Linear Pseudoelastic Guide Wire Tip for Solderable Shape Retention
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Solution Overview
Problem
Guide wires used in medical procedures require materials that balance flexibility, pushability, torque transmission, and kink resistance, but existing superelastic materials like Ni-Ti alloys can be permanently deformed and are difficult to solder, limiting their versatility and durability.
Innovation Solution
A guide wire device with a shapeable distal end section formed from a linear pseudoelastic nickel-titanium alloy, which is cold-worked to maintain its martensitic phase and durability, and soldered with a suitable alloy to prevent loss of pseudoelasticity, allowing for user-shaping and improved durability compared to stainless steel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If superelastic Ni-Ti alloy is used for the guide wire core member, then flexibility and torque transmission are improved, but the material can be permanently deformed and is difficult to solder
Solution Approach 1:
The guide wire is designed with different material properties in different sections: the distal end section uses linear pseudoelastic Ni-Ti alloy for shapeability and durability, while other sections may use different materials optimized for their specific functions. This local differentiation resolves the contradiction by applying the right material properties where needed without compromising overall performance.
Solution Approach 2:
The patent changes the material parameter from non-linear pseudoelastic (superelastic) to linear pseudoelastic Ni-Ti alloy. This parameter change fundamentally alters the stress-strain behavior, eliminating the flat plateau region and enabling the material to maintain martensitic phase stability during soldering while preserving flexibility and shapeability in the distal end section.
2Adaptability or versatility
If the distal end section is cold-worked to achieve linear pseudoelasticity, then shapeability and durability are improved, but the material becomes more difficult to solder
Solution Approach 1:
The cold working process is performed before soldering to establish the linear pseudoelastic properties and martensitic phase structure. By preparing the material in advance with the correct microstructure, the subsequent soldering process can be optimized to minimize heat input and prevent phase transformation, thus maintaining both shapeability and solderability.
Solution Approach 2:
The patent changes the material parameter from non-linear pseudoelastic (superelastic) to linear pseudoelastic Ni-Ti alloy. This parameter change fundamentally alters the stress-strain behavior, eliminating the flat plateau region and enabling the material to maintain martensitic phase stability during soldering while preserving flexibility and shapeability in the distal end section.
3Reliability
If stainless steel is used for the distal end section, then durability is improved, but shapeability is reduced
Solution Approach 1:
The guide wire is designed with different material properties in different sections: the distal end section uses linear pseudoelastic Ni-Ti alloy for shapeability and durability, while other sections may use different materials optimized for their specific functions. This local differentiation resolves the contradiction by applying the right material properties where needed without compromising overall performance.
Solution Approach 2:
The guide wire employs a composite structure combining linear pseudoelastic Ni-Ti alloy distal end section with other materials in the shaft. This composite approach allows the distal end to provide superior shapeability and durability compared to stainless steel, while the overall wire maintains the required mechanical properties through material combination.
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 guide wire device exhibits enhanced durability and shapeability, enabling it to navigate tortuous anatomy and treat multiple lesions without significant loss of pseudoelasticity, potentially reducing procedure time and costs.
Implementation Method 1
the shapeable distal end section includes a cold-worked nickel titanium alloy exhibiting linear pseudoelasticity
Implementation Method 2
A shapeable guide wire device includes an elongate shaft member that includes a proximal end section and a shapeable distal end section having a solder material applied thereto
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A shapeable guide wire device configured to allow a practitioner to shape a distal end to a desired shape for tracking through a patient's vasculature, the shapeable guide wire comprises: an elongate shaft member that includes a practitioner-shapeable distal end section formed of a linear pseudoelastic nickel titanium alloy such that the distal end section does not exhibit a phase transformation or onset of stress-induced martensite as the distal end section is stressed, the distal end section having a metallic material applied over the linear pseudoelastic nickel titanium alloy before cold working of the distal end section of the elongate shaft member; wherein the practitioner-shapeable distal end section has a yield stress from about 100 ksi to about 300 ksi; a helical coil section disposed about at least the practitioner-shapeable distal end section; and an atraumatic cap section attached to the helical coil section and the metallic material of the practitioner-shapeable distal end section.