Electrospun Graft Layer Porosity Control for Stent Sealing
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Solution Overview
Problem
Current stent-graft treatments for aneurysms, while less invasive than traditional surgery, face challenges in ensuring long-term sealing and preventing endoleaks, particularly in maintaining structural integrity and promoting endothelialization.
Innovation Solution
A method of electrospinning a graft layer with two distinct layers, where the inner layer is more porous to encourage endothelialization and the outer layer is less porous for structural stability and to prevent endoleaks, achieved by varying electrospinning parameters such as needle size, flow rate, and humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-layer graft structure is used, then the device complexity is reduced, but the ability to simultaneously provide structural stability and promote endothelialization is compromised
Solution Approach 1:
The graft layer is divided into two distinct layers: an inner layer with higher porosity (40-70%) to promote endothelialization and cell infiltration, and an outer layer with lower porosity (10-30%) to provide structural stability and prevent endoleaks. This segmentation allows each layer to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the graft layer are given different properties: the inner layer contacting the aneurysm cavity has high porosity to facilitate biological integration, while the outer layer has low porosity to provide mechanical strength. This local differentiation of properties enables the graft to simultaneously meet conflicting functional requirements.
2Reliability
If the graft layer is made more porous to encourage endothelialization, then the biological integration is improved, but the structural stability and sealing capability deteriorate
Solution Approach 1:
The graft is segmented into two layers with different porosity levels. The inner layer has porosity of 40-70% to allow cell penetration and endothelialization, while the outer layer has porosity of 10-30% to maintain structural integrity and prevent fluid leakage.
Solution Approach 2:
The graft exhibits spatially varying porosity: high porosity (40-70%) in the inner layer for biological integration, and low porosity (10-30%) in the outer layer for mechanical strength. This local quality differentiation resolves the contradiction between biological and mechanical requirements.
3Reliability
If the graft layer is made less porous to prevent endoleaks, then the sealing capability is improved, but the endothelialization and cell infiltration are hindered
Solution Approach 1:
The graft structure is segmented into an inner high-porosity layer (40-70%) that facilitates endothelialization and an outer low-porosity layer (10-30%) that provides sealing capability. Each layer is optimized for its specific function through controlled porosity differentiation.
Solution Approach 2:
Different porosity levels are applied locally: the inner layer has high porosity (40-70%) to encourage cell infiltration and endothelial growth, while the outer layer has low porosity (10-30%) to prevent endoleaks and provide structural support.
4Ease of manufacture
If electrospinning parameters are kept constant for simplicity, then the manufacturing process is simplified, but the ability to create differentiated porosity in different layers is lost
Solution Approach 1:
Electrospinning parameters are changed between layers to achieve different porosity levels. The inner layer is electrospun with parameters that produce 40-70% porosity, while the outer layer is electrospun with different parameters to achieve 10-30% porosity. This parameter differentiation enables precise control over the porous structure of each layer.
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 approach enhances the structural stability of the graft layer while promoting endothelialization and reducing the risk of endoleaks, leading to improved sealing and reduced recovery time for patients.
Implementation Method 1
A method for electrospinning a graft layer
Data Source
AI summary
A method for making a graft layer is provided. The graft layer has at least two layers with different porosities. The two layers are applied by electrospinning. The parameters of the electrospinning may be varied when applying the first and second layers in order to achieve different porosities of the first and second layers.