Medical Guide Wire Hardness Gradient for Resilient Navigation
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Solution Overview
Problem
Existing guide wires lack resilience, which affects their operability and ability to restore shape after bending, especially in treating stenosis and chronic total occlusion in blood vessels.
Innovation Solution
A medical wire material made of stainless steel with a specific hardness distribution, where the outer peripheral portion of the transverse section has an average hardness of 8.0 GPa or higher, achieved through a combination of wire drawing and specific straightening processes, including plastic deformation and tension annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional guide wire materials (such as SUS304) are used, then manufacturing is straightforward, but resilience is insufficient
Solution Approach 1:
The patent applies local quality by creating a hardness gradient within the wire cross-section. The outer peripheral portion (within d/17 mm from the surface) is hardened to 8.0-12.0 GPa through selective heat treatment, while the central portion maintains lower hardness (3.0-6.0 GPa). This localized property differentiation provides resilience at the surface while maintaining ductility and manufacturability in the core.
Solution Approach 2:
The patent changes physical parameters by controlling the hardness distribution through specific heat treatment parameters. By adjusting heating temperature (500-750°C), holding time (1-30 minutes), and cooling rates, the outer peripheral hardness is optimized to 8.0-12.0 GPa while the center remains softer. This parameter control resolves the contradiction between resilience and manufacturability.
2Strength
If wire hardness is increased throughout the cross section, then strength improves, but rotation operability deteriorates
Solution Approach 1:
The patent applies local quality by creating a hardness gradient within the wire cross-section. The outer peripheral portion (within d/17 mm from the surface) is hardened to 8.0-12.0 GPa through selective heat treatment, while the central portion maintains lower hardness (3.0-6.0 GPa). This localized property differentiation provides resilience at the surface while maintaining ductility and manufacturability in the core.
3Ease of operation
If the guide wire is made more flexible to navigate complex pathways, then operability improves, but shape restoration capability worsens
Solution Approach 1:
The patent applies local quality by creating a hardness gradient within the wire cross-section. The outer peripheral portion (within d/17 mm from the surface) is hardened to 8.0-12.0 GPa through selective heat treatment, while the central portion maintains lower hardness (3.0-6.0 GPa). This localized property differentiation provides resilience at the surface while maintaining ductility and manufacturability in the core.
Solution Approach 2:
The patent creates a composite structure within the homogeneous wire material by inducing a hardness gradient through differential heat treatment. The wire effectively becomes a composite of hard outer layer and soft core, combining the benefits of flexibility (from soft core) and shape restoration (from hard outer layer) without requiring multi-material construction.
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 solution enhances the guide wire's resilience and rotation operability, allowing it to maintain shape integrity and navigate complex vascular pathways effectively.
Implementation Method 1
a wire diameter of the wire material is reduced by wire drawing
Implementation Method 2
an average value of hardness of an outer peripheral portion of a transverse section of the wire material, as measured by a Nanoindentation method, is equal to or greater than 8.0 GPa
Implementation Method 3
including plastic deformation and tension annealing
Data Source
AI summary
A medical wire material including stainless steel. A shape of a transverse section of the wire material is a circle having a diameter of d mm, and an average value of hardness of an outer peripheral portion of the transverse section of the wire material, as measured by a Nanoindentation method, is equal to or greater than 8.0 GPa. The outer peripheral portion is a region that extends radially inward from an outer peripheral edge of the transverse section by a distance of d/17 mm.