Asymmetric Coil Cross-Section for Guide Wire Friction Reduction
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Solution Overview
Problem
Existing guide wires experience plastic deformation and reduced operability when inserted into steeply curved coronary arteries, leading to bulging and increased friction resistance, which impairs the transmission of pushing and torque forces.
Innovation Solution
A coil with a cross-sectional shape featuring a curved portion, a flat portion, and protruding portions at the boundaries, designed to prevent wire rod sticking and allow for resilient return to the original position, reducing friction and enhancing force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the guide wire is pushed into a steeply curved portion of the coronary artery, then the coil reaches the target portion, but excessive force causes plastic deformation of the coil and wire rods stick to each other
Solution Approach 1:
The wire rod cross-section is designed with asymmetric features including a curved portion with large curvature radius, a flat portion with small curvature radius, and protruding portions at the boundaries. This asymmetric geometry prevents adjacent wire rods from sticking together while maintaining flexibility for navigation through curved coronary arteries.
Solution Approach 2:
Different portions of the wire rod cross-section have different local properties: the curved portion provides flexibility and conformability to vessel walls, the flat portion prevents sticking between adjacent rods, and the protruding portions further eliminate contact between wire rods. Each local region serves a specific function to resolve the contradiction.
2Adaptability or versatility
If the coil undergoes plastic deformation, then the guide wire can reach curved portions, but the guide wire bulges and the catheter cannot be inserted
Solution Approach 1:
The asymmetric cross-sectional design with flat portions and protruding features prevents wire rods from sticking together during deformation, allowing the coil to navigate curved portions while maintaining a consistent outer diameter that prevents bulging and enables catheter insertion.
Solution Approach 2:
The curvature radius parameter is varied across different portions of the wire rod cross-section. The curved portion has a large curvature radius for flexibility, while the flat portion has a small curvature radius to prevent sticking. This parameter variation allows the coil to adapt to curved anatomy without permanent deformation or bulging.
3Adaptability or versatility
If the guide wire bulges due to plastic deformation, then the coil can navigate curved portions, but friction resistance increases and torque transmission performance decreases
Solution Approach 1:
The asymmetric cross-section with flat portions and protruding features eliminates sticking between wire rods, preventing bulging and maintaining low friction resistance. This ensures reliable torque transmission from the proximal end to the distal end while retaining the ability to navigate curved coronary arteries.
Solution Approach 2:
The flat portion and protruding portions locally modify the wire rod geometry to prevent inter-rod contact and sticking. This local modification reduces friction resistance along the entire coil length, enabling effective torque transmission while maintaining adaptability to curved anatomy.
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 coil design prevents wire rod sticking and bulging, ensuring reliable transmission of pushing and torque forces, thereby improving the guide wire's operability and reducing friction resistance.
Implementation Method 1
when the external force is reduced or released, due to the resilience of the one wire rod, the one wire rod returns to an original position thereof while the curved portion of the one wire rod slides against the protruding portion of the other wire rod
Data Source
AI summary
A coil is made by helically winding a wire rod. A cross-sectional shape of the wire rod of the coil includes a curved portion that is arcuately curved toward a center axis of the coil; a flat portion that is provided on an outer circumference of the coil, and is formed in a flat shape with a curvature that is smaller than a curvature of the curved portion; and at least one protruding portion that is provided at the boundary between the curved portion and the flat portion or in the vicinity of the boundary, and protrudes toward an adjacent wire rod.