Catheter Lubricious Linings via Sheet Inversion and Lamination
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Solution Overview
Problem
Current methods for coating the inner surfaces of catheters with hydrophilic materials are hindered by technical challenges, such as difficulty in evenly applying solutions to small lumens and issues with bonding and sterilization, leading to suboptimal lubricity and increased manufacturing complexity.
Innovation Solution
A method involving coating a thin sheet with a hydrophilic material, rolling it into a sleeve, and attaching a tubular structure to maintain the coating properties, using techniques like heat shrinkage and lamination to create tubular devices with coated inner and outer surfaces for improved lubricity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrophilic coatings are applied to inner surfaces of catheters using conventional dipping methods, then coating coverage is achieved, but even distribution is difficult due to small lumen geometry causing solution beading
Solution Approach 1:
The catheter is inverted so that the inner surface to be coated becomes the outer surface, allowing conventional dipping coating methods to be applied effectively. This inversion enables even coating distribution on small lumens by transforming the geometric constraint into an advantage.
Solution Approach 2:
The catheter is pre-inverted before the coating process, preparing the surface geometry in advance to receive the hydrophilic coating solution. This preliminary positioning ensures that the coating solution flows evenly over the inner surface during the dipping process.
2Ease of operation
If PTFE or PE inner cores are used to provide lubricious surfaces, then lubricity is improved, but bonding to outer portions becomes extremely difficult
Solution Approach 1:
The surface properties of PTFE or PE are modified through etching or chemical treatment to change their bonding parameters. This creates a surface that retains lubricity while gaining bondability to outer catheter portions.
Solution Approach 2:
An intermediary adhesive layer or coupling agent is introduced between the PTFE/PE core and the outer catheter material. This intermediary enables bonding between the two materials without compromising the lubricious properties of the inner core.
3Ease of manufacture
If mechanical abrasion or etching is performed on inner surfaces to facilitate bonding, then bondability is improved, but the process becomes extremely difficult to complete due to inaccessibility
Solution Approach 1:
The catheter is inverted during the surface modification process, making the previously inaccessible inner surface the accessible outer surface. This allows mechanical abrasion or etching to be performed easily while maintaining the integrity of the lumen.
Solution Approach 2:
The catheter is pre-inverted and positioned in a fixture that provides access to the entire inner surface before surface modification begins. This preliminary setup enables complete and uniform treatment of the bonding surface without complex tooling.
4Ease of operation
If PTFE material is used for inner cores, then lubricity is enhanced, but the material degrades under commonly used sterilization techniques such as gamma sterilization
Solution Approach 1:
The sterilization parameters are changed from gamma radiation to alternative methods such as ethylene oxide sterilization or autoclaving. These alternative parameters achieve sterilization without degrading the PTFE material, preserving its lubricious properties.
Solution Approach 2:
A disposable protective coating or sacrificial layer is applied over the PTFE inner core. This protective layer absorbs the sterilization stress and can be removed or discarded after sterilization, protecting the PTFE from degradation.
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
This approach simplifies the manufacturing process, ensures even coating distribution, and enhances the lubricity and durability of catheter surfaces, facilitating easier device assembly and improved performance in medical procedures.
Implementation Method 1
evaporation of the solvent
Implementation Method 2
heat shrinkage
Data Source
AI summary
Apparatus and methods are provided for creating tubular devices, e.g., as components for catheters, sheaths, and or other devices sized for introduction into a patient. In one embodiment, a method is provided for making a tubular device using a sheet of material including a coated first surface. The sheet is rolled around a mandrel until longitudinal edges of the sheet are disposed near or adjacent one another, e.g., without attaching the longitudinal edges together. A tubular braid is positioned over the sheet-wrapped mandrel, one or more tubular segments are positioned over the tubular braid, and heat shrink tubing is positioned over the tubular segments. The resulting assembly is heated to cause the tubular segments to at least partially reflow and/or otherwise laminate the tubular segments to the tubular braid and sheet. The heat shrink tubing and mandrel are then removed to create the tubular device.