MRI Implantable Lead Multi-Layer Coil Segmentation
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Solution Overview
Problem
Existing MRI compatible leads face issues with unwanted currents and tissue heating due to electromagnetic interactions, and the zebra coil structure's performance is affected by varying DC resistance and unstable resonant frequencies, especially during cyclic deformation.
Innovation Solution
A multi-layer coil configuration with alternating insulated and non-insulated segments and a winding turn connective layer is used to maintain stable and small DC resistance, ensuring consistent electromagnetic performance and reducing RF heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a zebra coil structure with alternating insulated and non-insulated segments is used, then RF heating is reduced, but DC resistance becomes unstable during cyclic deformation
Solution Approach 1:
The coil is divided into alternating insulated and non-insulated segments along its length. The insulated segments (first and second) reduce RF current flow and heating, while the non-insulated segment (third) provides stable electrical connection. This segmentation allows the lead to benefit from reduced RF heating while maintaining stable DC resistance through the dedicated non-insulated connection segment.
Solution Approach 2:
Different segments of the coil have different insulation properties tailored to their specific functions. The first and second segments have insulation to reduce RF heating in those regions, while the third segment has no insulation to ensure stable DC electrical connection. This local differentiation of properties resolves the contradiction between RF heating reduction and DC resistance stability.
2Object-affected harmful factors
If insulated wire is used to form an inductor, then tissue heating is reduced, but electromagnetic performance becomes inconsistent
Solution Approach 1:
The inductor is constructed with segmented insulation along its length, with specific segments having insulation and others being non-insulated. This segmentation allows different portions to serve different functions: insulated portions reduce tissue heating, while non-insulated portions maintain consistent electromagnetic performance and stable electrical connection.
Solution Approach 2:
The inductor uses a composite structure combining insulated and non-insulated wire segments in a specific pattern. This composite approach allows the inductor to simultaneously achieve reduced tissue heating from the insulated portions and consistent electromagnetic performance from the non-insulated connection portions.
3Strength
If bare coil segments are used for torque transfer, then mechanical strength is improved, but resonant frequencies become unstable
Solution Approach 1:
The coil structure applies different properties to different segments: the first and second segments have insulation that stabilizes resonant frequencies and reduces RF heating, while the third segment is non-insulated to provide stable electrical connection. This local differentiation resolves the contradiction between mechanical strength and resonant frequency stability.
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
The multi-layer coil design stabilizes DC resistance and resonant frequencies, reducing unwanted tissue heating and improving the reliability of MRI compatible leads during cyclic deformation.
Implementation Method 1
The coil includes a first winding formed with multiple winding turns, the winding turns being segmented in an alternating pattern of insulated segments and non-insulated segments along the length of the lead body
Implementation Method 2
When exposed to electromagnetic fields, such as for example those present in magnetic resonance imaging ('MRI') systems, these leads may sustain undesired currents and or voltages that interact with the surrounding blood and tissue, potentially resulting in unwanted tissue heating
Data Source
AI summary
An implantable lead is provided that includes a lead body configured to be implanted in a patient. The lead body has a distal end and a proximal end, and a lumen extending between the distal and proximal ends and includes a connector assembly provided at the proximal end of the lead body. The connector assembly is configured to connect to an implantable medical device and includes an electrode provided proximate to the distal end of the lead body with the electrode configured to at least one of deliver stimulating pulses and sense electrical activity. A multi-layer coil is located within the lumen and extends at least partially along a length of the lead body. The coil includes a first winding formed with multiple winding turns, the winding turns being segmented in an alternating pattern of insulated segments and non-insulated segments along the length of the lead body. The multi-layer coil further includes a winding turn connective layer extending along and interconnecting the winding turns within at least one of the non-insulated segments. The multi-layer coil further includes a first winding formed with multiple winding turns, the winding turns being segmented into an alternating pattern of insulated segments and non-insulated segments along a length of the winding with a winding turn connective layer extending along and interconnecting the winding turns within at least one of the non-insulated segments.