Polymer-Matrix Composite Shield for Medical Leads
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Solution Overview
Problem
Implantable medical device leads are not adequately shielded against electromagnetic radiation, leading to tissue heating and inappropriate device responses due to induced electric currents, which existing polymer-matrix composite coverings with discontinuous fillers fail to effectively mitigate.
Innovation Solution
A medical electrical lead with a conductor assembly covered by an insulating layer and a polymer-matrix composite shield containing nano-sized metal and non-metallic conductive structures, such as carbon nanofibers and nano-sized metal structures, which provide enhanced electromagnetic shielding effectiveness by minimizing the skin effect and increasing the usable cross-sectional area for conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional metal wire shields are used, then electromagnetic shielding effectiveness is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies composite materials by combining polymer matrix with discontinuous conductive fillers (metal particles, carbon fibers, or carbon nanotubes) to create a shield covering that provides electromagnetic shielding without the complexity of traditional metal wire braids. The composite material integrates multiple functions (shielding, flexibility, insulation) into a single layer, resolving the contradiction between shielding effectiveness and device complexity.
2Ease of manufacture
If discontinuous filler polymer-matrix composites are used, then ease of manufacture and moldability are improved, but electromagnetic shielding effectiveness deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the size, shape, concentration, and distribution of discontinuous conductive fillers within the polymer matrix. By controlling filler parameters (e.g., using nanoscale particles or fibers, adjusting volume fraction, modifying aspect ratio), the patent achieves effective electromagnetic shielding while maintaining the ease of manufacture and moldability inherent to polymer-matrix composites.
3Reliability
If larger cross-sectional area fillers are used, then conductivity is improved, but skin effect increases reducing usable area
Solution Approach 1:
The patent applies segmentation by using discontinuous conductive fillers (particles, short fibers, or nanotubes) distributed throughout the polymer matrix rather than continuous large conductors. This segmentation creates multiple small conductive pathways that reduce the skin effect while maintaining overall conductivity, as the electromagnetic fields interact with many small surfaces rather than one large surface.
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 use of nano-sized conductive structures in polymer-matrix composites significantly enhances electromagnetic shielding, reducing tissue heating and inappropriate device responses, while offering improved mechanical properties and cost-effectiveness compared to traditional metal wire shields.
Implementation Method 1
provide enhanced electromagnetic shielding effectiveness by minimizing the skin effect and increasing the usable cross-sectional area for conductivity
Implementation Method 2
A medical electrical lead with a conductor assembly covered by an insulating layer and a polymer-matrix composite shield containing nano-sized metal and non-metallic conductive structures, which provide enhanced electromagnetic shielding effectiveness
Data Source
AI summary
A medical electrical lead having a conductor assembly covered by an insulating layer, and a shield covering positioned adjacent or proximate to at least a portion of the insulating layer in order to shield the conductor assembly from one or more electromagnetic fields. The shield covering is formed of a polymer-matrix composite. The polymer-matrix composite includes a polymeric resin having discontinuous conductive fillers provided therein. The discontinuous conductive fillers include one or more of nano-sized metal structures and nano-sized non-metallic conductive structures. The nano-sized non-metallic conductive structures can have a coating formed of one or more metals. The nano-sized non-metallic conductive structures can be formed of carbon. In turn, the nano-sized non-metallic conductive structures can include one or more of carbon nanofibers, carbon filaments, carbon nanotubes, and carbon nanoflakes.