Injection molders possessing the required skill sets and with the appropriate quality systems in place are eager to enter into partnerships with medical device OEMs. The reasons are simple: The margins are good and, provided that the vendor delivers on its promises, medical device OEMs tend to be loyal and are not constantly shopping around to shave a penny or two from their costs. So, Diversified Plastics Inc. (DPI), an employee-owned custom molder based in Vista, CA, was understandably delighted when a senior buyer from Nonin Medical came knocking. Nonin’s John Scrivener was leading the supplier selection process; as an FDA-registered molder certified to ISO 13485:2003, DPI clearly had the credentials to be considered. As it happened, the selection process began about a year before the COVID-19 outbreak, giving DPI a golden opportunity to show its prowess just as demand for Nonin’s signature Onyx fingertip pulse oximeters began to skyrocket.

The vendor selection matrix

When Nonin started the selection process, DPI was one of three injection molding companies under consideration. The medical device OEM based in Plymouth, MN, had developed a vendor selection matrix, the key considerations of which included a robust quality control system and validation process along with a convenient location. “We were transitioning from another plastic injection molder,” explained Kristin Finberg, Project Manager at Nonin. “Searching for a new supplier was a big step for Nonin. We needed to be confident that the chosen vendor could meet our needs today and in the future. We ranked the companies based on the selection matrix criteria. DPI came out on top as a great fit.”

In addition to molding the plastic parts of the Onyx fingertip pulse oximeter, DPI also was tasked with replacing the aged tooling and integrating some design changes. Nonin had completed the product design, and DPI contributed its expertise in tool design. The contract molder also had to participate in an advanced validation protocol, which Nonin had implemented as part of its continuous improvement process. Before the molds were made, the teams reviewed the tool design. Once the tool was complete, prototypes were developed, and the first article inspection was successfully completed.

The first fingertip pulse oximeter on the market

The small, lightweight Onyx device from Nonin Medical was the first fingertip pulse oximeter on the market. These medical devices measure and display functional oxygen saturation of arterial hemoglobin (SpO₂) and pulse rates. Onyx has a durable hard plastic case designed to withstand vibration, shock, bumps, and drops. Manufactured in black, blue and red, it has plastic channels that hold the batteries securely in place. Already ubiquitous in healthcare settings, pulse oximeters are in even greater demand since the COVID-19 pandemic started, because it can detect silent hypoxia, an early warning sign of COVID-19.

Silent hypoxia is a condition in which oxygen levels in the tissue have dropped, but the individual has no signs that something is wrong, explained DPI in a press release. “A pulse oximeter identifies patients with silent hypoxia, alerting physicians early on that treatment may be indicated. Early treatment can keep COVID-19 patients off ventilators — and alive,” said DPI.

“Just as we were getting close to going into production, COVID-19 happened,” said Finberg. “That’s when Onyx product sales rapidly accelerated. Fortunately, we were already working with DPI to manufacture, decorate, and assemble components of the Onyx fingertip pulse oximeters. The team at DPI was able to quickly assess the surge in volume and develop a plan, including additional tooling, to increase capacity. DPI has done an amazing job meeting our needs for increased production, and DPI was in the right place at the right time. Everything is going well,” said Finberg.

Today, DPI is manufacturing all plastic parts on the Onyx fingertip pulse oximeters, including the enclosure and the soft-touch material that clamps onto the finger. Some of the parts require complex overmolding of different materials, which DPI said is one of its areas of expertise. DPI also manages direct sourcing of lens components with one of Nonin’s other vendors. Additionally, the manufacturer is sourcing product decorating and completing some of the assembly. Once completed, the parts go back to Nonin where the electronics are integrated and final assembly and packaging is done. Anticipating continued high demand for the devices as a second wave of COVID-19 spreads in late fall or early winter, DPI said that it is investing in additional presses.