As has quickly become apparent in the fight against COVID-19, one of the critical factors in stemming the spread of the virus and understanding its reach is widespread testing. The World Health Organization (WHO) has promoted testing in its guidance to governments, but on the ground many countries have struggled to scale up testing operations to the point required. One of the key inhibitors to adopting more broad testing is a lack of supplies, including test kits and personal protective equipment for healthcare workers.
In the case of the latter, we’ve seen how 3D printing has been implemented by companies and makers around the globe to produce face shields on an impressive scale. (Though it should be noted that these face shields are meant to be worn in combination with an N95 face mask.) What is perhaps less known is that additive manufacturing technologies are also being used to produce nasal swabs for the COVID-19 testing process. In this article we will look at why 3D printing is a suitable process for swabs and who is making them today.
The COVID-19 test
Many people around the world will know first-hand what the coronavirus detection test is. For those who don’t, one of the most common processes consists of inserting a five-inch-long nasal swab along the nasal septum until the nasopharynx is reached. The swab must then be rotated for up to 15 seconds to collect secretions before being removed and placed in a sterile container for lab testing. The swabbing process is somewhat uncomfortable, as the swab must be inserted several inches deep.
Though the swabs used look like elongated Q-tips, they are not so readily available. That is, because the swabs should not affect the Ribonucleic acid (RNA) of the collected sample, they cannot be made from more common materials like cotton and wood. The nasal swabs being used for COVID-19 testing are also specifically designed: they have a small brush at the end which gathers mucous and a hollow stem to hold it.
As the need for COVID-19 diagnostic testing increases around the world, the question of how to scale up production of these nasal swabs has become paramount. 3D printing—and specifically, resin-based 3D printing—is one potential solution that is being explored and a select number of companies are leading the effort.
Why 3D printing
As we’ve seen over the course of this global pandemic, the additive manufacturing industry has demonstrated that 3D printing can be used to enable production when ruptures in supply chain occur or traditional manufacturing is limited. The technology’s benefits, including rapid prototype iteration and flexible, on-demand production, have been used to produce much-needed equipment for COVID-19 relief efforts, including face shields and parts for ventilators and respirators.
In the case of the nasal swabs, medically recognized SLA 3D printing systems and materials—commonly used in the dental industry—have been adapted to fulfill production of nasal swabs. The resin-based process offers high-resolution printing, which is needed for the fine components, while biocompatible materials that have already undergone certification for dental applications can be used right away. HP’s powder-based Multi Jet Fusion technology is also being explored for the production of nasal swabs, as it too is capable of high resolution and fine detail printing.
Formlabs, Carbon, EnvisionTEC and HP are four of the companies that are working closely with healthcare providers to develop, validate and produce the COVID-19 nasal swabs.
Formlabs’ test swabs
SLA 3D printing specialist Formlabs, which has extensive experience in the dental industry, has teamed up with the University of South Florida (USF), Tampa General Hospital and NY-based hospital system Northwell Health to develop and print nasopharyngeal swabs.
The swabs were designed by health professionals from USF and Northwell Health and are now being optimized by Formlabs for 3D printing. To date, Formlabs has 3D printed hundreds of test swab samples using its biocompatible Surgical Guide Resin, which have undergone and passed several tests at USF Health. (USF Health, for its part, has received Emergency IRB approval and regulatory, infectious disease and virology authorization.)
Formlabs adds: “These swabs are Class I medical devices exempted from premarket notification requirements and require manufacturers to register and list the products. Formlabs will produce swabs in its FDA-registered, ISO 13485 certified facility in the United States.”
The swabs themselves are designed to be printed in a single piece and consist of a flexible stick with an intentional weak point and a bristled tip. The weak point on the stick, located 7 to 8 cm from the tip, allows the stick to be broken so that the vial can be capped for transport to the lab.
As soon as possible, the partners plan to release the designs for the prototype swab so that any hospital with an SLA system and the right material can produce the swabs. A spokesperson for Northwell Health told the New York Times that it has the capacity to print up to 3,000 swabs per day.
Carbon’s lattice swabs
In addition to designing a face shield to be printed using its Digital Light Synthesis (DLS) platform, Carbon has also partnered with several healthcare institutions to develop designs for 3D printed test swabs, which leverage its Lattice Engine software.
The company says it is progressing with three Lattice Swab designs, which are being evaluated by clinical partners. This testing initiative is being conducted in collaboration with Stanford Medical Center, Harvard Medical School/Beth Israel Deaconess Medical Center, Desktop Metal’s Ric Fulop, Chan Zuckerberg BioHub and University of North Carolina at Chapel Hill.
The lattice structure integrated into the swab seems to have a double purpose: not only does it reduce the amount of material required and enable faster printing times, but it also creates a brush-like texture, which can collect mucous from inside the nasal passage.
At this stage, Carbon says it will not be sharing its swab designs with the public. The company says: “Because this product requires special certification and equipment to produce for safety and compliance with federal regulations, we are not sharing this print file at this time and are not currently in need of additional production partners. We will update partners if this situation changes.”
[Update April 8, 2020]: Carbon announced that it is now producing upwards of 1 million 3D printed nasopharyngeal swabs per week. The swabs will be distributed to medical professionals in collaboration with Resolution Medical, an in vitro diagnostic and medical device manufacturer. The Lattice Swab is printed from a biocompatible material, KeySplint Soft Clear, and is classified by the FDA as a Class I 510(k) Exempt in vitro diagnostic medical device.
