Multistranded Conductor Assembly for Flexible Implant Fatigue Life
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Solution Overview
Problem
Multistranded conductors used in medical implants face challenges with durability and electrical performance due to repeated flexing and bending, leading to potential damage and compromised signal quality, particularly in applications requiring fine wires and high flexibility.
Innovation Solution
A new assembly sequence for multistranded conductors involves twisting and wrapping individual wires and bundles in the same direction to form a multistranded structure with improved wire density and reduced friction, using specific coatings to enhance durability and electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional multistranded conductors are used with fine wires for high flexibility, then flexibility is improved, but fatigue resistance deteriorates due to repeated flexing and bending
Solution Approach 1:
The conductor is divided into multiple individual wires (e.g., 7, 19, or 37 wires) stranded together in a hierarchical structure. Each wire is isolated from others, allowing independent movement during flexing, which prevents stress concentration and fatigue failure while maintaining overall flexibility of the conductor assembly.
Solution Approach 2:
The conductor uses composite construction combining multiple metal wires (such as iridium-coated platinum or other biocompatible metal combinations) with different mechanical and electrical properties. This composite structure optimizes both flexibility and fatigue resistance by distributing mechanical stresses across materials with complementary characteristics.
2Ease of operation
If fine wires are used to increase flexibility, then flexibility is improved, but wire density and signal quality deteriorate
Solution Approach 1:
The conductor transitions from a simple parallel arrangement to a three-dimensional helical stranding pattern. This dimensional change allows wires to be packed more efficiently in space, increasing effective wire density and cross-sectional area without compromising flexibility, as the helical structure naturally accommodates bending and flexing motions.
3Ease of manufacture
If conventional assembly sequences are used for multistranded conductors, then manufacturing is simpler, but friction between wires increases leading to damaged insulation and compromised electrical performance
Solution Approach 1:
Each wire is pre-coated with biocompatible metal layers (such as iridium, platinum, or other corrosion-resistant coatings) before stranding. This preliminary protective action prevents inter-wire corrosion and insulation damage that would otherwise occur during the stranding process and subsequent implantation, ensuring long-term electrical performance without complicating the assembly process.
Data Source
AI summary
Multistranded conductors adapted to in vivo environments and methods of making same are disclosed, wherein specific configurations, sequences and directions of wire wraps provide implantable multistranded coils with increased cycle life in in vivo environments as well as desirable electrical performance characteristics.