Quality and precision play a significant role in medical device manufacturing around the world, and strict regulatory standards drive the need for devices to pass rigorous inspections. Catheters are no exception.

Originally catheters had a single function, to drain out urine from urinary tracts. Today, because of many advances in materials, design techniques, fabrication technology, and manufacturing capability, catheters are being used for a range of medical functions, which span from urethral to cerebral catheters.

Depending on the function in which the catheter will be used, designers must take many characteristics into consideration when developing these devices, including flexibility, steerability, and the ability to handle greater torque or pressure forces.

Catheter bonding and assembly processes can be exceptionally difficult and cumbersome to execute due to the small form factor of these devices, and the need to dispense microdots of adhesive repeatedly and reproducibly onto an area not much bigger than the tip of a pen.

Figure 1: Typical Balloon Catheter

Nordson EFD's UltimusPlus benchtop fluid dispensers helped one medical device company significantly improve efficiency and accuracy to elevate catheter manufacturing to a world-class standard, while meeting necessary regulatory standards.

Fluids Used

Cyanoacrylate

Application Requirements

• Apply consistent and precise quantities of material onto catheters
• Handle and dispense material quickly before it cures
• Dispense into tight tolerance locations

Previous Process

Prior to purchasing the UltimusPlus, the cyanoacrylate was applied by hand using a squeeze bottle. This involved holding the squeeze bottle over the desired area on the catheter, and literally squeezing the adhesive onto the relevant catheter components. This was a new application for the development team. In the beginning phases the team had planned to continue using a squeeze bottle to bond the catheter parts.

Issues with Previous Process

As they started implementing this process, the development team quickly realized that they were facing many challenges.

First, the material handling of the cyanoacrylate was cumbersome. Using a squeeze bottle to apply the adhesive was an inconsistent and very inaccurate process.

Since cyanoacrylate is a moisture-cure adhesive, it has a very short potting life. Therefore, it would start to cure before the team could fully empty the squeeze bottle. This provided a very small timeframe to handle the material and apply it onto the substrate.

The second challenge was not being able to apply the correct dose of material to bond the necessary catheter components together. The team could not accurately measure the amount of fluid that was applied by the squeeze bottle. They also could not ensure repeatability of the fluid dose each time. The inconsistent fluid application process led to significant waste, higher cost of materials, and an out-of-control manufacturing process.

Lastly, using the squeeze bottle to apply the material into the tight tolerance dispense area proved to be a significant challenge. This specific catheter system had a shaft diameter smaller than 0.052" (1.33 mm). The development team needed a more precise method for applying the quick-curing adhesive to these precision components.

Solution

• UltimusPlus fluid dispensers
• Optimum 27 ga SmoothFlow tapered tips
• Optimum Class VI syringe barrels

Results

When the team was introduced to the UltimusPlus fluid dispenser they experienced an immediate, and positive improvement to their production process. With touchscreen control of its intuitive interface, the UltimusPlus provided simplified setup.

The team was able to set and adjust the dispensing parameters with ease and speed and could focus more on applying the fluid in the correct location.

The 27 ga SmoothFlow tapered tip attached to a syringe barrel allowed the precise application of highly controlled fluid deposits. Filling the syringes with cyanoacrylate became much easier than the previous handheld squeeze bottle method.

The dispensing process was no longer messy or unmeasured, and the fluid didn’t cure as quickly once it was filled into the syringe. The small gauge dispensing tip allowed for effortless dispensing onto the precision components of the balloon catheter. The UltimusPlus dispenser provided an exact amount of fluid each time to reduce waste and cost.

The dispenser was able to solve all the development team’s challenges. They also benefited from many other features the unit had to offer, such as:

• Full Operator Lockout

This feature was important because many operators used the dispenser throughout the day. Full operator lockout gave the development team the ability to set the validated dispensing parameters required without any potential for the parameters to be changed. This made every deposit the same as the previous deposit, and within the validated settings.

• Dispense Log

This feature gave the medical device company the opportunity to record and download dispense data, such as dispense time, dispense pressure, and vacuum applied. Each dispense record also identified the dispense program used and was date/time stamped so the team could easily identify which production batch the dispense information was related to. This data could then be downloaded onto a CSV file, which could be used to identify trends in the production process and help uncover any anomalies that could lead to quality issues that may affect the functionality of the device.

• Self-Calibration

Traditionally, dispensers use solenoids and regulators, mostly mechanical hardware, that requires calibration to ensure displayed settings on the dispenser are true against the internal performance of the solenoid and regulator. The UltimusPlus is different in that it features proprietary technology that calibrates each dispense. This technology ensures if, for example, the operator sets air pressure to 10 psi, it is 10 psi of pressure being generated and supplied to the syringe barrel.

This feature reduced setup time for the medical device manufacturer by eliminating the need to experience downtime while the dispenser was calibrated by a third party. It also eliminated costs associated with getting the dispenser calibrated. This self-calibrating feature also ensured first-shot accuracy that helped the team create higher-quality catheters with less rework and scrap. First-shot accuracy means each dispensed deposit from the first to the last is validated and calibrated for the best possible process control.

The development team had so much success with the UltimusPlus, they plan to purchase the optional barcode scanner that is compatible with the unit. This will allow a part to be scanned as it comes through the assembly line and its dispensing parameters will automatically load into the dispenser.

The barcode scanner takes the guesswork out of programming the dispenser, while ensuring dispenser setup to the validated parameters each time. It also allows the operator to apply a more precise, repeatable amount of fluid required for the application, every time.

Nordson EFD is here to help meet all of your medical application requirements, whether it be for a catheter or other life-saving device. Don't hesitate to contact us if you have any questions.

— By Ahmed Khan, Global Product Line Manager for Dispensers at Nordson EFD. Ahmed provides recommendations and solutions to customers, and helps with initial system integration. He joined Nordson EFD in 2013 and is based in the United Kingdom.