Curved Strut Stent Resolving Radial Strength and Flexibility Trade-off
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Solution Overview
Problem
Stents with high radial strength tend to have lower longitudinal flexibility, leading to potential trauma and failure when deployed in vessels that flex or bend, as they often undergo severe strain and fatigue, and existing designs struggle to maintain structural integrity during crimping and expansion.
Innovation Solution
A close-cell structured stent with curved struts intersecting at angles between 90 to 170 degrees, featuring a three-dimensional tubular design, varying strut diameters, and a coating or fabric attachment for enhanced mechanical properties and delivery, manufactured using laser cutting or 4-axis rapid polymer fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stent design uses high radial strength structure, then radial strength is improved, but longitudinal flexibility deteriorates
Solution Approach 1:
The patent applies curved struts with specific curvature radii (R1, R2, R3) instead of straight struts. The curved geometry allows the stent to achieve both radial strength through the arching effect and longitudinal flexibility through the ability of curves to deform elastically during axial compression and flexing, resolving the contradiction between radial strength and longitudinal flexibility.
Solution Approach 2:
The patent optimizes specific geometric parameters including crossing angles (α, β, γ between 60-120 degrees), curvature radii (R1, R2, R3), and strut thickness ratios to achieve the desired balance. By carefully controlling these parameters, the stent structure achieves sufficient radial strength while maintaining longitudinal flexibility to accommodate vessel movement without fracture.
2Strength
If stent has high longitudinal rigidity, then radial strength is improved, but trauma to vessel increases due to compliance mismatch
Solution Approach 1:
The curved strut design with multiple arc segments allows the stent to better conform to the natural curvature of blood vessels. This geometric configuration reduces compliance mismatch by enabling the stent to flex with vessel movement while maintaining radial support, thereby reducing trauma at the stent-vessel interface.
Solution Approach 2:
The patent optimizes crossing angles (60-120 degrees) and curvature radii to create a structure that matches physiological vessel compliance. The specific parameter ranges are designed to allow the stent to deform elastically with vessel pulsation and movement, preventing stress concentration and trauma while maintaining sufficient radial strength for vessel support.
3Strength
If stent structure is made rigid for support, then radial strength is improved, but strain and fatigue increase under flexing and bending
Solution Approach 1:
The curved strut configuration with multiple arc segments distributed around the stent circumference creates a flexible framework that can accommodate flexing and bending without concentrating stress. The curved geometry allows for elastic deformation during physiological movement, distributing strain evenly across the structure and preventing fatigue failure while maintaining radial strength.
Solution Approach 2:
The stent is divided into multiple segments with curved struts arranged in a periodic pattern around the circumference. This segmentation allows each segment to deform independently during flexing and bending, distributing mechanical stress and preventing fatigue accumulation in any single location, thereby improving reliability under cyclic loading conditions.
4Ease of manufacture
If stent uses straight struts for simple structure, then manufacturing is easier, but radial strength and flexibility are compromised
Solution Approach 1:
The patent employs curved struts with defined curvature radii that can be manufactured using standard laser cutting or成形 techniques on tubular substrates. The curved geometry is achieved through controlled material removal or forming processes, maintaining ease of manufacture while significantly improving both radial strength through the arching effect and longitudinal flexibility through elastic deformation of the curved segments.
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 stent achieves excellent longitudinal flexibility and radial strength, allowing for effective crimping and expansion without structural damage, with curved struts providing greater strength and minimizing stent shortening ratio, thus reducing the risk of fracture and improving clinical applicability.
Implementation Method 1
The curved fiber struts may be made by any suitable method known in the art, for example, they may be laser cut from a tubular substrate
Data Source
Figure 1~2B
Figure 3~4B
Figure 5~5C
AI summary
Disclosed herein is a close-cell structured stent which is composed of curved struts that intersect at a crossing angle of 90 to 170 degrees in the longitudinal direction. Methods for making the stent, use of the stent as a vascular stent, an esophagus stent, an intestine stent, a bile conduct stent, or a urinary tract stent, and use of the stent in the manufacture of stent graft for the treatment of abdominal aortic aneurysms are also provided. The stent has both excellent longitudinal flexibility and radial strength.