Feature Article

By: EMDT Staff

The humble syringe, feared by generations of children, is typically used to administer vaccinations or to draw blood. But after talking to Mik Bajka, Engineering Manager of TriContinent Scientific in Northern California, the medical tool takes on a whole different meaning. Syringes used in life sciences and the field of biotechnology not only have to be precise and reliable. They also have to be long-lived and resilient in order to maintain automated instruments that are used for in vitro testing, chemical analysis and cytometry, the examination of microscopic particles contained in cells.

 

“In life sciences such instruments run 24/7, pumping out small but exact amounts of liquids or reagents,” explains Bajka. “A broken or leaking syringe translates into expensive downtime."

 

TriContinent Scientific and Trelleborg Sealing Solutions worked together to develop a novel pump platform seal design for one of TriContinent’s largest customers. Usually plastic plungers ride inside a bore made of glass or ceramics, and the seal between the two components is often the weakest link. Using a patented design that Bajka’s team had come up with, Trelleborg’s engineers helped select the right seal material and sealing element, or energizer. This keeps the syringe running even when it is dispensing harsh reagents that would damage other pumps.

 

“The success of this syringe pump design hinged on finding the perfect seal material and configuration,” explains Bajka.

In this particular case, reagents tended to crystallize along the outside of the ceramic piston that moves up and down the pump cylinder, creating an abrasive layer that caused the seals to fail prematurely, even leading to expensive leaks that could damage the motors powering the syringe pumps.

 

“We came up with a novel approach – a self-lubricating seal that withstands tough conditions,” says Bajka. “But we needed a competent partner for the sealing element.” Enter Trelleborg Sealing Solutions, whose experts recommended using an integrated polymer dynamic seal with a custom-shaped energizer tucked away inside a polyethylene jacket. Instead of the usual metal coil, the energizer is made from a glass fiber reinforced thermoplastic material sheathed in ultra-high molecular weight plastic.

 

The new design, explains Trelleborg Sales Engineer Andy Plantaz, was worked on and tested over the course of a year and a half, and it has several significant advantages. It exerts a more consistent force throughout the diameter of the seal’s surface, which allows the device to dispense liquids with more precision. It is also impervious to harsh reagents that would attack metal, keeping them from coating the bore.

 

The result is more reliable operation, without premature failure. Trelleborg Sealing Solutions had a team of seven to 10 experts working on this design challenge.

 

“We put a lot of focus on working with TriContinent’s experts to support our customer because this is an important growth area for us,” Plantaz says.

 

For its part, TriContinent has nothing but praise for the new syringe pump.

 

“It is a unique design where the pump is a single solid piece machined to our dimensions,” says Bajka. “Now the sealing lip can come in contact with the fluids inside the syringe.”

 

After building prototypes with Trelleborg’s help, TriContinent ran the new design through several million test cycles and came away satisfied with the results.

 

“Since the new pump has been installed in the customer’s instruments, downtime has been reduced from 28 percent to less than 1 percent,” says Bajka. “That is crucial, if you consider that each day an instrument is out of operation, it can cost the company between US$50,000 (€34,500) and US$100,000 (€69,000).”

 

What’s more, the new design allows maintenance workers to check on the syringe pumps and drop in individual replacements.

 

“We can now do preventive maintenance,” Bajka explains. “Significantly higher customer satisfaction is the biggest plus that came out of our work with Trelleborg."