Flexible Stent Graft Outer-Layer Ablation for Easier Assembly
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Solution Overview
Problem
The existing methods for manufacturing stent grafts are complex and prone to misalignment issues, leading to a high rate of defective products due to the difficulty in accurately aligning and maintaining the shape of the flexible base stent and its covering layers during assembly, which affects the flexibility and delivery profile of the stent graft.
Innovation Solution
A method involving a self-expanding base stent covered with ePTFE on both sides, where the outer layer is partially ablated using heat or mechanical means to increase flexibility, allowing for a simplified assembly process and improved design flexibility without requiring precise alignment of the outer layer during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the wall thickness of the base stent or the thickness of the ePTFE covering layers is reduced to achieve higher flexibility and reduced delivery profile, then the flexibility and deliverability improve, but the manufacturing complexity increases and misalignment issues occur during assembly
Solution Approach 1:
The outer ePTFE layer is applied to the base stent in its compressed delivery state before expansion. This preliminary covering action ensures that the outer layer is already in position and aligned with the stent structure before the assembly process begins, eliminating the need for complex post-assembly alignment adjustments and reducing manufacturing complexity while maintaining flexibility
Solution Approach 2:
Instead of the conventional approach of first assembling the stent structure and then applying covering layers, the invention inverts the sequence by applying the outer ePTFE layer to the compressed stent first. This reversal simplifies the assembly process and reduces misalignment issues while preserving the flexibility benefits of thinner walls
2Manufacturing precision
If the outer ePTFE layer is applied after the base stent assembly to maintain stent shape, then alignment precision is improved, but the manufacturing process becomes more complex and skill-intensive
Solution Approach 1:
The outer ePTFE layer is applied to the base stent while it is in its compressed delivery state, before the stent is expanded to its final shape. This preliminary application ensures proper alignment is achieved during the covering process itself, eliminating the need for complex post-assembly alignment procedures and reducing the skill level required for manufacturing
3Adaptability or versatility
If the base stent is made more flexible to improve compliance with patient anatomy, then the adaptability improves, but the stent strength may be compromised
Solution Approach 1:
The invention uses a composite structure combining the base stent (made of shape memory alloy such as nitinol) with ePTFE covering layers. This composite construction allows the stent to achieve high flexibility and compliance with patient anatomy while the layered structure and material properties maintain sufficient strength to prevent collapse post-implantation
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
This approach results in a highly flexible stent graft with reduced production of defective units, enhanced mechanical characteristics, and easier implantation by maintaining the integrity of the inner layer while allowing for controlled reduction of the outer layer thickness, thus improving compliance with the patient's anatomy.
Implementation Method 1
the second covering material is locally ablated (in embodiments by heat) without puncturing the first covering material
Implementation Method 2
the second covering material is locally ablated (in embodiments by heat)
Data Source
AI summary
The present invention relates to a method of making a highly flexible stent graft (100), the method comprising: providing a stent graft having a first and a second longitudinal end and a lumen extending longitudinally therethrough, the stent graft comprising a base stent (10), the base stent having a first covering material (14) provided on the inside of the base stent so as to line the lumen and a second covering material (12) provided on the outside of the base stent, locally ablating the second covering material without puncturing the first covering material to thereby increase the flexibility of the stent graft.