Removable Blood Clot Filter Using Shape Memory Alloy Anchors
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Solution Overview
Problem
Existing blood vessel filters are either permanent or difficult to remove without causing damage to the vessel wall, as the endothelium layer grows over the anchor members, making safe removal after two weeks challenging.
Innovation Solution
A removable blood filter design featuring a hub with anchors and locators, where the anchors include hooks that penetrate the vessel wall and locators with tips that engage the wall, allowing for safe anchoring and later withdrawal without significant injury, utilizing a shape memory alloy like Nitinol for deployment and retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rigid hooks are used to anchor the filter permanently in the vessel wall, then the filter is securely anchored and prevents migration, but the filter cannot be removed without risking injury to or rupture of the vessel wall
Solution Approach 1:
The hooks are designed with dynamic properties, being initially rigid for secure anchoring but capable of bending under sufficient force. This allows the filter to be firmly anchored during use while enabling safe removal when needed, as the hooks can deform to release from the vessel wall without causing rupture.
Solution Approach 2:
The mechanical properties of the hooks change based on applied force. Under normal conditions, the hooks maintain rigid characteristics for secure anchoring. When removal force is applied, the hooks transition to a flexible state, allowing bending and release from the vessel wall, thus enabling safe filter removal.
2Reliability
If the filter remains in place for more than two weeks allowing endothelium layer growth over the anchor members, then the filter becomes permanently locked in place, but removal attempts result in injury to the vessel wall
Solution Approach 1:
The hooks maintain their dynamic characteristic throughout the implantation period, allowing them to be firmly anchored while retaining the capability to bend during removal. This dynamic property ensures reliable anchoring over time while preventing vessel wall injury during subsequent removal, regardless of endothelium growth.
Solution Approach 2:
The hooks are pre-designed with bending capability before implantation. This preliminary design feature ensures that even after endothelium growth locks the filter in place, the hooks can still bend during removal to release from the vessel wall, preventing injury while maintaining reliable anchoring throughout the implantation period.
3Object-affected harmful factors
If locator members are drawn apart to remove the filter before endothelium growth, then vessel wall damage is minimized, but the filter cannot be removed after two weeks when endothelium has grown over the locators
Solution Approach 1:
The hooks' dynamic bending capability allows the filter to be removed at any time regardless of endothelium growth. When removal is attempted, the hooks bend to release from the vessel wall, enabling removal even after two weeks when endothelium has grown, while still minimizing vessel wall damage through controlled deformation.
4Duration of action of stationary object
If the filter is designed as a permanent implant with rigid anchoring structures, then the filter provides long-term protection against embolism, but the filter cannot be removed when the embolism risk disappears
Solution Approach 1:
The hooks combine rigid anchoring characteristics with flexible removal capability. During the protection period, the hooks provide stable anchoring for long-term embolism prevention. When removal is needed after the risk period, the hooks can bend to release, enabling the filter to be removed adaptively when embolism risk disappears, thus providing both long-term protection and removability.
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
Enables safe and effective filtering of embolus in blood vessels while allowing for removal without causing significant trauma to the vessel wall, even after the endothelium layer has formed, by using a shape memory alloy to facilitate hook straightening and filter retrieval.
Implementation Method 1
utilizing a shape memory alloy like Nitinol for deployment and retrieval
Implementation Method 2
by using a shape memory alloy to facilitate hook straightening and filter retrieval
Data Source
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AI summary
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