Braided Stent Radial Axial Force Ratio Optimization
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Solution Overview
Problem
Existing digestive tract stents fail to balance high expansion force with flexibility, often causing ulcers or perforations when placed in bent organs, and exhibit significant shortening during expansion.
Innovation Solution
A stent formed by braiding wire rods with a specific radial and axial force ratio, featuring a first mesh structure with intersecting loops and a second mesh structure with non-intersecting loops, optimized for radial force between 0.02 N/mm to 0.04 N/mm, axial force of 0.3 N or less, and shortening of 35% or less, ensuring close contact without damaging the organ wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the stent is designed to have high expansion force, then the stent can come into close contact with the inner wall to sufficiently expand the constricted part, but the flexibility deteriorates causing ulcers or perforations in bent organs
Solution Approach 1:
The patent applies parameter changes by precisely controlling the radial force (RF) to be 0.02 N/mm to 0.04 N/mm and the ratio of radial force to axial force (RF/AF) to be 0.14 mm−1 or more. These specific parameter ranges optimize the balance between expansion capability and flexibility, preventing both insufficient expansion and tissue damage in bent organs.
Solution Approach 2:
The stent employs a composite structure formed by braiding wire rods with specific configurations including circumferential units with meshes arrayed along the circumferential direction. This composite wire rod structure enables simultaneous achievement of high radial force for expansion and controlled axial force for flexibility in bent anatomical configurations.
2Force
If the stent is designed to have high expansion force, then the constricted part can be sufficiently expanded, but the shortening increases making precise placement difficult
Solution Approach 1:
The patent controls the shortening parameter to be 35% or less while maintaining the radial force ratio RF/AF at 0.14 mm−1 or more. This parameter optimization ensures that the stent achieves sufficient expansion force while limiting length reduction during deployment, enabling precise placement in the digestive tract.
3Adaptability or versatility
If the stent is designed to have good flexibility, then the stent can adapt to bent organs without causing ulcers or perforations, but the expansion force becomes insufficient
Solution Approach 1:
The patent establishes specific parameter ranges where radial force RF is 0.02 N/mm to 0.04 N/mm and the ratio RF/AF is 0.14 mm−1 or more. This optimized parameter combination ensures that the stent maintains sufficient expansion force while achieving the flexibility needed to adapt to bent organ configurations without causing tissue damage.
Solution Approach 2:
The stent structure incorporates dynamic characteristics through its wire rod braid configuration with circumferential units that can deform and adapt to bent geometries. The coupling points between adjacent circumferential units allow controlled movement and flexibility while maintaining overall structural integrity and expansion capability.
Data Source
AI summary
An object is to provide a stent having, in a well-balanced manner, a high expansion force that enables the stent to come into close contact with an inner wall of a tubular organ, such as a digestive tract, to sufficiently expand a constricted part and good flexibility by which none of an ulcer and a perforation is generated at sites with which both end parts of the stent come into contact even when the stent is placed in a bent tubular organ. A stent of the disclosure is a stent formed in a tubular shape by braiding one or more wire rods. A radial force (RF) ranges from 0.02 N/mm to 0.04 N/mm, and a ratio (RF/AF) of the radial force (RF) to an axial force (AF) is 0.14 mm−1 or more. The stent of the disclosure preferably has a shortening of 35% or less.