Hybrid Polymer Stent Radial Strength and Flexibility
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Solution Overview
Problem
Metallic stents cause anatomical and physiological mismatch, leading to irritation and complications due to their stiffness, and their rigidity can result in trauma and failure when subjected to flexing or bending, while single-material polymer stents lack the ability to incorporate different mechanical and biological properties.
Innovation Solution
A hybrid polymer stent with multiple polymer component structures integrated into its main structure, fabricated using a 4-axis RP system that allows for sequential deposition of different polymer filaments, providing controlled mechanical properties and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic stents are used to provide radial strength, then the stent can sufficiently support the lumen, but the stent causes anatomical and physiological mismatch leading to irritation and trauma due to its stiffness
Solution Approach 1:
The patent employs composite materials by integrating two or more different polymer components within the stent structure. Each polymer component can be selected with specific mechanical properties, allowing the stent to achieve sufficient radial strength while incorporating softer materials that reduce irritation and trauma to surrounding tissues. This composite approach enables simultaneous optimization of structural support and biocompatibility.
Solution Approach 2:
The patent applies local quality by assigning different polymer materials to different regions or components of the stent structure. High-strength polymers are used in areas requiring radial support, while softer, more compliant polymers are used in areas that contact surrounding tissues. This spatial differentiation of material properties allows the stent to provide necessary mechanical support while minimizing harmful effects on adjacent tissues.
2Object-affected harmful factors
If a single-material polymer stent is used to reduce stiffness, then the stent is less rigid and more flexible, but it lacks the ability to incorporate different mechanical and biological properties
Solution Approach 1:
The patent uses composite materials to combine multiple polymer components, each with distinct mechanical and biological properties. This allows the stent to achieve a balance between flexibility and strength while incorporating diverse functionalities such as different degradation rates, drug elution characteristics, and mechanical compliance. The composite structure enables simultaneous optimization of multiple properties that cannot be achieved with a single material.
Solution Approach 2:
The patent implements multi-functionality by designing the stent with multiple polymer components that perform different functions. One polymer may provide structural support, another may control drug release, a third may regulate degradation timing, and so on. This multi-functional approach allows a single stent device to incorporate diverse mechanical and biological properties, enhancing its adaptability to various clinical requirements.
3Strength
If a stent with high longitudinal rigidity is used to ensure radial strength, then the stent can support the lumen, but it causes trauma to the vessel at the ends due to stress concentrations from compliance mismatch
Solution Approach 1:
The patent applies local quality by using different polymer materials at different locations along the stent structure. Softer, more compliant polymers are placed at the distal and proximal ends where they contact healthy vessel tissue, reducing stress concentrations and compliance mismatch. Harder, high-strength polymers are positioned in the central region where radial support is most critical for maintaining lumen patency. This spatial gradient of material properties minimizes trauma while ensuring adequate support.
Solution Approach 2:
The patent uses composite materials with varying mechanical properties distributed throughout the stent structure. By combining polymers with different elastic moduli and mechanical characteristics, the stent creates a composite structure that provides high radial strength in the body while having softer interfaces at the ends. This composite design resolves the compliance mismatch problem by transitioning gradually from stiff central support to compliant end regions.
4Adaptability or versatility
If a stent is subjected to substantial flexing or bending and axial compressions to treat complex anatomy, then the stent can adapt to vessel geometry, but severe strain and fatigue result in failure of the stent
Solution Approach 1:
The patent employs composite materials where different polymer components contribute different mechanical characteristics to the stent structure. Some polymers are selected for their flexibility and ability to withstand repeated bending and compression cycles, while others provide structural reinforcement. This composite construction allows the stent to accommodate complex vessel geometries and physiological movements while maintaining fatigue resistance and preventing structural failure.
Solution Approach 2:
The patent applies local quality by placing flexible, fatigue-resistant polymers in regions subject to repeated bending and compression, such as the ends and hinges of the stent structure. High-strength polymers are positioned in regions requiring structural integrity but experiencing less cyclic loading. This localized optimization of material properties allows the stent to withstand substantial mechanical stresses while maintaining reliability in high-stress areas.
Data Source
AI summary
The present invention provides a hybrid polymer stent with two or more polymer component structures which are integrated in the polymer stent main structure. The methods for fabrication of the hybrid stents is also provided. It is a further object to the present invention to provide a 4 axis RP system in which the 4th axis is a computer controlled rotation shaft added to an xyz position system. In preferred embodiments, the 4 axis RP system also has 2 or more material delivery systems that sequentially deposit two or more polymer hot melt filaments or viscous solution filaments.