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Developing the vasculature of medical devices.

Tubing represents the veins and arteries of many different types of medical technologies. It carries critical elements wherever they need to be--within a device, throughout the human body, or as a bridge between the two. It must provide passage for gas, fluid, electronics, and even small devices to travel seamlessly, sometimes with several of those components within the same single tube (just through different lumens). Given its importance in medical technology and how critical it is for design engineers to stay abreast of the latest advances, we took this topic to the Roundtable.

Advancements

Since tubing is often such an integral part of a medical technology, the designers continue to demand that the limits be pushed in the development of tubing solutions. This is no different with some of the latest advancements realized recently.

"The extrusion of thermoplastic elastomer (TPE) tubing has improved processing and biocompatibility," says Tom Harrington, Technical Director at Kent Elastomer Products. "Extrusion offers synthetic materials with low extractible content. This improves biocompatibility when used in the body or in contact with pharmaceutical products."

Diego Sosa, Extrusion Manufacturing Engineer at Helix Medical shares his own thoughts on tubing advancements, "Tighter tolerances allow for smaller micro extrusions, and more precision applications. With micro extrusions, we are now able to go inside the body for ophthalmic, neurology, and cardiology applications. Advancements are enabling thin-wall, multi-lumen, and striped tubing configurations for complex tubing applications."

"Every day, we work with engineers where science is paired with supplier innovation to advance the performance of medical procedures and there, in turn, improve clinical outcomes," offers Emily Barnes, product development manager for medical sales at Zeus. "We see this most dramatically with bioabsorbable tubing, which is designed with tailored degradation profiles that allow the material to perform in the body for a finite period of time."

Materials

While Harrington and Barnes mention several very interesting advances that material innovations are enabling for medical technology through tubing, there are more worth noting.

"Ongoing advancements in materials offers improved functionality in radiopacity, anticoagulation properties, lubricity, and biostability, explains Andres Rodriguez, materials engineer at Avalon. "Polymer solution casting can easily provide seamless material transitions that can offer varied property profiles along the shaft of a medical device."

"Custom formulations can deliver unique project applications. UV cured silicone material, for example, cures more completely and at a much higher rate than traditional platinum-cured silicone and allows delivery of more product at a cost effective price," says Sosa. "Additionally, material properties can help to prevent infections when antimicrobial modifications are incorporated into the material."

Multi-Lumen Challenges

As devices become more sophisticated and offer greater functionality, more "stuff' has to travel through tubing. While single lumen tubing is needed for a range of applications, designers are looking at multiple lumens in order to cut down on the number of tubes required within an often already constrained space.

"With the request for tighter tolerances and the lot-to-lot variability of silicone material it can be difficult to maintain multiple lumens. Profiles may need to be modified slightly to ensure a robust and efficient production process. Multiple iterations of tooling may be required to hone in on the tighter tolerances. Having the proper fixtures for measurement and inspection technique is also helpful," says Sosa.

"Multi-lumen tubing has become more complex as medical devices are requiring or increasing the intended clinical application with newer technology," explains Ihab Khayal, product engineer at Avalon. "Multi-lumens now have various lumen sizes within the single shaft, making concentricity of each lumen more difficult to achieve along with obtaining the right wall thickness for each lumen's intended application."

Barnes adds, "The challenge comes with being presented with an idea for a design that may not be sustainable in full-scale production. There are times where multi-lumen profiles can be overdesigned with dimensions that are difficult--if not impossible--to measure."

To read more from the tubing Roundtable, check out this feature on the MDT website and we will also feature each Q&A with each participant.

By Sean Fenske, Editor-in-Chief
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Title Annotation:Roundtable: Tubing
Author:Fenske, Sean
Publication:Medical Design Technology
Date:Apr 1, 2015
Words:668
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