Self-Expanding Stent Cell Framework for Deformation-Free Loading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in manufacturing self-expanding stents is effectively loading them into a delivery system without causing deformation, particularly as stent sizes decrease and wall thicknesses become thinner.
Innovation Solution
The stent design features a framework with a sequence of cells, each composed of struts connected at vertices, and is attached by T-bars that include a column and a top bar. This design allows for orientation of struts parallel to the stent axis, facilitating loading by compressing the stent to a smaller diameter while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If stent size decreases and wall thickness becomes thinner, then stent can be loaded into smaller delivery systems, but structural integrity and resistance to deformation during loading deteriorates
Solution Approach 1:
The stent framework is divided into multiple cells with struts connected at vertices, where each cell is further segmented into flex cells and hoop cells with different structural configurations. This segmentation allows the stent to achieve both small size and adequate strength by distributing mechanical loads across multiple structural units rather than relying on a single thick wall.
Solution Approach 2:
Different regions of the stent framework have different structural qualities - flex cells have struts oriented parallel to the stent axis for flexibility and loading, while hoop cells have struts oriented circumferentially for radial support. This local differentiation allows thin-walled stents to maintain structural integrity in critical areas while remaining lightweight overall.
2Ease of operation
If stent is compressed to smaller diameter for loading, then loadability into delivery system improves, but risk of deformation and fractures increases
Solution Approach 1:
The stent framework is designed with dynamic structural characteristics where flex cells can deform and adapt during loading operations. The struts in flex cells are oriented parallel to the stent axis, allowing them to compress and flex during loading without permanent deformation, while hoop cells maintain radial support. This dynamic design enables the stent to be compressed to smaller diameters for loading while minimizing the risk of permanent deformation and fractures.
3Manufacturing precision
If stent uses thinner wall material, then manufacturing precision and size reduction are enabled, but radial stiffness and resistance to external forces deteriorates
Solution Approach 1:
The stent employs a composite structural design combining different cell types (flex cells and hoop cells) with different material orientations and configurations. This composite approach allows thin-walled stents to achieve adequate radial stiffness through the strategic arrangement of struts and cells rather than relying on material thickness alone.
4Strength
If stent framework uses more complex cell structures, then radial support and vessel patency improve, but difficulty of loading and manufacturing increases
Solution Approach 1:
The stent framework is divided into multiple cells with struts connected at vertices, where each cell is further segmented into flex cells and hoop cells with different structural configurations. This segmentation allows the stent to achieve both small size and adequate strength by distributing mechanical loads across multiple structural units rather than relying on a single thick wall.
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 enhances the stent's ability to be loaded into a delivery system without deformation, while maintaining high radial stiffness and flexibility, ensuring effective vessel patency and reduced risk of fractures during expansion and heat-setting operations.
Implementation Method 1
Self-expanding stents are increasingly used and accepted by physicians for treating a variety of ailments. Self-expanding stents are usually made of shape memory materials or other elastic materials that act like a spring.
Data Source
AI summary
A stent comprises a framework that includes a sequence of cells that each occupy a discrete segment of the stent length, and each of the cells includes a plurality of struts with ends connected at respective vertices. In some forms the hollow cylindrical shape of the framework is moveable among a loading diameter that is smaller than a tube diameter, which is smaller than an expanded diameter, and every strut of the framework is oriented parallel to the stent axis when the hollow cylindrical shape is at the tube diameter. In other forms the framework includes T-bars that connect adjacent cells, where the T-bars have a column that has a minimum width perpendicular to the long axis that is wider than a maximum width of each of the struts, and the column defines at least one slot. In still other forms, the framework exhibits geometries that facilitate a high packing density for the framework when the stent is in a compressed tube or loading configuration.