Stagger Zone Stent Design for Bending Tolerance
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Solution Overview
Problem
Metal stents face challenges in matching the flexibility of bodily tissue, particularly during severe bending after placement, leading to undesirable abutment or rubbing of stent components, which can be exacerbated by the design's peak-to-peak configuration.
Innovation Solution
Introducing stagger zones around the circumference of stenting rings with varying gap sizes between points of inflection, allowing for circumferential offset between adjacent rings to prevent abutment and enhance bending capability without compromising support for the stented tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a classic peak-to-peak stent design is used, then the stent structure is simple and manufacturing is easier, but the stent cannot withstand severe bending without abutment or rubbing of stent components
Solution Approach 1:
The patent applies asymmetry by offsetting the points of inflection of adjacent stenting rings circumferentially relative to each other. Instead of having points of inflection directly opposite (peak-to-peak), the design creates an asymmetric arrangement where points of inflection are staggered around the circumference. This asymmetric configuration allows the stent to bend without causing the points of inflection to abut or rub against each other, thereby improving bending tolerance while maintaining structural simplicity.
2Reliability
If the points of inflection are offset circumferentially between adjacent rings, then bending capability is improved, but the stent structure becomes more complex
Solution Approach 1:
The patent applies local quality by varying the gap sizes between points of inflection at different locations around the circumference of the stenting rings. Specifically, the design incorporates different gap sizes in different circumferential positions, creating zones with larger gaps that accommodate bending movements. This localized variation in gap size allows the stent to achieve improved bending tolerance without requiring a complete redesign of the entire structure, thereby limiting the increase in overall complexity.
3Reliability
If stagger zones with varying gap sizes are introduced, then abutment is prevented during bending, but the uniformity of stent structure is reduced
Solution Approach 1:
The patent introduces stagger zones with varying gap sizes at specific locations around the circumference of the stenting rings. These local variations create regions that are optimized for bending accommodation, where gaps are larger to prevent abutment. The rest of the stent structure maintains its regular, uniform configuration, thereby preserving overall structural stability while providing localized functionality for bending tolerance.
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 stagger zone design improves the stent's ability to withstand extreme bending without abutment or rubbing, maintaining even support for the tissue while maintaining the simplicity and cost-effectiveness of the stent's manufacturing and stress distribution.
Implementation Method 1
a nickel titanium shape memory alloy stent for a bodily lumen
Data Source
AI summary
A tubular prosthesis having at least two helical loops or discrete loops, linked by a bridge, includes at least two regular struts connected by a regular inflection point forming a regular gap between the regular struts and at least two stagger struts connected by a stagger inflection point forming a stagger gap wherein the regular gap has a size different from the stagger gap.