Pocket-Coated Stent Structure for Anti-Migration and Easy Removal
Solution Overview
Problem
Existing stents used in body lumens, such as the esophageal and gastrointestinal tract, tend to migrate due to peristalsis, making them difficult to remove and increasing the risk of complications like tissue ingrowth.
Innovation Solution
A stent design featuring a tubular member with a polymeric coating that forms pockets and partitions within the cells, increasing friction and reducing tissue ingrowth, while allowing for easy removal by expanding and collapsing configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a stent is designed to be compressible and flexible for delivery, then delivery ease is improved, but the stent develops a tendency to migrate from its deployed position
Solution Approach 1:
The stent is divided into multiple cells formed by struts, with each cell containing a pocket structure. This segmentation allows the stent to maintain flexibility for delivery while the distributed pocket structures provide cumulative anchoring force to prevent migration.
Solution Approach 2:
The coating material is configured to form pockets with specific geometric characteristics (convex or concave shapes) at localized positions within the stent cells. These localized structural variations create differential friction and anchoring forces at specific contact points with the body lumen wall, preventing migration while preserving overall stent flexibility.
2Stability of the object's composition
If a stent is designed with features to prevent migration, then position stability is improved, but the stent becomes difficult to remove after deployment
Solution Approach 1:
The stent structure transitions from a static design to a dynamic one where the pockets and partitions can deform reversibly. During deployment, the pockets expand to engage the lumen wall for anchoring; during removal, the pockets can compress to reduce friction and facilitate extraction, allowing the stent to adapt its friction characteristics based on the operational phase.
Solution Approach 2:
The coating structure is designed with preliminary anti-migration features (pockets and partitions) that create friction forces opposing migration. However, these same features are geometrically configured to allow controlled deformation that reduces their gripping effect during removal, effectively creating an anti-anchoring mechanism when needed.
3Stability of the object's composition
If the coating material is stretched to delay wrinkling, then coating integrity is improved, but the onset of wrinkling is delayed rather than eliminated
Solution Approach 1:
The coating is pre-configured with convex or concave shaped features that are designed to straighten and stretch in a controlled manner during stent expansion. This preliminary structuring of the coating material allows it to accommodate expansion forces more uniformly, delaying the onset of random wrinkling and maintaining integrity for a longer period.
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 effectively reduces migration and tissue ingrowth, maintaining luminal patency and facilitating easy retrieval by enhancing frictional forces and providing anti-migration flared regions.
Implementation Method 1
The design reduces stent migration and facilitates removal by enhancing frictional forces
Data Source
Figure 1
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Figure 2B
AI summary
An illustrative stent includes an elongated tubular member comprising at least one strut or filament forming a tubular wall having a plurality of cells extending through a thickness of the tubular wall. The elongated tubular member may be configured to move between a radially collapsed configuration and a radially expanded configuration. A coating is disposed on the elongated tubular member and spanning the plurality of cells. The coating forms a pocket within at least some of the cells of the plurality of cells and extends radially inward of the tubular wall to define a void. In some instances, a partition or wall is positioned within at least some of the pockets and transects the void.