Composite Elongate Shaft Structure for Flexibility and Stretch Resistance
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Solution Overview
Problem
There is a need for alternative medical devices and manufacturing methods that provide flexibility and resistance to stretching for intracorporeal devices such as guidewires and catheters.
Innovation Solution
A method involving the use of a polymeric sheath and metallic tubular member, secured by a longitudinal support filament, where a polymeric tubular member is reflowed to secure the filament relative to the sheath and tubular member, creating a flexible yet stretch-resistant elongate shaft for medical device delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polymeric shaft is used to provide flexibility, then the shaft can bend and navigate complex anatomical paths, but the shaft becomes susceptible to axial stretching which compromises delivery control
Solution Approach 1:
The shaft is constructed as a composite structure with a polymeric outer sheath providing flexibility and a longitudinal support filament (metallic or stiff polymeric) embedded within to resist axial stretching. This combination allows the shaft to bend easily while maintaining resistance to elongation during device delivery.
Solution Approach 2:
The support filament is positioned specifically along the longitudinal axis within the polymeric sheath, providing localized reinforcement only where axial strength is needed, while the rest of the polymeric structure maintains its flexibility for navigation.
2Reliability
If multiple components (polymeric sheath, metallic tubular member, support filament) are assembled to achieve both flexibility and stretch resistance, then performance requirements are met, but the manufacturing process becomes more complex
Solution Approach 1:
The support filament is inserted into the polymeric sheath and positioned alongside the metallic tubular member before the polymeric tubular member is reflowed. This preliminary positioning ensures proper alignment and integration of components, simplifying the overall assembly process while achieving the desired composite structure.
Solution Approach 2:
Multiple components (polymeric sheath, metallic tubular member, support filament) are combined into a single integrated assembly through the reflowing process, where the polymeric tubular member is heated to fuse the components together, creating a unified structure that functions as one cohesive unit.
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 method produces a shaft that maintains flexibility while resisting axial stretching, facilitating the delivery of medical devices like stents and embolic coils with enhanced control and stability.
Implementation Method 1
reflowing the polymeric tubular member to secure the longitudinal support filament relative to the polymeric sheath and the metallic tubular member
Data Source
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AI summary
A method of manufacturing an elongate shaft for delivery of a medical device may include disposing a polymeric sheath having a lumen extending therethrough over a mandrel; sliding a proximal portion of the polymeric sheath into a lumen of a metallic tubular member; placing a polymeric tubular member over the distal portion of the polymeric sheath and a distal portion of the metallic tubular member; fixedly attaching a proximal coupler to a distal end of a longitudinal support filament; inserting a proximal end of the longitudinal support filament between the polymeric sheath and the polymeric tubular member to position the longitudinal support filament alongside the distal portion of the metallic tubular member and a distal portion of the polymeric sheath; and reflowing the polymeric tubular member to secure the longitudinal support filament relative to the polymeric sheath and the metallic tubular member.