Superelastic Stent with Integrated Radiopaque Marker
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Solution Overview
Problem
Existing methods for fabricating intraluminal medical devices with radiopaque markers are labor-intensive and require post-heat setting processes, such as electropolishing, and do not easily allow for complex shapes with integrated markers that provide adequate x-ray visibility.
Innovation Solution
A method involving threading a radiopaque marker over a shape memory alloy wire, securing it to a mandrel, and heat-setting in an inert gas atmosphere to form a superelastic medical device with the marker integrated before heat-setting, eliminating the need for post-heat setting electropolishing and enabling complex shapes with enhanced x-ray visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radiopaque markers are attached to the stent after heat setting, then the markers can be added to improve x-ray visibility, but the process becomes labor-intensive and requires additional post-heat setting steps such as electropolishing
Solution Approach 1:
The radiopaque marker is threaded over the wire before the heat setting process, rather than being attached afterward. This preliminary action eliminates the need for post-heat setting attachment steps and associated electropolishing processes, reducing manufacturing complexity while maintaining x-ray visibility
Solution Approach 2:
The method combines the marker integration and heat setting processes into a single sequence, where the marker is in place before heat setting occurs. This merging of operations eliminates separate attachment and electropolishing steps, simplifying the overall fabrication process
2Productivity
If the wire is heat set in air, then the heat setting process can proceed normally, but oxide formation occurs on the surface of the wire requiring additional electropolishing steps
Solution Approach 1:
The heat setting process is performed in an inert gas atmosphere (such as nitrogen or argon) instead of air. This prevents oxidation of the wire surface during heat setting, eliminating the need for subsequent electropolishing steps to remove oxides, thereby maintaining productivity while preventing harmful oxide formation
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
This method simplifies the fabrication of superelastic medical devices with integrated radiopaque markers, reducing labor and avoiding oxide formation, while ensuring high x-ray visibility and biocompatibility, facilitating precise placement during medical procedures.
Implementation Method 1
threading a radiopaque marker having an elongated shape over a wire comprising a shape memory alloy. After the threading, the wire is secured in a predetermined configuration to a mandrel. While secured to the mandrel, the wire is heat set in an environment comprising an inert gas so as to impart a memory of the predetermined configuration to the wire and superelastic properties to the shape memory alloy
Implementation Method 2
the heat setting is carried out in an inert atmosphere. Thus, oxide formation on surfaces of the medical device can be avoided during heat-setting
Data Source
Figure 1A~2
Figure 3A~4C
AI summary
A method of making a superelastic medical device with a radiopaque marker includes threading a radiopaque marker (102) having an elongated shape over a wire (104) comprising a shape memory alloy. After the threading, the wire is secured in a predetermined configuration (106) to a mandrel (108). While secured to the mandrel, the wire is heat set in an environment comprising an inert gas so as to impart a memory of the predetermined configuration (106) to the wire (104) and superelastic properties to the shape memory alloy. A superelastic medical device including the radiopaque marker is thus formed.