Segmented Guide Wire Shaft for Faster Torque Response
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Solution Overview
Problem
Existing guide wires, particularly those with a shaft formed of nickel-titanium alloy, suffer from delayed torque response when inserted into bodily organs, leading to issues such as coil riding and collapse.
Innovation Solution
A guide wire design featuring a core shaft with a tapered portion and an intermediate portion of specific diameters, covered by a coil body with a controlled outer diameter, and incorporating materials with varying deformability to enhance rotational performance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shaft is formed of nickel-titanium alloy to improve restorability and corrosion resistance, then restorability and corrosion resistance are improved, but torque response is delayed
Solution Approach 1:
The shaft is divided into multiple sections with different diameters: a large-diameter proximal portion, a small-diameter intermediate portion (0.22-0.24mm), and a tapered distal portion. This segmentation allows the thin intermediate section to provide rapid torque response while the thicker proximal portion maintains overall structural integrity and restorability of the nickel-titanium alloy shaft.
Solution Approach 2:
Different sections of the shaft have different local properties: the intermediate portion has a reduced diameter (0.22-0.24mm) to enhance torque response and rotational performance, while the proximal portion has a larger diameter to maintain restorability and corrosion resistance. This local quality variation resolves the contradiction between overall shaft performance and torque response speed.
2Volume of moving object
If the coil body outer diameter is reduced to ensure proper guide wire size, then guide wire size control is improved, but coil body stability deteriorates
Solution Approach 1:
The coil body is positioned specifically on the small-diameter intermediate portion (0.22-0.24mm) of the shaft. This local positioning allows the coil to be supported by the thickest part of the shaft, providing stability and preventing collapse, while the overall guide wire maintains a small outer diameter for proper sizing in medical applications.
3Speed
If the core shaft diameter is reduced to improve torque response, then torque response is improved, but pushdown capability deteriorates
Solution Approach 1:
The shaft is segmented into a small-diameter intermediate portion (0.22-0.24mm) for rapid torque response and a large-diameter proximal portion for strong pushdown capability. The tapered portion connects these two sections, creating a gradient transition that balances rotational performance with delivery force.
Solution Approach 2:
The solution transitions from a uniform diameter shaft to a multi-dimensional diameter profile along the shaft length. The diameter varies along the longitudinal axis, with the thinnest section (0.22-0.24mm) at the intermediate portion for torque response and thicker sections at the proximal end for pushdown, effectively using dimensional variation to resolve the force-speed contradiction.
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 suppresses delay of torque response, ensures proper size and shape integrity, and improves pushdown and delivery capabilities while maintaining superior restorability and corrosion resistance.
Implementation Method 1
a core shaft formed of superelastic metal
Data Source
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AI summary
A guide wire includes a core shaft formed of superelastic metal, where the core shaft has a tapered portion having a diameter reducing from its own proximal end side toward the distal end side, an intermediate portion having an approximately cylindrical shape adjacent to the proximal end side of the tapered portion, and a proximal end portion adjacent to the proximal end side of the intermediate portion and having a diameter more increased than the intermediate portion; a coil body covering at least a part of the intermediate portion and the tapered portion of the core shaft, the coil body having an outer diameter of 0.36 mm or less; and a distal tip disposed at the distal end of the coil body and forming the distal end of the guide wire, the diameter of the intermediate portion being 0.22 mm or more to 0.24 mm or less.