Thin-Wall Catheter Shaft Assembly for Larger Working Lumens
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Solution Overview
Problem
Existing catheter designs face challenges in achieving a small cross-sectional profile and large working lumen due to limitations in wall thickness and manufacturing tolerances, particularly in small caliber anatomy, where conventional extrusion processes struggle to produce walls thinner than 0.0015″ with tolerances tighter than 0.0005″.
Innovation Solution
Employing thin film extrusion techniques to produce catheters with wall thicknesses less than 0.0015″ and tolerances tighter than 0.0005″, utilizing adjustable tooling during the extrusion process to achieve precise dimensions and reduce sensitivity to extruder pump performance variations, allowing for thinner walls and larger lumens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional tubular extrusion is used, then manufacturing process is simple, but wall thickness cannot be made thinner than 0.0015″ with tolerances tighter than 0.0005″
Solution Approach 1:
The extrusion process is segmented into two distinct stages: first extruding a thick-walled tubular preform with relaxed tolerances, then applying a thin film coating to achieve the final ultra-thin wall thickness with tight tolerances. This segmentation allows each stage to be optimized independently, solving the contradiction between manufacturing simplicity and precision.
Solution Approach 2:
The thick-walled tubular preform is extruded first as a preliminary structure that provides mechanical strength and dimensional stability. This preliminary action creates a robust substrate that can support the subsequent thin film application, enabling achievement of tight tolerances that would be impossible in a single-step extrusion process.
2Length of moving object
If wall thickness is reduced to achieve smaller profile, then catheter flexibility improves, but manufacturing control becomes difficult
Solution Approach 1:
The catheter wall is segmented into two functional layers: an inner thick-walled extruded tube providing structural integrity and dimensional control, and an outer thin film coating providing the ultra-thin profile. This segmentation allows the bulk of the wall thickness to be controlled by robust extrusion processes while the final thin profile is achieved through controlled film deposition.
Solution Approach 2:
A thin polymeric film is applied as a coating on the extruded tubular preform. This thin film provides the final ultra-thin wall thickness with tight tolerances while the underlying thick-walled preform maintains dimensional stability and structural control during manufacturing.
3Manufacturing precision
If thin film extrusion is used, then wall thickness can be reduced below 0.0015″, but polymer degradation increases due to low volume flow
Solution Approach 1:
The manufacturing process is segmented so that the bulk polymer extrusion occurs at high volume flow rates in the thick-walled preform stage, ensuring adequate polymer flow and preventing degradation. The thin film stage then applies the final ultra-thin layer without requiring high-volume flow, thus avoiding polymer degradation while achieving the desired thin wall thickness.
Solution Approach 2:
The thick-walled tubular preform is extruded first as a preliminary structure with sufficient polymer volume flow to prevent degradation. This preliminary high-volume extrusion establishes the bulk material properties and structural integrity before the thin film coating is applied to achieve the final ultra-thin dimensions.
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 use of thin film extrusion enables catheters with lower profiles and larger working lumens, improving performance in navigating small caliber anatomy by reducing polymer degradation and processing variations, thereby enhancing flexibility and pushability.
Implementation Method 1
The polymeric tubes are generally formed by extrusion. The profile of the catheter is substantially influenced by the wall thickness of the tubular extrusion.
Implementation Method 2
the extrusion process is generally governed by the control of polymer volume flow. Tight mechanical control of the extruder lead screw (pump) provides tight control of final dimensions of any extruded part.
Data Source
AI summary
Methods for making medical devices and portions of medical devices (e.g., intravascular catheters, catheter shafts, and tubular guiding members) are provided. Example methods may include cutting a thin film extruded thermoplastic sheet into at least one ribbon and forming a first assembly by positioning the ribbon inside a shrink tube and urging the ribbon to assume a tubular shape in which the first ribbon defines a ribbon lumen. A second assembly may be formed by loading a lubricious inner tubular member over a mandrel and forming or placing a support structure over an outer surface of the lubricious inner tubular member. A third assembly may be formed by inserting the second assembly into the ribbon lumen defined by the ribbon of the first assembly. The third assembly may be heated to a process temperature, and the shrink tube may be removed.