EnvisionTEC’s nasal swabs
3D printing company EnvisionTEC recently made public its efforts in the fight against COVID-19. The company says that it is using its resources to address the lack of ventilators, personal protection equipment and nasopharyngeal swabs. In the case of the latter, the company has been working with the Harvard Microbiology Lab in the context of a larger group connecting academia with the manufacturing industry.
Engineers from EnvisionTEC have come up with a series of 3D printed nasal swab designs, which have been printed by dental laboratory Nilson Laboratories for testing. According to EnvisionTEC, the lab was able to 3D print 400 swabs using an Envision One cDLM 3D printer and Class 1 approved E-Guide material in just two hours.
The testing process for the 3D printed nasal swabs consists of several phases, including a two-part absorption test; a biological/chemical testing procedure that will ensure the swab does not interfere with the RNA particles or PCA/reagents; and a sample collection testing process. The key requirements for the nasal swab are that it can bend 180 degrees without breaking, be made from a chemically safe material and can collect enough virus particles for effective testing.
EnvisionTEC’s E-Guide material has already passed some of the tests and the company is now awaiting results from IRB testing. “Under FDA regulations, an IRB group that has been formally designated to review and monitor biomedical research involving human subjects has the authority to determine that E-Guide is suitable for the mass production of the NP swabs for COVID-19 testing,” the company specifies.
When testing is complete, EnvisionTEC—along with its network of partners—will have the capacity to 3D print hundreds of thousands of nasal swabs per day.
[Update April 15, 2020] EnvisionTEC announced today that it successfully completed a clinical trial for its 3D printed Nasopharyngeal (NP) Swabs for COVID-19 testing. The company, as well as a number of Envision One cDLM customers that have registered with the FDA will now commence the mass production of the nasal swabs, in quantities of up to one million swabs per day.
HP’s PA 12 swabs
HP is also investigating the production of nasal swabs using its Multi Jet Fusion technology. Working with various partners, including Harvard University and Beth Israel Deaconess Medical Center, the company says it is going through the same validation, testing and regulatory processes required as the others. When approval is given, HP and its global network of partners plan to launch mass production of the test swabs using its industrial-grade Jet Fusion systems and HP 3D High Reusability PA 12 material.
Thanks to the company’s expansive manufacturing network, it says it would be able to deliver the critical testing devices at a mass scale. For instance, the company operates 3D printing R&D centers with over 100 systems in Barcelona, as well as in San Diego, CA and Corvallis, OR. The company also has several partners with industrial-scale capability, including Smile Direct Club and GKN/Forecast.
In addition to the nasal swabs, HP is also validating and finalizing production of 3D printed face masks, face shields, mask adjusters, hands-free door openers and respirator parts.
Markforged & Neurophotometrics’ Fiberflex Rayon swabs
Markforged revealed that it is working in collaboration with optical equipment provider Neurophotometrics to 3D print nasopharyngeal swabs for COVID-19 testing. The swabs, called Fiberflex Rayon, consist of a 3D printed base made from nylon and a wrapped 100% rayon tip that gathers the viral specimens from inside the nasal cavity. The testing devices were developed through a collaboration between Neurophotometrics, the San Diego Covid Research Enterprise Network (SCREEN) initiative, Rady Children’s Hospital-San Diego, the Scripps Research Institute and the University of California San Diego.
The development process consisted of designing the swab and testing it on a group of 50 volunteers. Patients who were confirmed positive for the virus were re-tested 3-14 days later using both the 3D printed and commercial swabs. The former’s results were all positive, while the commercial swab had instances of falsely reporting negatives. Markforged says it is now producing 10,000 nasal swabs per day and plans to scale production up to 100,000 per day.
Origin, a San Francisco-based 3D printing company, has also teamed up with the Beth Israel Deaconess Medical Center (BIDMC) to develop 3D printed nasal test swabs for COVID-19 diagnosis. In recent weeks, the company has reportedly transitioned most of its operations to developing and producing products for COVID-19 response. Its test swab was chosen by BIDMC to participate in a clinical trial. On April 13, 2020, Origin revealed its 3D printed swab had successfully passed an initial clinical evaluation for human factors, materials testing and PCR compatibility.
The 3D printed test swabs, designed using nTopology’s nTop Platform, are considered an FDA Class 1 Exempt Device. The swabs have also reportedly undergone testing by the U.S. Army, Origin material partners, universities and independent medical labs. The swabs are now available for order.
Test, test, test
Of course, swabs are only part of the COVID-19 testing equation, and other crucial elements of the testing process need to be scaled too. The most common diagnostic test currently used for detecting the coronavirus in mucous samples is PCR, a polymerase chain reaction test that can detect nucleic acid from SARS-CoV-2 in respiratory specimens.
As labs across the globe scale up PCR testing, the need for certain supplies is growing and in many cases not being met. Nasal swabs are one key part, but so are the chemical reagents needed in the PCR process. The lack of supply of reagents is now starting to lead to delays in test processing and diagnosis. Thankfully, reagent manufacturers are doing their best to respond to the increasing and urgent demand, while other testing processes are being explored and undergoing validation.
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