealing material is introduced as an intermediary substance within the openings of the housing. This material hermetically seals the openings while simultaneously blocking eddy current paths, mediating between the need for structural integrity and the need to reduce electromagnetic interference.
2Loss of energy
If openings are created in the housing to reduce eddy currents, then energy transfer efficiency is improved, but the housing hermeticity is compromised
Solution Approach 1:
Hermetic sealing material is used as an intermediary to fill and seal the openings in the housing. This material simultaneously maintains the hermetic seal required for implantable device reliability and creates sufficient resistance to eddy current paths to improve wireless energy transfer efficiency.
Solution Approach 2:
The housing structure is modified with localized openings at specific positions and dimensions that are optimized to disrupt eddy current paths while minimizing impact on overall hermeticity. The sealing material properties are also locally optimized to provide both hermetic sealing and appropriate electrical resistance.
3Productivity
If the surface area of conductive material exposed to electromagnetic energy is reduced, then eddy currents are minimized and recharge efficiency is improved, but the housing structural integrity is compromised
Solution Approach 1:
The continuous conductive surface of the housing is segmented into isolated regions by openings, reducing the effective surface area exposed to electromagnetic energy. This segmentation minimizes eddy current generation while the strategic design of opening size and placement preserves the structural integrity of the remaining housing material.
Solution Approach 2:
The housing is transformed from a solid conductive material into a composite structure combining conductive titanium with nonconductive sealing materials. This composite approach reduces the effective conductive surface area for eddy currents while maintaining structural strength through the combination of materials and optimized geometry.
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 design enhances the efficiency of energy transfer to the device by minimizing eddy currents and ensuring effective recharging of implantable medical devices, such as pacemakers and leadless cardiac monitors, by creating pathways that reduce the surface area of conductive materials exposed to electromagnetic energy.
Implementation Method 1
The openings can be hermetically sealed by a nonconductive material disposed on the housing
Implementation Method 2
At least one of the window or the sealed opening is adapted to transmit electromagnetic energy
Implementation Method 3
The implementation of an implantable medical device with openings in its sidewall hermetically sealed by nonconductive materials and windows on its housing, which form high resistance tortuous paths for eddy current loops, reducing the intensity of interfering magnetic fields
Implementation Method 4
a charging coil disposed within the housing and adapted to receive electromagnetic energy directed through the window or the sealed opening
Data Source
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AI summary
Various embodiments of an implantable medical device and a wireless energy transfer system that includes the implantable medical device are disclosed. The device includes a housing that has a first major surface and a second major surface, a sidewall that extends between the first major surface and the second major surface, and an opening disposed in the sidewall. The device further includes a window disposed on at least one of the first major surface or second major surface of the housing, and a nonconductive material disposed on the housing, wherein the opening is hermetically sealed by the nonconductive material. At least one of the window or the sealed opening is adapted to transmit electromagnetic energy.