By Sean Fenske, Editor-in-Chief

Minimally invasive procedures are the goal for most healthcare techniques. As such, technologies that enable these to be performed are required. This ongoing effort demands advancements that allow for the miniaturization of the finished device as well as its components. One area where this can take place is in the delivery mechanism used to ensure the arrival of the therapeutic device at the necessary location.

Often, the delivery system leverages a catheter to transport technologies such as stents, replacement valves, drug delivery devices, or other innovations that need to be placed somewhere within the body. Making these catheters smaller is no easy task, as they must provide a certain degree of strength and durability. Polyimide is often selected as the material of choice for this effort, but recently, a new option has been announced.

To explain this new material option further, two representatives from Confluent Medical Technologies responded to several questions about it. In the following Q&A, Dean Burke, Business Development Director, and Shane Wood, Director of Technologies—Polymers, provide insights on the company’s new Ultra Polyimide material, the benefits it offers, and its compatibility with restrictions against certain solvents.

Sean Fenske: What makes traditional polyimide a good material for medical tubing and catheters?

Dean Burke: Polyimide is the preferred material for devices where exceptional column and/or tensile strength is required. It can be manufactured as a discrete tube or built into a composite construction. As a thermoset, it will not melt and thus can be utilized in braided constructions to secure the braid wire during subsequent thermal processing. Polyimide also has excellent dielectric properties, provides thermal resistance, is resistant to a wide range of chemicals, and is gamma, EtO, and E-beam sterilizable.

Fenske: With your new Ultra Polyimide, the strength is improved. How much is it improved and why is this important? What advantages are realized?

Shane Wood: Although traditional polyimide is known for its strength, with the constant evolution of medical device designs, there is an increased demand for a tubing solution with decreased wall thickness without compromising that strength. Confluent’s Ultra Polyimide offers about double the strength of traditional polyimide without limiting the real estate inside the tube. Ultra Polyimide will allow design teams to reduce the amount of material needed in a new medical device while providing the same column and/or tensile strength required for the application. This solution allows customers greater flexibility to address other design constraints by creating additional space within the device.

Fenske: With significant attention being given to the solvents used in tubing materials, such as NMP and PFAS, how does Ultra Polyimide stand up to those concerns, such as REACH restrictions?

Burke: Polyimide suppliers have historically used NMP (N-Methyl-2-pyrrolidone) as a solvent in the manufacturing process. This solvent is a restricted substance in the EU. In an effort to continually improve our product offerings and our environmental stewardship, Confluent was the first to offer REACH-compliant polyimide that contains no restricted substances. From the customer’s perspective, no additional testing needs to be performed to ensure the residual solvents have been removed.

Based on the market’s acceptance for REACH-compliant polyimide, our Ultra Polyimide offering is also REACH compliant, which should remove any concerns for our customers selling product in the EU market.

Fenske: Where is Ultra Polyimide ideally used? For what types of applications? Where could it be used given its unique performance attributes?

Burke: Ultra Polyimide would be a prime candidate where strength and wall minimization are paramount to the intended design requirements. One such application could be for steerable catheters. Polyimide is leveraged as the conduit for the pull wires that articulate the distal end of the device. By achieving the same strength in a thinner construction, it can reduce the overall shaft OD, which is key for customers trying to reduce the overall size of the device.

Fenske: What should device manufacturers keep in mind when sourcing tubing for medical devices and catheters with regard to the material used? What is often overlooked or forgotten?

Wood: Design engineers need to be cognizant of the intended performance attributes since material selection will impact this. The sterilization method for the final device can also dictate what materials must be used and which are to be avoided. I think one forgotten aspect is choosing materials and constructions that are manufacturable. At Confluent, we have experts who can assist with recommendations for materials and are always innovating with new materials to optimize device performance.

Fenske: Do you have any additional comments you’d like to share based on any of the topics we discussed or something you’d like to tell medical device manufacturers?

Burke: As the demand for minimally invasive procedures continues to grow, devices are becoming increasingly smaller while still needing strength and extensive real estate available within the delivery device. Confluent is staying at the forefront of innovation within the polymer tubing space and continuing to advance our materials science offerings. We are currently working on a next-generation material that we are preparing to unveil within the next few months, so keep an eye out for another exciting announcement coming soon!

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