Microstructured Bioresorbable Magnesium Alloy Stent Surface
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Solution Overview
Problem
Bioresorbable magnesium alloy stents face challenges with insufficient polymer adhesion, corrosion resistance, and mechanical stability, leading to issues like in-stent restenosis and premature degradation.
Innovation Solution
A microstructured surface is created on magnesium alloy stents using a combination of pickling and electrochemical micropolishing, resulting in a surface with enhanced adhesion for polymer coatings and increased corrosion resistance, maintaining structural integrity under mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a smooth surface is used on magnesium alloy stents, then manufacturing is easier, but polymer adhesion is insufficient
Solution Approach 1:
The surface parameters of the magnesium alloy stent are changed by applying a microstructured coating that modifies surface roughness and topology. This coating transforms the smooth surface into a microstructured surface with enhanced mechanical interlocking capability, thereby improving polymer adhesion without complicating the manufacturing process
Solution Approach 2:
A composite structure is created by applying a microstructured coating layer on top of the magnesium alloy stent surface. This coating acts as an intermediate layer that provides both good adhesion to the metal substrate and excellent adhesion to the polymer coating, resolving the adhesion problem through material composition rather than surface geometry modification
2Strength
If the stent provides strong mechanical support, then structural integrity is maintained, but degradation time is too short
Solution Approach 1:
The stent is designed with heterogeneous material distribution, where the bulk material provides strong mechanical support and the surface coating provides controlled degradation properties. This local differentiation allows the interior to maintain structural integrity while the surface degrades at a controlled rate to extend therapeutic action
Solution Approach 2:
The microstructured coating is applied in advance to the stent surface before implantation. This pre-applied coating serves as a protective layer that controls the initial degradation rate, allowing the stent to maintain mechanical strength for the required therapeutic period before gradually degrading
3Duration of action of stationary object
If the stent degrades quickly, then it fulfills temporary support function, but corrosion resistance is insufficient
Solution Approach 1:
The microstructured coating acts as an intermediary layer between the magnesium alloy stent and the corrosive physiological environment. This coating provides the first line of defense against corrosion, protecting the metal substrate during the support period while allowing controlled degradation after the stent fulfills its mechanical function
Solution Approach 2:
The coating is applied in advance to the stent surface to provide protective cushioning against corrosion. This pre-established protective layer buffers the metal substrate from direct exposure to corrosive bodily fluids, maintaining corrosion resistance throughout the required support 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 microstructured surface improves polymer adhesion, extends degradation time, and enhances corrosion resistance, ensuring the stent's mechanical stability and prolonged therapeutic effectiveness.
Implementation Method 1
a surface of a bioresorbable magnesium alloy by a pickling process and an electropolishing process treated
Implementation Method 2
a surface of a bioresorbable magnesium alloy by a pickling process and an electropolishing process treated
Data Source
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AI summary
Producing a micro structured surface from a bioresorbable magnesium alloy optionally containing zinc and/or aluminum, comprises treating the surface with a pickling process and/or an electropolishing process. The surface comprises a grain structure having a mean grain size of = 10 mu m, preferably = 5 mm, of a bioresorbable magnesium alloy, containing magnesium as the major constituent, zinc and/or aluminum as the major alloying elements, and optionally containing zinc as the major alloying element. Producing a micro structured surface from a bioresorbable magnesium alloy optionally containing zinc and/or aluminum, comprises treating the surface with a pickling process and/or an electropolishing process. The surface comprises a grain structure having a mean grain size of = 10 mu m, preferably = 5 mm, of a bioresorbable magnesium alloy, containing magnesium as the major constituent, zinc and/or aluminum as the major alloying elements, and optionally containing zinc as the major alloying element. The magnesium alloy comprises a composition comprising: 80-99 wt.%, preferably 94.5-95.5 wt.% magnesium; optionally 1-20 wt.%, preferably 4.5-5.5 wt.% of zinc and/or aluminum; and optionally 0.01-2 wt.%, preferably 0.2-1.2 wt.% of at least one further alloying additions that are customary for magnesium alloys. Independent claims are also included for: (1) the microstructured surface made of a bioresorbable magnesium alloy which is optionally a wrought alloy, where the microstructured surface comprises microstructure having raised grain boundaries and neighboring depressions, optionally a microstructure made of raised grain boundaries and neighboring depressions designed as crater-shaped microstructures; and (2) an implant, comprising a microstructured surface made of bioresorbable magnesium alloys, optionally containing zinc and/or aluminum as the major alloying element.