Stress-Induced R-Phase Loading of Nitinol Stents
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Solution Overview
Problem
Current medical devices utilizing self-expanding stents made from shape memory alloys, such as Nitinol, often overlook the R-phase transformation, which could provide advantages for medical devices, leading to limitations in delivery and deployment configurations.
Innovation Solution
A method involving a stress-induced R-phase transformation in a two-stage shape memory alloy is employed to load medical devices into a delivery system, where the alloy is processed to maximize phase transformation temperature differences, allowing for a delivery configuration with stress-induced R-phase without inducing martensite, enabling efficient loading and deployment of stents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If stress is applied to the medical device to obtain a delivery configuration, then the medical device can be loaded into the restraining member, but stress-induced martensite may form which compromises device performance
Solution Approach 1:
The patent applies parameter changes by controlling the temperature of the shape memory alloy to remain above the martensite transformation temperature during stress-induced loading. This temperature parameter control prevents the formation of stress-induced martensite while still allowing the alloy to undergo R-phase transformation, thereby enabling easy loading into the delivery system without compromising device performance or reliability.
2Manufacturing precision
If the alloy is processed to maximize phase transformation temperature differences, then R-phase transformation can be optimized, but the process complexity increases
Solution Approach 1:
The patent utilizes phase transitions by leveraging the R-phase transformation characteristics of two-stage shape memory alloys. By processing the alloy to maximize the temperature difference between R-phase and martensite transformations, the invention achieves precise control over which phase transition occurs during loading. This approach optimizes R-phase transformation for delivery configuration while preventing unwanted martensite formation, balancing manufacturing precision with acceptable process complexity.
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 approach allows for a more controlled and efficient loading of self-expanding stents into delivery systems, optimizing the use of R-phase transformation to achieve desired deployment configurations without the formation of stress-induced martensite, enhancing the medical device's performance and functionality.
Implementation Method 1
A stress is applied to the medical device at the temperature, and the stress is sufficient to form R-phase from at least a portion of the austenite
Implementation Method 2
self-expanding stents made from shape memory alloys, such as Nitinol, which can 'remember' and recover a previous shape
Implementation Method 3
The medical device is maintained in a delivery configuration by the restraining member
Data Source
AI summary
A method of loading a medical device into a delivery system includes providing a two-stage shape memory alloy at a temperature at which at least a portion of the alloy includes austenite. A stress which is sufficient to form R-phase from at least a portion of the austenite is applied to the medical device at the temperature. A delivery configuration of the medical device is obtained, and the medical device is loaded into a restraining member. Preferably, the delivery configuration of the medical device includes stress-induced R-phase.