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Roundtable: Advances in extrusions, tubing & coatings.

Since extruded components and coatings play many important roles in medical devices and medical care equipment, we put the following question to several leaders:

"How are advances in extrusion and coating technology helping designers create innovative medical devices and improve clinical outcomes?"

Adam Nadeau - Process Technology R&D Manager, Saint-Gobain Performance Plastics


Healthcare providers are demanding value-based medical devices that deliver enhanced patient outcomes while minimizing patient risk. This demand has challenged medical designers to create devices that are less invasive, combine multiple functions, allow for better patient mobility, and provide higher control and accuracy--all while keeping an eye on cost. For medical tubing, designers are relying on manufacturers to become more accurate, eliminate variation, create smaller and thinner products, and add additional functions to the product. Medical tubing manufacturers are reacting to these challenges through advancements in extrusion and post-processing steps, for example Saint-Gobain's Compass Technology for silicone tubing. This technology includes customizing a silicone formulation to the specific application and then utilizing a patented extrusion process to minimize dimensional and physical property variation within the tube. In the example of an infusion pump, this approach would result in a tube solution with higher accuracy and consistency, allowing for better control of the treatment to the patient. Or in the example of a wearable pump, the tube solution could provide high accuracy but low compression force of the tube to create less drain on the battery, thereby creating a longer wearable time for the patient.

Craig Ingalls - President, ProPlate www.


Metal on polymers was first widely used by the automotive industry in the 1960s. It is commonly achieved through the electroless plating process. Before the metal coating can be applied, a chemical etching process is performed to activate the surface of the polymer. The chemical etching process traditionally used to prepare the plastic surface for plating involves toxic chromic acid-based solutions.

New technology currently under development at ProPlate involves direct coating of gold, silver, nickel, or copper to the surface of extruded polyurethane medical tubing. In this innovation, a special compounded polyurethane surface is "activated" by a proprietary laser process. The activated areas are then direct coated using novel metal deposition techniques. This method permits custom, complex, and finely dimensioned features to be applied. Tight dimensional tolerances on the order of 0.006 inches are possible. Outcomes include geometrically complex electrical conductive traces over segment lengths of up to 72 inches along the extruded polymer; and precise, intricate radiopaque marker bands either longitudinally or circumferentially.

Dr. Bruce Anneaux, Ph.D. - Corporate Director, Research, Zeus


Magnetic Resonance Imaging (MRI) provides detailed images of anatomical structures inside the body and is especially useful for comprehensive imaging of soft tissues and physiological processes. In cardiac imaging, MRI is preferred over traditional fluoroscopy because the images are clearer, and neither the physician nor the patient is exposed to potentially harmful ionizing radiation from X-rays. Most diagnostic and therapeutic catheters require a metallic reinforcing braid in the shaft. Metallic braids make using MRI impossible because the strong magnetic fields employed create a risk of injury to the patient.

Component suppliers serving the medical device community have offered several non-metallic products to overcome this obstacle. Although polyethylene napthalate monofilament, glass, Kevlar, and liquid crystal polymer multifilament fibers have been tried, none of them has been widely accepted in manufacturing. In addition to being non-metallic, the reinforcing fiber braid must provide several key attributes including flexibility, kink resistance, and torque transfer. The fiber must also be able to withstand the heat used in the reflow of jacketing material in the catheter construction process. Researchers need to focus on more than just the fiber attributes to be successful. In order to create a new product that has wide adaptation in a variety of catheter builds, they also must consider how catheters are made and used.

Liquid crystal polymer (LCP) monofilament fiber is an innovation that is shaping the future of catheter braiding. Advancements in extrusion have made this monofilament fiber available in the same forms and sizes used in traditional metallic reinforcing braiding. LCP monofilament fiber also offers similar mechanical properties that enable the construction of MRI compatible catheters. It provides a non-metallic catheter solution that also has the required flexibility, kink resistance, torque transfer, and distal end deflectability required for wide adaptation.

Additionally, LCP monofilament does not interfere with the jacketing reflow process as it is heat resistant and has different characteristics when compared to a multifilament. Multifilament fibers tend to flatten or spread during braiding, which interferes with the reflow process. LCP monofilament fibers work well with standard braiding equipment currently used in catheter construction and have fewer fiber breaks associated with multifilament materials.

This extruded innovation brings with it the capability to make new catheters for a variety of medical markets. MRI compatible catheters will give physicians better imaging ability while removing exposure to harmful radiation, which lowers risk and translates into better patient care.
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Title Annotation:Roundtable: Tubing & Coatings
Publication:Medical Design Technology
Date:May 1, 2017
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