Fine-Grained Biodegradable Metallic Implants for Controlled Corrosion
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Solution Overview
Problem
Long-term metal implants, such as stents, can cause damaging side effects and are difficult to remove, leading to complications like in-stent restenosis, while biodegradable polymer stents face issues with inflammation and toxicity, necessitating the development of biodegradable metallic implants that are radiopaque and have controlled corrosion rates.
Innovation Solution
Biodegradable medical implants comprising at least partially fine-grained metallic materials, specifically iron or zinc with crystalline microstructures of 2 nm to 10 μm grain size, applied as coatings or fillers, which degrade within one to twelve months, providing enhanced mechanical properties and radiopacity for precise imaging and controlled dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If permanent metal implants are used, then mechanical strength and durability are improved, but long-term side effects and difficulty of removal worsen
Solution Approach 1:
The patent changes the key parameter of material biodegradability while maintaining mechanical strength through fine-grained microstructure. The metallic material is engineered with grain sizes of 1-100 micrometers, which significantly enhances strength and slows corrosion rates, allowing the implant to provide long-term mechanical support before gradually degrading in the body over 1-10 years.
Solution Approach 2:
The patent employs composite material structure by combining fine-grained metallic material with specific grain size control. This creates a material system where the microstructure itself (grain size) acts as the composite feature, providing both mechanical strength and controlled biodegradability simultaneously.
2Duration of action of stationary object
If biodegradable polymer stents are used, then removability is improved, but inflammation and toxicity worsen
Solution Approach 1:
The patent changes the material class from polymer to fine-grained metal, fundamentally altering the degradation mechanism. The metallic material degrades through controlled corrosion rather than polymer hydrolysis, producing metallic ions instead of polymer fragments, thereby avoiding polymer-specific inflammatory responses while maintaining temporary functionality.
Solution Approach 2:
The patent applies the disposable concept by designing a biodegradable implant that fulfills its mechanical support function temporarily (1-10 years) and then naturally degrades in the body, eliminating the need for removal surgery. The fine-grained structure ensures controlled degradation rate, making the implant effectively self-limited in its presence.
3Strength
If fine-grained metallic material is used, then mechanical strength and corrosion resistance are improved, but manufacturing complexity worsens
Solution Approach 1:
The patent changes the microstructural parameter of grain size to the fine range (1-100 micrometers) through controlled solidification or thermomechanical processing. This parameter change simultaneously achieves enhanced mechanical strength via Hall-Petch relationship and improved corrosion resistance, while the processing methods, though specialized, follow established metallurgical principles.
4Duration of action of stationary object
If fine-grained metallic material is used, then corrosion rate control is improved, but imaging capability worsens
Solution Approach 1:
The patent changes the grain size parameter to fine dimensions (1-100 micrometers), which slows the corrosion rate by reducing the total grain boundary area and creating a more uniform degradation pattern. This extended degradation time (1-10 years) provides prolonged mechanical support while the metallic composition maintains sufficient radiopacity for medical imaging.
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 use of fine-grained metallic materials in biodegradable implants reduces toxicity and systemic effects, allows for accurate imaging and placement, and achieves controlled degradation, minimizing volume and weight while maintaining mechanical strength and biocompatibility, thus addressing the limitations of traditional metal and polymer-based implants.
Implementation Method 1
biodegradable materials that can be absorbed by the body over time... slowly degrade/dissolve in the body
Implementation Method 2
radiopaque and have controlled corrosion rates... allows for accurate imaging and placement
Data Source
AI summary
In-vivo biodegradable medical implants, containing at least in part at least partially fine-grained metallic materials provide a strong, tough, stiff and lightweight implant. The in-vivo biodegradable implants are used in a number of stent applications, for fracture fixation, sutures and the like. The in-vivo biodegradable medical implants enable the reduction of implant size and weight and consequently result in reducing the release of implant degradation products into the body.