Variable Stiffness Catheter Liners with Inner Grooves
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Solution Overview
Problem
Conventional catheter devices face limitations in axial and torsional response, distribution of bending forces, and smooth bending stiffness profile due to abrupt changes in material stiffness, leading to mechanical stress concentration, kinking issues, and navigation complications in tortuous vasculature.
Innovation Solution
The catheter design incorporates a liner with grooves on its inner surface, which increases flexibility by reducing material resistance to bending while maintaining pushability, featuring a variable stiffness profile achieved through helical, ring, or short disconnected groove patterns, and formed using extrusion over a mandrel or cutting methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional catheter devices use different materials to provide a gradient in bending stiffness, then the bending stiffness varies from proximal to distal end, but abrupt step changes in stiffness occur at material transitions causing mechanical stress concentration and kink points
Solution Approach 1:
The liner incorporates grooves with varying depth, width, and spacing at different locations along its length. This creates local variations in wall thickness and material distribution, producing a gradient in bending stiffness without abrupt material transitions. The grooved structure allows each section to have customized mechanical properties while maintaining material continuity throughout the liner.
2Ease of operation
If the catheter liner is made more flexible to navigate tortuous vasculature, then navigation capability improves, but pushability and structural integrity deteriorate
Solution Approach 1:
The liner is segmented into multiple sections along its length, with each section containing grooves of specific depth, width, and spacing patterns. This segmentation allows different portions of the liner to have different flexibility characteristics - distal sections can be more flexible for navigation while proximal sections maintain greater stiffness for pushability. The grooved structure effectively divides the liner into functional zones with optimized mechanical properties.
3Stability of the object's composition
If grooves are added to the inner surface of the liner to increase flexibility, then bending resistance decreases, but manufacturing complexity increases
Solution Approach 1:
The grooves are formed in the liner during the extrusion or molding process itself, rather than as a separate post-processing step. By incorporating groove-forming features into the mold or extrusion tooling, the complex grooved structure is created simultaneously with the liner formation. This preliminary action integrates what would otherwise be separate manufacturing operations into a single process, reducing overall manufacturing complexity despite the intricate groove patterns.
Data Source
AI summary
Disclosed are embodiments for catheters and catheter liners including grooves on the inner surface of the liner. The grooves may improve the flexibility of the catheter while retaining a good stiffness profile. Also disclosed are methods for introducing the grooves on the inner surface of the liner.