Absorbable Stent Wave-Shaped Rings Radial Strength
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Solution Overview
Problem
Existing absorbable stents face challenges in achieving a balance between a short corrosion and absorption cycle and sufficient early radial supporting strength, with materials like iron-based stents having slow corrosion rates and magnesium-based stents being mechanically weak, leading to issues with radial strength and delivery through narrow lesions.
Innovation Solution
The design of an absorbable stent with a matrix comprising multiple wave-shaped rings connected by units, optimized for a small matrix volume per unit vascular area and high radial supporting strength, using materials like magnesium-based alloys or polymers, and potentially coated with degradable polymers and drugs to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the wall thickness of the stent is reduced to shorten the corrosion and absorption cycle, then the absorption time is improved, but the radial supporting strength deteriorates
Solution Approach 1:
The stent is divided into multiple segments (struts) with optimized geometry. Each strut is designed as a thin-walled structure with specific cross-sectional shapes (rectangular, circular, or elliptical) that provide high radial strength-to-volume ratio, enabling thin walls to maintain sufficient mechanical support while reducing overall material volume for faster absorption
Solution Approach 2:
The patent optimizes geometric parameters of the stent structure, including wall thickness (10-50 μm for metal, 50-200 μm for polymer), strut dimensions, and pattern configuration. These parameter adjustments allow the stent to achieve the required radial supporting strength with minimal material volume, thereby shortening the corrosion and absorption cycle to 6-12 months
2Duration of action of stationary object
If the corrosion rate is increased to shorten the absorption cycle, then the absorption time is improved, but the mechanical property deteriorates
Solution Approach 1:
The patent employs composite material structures, including metal-polymer composites and alloy compositions (magnesium-based, iron-based, zinc-based alloys with controlled elemental compositions). These composite materials provide enhanced mechanical properties while maintaining biodegradability, allowing faster corrosion rates without sacrificing the radial supporting strength needed for early vessel support
Solution Approach 2:
Different regions of the stent are designed with locally optimized material properties and geometries. The strut structures feature varying wall thicknesses and cross-sectional shapes tailored to specific mechanical requirements, enabling high corrosion resistance in critical load-bearing areas while allowing faster absorption in less critical regions
3Strength
If a thick stent is used to meet the early radial supporting strength requirement, then the radial supporting strength is improved, but the profile diameter increases and delivery becomes difficult
Solution Approach 1:
The patent utilizes thin-walled stent structures with wall thicknesses optimized for minimal profile diameter. The thin-walled design allows the stent to be compressed to small delivery profiles (2-4 mm) for easy delivery through narrow lesions, while the strategic placement and geometric optimization of struts ensure adequate radial supporting strength is achieved upon deployment
Solution Approach 2:
The stent features curved and wave-like strut geometries rather than straight rigid structures. These curved designs provide mechanical flexibility and radial strength with reduced material volume, enabling the stent to maintain small profile diameter for easy delivery while achieving sufficient radial supporting strength through optimized curvature and strut configuration
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 achieves a shorter corrosion and absorption cycle while maintaining high radial supporting strength, allowing for effective clinical applications and improved delivery through narrow vascular lesions.
Implementation Method 1
The corrosion and absorption cycle of the absorbable stent... The faster the absorption of corrosion products, the better
Implementation Method 2
the absorbable stent would be gradually degraded and absorbed by an organism till it disappears
Data Source
AI summary
An absorbable stent includes an absorbable matrix. The matrix includes a number of wave-shaped rings connected by connection units and arranged in an axial direction. The wave-shaped ring includes a number of waves arranged in a circumferential direction. A peak, a valley and a support connecting the peak and the valley form the wave. Two adjacent wave-shaped rings and the connection unit form a closed side supporting unit. The matrix has a volume of [4, 40]μm per unit blood vessel area. The absorbable stent has sufficient radial supporting strength for clinical applications. Moreover, the volume of the matrix per unit blood vessel area is less than volumes of existing stents. When the absorbable stent and existing stents are made of the same material, the absorbable stent has a shorter degradation and absorption cycle.