ePTFE Catheter Liners with Thermoplastic Tie Layer
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Solution Overview
Problem
Catheter liners face challenges in providing both surface lubricity and flexibility, especially when navigating smaller vessels and sharper turns in minimally invasive surgical procedures, as existing materials struggle to balance these properties effectively.
Innovation Solution
A catheter liner is developed using an expanded polytetrafluoroethylene (ePTFE) tubing with a thermoplastic tie layer coating, comprising materials like PEBA, nylon, or polyurethane, applied via dip coating, which adheres to the outer surface and penetrates into the wall to enhance adhesion and flexibility without increasing the coefficient of friction on the inner diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a traditional PTFE liner is used to provide low coefficient of friction, then lubricity is improved, but flexibility deteriorates
Solution Approach 1:
The patent uses a composite structure combining ePTFE (expanded polytetrafluoroethylene) with a thermoplastic tie layer coating. The ePTFE provides the low coefficient of friction while the thermoplastic coating (comprising polyether block amide, polyurethane, or nylon) provides flexibility and adhesion. This composite material approach allows simultaneous achievement of lubricity and flexibility, resolving the contradiction between these two properties.
Solution Approach 2:
The patent applies the thermoplastic tie layer coating specifically to the outer surface of the ePTFE liner, creating different properties in different regions. The inner surface maintains the low-friction ePTFE property, while the outer surface gains the flexibility and adhesion properties from the thermoplastic coating. This local differentiation allows the liner to simultaneously provide lubricity and flexibility.
2Object-generated harmful factors
If the catheter liner is made thinner to reduce friction, then lubricity is improved, but structural strength deteriorates
Solution Approach 1:
The composite structure of ePTFE with thermoplastic tie layer coating allows the liner to maintain thin walls for low friction while the thermoplastic layer provides structural support and strength. The thermoplastic coating acts as a reinforcing layer that compensates for the reduced wall thickness, enabling the liner to be thinner without compromising structural integrity.
Solution Approach 2:
The ePTFE liner utilizes its porous structure with controlled pore size and distribution to maintain mechanical strength while allowing thin wall design. The porous structure provides both structural support and the low friction surface, while the thermoplastic coating fills and reinforces the pore structure to enhance overall strength without increasing friction.
3Ease of operation
If the catheter is designed for high flexibility to navigate tortuous vessels, then ease of operation is improved, but surface lubricity deteriorates
Solution Approach 1:
The patent combines ePTFE with thermoplastic tie layer coating to achieve both flexibility and lubricity. The ePTFE maintains the low coefficient of friction on the inner surface while the thermoplastic outer layer provides the flexibility needed to navigate tortuous vessels. This composite approach resolves the contradiction by assigning different functional properties to different parts of the liner structure.
Solution Approach 2:
The thermoplastic tie layer coating is applied selectively to the outer surface, providing flexibility and adhesion where needed for navigation, while the inner surface retains the smooth, low-friction ePTFE property. This local differentiation allows the catheter to be flexible during insertion while maintaining lubricity during the procedure.
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 catheter liner with improved flexibility and lubricity, allowing for safer and more effective navigation through tortuous blood vessels while maintaining low friction, thus enhancing the success of minimally invasive procedures.
Implementation Method 1
a thermoplastic tie layer coating on at least a portion of an outer surface... to allow the tie layer material to better adhere to the outer surface of the ePTFE tubing
Implementation Method 2
an ePTFE tubing is placed on a mandrel and dipped at an angle into a solution of the thermoplastic. The coated tube is then removed from the solution and removed from the mandrel and dried, forming the thermoplastic-coated surface
Data Source
AI summary
Expanded polytetrafluoroethylene (ePTFE) tubings are provided with a thermoplastic tie layer coating on the outer surface thereof to serve, e.g., as flexible liners for catheters. The thermoplastic tie layer coating can be anchored into the pores of the ePTFE but advantageously does not permeate through to the inner surface of the tubing. In this way, the outer surface of the tubing can adhere to an outer jacket material while the inner surface of the tubing remains lubricious.