Segmented Guide Wire With Intermediate Member For Joint Strength
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Solution Overview
Problem
Guide wires used in minimally invasive procedures, such as PTCA and PTA, face challenges in navigating complex blood vessels due to insufficient flexibility, steerability, and kink resistance, particularly in the distal portion, where existing materials and welding methods fail to provide adequate joint strength and stress dispersion.
Innovation Solution
A guide wire design featuring a first wire made of a Ni—Ti alloy and a second wire made of stainless steel, connected through an intermediate member with a core and outer layer, where the core and outer layer materials can differ, and the wires are joined by welding or brazing to enhance flexibility, steerability, and kink resistance, maintaining a constant outer diameter to prevent kinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a guide wire uses a single material for the entire wire body, then manufacturing is simple, but it cannot provide both flexibility at the distal portion and rigidity at the proximal portion simultaneously
Solution Approach 1:
The guide wire is divided into multiple segments with different materials: a distal portion made of flexible material (e.g., Ni-Ti alloy) and a proximal portion made of rigid material (e.g., stainless steel), allowing each segment to perform its specific function optimally
Solution Approach 2:
The guide wire uses composite construction combining different materials (Ni-Ti alloy and stainless steel) in a single wire body, achieving both flexibility and rigidity properties that cannot be obtained with a single material
2Strength
If different materials are joined by butt resistance welding, then joint strength is improved, but brittle Fe-Ti intermetallic compounds form causing insufficient joint strength
Solution Approach 1:
An intermediate layer (such as a Ni layer or transition layer) is introduced between the Ni-Ti alloy and stainless steel to prevent the formation of brittle Fe-Ti intermetallic compounds, serving as a mediator that improves both joint strength and reliability
Solution Approach 2:
The welding parameters (temperature, time, pressure) are optimized and controlled to prevent excessive intermetallic compound formation while achieving strong joints between different materials
3Adaptability or versatility
If the wire body outer diameter varies along the longitudinal direction, then flexibility is improved, but kink resistance deteriorates
Solution Approach 1:
Different local regions of the wire body are assigned different properties: the distal portion has smaller outer diameter for flexibility, while the proximal portion maintains larger outer diameter for kink resistance and torque transmission
4Ease of operation
If the distal portion is made more flexible to navigate complex vessels, then steerability is improved, but pushability from the proximal portion deteriorates
Solution Approach 1:
The wire is segmented into a flexible distal portion for steerability and a rigid proximal portion for pushability, with each segment optimized for its specific function
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 design ensures improved flexibility and steerability in navigating complex blood vessels while maintaining high kink resistance and joint strength, allowing for effective guidance of catheters in minimally invasive procedures.
Implementation Method 1
the first and second wires are joined by butt resistance welding
Implementation Method 2
the wires are joined by welding or brazing
Data Source
AI summary
A guide wire includes a first wire disposed on the distal side and composed of a first material, and a second wire disposed on the proximal side of the first wire and composed of a second material. The first and second wires are connected to each other through an intermediate member which includes a core portion and an outer layer covering the outer periphery of the core portion. The core portion is wholly or partly composed of a material different from the material of the outer layer, and at least one of the core portion and the outer layer is composed of the first material or the second material. The proximal portion of the first wire and the distal portion of the intermediate member are joined to each other, and the distal portion of the second wire and the proximal portion of the intermediate member are joined to each other.