Novel COVID-19 swabs to address shortage

Professor Freddy Boey (centre, showing the swabs), and (from left) Dr Alfred Chia, Associate Professor David Allen, and Associate Professor Yen Ching-Chiuan are part of two NUS teams that developed three nasopharyngeal swab designs for COVID-19 testing.


Since the outbreak of COVID-19, there has been a global surge in demand for nasopharyngeal (NP) swabs, a key element in testing for the coronavirus. Singapore is no exception. Commercially available NP swabs used in COVID-19 test kits are often out of stock due to supply chain disruptions. 

To help address the global shortage, and to ensure Singapore has a sustainable supply of these swabs, two multidisciplinary research teams from NUS have developed a total of three swab designs that are comparable to the current ‘gold standard’ swabs.

A team led by Professor John Eu-Li Wong, NUS Senior Vice President (Health Innovation & Translation), Associate Professor David Allen, Associate Vice President (Health Innovation & Translation), Associate Professor Yen Ching-Chiuan, Co-Director of the Keio-NUS CUTE Center, and Professor Jerry Fuh, Director of the NUS Centre for Additive Manufacturing (AM.NUS), in collaboration with the National University Hospital (NUH), and an industry consortium led by Dr Ho Chaw Sing, Managing Director of the National Additive Manufacturing Innovation Cluster (NAMIC), successfully developed a patient-trialled, cost-effective and manufacturable 3D-printed NP swab named ‘Python’. 

The team worked with Professor Wang De Yun and Associate Professor Vincent Chow from the NUS Yong Loo Lin School of Medicine, Mr Eason Chow from Keio-NUS CUTE Center, Mr Willie Tay and Mr Chen Chee Keong from the Division of Industrial Design at the NUS School of Design and Environment, Ms Gan Soo Wah, Mr Saraf Anmol and Ms Guo Yilin who are from AM.NUS and NUS Faculty of Engineering, as well as Dr Joshua Tay Kai Xun, Dr Gail Brenda Cross, Dr Benedict Yan, Mr Lee Chun Kiat, and Ms Tong Kim Loo from NUH, on the design, pre-clinical testing and clinical validation. 

“Designing the Python swab from scratch, testing it to make sure it’s safe for patients and bringing it to full-scale manufacturing within a very tight timeline of two months is an extraordinary endeavour. This is truly a team effort by NUS, NUH and the industry consortium headed by NAMIC. We shared a common sense of urgency to address a pressing need, so we came together and did what we need to do as quickly as we could,” said Prof Wong.

Additionally, to further increase the production of suitable swabs for Singapore and the region, another NUS team led by Professor Freddy Boey, NUS Deputy President (Innovation & Enterprise), introduced two new designs, named ‘IM2’ and ‘IM3’, that could be manufactured using injection moulding. 

The University extends its appreciation to all partners and collaborators for their contributions to the development of these swabs.

Nasopharyngeal swabs and screening accuracy

NP swabs are flexible sticks with a carefully designed tip section. They are inserted through the nose to the back of the nasal cavity to collect fluid samples from an individual. 

NP swabs used for COVID-19 testing have a carefully designed tip section that serves to collect and retain sufficient nasopharyngeal fluids which are channelled into a holder for further testing. These are critical design factors as they could affect the accuracy of the test result when screening for the coronavirus.

Python, the 3D-printed swab

To derive a viable alternative, the NUS team led by Prof Wong, Assoc Prof Allen, Assoc Prof Yen, and Prof Fuh combined their experience to design, test, and clinically validate the utility of a 3D printed NP swab for the identification of the coronavirus. After considering the clinical requirements of the swab in relation to its mechanical, material and biological properties, a double helix structure was used for the swab tip, as it had excellent fluid adsorption and caused minimal discomfort to the patient. 

The development of 3D printed NP swabs is also part of NAMIC’s COVID-19 response initiative and is supported by the National Research Foundation (NRF) under the Prime Minister’s Office, Temasek Holdings and Singapore Economic Development Board (EDB). 3D printing enables the fabrication of a product based on a digital design, resulting in rapid product development and validation cycles.

To address the immediate global shortage, a multi-disciplinary team was assembled. The members include local small and medium enterprises Eye-2-Eye Communications, Structo, and Forefront Medical Technology; Boston-based unicorn startup Formlabs, as well as German testing, certification, auditing, inspection and technical advisory services company TÜV SÜD. The team, led by Dr Ho, dovetailed its efforts with the NUS team. From design to completion of patient trials, the process took less than two months. 

The clinical efficacy of the shortlisted swab design, named Python, was compared to an industry standard swab in NUH. This was carried out in a case-controlled study of 40 patients diagnosed with COVID-19, and 10 control patients with acute respiratory illness who had tested negative for the coronavirus.

The Python swab demonstrated comparable accuracy and performance, with no significant difference against the standard swab. As such, the Python swab was deemed safe and acceptable for patient use, and will help mitigate strained resources in the escalating COVID-19 pandemic. 

Assoc Prof Allen shared, “Obtaining a specimen for COVID-19 testing by swabbing may be a little uncomfortable for some. With patient comfort and test efficiency in mind, our team considered several different swab materials and designs to find the best match. We ultimately swabbed ourselves with the leading swab candidates to ensure our final choices were safe before the team conducted further tests. After numerous rounds of testing and fine-tuning, we finally arrived at the right combination in Python.”

