Moving beyond convention in tubing

Mike Winterling, Junkosha’s vice president of business development for USA & Europe, takes us through the latest developments in the company’s PHST portfolio and introduces the newly launched PTFE Liner Challenge.

For manufacturers and consumers in the medtech sector, ever-advancing tubing and catheter applications have highlighted several unmet needs. To address these gaps, Junkosha has designed peelable fluorinated ethylene propylene (FEP) heat shrink tubing (PHST) to give catheter manufacturers cost-effective, lower tolerance baseline materials to achieve reflow into a single smooth construct.

The key advantage to PHST is its peelable design, which makes removing it significantly easier compared with the traditional method of skiving, thereby saving time and reducing risk of damage to the underlying construct. Junkosha’s PHST solutions are ideal for particularly small devices such as micro-catheters due to their simplicity in removal. Conventional skiving techniques do not work well on smaller reflowed catheters, frequently leading to scoring or kinking of the catheter shaft, rendering them useless.

The move towards miniaturisation in medical tubing is picking up pace, with medical device manufacturers demanding catheter solutions that can readily penetrate harder to reach anatomy to treat a broader range of patients and conditions. Junkosha has developed a range of medical tubing innovations, including the first ultra-small PHST — a tubing solution suited for laminated jacket coating of tiny guide wires (down to 0.011” and 0.014”), leveraging the fact that PHST has a recovered interior diameter (ID) down to 0.009”. These miniature guide wires are perfect for applications such as the navigation of vessels to hard-to-reach locations in the brain.

Beyond ultra-small, the company’s 2.5:1 PHST solution equips catheter manufacturers with the highest shrink ratio currently possible in peelable FEP. Last year, the company also launched Cut-To-Length and Slit PHST which eliminates the need for customers to make the initial slit, further simplifying the manufacturing process.

Junkosha also provides clear PHST, which exhibits the same product quality as its ‘natural’ PHST but is optically transparent (Figure 1). This visual clarity is a critical requirement for manufacturers seeking to bond, weld or tip catheters, as well as needing to see what is happening underneath along the underlying substrate for quality control.

Using the clear format of PHST enables manufacturers to visually inspect the catheter shaft before and after reflow, enabling identification of any bubbles in the tubing and any gaps or overlap within the joints of the catheter shaft. This is particularly useful for manufacturers using catheter constructs with joints in tight proximity, or multiple Pebax layers demanding close inspection to ensure extrusions do not shift.

The PTFE Liner Challenge

Thanks to proprietary processing techniques, the company’s etched polytetrafluoroethylene (PTFE) liners (EPL) provide considerable robustness, high tensile strength, have superior consistency in elongation, and are available with ultra-thin walls to deliver increased flexibility and smaller outer diameters for increased catheter real estate (Figure 2). In addition, they incorporate consistent etched surface treatment to provide confidence of adhesion during reflow even in the most demanding catheter designs.

Earlier this year, Junkosha launched its PTFE Liner Challenge by making a pledge to manufacturers — by partnering with Junkosha, they will not need a tie layer to improve yields for applications under 3.0 mm ID.

Evidence of the robustness of Junkosha’s EPL products has emerged through customer feedback. In a field that demands high levels of consistency and reliability, the durability has been welcomed by manufacturers of small format catheters worldwide. For example, in some situations customers had been considering the use of a tie layer, which is an additional thermoplastic coating on the outside of the PTFE liner, to minimise the appearance of small imperfections as well as increase the bond strength between the layers of the catheter.

In doing so, however, they had added unnecessary thickness and stiffness, therefore finding that the tie layer limited the amount of stretch they could use in their manufacturing processes. Overall, Junkosha has yet to come across a customer application where the performance of its liners required the addition of a tie layer to meet performance or yield targets for the device.

Consistent positive feedback from customers regarding its EPL range has led the company to formulate a service package which makes it easy for customers to experience the product benefits for themselves. This includes free standard samples for testing, free application support including a full problem audit and solution identification, alongside shorter lead times than competitors.

Looking ahead

As increasingly intricate procedures become viable, medical devices will become even more complicated. Device manufacturers are utilising combinations of braiding, coils, laser cut tubing, and multiple durometer jacketing materials to increase flexibility where it is needed, while maintaining the mechanical performance necessary for a smooth delivery. With a number of milestones already under our belt, we are looking forward to leveraging our technologies and enabling technology innovators well into the future.