Platinum-Tungsten Intravascular Implants for Strength and MRI Compatibility
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Solution Overview
Problem
Existing intravascular medical devices face limitations in mechanical strength, radiopacity, and magnetic susceptibility, particularly with platinum-tungsten alloys containing up to 8% tungsten, which compromise radial expansion force and manufacturability.
Innovation Solution
Development of platinum-tungsten alloys with tungsten content between 10% to 25% weight, optionally including zirconium, to enhance mechanical properties and reduce magnetic susceptibility, allowing for improved radiopacity and manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If platinum-tungsten alloy with up to 8% tungsten is used, then magnetic susceptibility is reduced and radiopacity is improved, but mechanical strength and radial expansion force are insufficient
Solution Approach 1:
The patent changes the chemical composition parameter of the platinum-tungsten alloy by increasing tungsten content from the conventional maximum of 8% to a range of 9-20%. This parameter change simultaneously improves mechanical strength, radial expansion force, and manufacturability while maintaining acceptable magnetic susceptibility and radiopacity characteristics for medical device applications
Solution Approach 2:
The patent creates a composite metal alloy material by combining platinum with higher concentrations of tungsten (9-20% by weight). This composite material achieves superior mechanical properties and radial expansion force compared to conventional Pt-8%W alloy, while the tungsten content remains within a range that maintains suitable magnetic and radiographic properties for intravascular devices
2Strength
If cobalt-chromium alloy is used to increase radial force, then mechanical strength is improved, but magnetic susceptibility increases causing MRI artifacts and radiopacity decreases
Solution Approach 1:
The patent modifies the alloy composition by increasing tungsten content to 9-20% in platinum-tungsten alloys, achieving superior radial force and mechanical strength comparable to or exceeding cobalt-chromium alloys. Simultaneously, this composition maintains low magnetic susceptibility because tungsten is non-magnetic, eliminating MRI artifacts while preserving high radiopacity
Solution Approach 2:
The patent develops a platinum-tungsten composite alloy that combines the non-magnetic properties of platinum with the high-strength characteristics of tungsten. This composite material provides radial force comparable to cobalt-chromium alloys while maintaining excellent magnetic compatibility for MRI imaging and superior radiopacity for fluoroscopic visualization
3Strength
If tungsten content is increased above 8% in platinum alloy, then mechanical strength and radial expansion force are improved, but brittleness increases compromising device performance
Solution Approach 1:
The patent optimizes the tungsten content parameter within a specific range of 9-20% by weight, which provides sufficient mechanical strength and radial expansion force while avoiding excessive brittleness. This controlled parameter change ensures the alloy maintains adequate ductility and formability for device manufacturing and deployment
Solution Approach 2:
The patent applies the concept of local quality by controlling the distribution and concentration of tungsten within the platinum matrix at an optimal level (9-20%). This localized optimization of composition ensures that strength and radial expansion force are enhanced in the critical regions where these properties are needed, while maintaining overall ductility and reliability of the device structure
Data Source
AI summary
An implant includes a layer formed from an alloy having platinum (Pt) and tungsten (W); wherein the platinum (Pt) and the tungsten (W) together constitute a majority of the alloy by weight; wherein a percentage of the tungsten (W) in the alloy is equal to or greater than 10% by weight and is less than 20% by weight; wherein the alloy further comprises zirconium (Zr), and a percentage of the (Zr) in the alloy of the layer of the implant is equal to or less than 5% by weight.