Medical Stent Intermediate Configuration Strain Reduction
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Solution Overview
Problem
Conventional medical devices, such as stents, experience high strains and fatigue when deployed in body lumens that change shape significantly, leading to potential fracture and reduced lifespan due to excessive deformation from straight to curved configurations.
Innovation Solution
A medical device designed to move between a first loaded configuration and a second loaded configuration via an intermediate unloaded configuration, minimizing strains by matching its shape to an intermediate configuration between two extremes, using materials like Nitinol and incorporating alignment markers for optimal deployment in vessels like the popliteal artery and coronary arteries, reducing maximum strain below the fatigue limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device is configured to match the shape of the vessel in the unloaded state, then the strains in the device during initial deployment are minimized, but when the vessel changes to an extreme position the device experiences high strains leading to potential fracture
Solution Approach 1:
The device is pre-configured with an intermediate shape that anticipates the vessel's deformation range. By setting the device's natural configuration to match an intermediate vessel state rather than the unloaded state, the device is prepared in advance to accommodate vessel deformation, distributing strains more evenly across the deformation cycle and preventing extreme strain concentrations that would lead to fatigue failure.
Solution Approach 2:
The invention changes the geometric parameters of the device by configuring it to an intermediate shape that is neither fully straight nor fully curved. This parameter adjustment allows the device to operate within an optimized strain range, where the maximum strains are reduced compared to conventional devices that start from a straight configuration. The intermediate configuration optimizes the device's mechanical response to vessel deformation.
2Reliability
If the device is delivered in a curved configuration to match the vessel shape, then initial strains are reduced, but the device complexity increases due to the need for precise shape matching and delivery mechanisms
Solution Approach 1:
The device incorporates dynamic shape-matching capabilities that allow it to adapt its configuration based on the vessel's state. The device can transition between different shapes (straight, intermediate, and curved configurations) depending on the delivery requirements and the vessel's deformation state. This dynamic adaptability reduces the need for complex pre-configured delivery systems while maintaining optimal strain distribution.
3Adaptability or versatility
If the device undergoes large deformation from straight to curved configuration, then it can accommodate extreme vessel positions, but the maximum strain increases beyond the fatigue limit reducing device lifespan
Solution Approach 1:
The device's deformation is segmented into multiple stages by introducing an intermediate configuration. Instead of undergoing a single large deformation from straight to curved, the device progresses through intermediate shapes that distribute the total deformation into smaller increments. This segmentation of the deformation path ensures that the maximum strain at any point remains below the fatigue limit, extending the device's operational lifespan while still accommodating extreme vessel positions.
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 device reduces strain and fatigue by distributing deformation across intermediate configurations, enhancing mechanical performance and reducing the risk of fracture, with strains maintained below the material's fatigue limit, thereby extending the device's lifespan and effectiveness.
Implementation Method 1
The device may be deformable between the first loaded configuration and the second loaded configuration. In one case the device is bendable between the first loaded configuration and the second loaded configuration.
Data Source
AI summary
A medical device suitable for location in a body lumen is movable between a first loaded configuration and a second loaded configuration. The device has an unloaded configuration which is intermediate the first loaded configuration and the second loaded configuration. The device can be a stent for deployment in a blood vessel.