Flexible Stent Meandering Patterns Resolve Radial Strength Trade-off
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Solution Overview
Problem
Existing stents face challenges such as causing obstruction or stenosis, inadequate flexibility, difficulty in navigating three-dimensional meandering lumens, and potential injury to blood vessels during introduction, especially when placed near branched vessels or requiring lateral holes, due to insufficient radial strength and flexibility.
Innovation Solution
A flexible stent design featuring two waved elements that are parallel and coupled by connecting elements, with adjustable gap widths between 40 to 70 µm, and materials like stainless steel or nickel-titanium alloys, allowing for improved radial strength and flexibility through meandering patterns and selective connection at wave crests and troughs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the stent is expanded to maintain luminal diameter, then the luminal diameter is held open, but the stent causes obstruction or stenosis at the edges due to inadequate flexibility
Solution Approach 1:
The stent is divided into multiple unit structures, each comprising two waved elements coupled by connecting elements. This segmentation allows each unit to independently flex while collectively providing radial strength, resolving the contradiction between flexibility and strength.
Solution Approach 2:
The stent employs waved elements with meandering patterns instead of straight rigid structures. The curved, wave-like geometry enables the stent to flex and conform to meandering lumens while the wave crests and troughs provide structural support for radial strength.
2Strength
If the stent structure is made rigid to provide radial strength, then radial strength is improved, but the stent cannot navigate three-dimensional meandering lumens
Solution Approach 1:
The stent transitions from a static rigid structure to a dynamic flexible structure. The waved elements can deform and adapt to the three-dimensional meandering lumens during introduction, while the connecting elements maintain structural integrity and radial strength when expanded.
Solution Approach 2:
The gap width between waved elements is optimized to 40-70 µm, and the amplitude and wavelength of the waved elements are carefully controlled. These parameter changes enable the stent to achieve both flexibility for navigation and radial strength for vessel support.
3Strength
If the gap between waved elements is reduced to increase radial strength, then radial strength is improved, but manufacturing precision becomes difficult to achieve
Solution Approach 1:
The gap width is optimized to a specific range of 40-70 µm, which balances radial strength requirements with current laser beam machining capabilities. This parameter optimization resolves the contradiction between achieving sufficient radial strength and maintaining manufacturability.
4Ease of operation
If the stent is made flexible to improve trackability, then the stent can navigate meandering lumens, but the stent may cause injury to the blood vessel during introduction
Solution Approach 1:
The stent employs thin waved elements with a meandering pattern that provide flexibility for navigation while maintaining structural integrity. The flexible design allows the stent to conform to the vessel geometry during introduction, reducing the risk of vessel injury.
Data Source
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AI summary
A flexible stent with excellent trackability and expandability comprises a plurality of radially expandable annular members 1 arranged in an axial direction thereof, and connecting elements 2 for connecting adjoining two annular members 1, adjoining annular members 1, 1 being connected by one or more of the connecting elements 2. The annular members 1 are radially expandable and each annular member 1 comprises two waved elements 11, 12 that repeatedly meander in parallel with or substantially parallel with each other and are coupled by coupling elements 13 at intermediate portions between wave crests and wave troughs of the waved elements 11, 12. The stent is excellent in trackability, which in turn makes it possible to pass through three-dimensionally meandering lumens. The stent is excellent in radial strength, substantially free from shortening and easy to provide a lateral hole.