3-D printed COVID-19 test swabs pass their own tests

Medical test swab package
As COVID-19 testing expands, more swabs are desperately needed. A multi-disciplinary team has shifted into gear to test and 3D print them.

A new industry consortium called PrintedSwabs.org, made up of multidisciplinary teams from the 3D printing industry, medical institutions and academia, has launched a wide-scale initiative to supply millions of COVID-19 test swabs.

One of the members, Origin, a developer of an open platform for additive mass manufacturing. has recently pivoted from being a 3D printer manufacturer to producing the swabs. A single Origin printer can print up to 1,500 swabs in a single print in under 8 hours.

Origin created various 3D-printed swab designs using its nTop Platform . Beth Israel Deaconess Medical Center (BIDMC), conducted a rigorous initial clinical evaluation for human factors, materials testing, and PCR compatibility, which the samples passed.

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3D printed swabs, however, are very different than the flocked swabs currently in use. So, the samples have undergone rigorous testing with several universities, independent medical labs, and Lawrence Livermore National Lab (LLNL), which discussed its procedures and findings with FierceElectronics.

Tensile tests prove swab's integrity

LLNL conducted tensile tests on almost two dozen different swab designs/materials from a number of different companies including Origin, HP, FATHOM, Abiogenix, and FormLabs in order to provide guidance on the design and any recommended improvements.

The most surprising thing for LLNL engineers was the sheer number of different design/material solutions that were rapidly prototyped by groups across the country to help address this shortage

“Testing was crucial, as the 3D-printed swab designs represent a significant departure from the flocked swabs currently used and are manufactured using a number of different technologies such as MJF, Injection Molding, and SLA,” said  Dr. Angela Tooker, an R&D engineer at Lawrence Livermore National Lab and co-author of the LLNL  report “Swab Tensile Testing Procedures.”  

The basic parameters for the tests conducted by the LLNL team were modified from existing ASTM standards for tensile testing and simulated the pulling of the swab back out of the nasopharyngeal space. “We were looking for how much force had to be applied to the swab to make it break and where it physically broke. to simulate actual use-case conditions and allow us to evaluate the potential failure modes for the swabs,” said Tooker.

One of the tricky design requirements of a swab is that it must be stiff enough to withstand the taking of a sample, yet flexible enough to easily break off at a predetermined breakline. Simulations of the designs were conducted to help optimize the design and ensure the swabs remained strong enough to withstand the testing, yet would break as required.

“We monitored the load applied during the testing. When the swab breaks, there is a rapid decrease in the load applied—which is considered the load applied to break the swab,” said Tooker. “In most cases, this happens because the swab has physically broken in pieces.  In some cases, this rapid change in load was observed, but the swab was physically intact in one piece. “

She added that sometimes a crack in the swab was observable in the head region of the swab, but due to some of the design details, that was not always the case.  “This could be due to a number of factors: physical defect in the swab, misplacement of the swab in the test setup, swab design,” Tooker said. “We could have continued applying load to these and broken them into pieces, but the data would be more difficult to interpret since there would now be known defects in the swab [which would affect the performance)].”

Overall, the LLNL team concluded that the sample swabs performed well and were able to withstand forces beyond what they would reasonably be expected to undergo in the clinical setting.

 LLNL is continuing to test swabs to help provide guidance on how to improve the designs. For the manufacturers, the next steps is to make sure that all required regulatory approvals are in place and to get the swabs into the hands of clinicians who need them.

RELATED: 3D printing of Covid-19 test swab sticks ramps up

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