Medical Wire with Variable Cross-Sectional Rigidity
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Solution Overview
Problem
Medical wires with varying rigidities arranged longitudinally and joined by welding lack stress concentration at join sites, leading to strength deterioration and inadequate driving force generation in flexible medical equipment.
Innovation Solution
A medical wire design featuring a main wire-strand portion and sub wire-strand portions with a diameter at least twice that of the main wire strand, forming a first region with a small cross-sectional area and a second region with a larger cross-sectional area, secured by methods like soldering or laser welding, to enhance flexibility and driving force responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two types of wires having different rigidities are arranged next to each other in a longitudinal direction and are joined by welding, then it is possible to generate driving force on the distal-end side, but stress concentration occurs at join sites leading to strength deterioration
Solution Approach 1:
The wire is divided into multiple wire-strand portions (first, second, third) with different rigidities arranged in the longitudinal direction. Each portion has a specific number of strands (e.g., 7, 19, 37) creating distinct rigidity zones without requiring welding joints between different rigidity sections, thereby eliminating stress concentration at join sites while maintaining driving force generation capability.
Solution Approach 2:
Different sections of the wire are designed with locally optimized properties: the first wire-strand portion has higher rigidity for manipulating portion connection, the second has intermediate rigidity for transitioning, and the third has lower rigidity for inserted portion connection. This local differentiation achieves both strength distribution and driving force generation without welding-induced stress concentration.
2Ease of manufacture
If a medical wire has uniform structure throughout its length, then manufacturing is simplified, but it cannot provide both flexibility for insertion and sufficient driving force generation
Solution Approach 1:
The wire is segmented into multiple wire-strand portions with different numbers of strands along its length. This segmentation allows the wire to exhibit varying rigidity characteristics (flexible in some regions, rigid in others) while maintaining a consistent manufacturing process of stranding multiple wires together, thus balancing manufacturing simplicity with functional performance.
3Power
If the lateral cross-sectional area of the wire is increased to enhance driving force, then the driving force generation improves, but the flexibility and ability to navigate tortuous paths deteriorates
Solution Approach 1:
The wire is designed with locally differentiated rigidity through varying the number of strands in different wire-strand portions. Regions requiring flexibility (for navigating tortuous paths) have fewer strands reducing cross-sectional area, while regions requiring driving force generation have more strands increasing cross-sectional area. This local optimization resolves the contradiction between driving force and flexibility.
Data Source
AI summary
Provided is a medical wire including: a main wire-strand portion that is formed of a plurality of main wire strands and that extends over the entire length of the medical wire; and at least one sub wire-strand portion that is disposed at an outer circumference of the main wire-strand portion, that is secured to the main wire-strand portion, and that is formed of a sub wire strand, wherein the diameter of the sub wire strand is at least twice the diameter of the main wire strand, and a first region having a relatively small lateral cross-sectional area and a second region having a lateral cross-sectional area that is greater than that of the first region are included.