Flexible Elongate Control Structure Sealing and Pull Wire Routing
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Solution Overview
Problem
Existing flexible and steerable elongate medical devices face challenges in forming strong seals between polymer and metallic materials to prevent biological matter and chemical entrapment, while also withstanding environmental and mechanical exposures.
Innovation Solution
Functionalizing the metallic sealing surface with a primer to enhance adhesion with polymer materials, creating a strong seal between the metallic control structure and polymer components, and using a circuitous internal pull wire path to secure the pull wires without crimp ferrules or welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal is formed between polymer and metallic materials in flexible elongate devices, then biological matter and chemical entrapment is prevented, but the seal strength and durability are insufficient under environmental and mechanical exposures
Solution Approach 1:
A primer layer is applied to the metallic sealing surface to serve as an intermediary between the metal and polymer materials. The primer enhances adhesion by chemically bonding to the metallic surface and providing a compatible interface for the polymer material, thereby creating a durable seal that withstands environmental and mechanical exposures without direct polymer-metal contact
Solution Approach 2:
The sealing interface is constructed as a composite structure consisting of multiple materials: metallic control structure, primer coating, and polymer material. This composite approach combines the advantages of each material - the strength and rigidity of metal, the adhesion properties of the primer, and the flexibility and sealing capability of the polymer - to achieve superior seal performance
2Ease of manufacture
If pull wires are secured using traditional methods (crimp ferrules or welding), then the pull wires are firmly attached to the control structure, but the securing process becomes complex and time-consuming
Solution Approach 1:
The complex securing mechanisms (crimp ferrules and welding equipment) are extracted from the assembly process. Instead, the pull wires are simply disposed through openings in the control structure segments, eliminating the need for additional securing components and complex fastening operations
Solution Approach 2:
The control structure is divided into multiple segments, each with openings that allow pull wires to pass through. This segmentation enables the pull wires to be routed through the control structure in a simplified manner, with each segment independently accommodating the wires without requiring complex inter-segment fastening
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 a durable seal that prevents biological and chemical entrapment, ensuring the longevity and functionality of flexible elongate medical devices while simplifying the securing process for pull wires.
Implementation Method 1
a sealing surface of the control structure functionalized by a primer... creating a strong seal between the control structure and polymer material
Data Source
AI summary
Flexible elongate devices and methods include an articulable body portion and a control structure attached with one or more pull wires that control articulation of the articulable body portion. The control structure includes a metallic material that defines a sealing surface functionalized by a primer. A polymer material disposed onto the sealing surface of the control structure creates a seal between the control structure and polymer material. Flexible elongate devices and methods also include a control structure and a pull wire configured to control articulation of the flexible elongate device. The control structure includes a plurality of control segments stacked along a longitudinal axis, where each of the control segments define a pull wire aperture, where pull wire apertures of adjacent control segments are offset relative to one another, such that a portion of the pull wire extending through the pull wire apertures has a non-linear shape.