Segmented Catheter Shaft Structure for Flexibility and Kink Resistance
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Solution Overview
Problem
Existing catheters face a compromise between kink resistance and flexibility due to the use of materials with significantly different moduli of elasticity for the outer and inner layers, resulting in reduced flexibility.
Innovation Solution
A catheter shaft design featuring a helically wound inner structure with overlapping segments that allows for sliding relative to the outer structure, enhancing flexibility while maintaining kink resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an inner liner material with low coefficient of friction is used to ease delivery, then the ease of operation is improved, but the flexibility of the catheter shaft deteriorates due to significantly higher modulus of elasticity
Solution Approach 1:
The inner liner is segmented into discrete sections rather than being a continuous tube. These segments are positioned along the catheter shaft with spaces between them, allowing relative movement and improving flexibility while maintaining the low friction surface where needed for device delivery.
Solution Approach 2:
The inner liner transitions from a static, continuous structure to a dynamic, segmented structure that can move relative to itself and the outer jacket. This dynamic configuration allows the liner to adapt to bending and flexing of the catheter while maintaining its low friction properties during delivery.
2Adaptability or versatility
If conventional low durometer polymers are used to improve flexibility, then the flexibility is improved, but the kink resistance deteriorates due to insufficient structural rigidity
Solution Approach 1:
The catheter shaft uses a composite construction with an outer jacket made of flexible low durometer polymer and an inner liner made of different material properties. This composite structure combines the flexibility of the outer layer with the structural support needed for kink resistance, achieving both properties simultaneously.
Solution Approach 2:
Different regions of the catheter shaft have different structural properties. The outer jacket provides flexibility and kink resistance, while the segmented inner liner provides low friction surfaces in specific locations. Each component is optimized for its specific function rather than requiring the entire shaft to have uniform properties.
3Strength
If an outer jacket with high longitudinal rigidity is used to resist kinks, then the kink resistance is improved, but the overall flexibility of the catheter shaft deteriorates due to the rigid structure
Solution Approach 1:
The inner liner is divided into segments that can move independently relative to each other and the outer jacket. This segmentation allows the catheter to flex and bend more easily while the outer jacket maintains its kink-resistant structure, resolving the contradiction between rigidity and flexibility.
Solution Approach 2:
The catheter shaft incorporates dynamic elements through the segmented inner liner that can shift and move during catheter manipulation. This dynamic behavior allows the shaft to adapt to bending forces while the outer jacket provides stable kink resistance, achieving both flexibility and structural integrity.
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 design achieves a 25-60% reduction in bending stiffness compared to conventional catheters, providing improved flexibility without compromising kink resistance, especially beneficial for larger diameter catheters.
Implementation Method 1
only a portion of the outer surface of the inner structure is bonded to the inner surface of the outer structure; and the second portion of the inner structure is configured to slide relative to the first portion
Data Source
Figure 1A~1D
Figure 2A~2B
Figure 2C~2F
AI summary
Catheter shafts and associated devices, systems, and methods are disclosed herein, A representative catheter in accordance with an embodiment of the disclosure includes a generally tubular outer structure and an inner structure surrounded by the outer structure. The inner structure surrounds a catheter lumen. The inner structure includes over-lapping edges such that, when the catheter is bent along its longitudinal axis, the over-lapping edges move relative to one another.