Flexible Stent with Sinusoidal Pattern and Coiled Elements
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Solution Overview
Problem
Conventional stents for cerebral blood vessels lack the necessary mechanical properties such as high conformability, effective diameter reduction, deliverability, and resistance to metallic fatigue, which are critical for navigating complex and tapered vessel structures without causing tissue damage or inhibiting blood flow.
Innovation Solution
A highly flexible stent with a closed cell structure featuring circular bodies with a wavy-line pattern and coiled elements that allow for flexible bending and radial contraction, reducing the risk of strut protrusion and metallic fatigue, while maintaining high conformability and diameter reduction capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional stent structure is used, then the stent can be delivered through catheters, but it lacks sufficient conformability to adapt to complex and bent vessel structures
Solution Approach 1:
The stent is divided into multiple struts arranged in a mesh pattern, with each strut acting as an independent element that can bend and deform. This segmentation allows the stent to conform to complex vessel geometries while maintaining overall structural integrity through the interconnected mesh design.
Solution Approach 2:
The stent incorporates dynamic elements including bends and curves in the strut configurations that allow the structure to adapt flexibly to vessel tortuosity. The mesh pattern enables the stent to dynamically adjust its shape during delivery and expansion to match the target vessel geometry.
2Ease of operation
If the stent is radially reduced for delivery through small catheters, then deliverability improves, but the structure becomes more susceptible to deformation and damage
Solution Approach 1:
The stent is designed to be nested within a delivery catheter in a radially reduced state. The mesh pattern and strut configuration allow the stent to be compressed into a small profile for delivery through catheters of limited diameter, then expand to its full diameter at the target site to restore structural integrity.
Solution Approach 2:
The stent utilizes thin-walled strut structures that provide flexibility during delivery while maintaining sufficient strength when expanded. The mesh pattern creates a structure that can be compressed for delivery but rebounds to its original configuration at the target vessel, resisting deformation and damage.
3Force
If the stent has high radial force for vessel support, then expansion capability improves, but the risk of tissue damage increases
Solution Approach 1:
The stent applies radial force locally at the expansion site through its mesh pattern, providing vessel support where needed without excessive force. The strut configuration and mesh design distribute the radial force evenly across the vessel wall, reducing the risk of localized tissue damage while maintaining effective expansion.
Solution Approach 2:
The stent's radial force characteristics are optimized through parameter selection including strut thickness, mesh pattern geometry, and material properties. These parameters are chosen to provide sufficient radial force for vessel expansion and support while remaining below the threshold that would cause tissue damage.
4Adaptability or versatility
If the stent structure is made more flexible for conformability, then adaptability to bent vessels improves, but resistance to metallic fatigue decreases
Solution Approach 1:
The stent is segmented into multiple struts connected in a mesh pattern, with each segment designed to flex independently. This segmentation allows the stent to conform to bent vessel geometries while distributing mechanical stresses across multiple elements, reducing fatigue accumulation in any single strut.
Solution Approach 2:
The stent utilizes materials with optimized mechanical properties that balance flexibility and fatigue resistance. The mesh pattern and strut design create a composite structure that provides the necessary conformability for bent vessels while maintaining sufficient fatigue resistance for long-term vascular support.
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 improved conformability and diameter reduction, reducing the risk of tissue damage and metallic fatigue, enabling secure placement in complex vessel structures while maintaining effective blood flow and delivery through tortuous paths.
Implementation Method 1
the adjacent circular bodies are connected by way of a plurality of coiled elements extending in a spiral manner around the axis. Therefore, for these coiled elements, flexible bending deformation can occur in an axis direction like a coil spring
Implementation Method 2
the circular body of a wavy-line pattern can be easily radially contracted in a circumferential direction
Implementation Method 3
the coiled element working like a coil spring is contracted in a radial direction by elongating in an axis direction
Data Source
AI summary
A stent has circular bodies having a wavy-line pattern and arranged side-by-side and coiled elements 15 arranged between the circular bodies that are adjacent and extending in a spiral manner, and apices on opposite sides of the wavy-line pattern of the circular bodies that are adjacent are connected by way of the coiled elements 15. A knob portion 19 is formed at each apex of the wavy-line pattern, and the knob portion 19 includes an extension portion 19a extending in the axis direction and a semicircle portion 19b formed at a tip of the extension portion, and the coiled element 15 is connected with the knob portion 19. A slit is formed at a part of the extension portion 19a of the knob portion 19, and the slit 21 extends in the axis direction from an inner peripheral portion at the apex of the wavy-line pattern of the circular body.