A patent for the Python swab has been filed by NUS. Facilitated by NAMIC, NUS has licensed the design to four companies based in Singapore, Indonesia and the US, out of which Structo and Eye-2-Eye Communications have commenced manufacturing since mid-June 2020. The availability of locally produced 3D printed NP swab test kits will enable Singapore to ramp up testing significantly as the country eases its lock-down measures. With daily production of 100,000, more than 12 million Python swabs will be produced in Singapore over the next few months. Additional swing capacity has also been secured in the US and Indonesia by NAMIC. 

Assoc Prof Yen, one of the lead researchers of the project, said, “We are pleased to contribute our expertise to address the pressing need for nasopharyngeal swabs. As part of NUS’ contribution towards the nation’s fight against COVID-19, the design of the Python swab is free for use in Singapore.”

“We are proud to play a part in Singapore’s efforts to help combat COVID-19,” said Mr Miles Podmore, Chief Executive Officer of Eye-2-Eye Communications. “It has not only been an excellent opportunity to showcase the advantages of 3D printing for rapid design and development, but it has also shown its effectiveness in being able to mass produce products in very short timeframes.” 

“In today’s climate, it’s imperative that we come together to offer our expertise and resources and help in the fight against COVID-19. When we first got the call from NAMIC, we quickly assembled a team to offer our design and manufacturing experience with the task force,” shared Structo Chief Executive Officer Mr Huub van Esbroeck. “After months of hard work, we’re proud to have been part of the production of Python and are now ramping up our manufacturing to deliver millions of nasopharyngeal swabs.”

Formlabs CEO and co-founder Mr Max Lobovsky said, “We are extremely proud to be helping in the global fight against COVID-19. NP swabs enable testing, which is a critical element in controlling the pandemic, and this project will provide Singapore with significant domestic production capabilities of these swabs. We have now helped establish swab manufacturing facilities in several countries around the world, which is a testament to the agility and distributed manufacturing capabilities 3D printing can offer.”

“Our independent perspective allows our industry partners to harness the benefits of 3D printing technology while being able to identify and manage its specific technological risks. Our accredited laboratories for mechanical, environmental, and sterility tests provide crucial data to validate and support decisions of the taskforce. We are proud to contribute to a national effort beyond test bedding and to further increase the international competitiveness of domestic companies and our ecosystem,” said Mr Holger Lindner, CEO of Global Product Service Division, TÜV SÜD. 

A large-scale solution: Injection moulded swabs 

To further increase the production of NP swabs, another NUS team led by Prof Boey developed an injection moulding process.

“Injection moulding as a manufacturing process is inherently faster than 3D printing as multiple units of the swabs can be produced in a given cycle. Several hundred swabs can be produced in a few minutes using the moulding process,” explained Prof Boey.

His team introduced a new design that could be injection moulded, named IM2. It was tested for its mechanical strength after sterilisation, and for its efficacy in picking up viral loads. The results showed that its performance was comparable to the current commercially used swabs.

The team also redesigned the Python swab to enable it to be injection moulded by increasing the circumferential strength, and working with the manufacturer to design a mould that enables the moulding of the central hollow cavity. This design was coined IM3. Similar tests were performed to show that the design was comparable to the current commercially used swabs.   

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NUS researchers have designed three nasopharyngeal swabs for COVID-19 testing: (from left) IM2, IM3 and Python.


Within three months, the NUS team designed and tested these injection moulded swabs, and is carrying out clinical trials in NUH and the Singapore General Hospital. Patents have been filed for the two designs.

“The use of injection moulding ensures a secure source to supply high volumes of swabs at a low cost, to meet the needs of our community and beyond. This is crucial in our continued fight against the pandemic. The NUS IP for the injection moulded designs will also be available free for use in Singapore,” shared Prof Boey, who also led the research team that designed the portable Droplet and Aerosol Reducing Tent (DART), which provides additional protection for healthcare workers.

Prof Boey and his team are now working with four companies, TNC Optics & Technologies Pte Ltd, Meiban Group Pte, Inzign Pte Ltd and Forefront Medical Pte Ltd, to mass manufacture and sterilise the injection moulded swabs. 

About 40 million pieces of the IM2 and IM3 swabs are expected to be produced over the next few months, and these locally-produced swabs will be priced lower than the current commercially available imported swabs.

NUS President Professor Tan Eng Chye said, “As countries progressively emerge from lockdowns and reopen their economies, mass, repeated, testing is being widely adopted as a key public health strategy to prevent a resurgence of COVID-19 infections. This has resulted in a global shortage of commercial nasopharyngeal swabs. 

We are proud that our researchers have stepped forward at this time of need. They have worked very hard, under great time pressure, to design, test and clinically validate three types of nasopharyngeal swabs within a few short months, so that these swabs can be mass manufactured locally and affordably to meet Singapore’s needs.” 

These custom-designed NP swab designs are part of the various innovations and solutions developed by NUS researchers to tackle the COVID-19 pandemic. The University has been actively working on initiatives to fight the coronavirus since it began, with research ranging from diagnostic tests to vaccine development, as well as tapping on information and technology for solutions. 

More information on NUS’ efforts to address the COVID-19 pandemic can be seen here.