Shapeable Ni-Ti Guidewire Tip That Stays Solderable and Durable
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing guide wires used in medical procedures, such as PTCA, face challenges in achieving the right balance of flexibility, pushability, torque transmission, and kink resistance, particularly due to the limitations of materials like superelastic Ni-Ti alloys which can be permanently deformed and lack durability for repeated use.
Innovation Solution
A guide wire device with a shapeable distal end section made from linear pseudoelastic nickel-titanium alloy, which is more durable and corrosion-resistant, allowing for user-shaping without phase transformation or stress-induced martensite, combined with a helical coil section and atraumatic cap, and a method involving cold working and soldering to maintain pseudoelasticity, enabling effective navigation through tortuous anatomy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If superelastic Ni-Ti alloy is used for the core member, then flexibility and kink resistance are improved, but durability and resistance to permanent deformation deteriorate
Solution Approach 1:
The patent applies cold working processes (drawing, rolling, flattening) to change the microstructural parameters of the Ni-Ti alloy, transforming it from an austenitic structure to a martensitic structure. This parameter change enables the material to exhibit linear pseudoelasticity with higher stiffness and resistance to permanent deformation, while maintaining the flexibility needed for guide wire operation through controlled reversible deformation.
2Strength
If cold working is applied to achieve linear pseudoelasticity, then stiffness and durability are improved, but shapeability deteriorates
Solution Approach 1:
The patent applies different degrees of cold working to different sections of the guide wire core member. The distal end section receives greater cold working (flattening) to achieve high stiffness and linear pseudoelasticity for durability, while the proximal section maintains less cold working to preserve shapeability. This local differentiation of material properties allows the wire to be both stiff enough for pushability and shapeable for navigation.
3Strength
If soldering is applied to attach components, then structural integrity is improved, but linear pseudoelasticity is lost
Solution Approach 1:
The patent applies preliminary protective coatings (such as electroplating with rhodium, palladium, or other inert metals) to the Ni-Ti alloy surfaces before soldering. This preliminary action creates a barrier that protects the martensitic microstructure from thermal damage during the soldering process, allowing the attachment of components while preserving the linear pseudoelastic properties of the cold-worked Ni-Ti alloy.
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 provides enhanced durability, shapeability, and cost-effectiveness by allowing a single wire to treat multiple lesions, reducing procedure time and costs, while maintaining the necessary mechanical properties for medical procedures.
Implementation Method 1
a cold-worked nickel titanium alloy exhibiting linear pseudoelasticity
Implementation Method 2
having a solder material applied thereto
Data Source
AI summary
Shapeable guide wire devices and methods for their manufacture. Guide wire devices include an elongate shaft member having a shapeable distal end section that is formed from a linear pseudoelastic nickel-titanium (Ni—Ti) alloy that has linear pseudoelastic behavior without a phase transformation or onset of stress-induced martensite. Linear pseudoelastic Ni—Ti alloy, which is distinct from non-linear pseudoelastic (i.e., superelastic) Ni—Ti alloy, is highly durable, corrosion resistant, and has high stiffness. The shapeable distal end section is shapeable by a user to facilitate guiding the guide wire through tortuous anatomy. In addition, linear pseudoelastic Ni—Ti alloy is more durable tip material than other shapeable tip materials such as stainless steel.