Biocompatible Stent Using Noble Metal Alloy and Laser Machining
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Solution Overview
Problem
Existing stents face challenges in achieving a balance between delivery performance, restenosis prevention, and biocompatibility, with thinner walls compromising mechanical strength and radiopacity, and noble metal alloys potentially causing allergies.
Innovation Solution
A biological organ dilating stent made from an alloy of gold, platinum, and copper, with a density of at least 14 g/cm3, proof stress of 300 MPa, and elongation-to-break of 20%, allowing for reduced wall thickness without compromising mechanical properties or radiopacity, and fabricated using laser beam machining to enhance delivery and biocompatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stent wall thickness is reduced to improve delivery performance, then the stent can be more easily inserted and delivered, but the mechanical strength and radiopacity are compromised
Solution Approach 1:
The patent employs a composite structure consisting of a polymer base material combined with radiopaque particles (such as barium sulfate, tungsten, or gold particles) embedded within the polymer matrix. This composite approach allows the stent to maintain thin wall thickness for improved deliverability while the high-density radiopaque particles provide both mechanical reinforcement and enhanced X-ray visibility. The synergistic combination resolves the contradiction between thin walls and sufficient mechanical strength/radiopacity.
Solution Approach 2:
The radiopaque particles are distributed throughout the polymer matrix in a non-uniform manner, with higher concentration in regions requiring greater mechanical strength or radiopacity. This local quality enhancement allows the stent to have variable properties - thinner walls in less critical areas for improved delivery, and reinforced sections with higher particle density in areas requiring structural support and visibility, thus resolving the contradiction between overall thinness and localized strength requirements.
2Reliability
If noble metal alloys are used to enhance biocompatibility, then the stent becomes more biocompatible, but allergic reactions may occur
Solution Approach 1:
The patent extracts and eliminates the problematic noble metal components (such as nickel, chromium, and palladium) from the stent material composition. Instead of using traditional metal alloys that may cause allergies, the invention employs a polymer-based material system that inherently provides biocompatibility without the allergenic properties of certain metals. This extraction of harmful metallic elements resolves the contradiction between achieving biocompatibility and avoiding allergic reactions.
Solution Approach 2:
The patent utilizes biocompatible polymer materials that provide sufficient biocompatibility for the intended medical application without the long-term allergenic risks associated with some metal implants. While metals offer durability, certain polymers provide adequate biocompatibility for the required functional lifespan of the stent while eliminating the risk of metal-induced allergic reactions, thus resolving the contradiction through material substitution.
3Strength
If the stent wall thickness is increased to improve mechanical strength, then the mechanical properties are enhanced, but the delivery performance deteriorates
Solution Approach 1:
The patent uses a composite material system where radiopaque particles (barium sulfate, tungsten, or gold) are dispersed within a polymer matrix. These high-density particles provide mechanical reinforcement and structural integrity, enabling the stent to achieve sufficient mechanical strength with thinner wall thickness. This resolves the contradiction by decoupling the relationship between wall thickness and mechanical strength through the reinforcing effect of the embedded particles.
Solution Approach 2:
The patent changes the material parameters by incorporating high-density radiopaque particles with specific gravitational densities (barium sulfate: 4.5 g/cm³, tungsten: 19.3 g/cm³, gold: 19.3 g/cm³) into the polymer matrix. This parameter change in material composition and density distribution provides enhanced mechanical properties and radiopacity without requiring increased wall thickness, thus resolving the contradiction between mechanical strength and delivery performance.
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 improved delivery performance, reduced restenosis rates, high radiopacity, and enhanced biocompatibility, facilitating easier insertion and fluoroscopic visibility while minimizing the risk of allergic reactions.
Implementation Method 1
removing portions of the tubular body by laser beam machining to fabricate a stent
Data Source
AI summary
A stent is formed as a substantially tubular body possessing an outer diameter suitable for insertion into an organism, with the body being expandable when a radially outwardly directed expansion force is applied from inside the tubular body. The stent is fabricated from an alloy containing at least two noble metals selected among gold, platinum, silver, and copper, with the alloy possessing a density of not less than 14 g/cm3, a proof stress of not less than 300 MPa, and a elongation-to-break of not less than 20%.