Polymer Stent Radial Deformation for Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polymeric stents face challenges in meeting mechanical requirements such as radial strength, flexibility, and biocompatibility due to their inherent material properties, leading to issues like recoil and mechanical failure.
Innovation Solution
A method of radially deforming a polymer tube to increase radial strength by forming linear ring struts and curved hinge elements, allowing the rings to move from a non-deformed to a deformed configuration, and creating W-shaped closed cells to enhance structural integrity and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymeric stents are used to maintain vascular patency, then biocompatibility is improved, but radial strength is insufficient leading to recoil and mechanical failure
Solution Approach 1:
The patent employs polymeric materials that combine biocompatibility with enhanced mechanical strength through specific polymer selection and structural design. The composite approach integrates the biocompatible polymer matrix with structural configurations that provide the necessary radial strength to prevent recoil while maintaining vascular patency.
Solution Approach 2:
The patent utilizes curved and angled strut designs within the stent framework. The curved hinge elements and angled connections between struts create a geometric configuration that enhances radial strength through distributed stress pathways, allowing the stent to resist compressive forces while maintaining flexibility and biocompatibility.
2Strength
If the stent structure is made more rigid to increase radial strength, then recoil is reduced, but flexibility for crimping and maneuvering through tortuous paths is compromised
Solution Approach 1:
The patent divides the stent structure into discrete modular units consisting of interconnected struts and hinge elements. This segmentation allows each unit to maintain structural integrity for radial strength while the connections between units provide articulation points that enable flexibility during crimping and deployment through tortuous vascular paths.
Solution Approach 2:
The patent incorporates movable hinge elements that allow the stent structure to dynamically adapt during deployment. These hinges enable the stent to transition from a compressed delivery state to an expanded deployed state, providing the necessary flexibility for maneuvering while maintaining radial strength once deployed through the rigidified strut configuration.
3Reliability
If the stent is designed with complex structural elements to enhance radial strength, then mechanical failure is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent employs a modular segmented design where complex structural elements are broken down into repeating units of struts and hinges. This segmentation allows the complex geometry to be manufactured using standardized processes applied repeatedly to each module, reducing overall manufacturing complexity while maintaining the mechanical integrity provided by the complex structural configuration.
Solution Approach 2:
The patent utilizes curved strut designs and angled connections that, while geometrically complex, can be manufactured using consistent forming processes. The curvature and angles are designed to distribute stresses evenly, reducing the need for additional reinforcement elements and simplifying the manufacturing process despite the apparent structural complexity.
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 method significantly enhances the radial strength and flexibility of polymeric stents, reducing recoil and improving their ability to maintain vascular patency and withstand cyclic loading, while maintaining biocompatibility.
Implementation Method 1
radially deforming a polymer tube to increase radial strength of the polymer tube
Implementation Method 2
the hinge elements adapted to allow the rings to move from a non-deformed configuration to a deformed configuration
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Polymeric stents having fracture toughness and resistance to recoil after deployment are disclosed along with methods of manufacturing such stents. Improvements to mechanical characteristics and other improvements may be achieved by having polymer chains within individual stent struts oriented in a direction that is closer to or in line with the axis of the individual stent struts. The desired orientation of polymer molecules may be achieved by one or any combination of extruding polymers into hollow tubes to induce axially oriented polymer chains, applying a tensile load to polymer tubes to induce axially oriented polymer chains, and radially expanding polymer tubes to induce circumferentially oriented polymer chains. Stent patterns include struts defining diamond shaped cells and/or W-shaped cells.