Engineering Insights: Polyimide, PTFE & Reinforced Tubing for Next-Gen Devices

Overview

This document is an expert interview featuring Gabrielle Fuller, Applications Engineer at MicroLumen, discussing the critical role and engineering considerations of polyimide and composite medical tubing in minimally invasive device design, especially catheters. As OEM engineers demand tighter tolerances, complex shaft architectures, and superior mechanical reliability, tubing selection has become a key differentiator in next-generation catheter development.

Polyimide is highlighted as a top material choice for high-precision medical tubing due to its ability to maintain structural integrity under mechanical and thermal stress. Unlike many thermoplastics, polyimide—being a thermoset—resists softening, creeping, and deformation, providing consistent inner diameter, stiffness, and dimensional stability critical to catheter performance. MicroLumen’s expertise lies in precision polyimide film casting and processing, ensuring repeatable production tolerances and high-volume consistency.

The discussion addresses reinforcement types: braided and coil. Braided reinforcement is favored for applications requiring excellent torque response, pushability, and column strength, enabling efficient rotational force transmission in steerable catheters. Coil reinforcement is preferred when flexibility, kink resistance, and trackability are needed to navigate tortuous anatomy without lumen collapse. Success hinges not only on offering these reinforcements but on precise control of variables like braid density and coil pitch to achieve consistent mechanical behavior.

Composite tubing combining PTFE and polyimide is gaining importance due to the need for multiple performance properties. PTFE offers low friction for smooth device passage, while polyimide provides strength and dimensional stability. However, bonding these dissimilar materials reliably demands specialized process expertise, an area where few suppliers excel.

Laser machining capability is emphasized as a crucial enabling technology for innovative catheter designs. It allows incorporation of micro-holes, flexibility-enhancing slots, bonding transitions, and complex cut geometries directly into tubing, facilitating multi-zone architectures with tailored mechanical properties.

When selecting tubing materials, engineers must balance multiple requirements such as stiffness, flexibility, torque transmission, lubricity, chemical resistance, thermal stability, and wall thickness. MicroLumen’s strength is its ability to engineer integrated tubing systems that combine reinforcement, composites, machining, and bonding in a controlled, predictable manner, supporting OEM development of advanced minimally invasive devices with confidence in both performance and manufacturability.

For further details, MicroLumen’s website provides additional resources.