Flexible Stent with Helical Segments for Bending
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Solution Overview
Problem
Conventional stents lack flexibility and durability after deployment, leading to mechanical failures under substantial flexing and repeated displacements, which can result in stent failure, especially in applications like the superficial femoral artery where bending and axial compression are common.
Innovation Solution
A stent design incorporating alternating strut and helical portions, where strut portions provide radial expansion and strength, and helical portions allow for repeated flexing and axial compression, enabling the stent to maintain structural integrity under bending and axial forces with minimal bending radius and significant axial expansion/compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a stent is designed to be flexible in its crimped state to facilitate delivery, then ease of operation is improved, but reliability deteriorates because the stent lacks flexibility after deployment and is subjected to severe strain and fatigue from flexing and bending
Solution Approach 1:
The stent is divided into multiple segments or units that can flex relative to each other. Each segment maintains structural integrity while allowing controlled movement at the interfaces between segments, enabling the stent to accommodate flexing and bending forces after deployment without catastrophic failure.
Solution Approach 2:
The stent structure incorporates elements with varying mechanical properties along its length, such as changes in wall thickness, material composition, or geometric configuration. This allows different portions of the stent to have optimized characteristics for both delivery flexibility and post-deployment durability under flexing conditions.
2Manufacturing precision
If a stent is designed with uniform structure throughout, then manufacturing precision is improved, but adaptability deteriorates because the stent cannot simultaneously optimize for radial strength and axial flexibility in different regions
Solution Approach 1:
The stent is divided into multiple segments or units that can flex relative to each other. Each segment maintains structural integrity while allowing controlled movement at the interfaces between segments, enabling the stent to accommodate flexing and bending forces after deployment without catastrophic failure.
Solution Approach 2:
The stent structure incorporates elements with varying mechanical properties along its length, such as changes in wall thickness, material composition, or geometric configuration. This allows different portions of the stent to have optimized characteristics for both delivery flexibility and post-deployment durability under flexing conditions.
3Adaptability or versatility
If a stent is designed to permit substantial flexing and axial compression, then adaptability is improved, but strength deteriorates because the stent may undergo mechanical failure under severe strain and fatigue
Solution Approach 1:
The stent is divided into multiple segments or units that can flex relative to each other. Each segment maintains structural integrity while allowing controlled movement at the interfaces between segments, enabling the stent to accommodate flexing and bending forces after deployment without catastrophic failure.
Solution Approach 2:
The stent structure incorporates elements with varying mechanical properties along its length, such as changes in wall thickness, material composition, or geometric configuration. This allows different portions of the stent to have optimized characteristics for both delivery flexibility and post-deployment durability under flexing conditions.
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 design enhances flexibility and durability by allowing up to 20% axial compression/expansion and bending with a minimum bending radius of 13mm, reducing the risk of mechanical failure and ensuring the stent remains effective in expanded states.
Implementation Method 1
the helical portions permit axial compression or expansion of about 20% (preferably between 15% and 25%)
Implementation Method 2
simultaneously permit bending with a minimum bending radius of about 13mm (preferably between 10mm and 16mm)
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A flexible stent structure (300) includes a plurality of axially spaced strut portions (302, 304, 305) defining generally tubular axial segments of the stent and constructed to be radially expandable. A helical portion (303, 309) is interposed axially between two strut portions and has a plurality of helical elements connected between circumferentially spaced locations on the two strut portions. The helical elements extend helically between those locations and the length of a helical element is sufficient so that, when the stent is in a radially expanded state, it can simultaneously withstand repeated axial compression or expansion and bending.