Biodegradable Composite Wire Stent for Controlled Degradation
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Solution Overview
Problem
Current biodegradable stents face challenges with mechanical strength and controlled biodegradation rates, often exhibiting low mechanical strength and inadequate control over bioabsorption rates, which can lead to inappropriate vessel remodeling and increased risk of restenosis.
Innovation Solution
A composite wire is developed with a biodegradable outer shell and inner core of different materials, such as pure iron and magnesium alloys, where the biodegradation rates are controlled by material selection and geometric configuration, allowing for tailored mechanical properties and degradation profiles to support vessel remodeling and prevent restenosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If biodegradable materials are used for stents, then the stent can be removed or absorbed after serving its purpose, but the mechanical strength and resilience are insufficient
Solution Approach 1:
The patent applies composite materials by combining two different biodegradable materials with complementary properties: Material A provides slow degradation and high mechanical strength, while Material B provides fast degradation and elasticity. This composite structure resolves the contradiction by integrating the advantages of both materials to achieve both durability during service and controlled removal afterward.
2Reliability
If biodegradable materials are used for stents, then the stent can be absorbed after vessel remodeling, but the control over bioabsorption rate is inadequate
Solution Approach 1:
The patent applies local quality by assigning different degradation rates to different regions of the stent structure. The stent is constructed with Material A in regions requiring long-term support and Material B in regions requiring faster absorption. This spatial differentiation of material properties enables precise control over the overall bioabsorption rate to match vessel remodeling timelines.
3Ease of manufacture
If single material is used for stent, then manufacturing is simple, but mechanical properties and degradation rates cannot be optimized
Solution Approach 1:
The patent uses composite materials to achieve optimized mechanical properties that cannot be obtained from single materials. By combining Material A (high strength, slow degrading) with Material B (elastic, fast degrading), the stent achieves superior overall performance. The composite structure is manufactured as a single integrated component, maintaining ease of manufacture while dramatically improving reliability.
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 composite wire provides enhanced mechanical strength and controlled biodegradation, promoting endothelial vasoreactivity, long-term hemodynamics, and enabling reintervention while reducing the risk of late closure and restenosis, making it suitable for non-coronary vasculature and other medical applications.
Implementation Method 1
the first biodegradable material may degrade relatively slowly for retention of the mechanical integrity of the stent during vessel remodeling
Implementation Method 2
the second biodegradable material may degrade relatively quickly
Implementation Method 3
the first biodegradable material may be selected from the group consisting of pure Fe, an Fe-Mn alloy, or another Fe-based alloy which degrades relatively slowly upon exposure to biological media
Data Source
AI summary
A bimetal composite wire including, in cross-section, an outer shell or tube formed of a first biodegradable material and an inner core formed of a second biodegradable material. When formed into a stent, for example, the first and second biodegradable materials may be different, and may have differing biodegradation rates. In a first embodiment, the first biodegradable material of the shell may degrade relatively slowly for retention of the mechanical integrity of a stent during vessel remodeling, and the second biodegradable material of the core may degrade relatively quickly. In a second embodiment, the first biodegradable material of the shell may degrade relatively quickly, leaving a thinner structure of a second biodegradable material of the core that may degrade relatively slowly. The biodegradation rates may be inherently controlled, such as by selection of materials, and also may be mechanically controlled, such as by material thicknesses and the geometric configuration of the shell, core, or overall device. In any embodiment, the metallic scaffold may also be coated with a drug-eluting, biodegradable polymer, to further inhibit neointimal proliferation and/or restenosis.