Dynamic Coil Conductor Assembly for Implantable Leads
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Solution Overview
Problem
Conventional biomedical implantable conductor assemblies face limitations in elongation and flex fatigue life due to the strain-induced coiling method, which restricts the number of conductors and compromises the mechanical properties of the leads.
Innovation Solution
A dynamic coil configuration formed at or below the yield point of insulated conductors, allowing for expansion and retention within tubular structures, enabling multiple conductors to elongate like a straight conductor while maintaining superior flex fatigue properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conductors are strained beyond the yield point to form self-supporting coils, then the coil configuration is retained, but the number of individual conductors is limited and flex fatigue life is reduced
Solution Approach 1:
The patent changes the stress parameter from beyond-yield-point straining to at-or-below-yield-point coiling. This parameter change allows the conductors to be coiled without permanent deformation, preserving their original mechanical properties and flex fatigue life while still achieving the desired coiled configuration through elastic deformation alone
Solution Approach 2:
The patent nests multiple conductors (16 or more) within a flexible polymer coating that forms the lead body structure. This nesting approach allows many conductors to be contained within the same spatial envelope without requiring each to be individually strained into a coil, thereby maintaining their flex fatigue properties while achieving high conductor density
2Quantity of substance
If multiple conductors are located in different planes for a given coil diameter, then conductor density increases, but flex fatigue life is reduced
Solution Approach 1:
The patent transitions from planar conductor arrangements to a three-dimensional configuration where conductors are distributed throughout the volume of the flexible lead body. By using the radial dimension (conductors at different radii from the central axis) in addition to angular positioning, the patent achieves high conductor density without the planar arrangement that causes flex fatigue
Solution Approach 2:
The patent changes the spatial distribution parameter from planar to three-dimensional radial distribution. This allows conductors to be positioned at multiple radii and angles within the lead body cross-section, maximizing the number of conductors that can be accommodated while maintaining adequate spacing and avoiding the flex fatigue issues associated with planar arrangements
3Reliability
If conductors are coiled at or below the yield point, then flex fatigue properties are maintained, but the conductors require mechanical restraints to retain coiled configuration
Solution Approach 1:
The patent merges the mechanical restraint function with the flexible polymer coating that forms the lead body. The coating itself serves as the restraint structure, eliminating the need for separate restraint components. This integration maintains the coiled configuration of conductors while preserving flex fatigue properties and reducing overall device complexity
Solution Approach 2:
The flexible polymer coating provides self-contained mechanical restraint through its elastic properties. The coating naturally constrains the conductors in their coiled configurations without requiring external restraint mechanisms. The material's inherent elasticity provides the restraint force, making the system self-sufficient and eliminating additional complexity
4Shape
If conventional coiling methods are used, then coil configuration is achieved, but elongation is limited to essentially zero
Solution Approach 1:
The patent creates a dynamic coil structure where the conductors can dynamically change their configuration between coiled and elongated states. The flexible polymer coating allows the conductors to expand axially under tension while maintaining their coiled configuration at rest, providing both coil shape and elongation capability through the dynamic interaction between conductor elasticity and coating flexibility
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 dynamic coil design allows for up to 16 discrete conductors to elongate by 10-35% while meeting bending radius and flex fatigue requirements, enhancing the mechanical performance and versatility of biomedical implantable conductor assemblies.
Implementation Method 1
A dynamic coil is located in the gap. The dynamic coil includes a plurality of insulated conductors that are coiled generally at or below a yield point. The dynamic coil is permitted to expand within the gap to engage an inner surface of the outer tubular structure in an expanded coiled configuration.
Implementation Method 2
At least one mechanical restraint at each of a distal end and a proximal end retains the dynamic coil in the tubular structures.
Data Source
AI summary
A method of making a therapy delivery element configured for at least partial insertion in a living body is disclosed. A conductor structure is coiled around a mandrel. A segment of the conductor structure is secured to the mandrel. After this, an outer tubular structure is positioned around the conductor structure. Portions of the conductor structure that are not secured are free to expand to an inside surface of the outer tubular structure. A lumen is formed by removing at least a portion of the mandrel.