Ultrafine Polyester Fiber Stent Graft Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ultrafine polyester fibers used in stent grafts face challenges with integration between the stent and graft, leading to blood leakage and poor handling during suturing due to thin wall thickness, which is exacerbated by thermal shrinkage stress issues.
Innovation Solution
Development of ultrafine polyester fibers with a polyethylene terephthalate content of 98 wt% or greater, specific viscosity, fineness, thermal shrinkage stress, and crystallinity to ensure improved integration and stability within the body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the wall thickness of stent graft fabric is reduced to achieve smaller stent graft diameters, then the scope of treatable patients is widened and physical burden is reduced, but the flexibility of the fabric increases making suturing difficult and integration with stent poor
Solution Approach 1:
The invention changes the physical parameters of the polyester fiber by controlling the crystallization process to achieve a specific crystallinity range (30-60%). This parameter change modifies the fiber's thermal shrinkage stress characteristics, allowing the fabric to maintain adequate stiffness for suturing while achieving thin wall thickness for smaller graft diameters.
Solution Approach 2:
The invention applies local quality control by specifying the crystallinity distribution within the fiber structure, particularly in the region from the fiber surface to a depth of 0.1 μm. This localized control of crystallinity creates optimal thermal shrinkage stress at the fiber level, which translates to improved fabric handleability and stent integration without compromising the overall thinness of the graft.
2Volume of moving object
If the wall thickness of stent graft fabric is reduced, then smaller stent graft diameters are achieved, but integration between stent and graft deteriorates leading to blood leakage
Solution Approach 1:
The invention changes the thermal shrinkage stress parameter of the polyester fiber by precisely controlling the crystallinity to be within 30-60%. This parameter optimization ensures that the fabric generates sufficient thermal shrinkage stress during sterilization to tighten around the stent, achieving reliable integration and preventing blood leakage even in thin-walled grafts with smaller diameters.
Solution Approach 2:
The invention performs preliminary action by pre-setting the crystallinity of the polyester fiber during manufacturing, which predetermines the thermal shrinkage stress characteristics. This preliminary structural preparation ensures that when the graft is sterilized, the fibers automatically generate the necessary shrinkage force to secure integration with the stent, preventing blood leakage before the graft is even implanted.
3Reliability
If conventional direct spun ultrafine polyester fibers are used, then biological safety is ensured, but thermal shrinkage stress is insufficient causing loosening between stent and graft
Solution Approach 1:
The invention changes the thermal shrinkage stress parameter by optimizing the crystallinity of the polyester fiber to within 30-60%. This parameter adjustment increases the thermal shrinkage stress from insufficient levels to an optimal range, enabling the fiber to generate adequate shrinkage force during sterilization to secure the graft to the stent, while maintaining the biological safety of using pure PET fibers.
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 ultrafine polyester fibers provide enhanced biological safety, improved integration with stents, and long-term stability, reducing blood leakage and handling difficulties while maintaining mechanical strength.
Implementation Method 1
a maximum thermal shrinkage stress of 0.05 cN/dtex or greater in a temperature range of between 80°C and 200°C
Implementation Method 2
a birefringence of 0.20 or greater in the region spreading from the surface of the fiber to a depth of 0.1 μm
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Provided is an ultrafine polyester fiber which is useful as a constituent material for a cloth for a stent graft or other medical device that is to be implanted in the body and which can simultaneously solve both a clinical need (diameter reduction) and a clinical challenge (integration of a stent with a stent graft). An ultrafine polyester fiber which has a polyethylene terephthalate content of 98 wt% or more, characterized by: having (1) a reduced viscosity (ηsp/c) of 0.80 dl/g or higher and (2) a total fineness of 7 to 120 dtex and a single-fiber fineness of 0.5 dtex or less; and exhibiting (3) a maximum thermal shrinkage stress of 0.05 cN/dtex or more in a temperature range of 80 to 200°C or (4) a degree of crystallinity of 35% or more in a region spreading from the surface of the fiber to a depth of 0.1 µm.