Multilayer Catheter Shaft Preventing Flattening Under Pressure
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Solution Overview
Problem
Conventional catheters experience reduced slidability due to flattening when pressurized, which deteriorates the insertion and passage of guide wires through blood vessels during angioplasty procedures.
Innovation Solution
A catheter design featuring a multilayer tube structure with a first layer and a second layer, where the second layer has a higher crystallinity degree and lower melting point than the first layer, and a cross-sectional area ratio of 0.7 or less, to maintain initial roundness and prevent flattening under pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer or multilayer shaft is used in a catheter, then the catheter can be manufactured with basic structural requirements, but the shaft flattens when pressurized which deteriorates slidability with guide wire
Solution Approach 1:
The patent applies composite materials by constructing the shaft from multiple layers with different material properties. Specifically, it uses an inner layer with high elasticity ( Shore hardness 50-80) and an outer layer with high rigidity (Shore hardness 30-60), creating a composite structure that prevents flattening while maintaining guidability. This composite approach resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The patent applies local quality by giving different regions of the shaft different mechanical properties through the layered structure. The inner layer provides local elasticity for guidability, while the outer layer provides local rigidity to prevent flattening under pressure. This spatial differentiation of material properties allows the shaft to simultaneously achieve roundness maintenance and good slidability.
2Shape
If the shaft is made more rigid to prevent flattening, then roundness is maintained under pressure, but flexibility and slidability deteriorate
Solution Approach 1:
The patent resolves this contradiction by using composite materials with differentiated Shore hardness values. The inner layer (Shore hardness 50-80) provides flexibility and slidability, while the outer layer (Shore hardness 30-60) provides rigidity for roundness maintenance. The combination allows the shaft to be both flexible enough for navigation and rigid enough to prevent flattening.
Solution Approach 2:
The patent applies segmentation by dividing the shaft into multiple functional layers. The inner layer segment handles the function of flexibility and guidability, while the outer layer segment handles the function of structural support and roundness maintenance. This segmentation allows each layer to optimize its specific function without compromising the other.
3Ease of operation
If the shaft is made more flexible to improve slidability, then guidability is enhanced, but the shaft is more likely to flatten when pressurized
Solution Approach 1:
The patent resolves this contradiction by using composite materials where the inner layer (higher Shore hardness 50-80) provides flexibility for slidability, while the outer layer (lower Shore hardness 30-60) provides structural support to prevent flattening. The composite structure allows the flexible inner layer to maintain guidability while the rigid outer layer preserves roundness under pressure.
Solution Approach 2:
The patent applies segmentation by separating the flexibility function (inner layer) from the structural support function (outer layer). This allows the inner layer to be optimized for slidability while the outer layer is optimized for preventing flattening, resolving the contradiction between flexibility and shape maintenance.
Data Source
AI summary
A catheter may include a distal side and a proximal side comprising a shaft having an outer tubular member, and an insertion member. The catheter may have at least a part of the insertion member in an axial direction disposed in the outer tubular member. At least one outer tubular member or insertion member is a multilayer tube having a first layer and a second layer laminated with the first layer. In a cross-section perpendicular to an axial direction of the multilayer tube, a ratio of cross-sectional areas of the second layer to the first layer is 0.7 or less.