Variable Helical Slot Tubular Sheath for Steerable Medical Devices
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Solution Overview
Problem
Conventional steerable guide wires and catheters face limitations in flexibility, steerability, and manufacturability, particularly in minimally invasive medical procedures, due to issues with fixed tip angles, material weakening during slot formation, and high costs associated with enhanced torsional stability.
Innovation Solution
A steerable device featuring a tubular sheath with reconfigurable sections and helical slots of variable width and pitch, allowing for axial force-induced changes in flexibility, rotatability, and pushability, along with an elastic bias section for shape variation and secure anchoring, to enhance maneuverability within tortuous paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If slots are cut into the tubular member wall to enhance flexibility, then flexibility is improved, but the material is weakened and fracture risk increases
Solution Approach 1:
The tubular member is segmented by forming slots that extend partially through the wall thickness, creating discrete segments that can flex relative to each other while maintaining overall structural integrity. The slots are interrupted before reaching the outer surface, preventing complete separation and maintaining strength.
Solution Approach 2:
The slots are positioned selectively at specific locations along the tubular member where flexibility is needed, rather than uniformly throughout. The slot depth and spacing are varied locally to achieve optimal balance between flexibility enhancement and structural strength preservation in different regions.
2Ease of manufacture
If conventional laser cutting is used to form slots, then manufacturing is simplified, but localized heating weakens the remaining material
Solution Approach 1:
The harmful thermal effect is extracted and removed from the manufacturing process by replacing laser cutting with a cold-forming technique. The slots are formed by mechanically displacing material rather than melting it, eliminating localized heating and associated material weakening while maintaining manufacturing efficiency.
Solution Approach 2:
The thermal field (laser) is replaced with a mechanical field (forming tool) to create the slots. This substitution eliminates the thermal damage to surrounding material while achieving the same geometric feature, thereby preserving material strength.
3Adaptability or versatility
If helical slots are used to promote flexibility, then steerability is improved, but reliable rotational correspondence between proximal and distal ends cannot be achieved
Solution Approach 1:
The slot configuration is designed to be dynamically responsive to axial forces. When axial force is applied, the slots close in a controlled sequence that enables predictable rotation at the distal end. The dynamic closing behavior of the slots creates a reliable mechanical linkage between proximal and distal rotational movements.
Solution Approach 2:
The slot geometry parameters (width, depth, spacing, and helical angle) are specifically optimized to achieve the desired balance between flexibility and rotational control. By adjusting these parameters, the device achieves both enhanced steerability and reliable one-to-one rotational correspondence between ends.
4Adaptability or versatility
If multiple slots are cut into the tubular member, then flexibility is enhanced, but manufacturing costs increase
Solution Approach 1:
The slots are formed as a single integrated feature during the tubular member manufacturing process, rather than being added as a separate post-processing step. The forming operation is performed while the material is in a convenient state, enabling multiple slots to be created simultaneously or in sequence without additional machining setup or tooling costs.
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 solution provides increased flexibility and steerability while maintaining structural rigidity, ensuring reliable rotational movement correlation and reducing the risk of fracture, while also simplifying manufacturing and reducing costs.
Implementation Method 1
an elastic bias section for shape variation and secure anchoring, to enhance maneuverability within tortuous paths
Implementation Method 2
one or more slots may include a variable slot width, a constant or variable slot pitch or both. By having variations in one or both of the slot width and pitch, an operator-induced axial force applied to the elongate control element can be used to cause the variation in the slot to produce at least one of a change of the flexibility, rotatability or pushability
Data Source
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AI summary
A device, a method of making a device and a method of inserting a device into a tubular path. The device includes a tubular sheath with one or more helical slots formed therein and a control element that fits within the sheath. In one form, the device is an endoluminal device that simultaneously improves flexibility and structural rigidity though variations in one or both of slot shape along the length of the slot and slot pitch along the length of the tubular sheath. When the operator pulls at the proximal end of the control element while holding the outer sheath in place, the slots will tend to close in a preferential manner such that more precise control of device length and bending is enabled, while simultaneously providing improvements in structural rigidity during device insertion and navigation through a body lumen or related tubular member where tortuous paths may be encountered along the member path.