Material Selection in Medical Tubing Applications
Medical device OEMs are continuously pushing the limits of design possibilities in order to get greater value and higher performance out of their tubing. They look to create tubing with tighter tolerances, more properties and at increasingly smaller sizes. Creative design concepts are dependent on materials that enable the delivery of physical properties which extend performance levels beyond previous boundaries, combined with a proven biocompatibility status. Mediprene Thermoplastic elastomers (TPEs) are one group of materials that have consistently been shown capable of the performance-stretch necessary to meet this challenge.
The Mediprene compounds have been designed to address a number of key requirements for medical tubing. These include a high level of transparency, allowing for clear visibility of the passage of liquids and anti-kinking properties to ensure the free flow of liquids and gasses through the tubing. Mediprene TPE tubing grades also display good damping properties, thereby slowly recovering after deformation like PVC, an important element in catheter tubing design. For catheter applications, the tubing is often coated in order to achieve a low-friction surface, Mediprene TPE compounds have been successfully modified for better wettability and adhesion of such coatings. Grades that do not contain any paraffinic oil are available which minimize the risk of leaching and extractables. Mediprene TPE compounds are resistant to many fluids used in the healthcare environment and are sterilizable with gamma, EtO and steam. Representative grades have passed cytotoxicity tests according to ISO 10993-5 and are compliant with USP Class VI. Mediprene TPE materials are PVC, silicone and latex free, making them allergen free and a viable alternative to PVC based compounds.
Mediprene TPE compounds are suitable for multi and single lumen tubing for catheters, IV, drug delivery, gas supply, respiration, inhalation, anaesthesia and tube based medical devices. They are also an optimum choice for multilayer tubing via coextrusion. Coextrusion is a powerful technique involving the simultaneous extrusion of two or more materials to form distinct layers in one tube. The layers can be different materials with each material bringing a set of distinct properties to the tube. For example, the application may require a flexible TPE midlayer between stiffer inside and outside functional layers. Mediprene TPEs bond very well to polyolefins like polyethylene and polypropylene in coextrusion.
An aging population and the introduction of new medical procedures have lead to a rapid growth in the medical tubing market. Coupled with this, tubing is being called on to perform more and more complex functions, therefore a greater demand has emerged for materials that provide durability, biocompatibility and the adaptability to perform a range of different tasks. Early choice of optimum materials with sure supplies at the right grading for both physical properties and to meet the regulatory requirements are critical factors in the raw material selection process. Niklas Ottosson, medical technical manager at ELASTO commented “The right TPE formulation is the key to a safe and successful medical product. That is why we have a collaborative approach, working with OEMs and tubing extruders to develop custom materials that precisely match the properties they’re looking for - kink resistance, flexibility, sterilizability, clarity and so on. Furthermore, as formulation stability and change notification is crucial for our medical customers, we work in close co-operation with our suppliers to be able to offer our customers the requested information and guarantees.”
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