Gallium-Enriched Magnesium Stents for Controlled Biodegradation
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Solution Overview
Problem
Biodegradable magnesium implants, such as stents, face issues with premature loss of mechanical integrity and variable degradation rates due to existing coatings and manufacturing processes, leading to inconsistent performance and increased costs.
Innovation Solution
A method involving a semifinished article made of magnesium or magnesium alloy, shaped using a tool with a metallic lubricant containing gallium or gallium compounds at temperatures between 250°C and 550°C, which diffuses into the surface to form an alloy, reducing friction and controlling degradation by adjusting the diffusion depth and composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If existing coatings and manufacturing processes are used on biodegradable magnesium implants, then the implant can be produced with standard methods, but the implant suffers from premature loss of mechanical integrity and variable degradation rates
Solution Approach 1:
The patent applies parameter changes by modifying the surface composition through gallium diffusion during the shaping process. By controlling the diffusion depth and composition of gallium in the surface region, the degradation rate is adjusted to extend the functional period while maintaining mechanical integrity. This resolves the contradiction by changing material parameters rather than using separate coating processes.
Solution Approach 2:
The patent creates a composite structure with a gallium-enriched surface layer on the magnesium alloy substrate. This composite material approach provides a protective surface layer that controls degradation while the bulk material maintains its mechanical properties, thus extending the functional period without compromising reliability.
2Object-generated harmful factors
If the implant material is made biodegradable to avoid permanent foreign body, then the implant can be absorbed by the organism, but the implant loses mechanical integrity too early and shows severely fluctuating loss of integrity
Solution Approach 1:
The patent changes the degradation parameters by introducing gallium into the surface region. This modification slows down the degradation rate, extending the functional period from 4-6 months to 7-8 months or longer, while still maintaining the biodegradable nature of the implant to avoid permanent foreign body response.
Solution Approach 2:
The patent applies local quality by creating a gallium-enriched surface layer with different properties than the bulk material. The surface layer controls the degradation rate and protects the bulk material, allowing the implant to maintain mechanical integrity longer while remaining biodegradable.
3Ease of manufacture
If conventional lubricants are used during shaping, then the shaping process can be performed, but the lubricants form crusts that require costly removal steps and may remain as residues
Solution Approach 1:
The patent changes the lubricant material from conventional options to gallium-containing lubricant. This parameter change allows the lubricant to be easily removed by melting and dripping off during or after the shaping process, eliminating the need for costly removal steps and avoiding residue formation.
Solution Approach 2:
The gallium-containing lubricant acts as a disposable element that is intentionally left in the process to facilitate shaping, then easily removed by melting. This eliminates the need for complex removal steps and residues, simplifying the overall production process.
4Duration of action of stationary object
If the implant is designed to maintain mechanical integrity for extended periods, then the implant can support the vessel longer, but the degradation rate becomes more variable and unpredictable
Solution Approach 1:
The patent changes the surface composition parameters by controlling the gallium diffusion depth and concentration. This creates a more uniform and predictable degradation rate, extending the functional period to 7-8 months or longer while reducing variability in degradation behavior.
Solution Approach 2:
The patent employs feedback control in the shaping process by monitoring and adjusting the gallium diffusion parameters. This ensures consistent surface composition and predictable degradation rates, improving reliability while extending the functional 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 method results in an implant with improved mechanical properties, extended degradation time, reduced susceptibility to cracking, and cost-effective production, with the average strut fracture diameter increased and degradation period extended from 4 to 6 months to 7 to 8 months.
Implementation Method 1
the lubricant contains gallium or a gallium compound which diffuses into the surface of the semifinished article during shaping
Implementation Method 2
forming an alloy, reducing friction and controlling degradation by adjusting the diffusion depth and composition
Implementation Method 3
shaping the semifinished article at a temperature of between 250° C. and 550° C. by means of a tool
Implementation Method 4
which diffuses into the surface to form an alloy during shaping at elevated temperatures
Implementation Method 5
a metallic lubricant containing gallium or a gallium compound on at least a part of its surface that will come into contact with the semifinished article
Data Source
AI summary
An implant, in particular an intraluminal endoprosthesis, or a semi-finished part for an implant, having a hollow cylindrical body, wherein the body includes magnesium, and the body is enriched with gallium or a gallium alloy in a region close to a surface.