Nitinol Guide Wire Tip Strain Hardening for Shapeability
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Solution Overview
Problem
Conventional guide wires made from superelastic nickel-titanium alloys face challenges in creating permanent kinks or bends at the distal end due to their highly elastic behavior, making it difficult for cardiologists to navigate tortuous blood vessels and maintain access for subsequent procedures.
Innovation Solution
A guide wire with a distal tip made from superelastic nickel-titanium alloy that undergoes strain hardening in multiple radial directions, reducing superelasticity and allowing for permanent deformation with finger pressure, enabling the creation of kinks, bends, or J-shapes, by modifying the crystallographic texture to align crystals in those directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If superelastic nickel-titanium alloy is used for the distal tip of the guide wire, then the guide wire exhibits high elasticity and resilience, but it becomes difficult to create permanent kinks or bends for navigating tortuous blood vessels
Solution Approach 1:
The guide wire features a tapered section with varying cross-sectional dimensions where the distal portion has reduced dimensions compared to the proximal portion. This creates a local region with different mechanical properties - the tapered section becomes more susceptible to permanent deformation while maintaining the superelastic properties in the proximal section for reliable tracking and support.
Solution Approach 2:
The patent modifies the physical parameters of the nickel-titanium alloy by creating a tapered geometry with specific dimensional ratios. The gradual reduction in cross-sectional dimensions changes the stress distribution and mechanical response, enabling the distal tip to be shaped by finger pressure while the proximal sections maintain their superelastic resilience.
2Ease of operation
If the distal tip is made more shapeable by reducing cross-sectional dimensions, then it becomes easier to create permanent bends, but the overall strength and support of the guide wire may be compromised
Solution Approach 1:
The guide wire is divided into distinct functional segments: a proximal section with larger cross-sectional dimensions providing strength and support, a tapered transition section with gradually reducing dimensions, and a distal tip with smallest dimensions for ease of shaping. This segmentation allows each region to optimize its properties without compromising the whole structure.
Solution Approach 2:
Instead of uniformly reducing the diameter of the entire guide wire, the patent applies dimensional changes only in the longitudinal dimension through the tapered section. The cross-sectional dimensions are gradually reduced along the length, creating a gradient that provides both shapeability at the tip and structural integrity in the proximal sections.
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
Enables the guide wire to be conveniently shaped and maintained in a desired configuration, improving navigation through complex vasculature and allowing for easier re-access during procedures without the need for additional shaping materials.
Implementation Method 1
the distal end of the elongated core having a tapered section leading to a shapeable distal tip... The shapeable tip includes the nickel-titanium alloy and further includes permanent deformation from at least two different radial directions that serves to reduce or eliminate superelasticity so that subsequent plastic deformation to shape the tip can be achieved with finger pressure
Implementation Method 2
an elongated core including a superelastic nickel-titanium alloy at a distal end
Implementation Method 3
modifying the crystallographic texture to align crystals in those directions
Data Source
AI summary
A guide wire for use in a medical procedure having a shapeable tip integral with and made from the distal end of a superelastic nitinol distal section of the guide wire, wherein the shapeable tip can be finger kinked. Such a guide wire includes an elongated core made from a superelastic nitinol alloy at the distal end, the distal end of the elongated core having a tapered section leading to a shapeable distal tip. The shapeable tip is an extension of the distal end of the nitinol distal section, and includes permanent strain hardening from at least two different radial directions imparting crystallographic texture in the radial directions that eliminate superelasticity so that permanent deformation can be achieved with finger pressure.