Absorbable Metal Stent Corrosion-Controlled Sequential Deconstruction
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Solution Overview
Problem
Absorbable metal stents face challenges with secondary hyperplasia and stenosis due to fractured rods, which are caused by material fatigue and corrosion, leading to long-term stimulation of neointimal tissues and vascular injury, especially in tortuous and angled coronary vessels.
Innovation Solution
The development of an absorbable metal stent with a corrosion-promoting coating on axial connecting portions and a degradable polymer layer on wave-shaped annular structures, where the corrosion-promoting coating accelerates corrosion of axial connecting portions, causing them to fracture before wave-shaped annular structures, allowing for sequential deconstruction and reducing mechanical stimulation of neointimal tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stent is designed with high fatigue resistance to prevent fracture, then the mechanical support is maintained, but the stent cannot achieve sequential deconstruction to reduce tissue stimulation
Solution Approach 1:
The stent is divided into multiple rod structures that can fracture independently at different locations. This segmentation allows controlled deconstruction where individual rods fail separately rather than simultaneously, enabling the stent to progressively deconstruct and reduce mechanical stimulation to tissues over time while maintaining overall structural integrity during the support period
Solution Approach 2:
The material properties of the rods are engineered with specific fatigue life parameters that allow them to maintain strength for a required support period, then progressively degrade. The rods are designed with controlled fatigue resistance parameters that enable them to withstand cyclic loading for a predetermined time, then fracture in a controlled manner to achieve deconstruction without causing harmful tissue stimulation
2Strength
If the stent maintains high mechanical strength for long-term support, then the structural integrity is preserved, but the stent causes secondaryhyperplasia and stenosis through continuous stimulation of neintimal tissues
Solution Approach 1:
The stent transitions from a static, permanently strong structure to a dynamic system where rods progressively fracture and deconstruct over time. This dynamic deconstruction allows the stent to provide strong mechanical support initially, then gradually reduce its presence and stimulation to tissues as rods fail and are absorbed, preventing secondaryhyperplasia and stenosis
Solution Approach 2:
The rod structures are designed to be temporarily useful for mechanical support, then deliberately discarded through controlled fracture and degradation. After fulfilling their support function, the rods fracture and are gradually absorbed by the body, eliminating the source of continuous tissue stimulation that causes secondaryhyperplasia and stenosis
3Reliability
If the axial connecting portions are made corrosion-resistant, then the stent maintains structural integrity, but the stent cannot achieve sequential deconstruction to improve bending performance
Solution Approach 1:
Different parts of the stent have different corrosion resistance properties. The axial connecting portions are designed with lower corrosion resistance than the radial support structures, creating local quality differences. This allows the connecting portions to fracture first in sequence, improving bending performance and compliance, while the main support structures maintain integrity longer to provide necessary mechanical support
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 design enhances the stent's bending performance and compliance, reducing secondary hyperplasia and stenosis by ensuring that the stent is axially deconstructed, with loose corrosion products wrapping fracture surfaces, thereby minimizing long-term tissue stimulation and improving clinical safety.
Implementation Method 1
a corrosion-promoting coating on axial connecting portions... the corrosion-promoting coating accelerates corrosion of axial connecting portions
Implementation Method 2
a degradable polymer layer on wave-shaped annular structures... sequential deconstruction
Data Source
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AI summary
An absorbable metal stent includes an absorbable metal substrate; the absorbable metal substrate includes a plurality of wave-shaped annular structures and a plurality of axial connecting portions, two ends of each axial connecting portion being connected to two adjacent wave-shaped annular structures, respectively, so as to axially connect the plurality of wave-shaped annular structures; a corrosion-promoting coating is formed on each axial connecting portion, the corrosion-promoting coating containing a corrosion-promoting substance, and the corrosion-promoting substance being selected from at least one of a degradable polymer and a degradable polymer antioxidant; the corrosion-promoting coatings cause the corrosion of the axial connecting portions to occur earlier than the corrosion of the plurality of wave-shaped annular structures. The absorbable metal stent has good bending performance and may prevent the problems of secondary hyperplasia after implantation and stenosis caused thereby.