It provides greater levels of comfort to those being tested due to its unique shrinking design and could help tackle potential swab shortages in the coming months as it can be printed on demand.

The team, Dr Arun Arjunan, John Robinson, Dr Ahmad Baroutaji and Suhaib Zahid from the School of Engineering have for the first time developed the one size fits all nasopharyngeal (the upper part of the throat behind the nose) swab using the concepts of mechanical meta-materials. This allows the 3D printed smart swab to navigate through the nasal cavity with significantly less stress on the surrounding tissues.

Diagnoses of COVID-19 are currently being confirmed using a test that relies on nasopharyngeal swabs. Many countries are now facing shortages of these swabs, and the shortages will become even more critical in the coming months due to increased testing and global concerns over a second COVID-19 wave. In addition, they cannot be made from more common materials, like cotton and wood, as they should not affect the Ribonucleic acid (RNA) of the collected sample.

The global shortage in swabs triggered the team to focus on the potential to create nasopharyngeal swabs through 3D printing at the University’s engineering laboratories. Support was also provided by Formlabs GmbH for the printing of the test samples.

Reader in Additive Manufacturing of Functional Materials Dr Arun Arjunan said: “This research is the first step in starting an open and collaborative process to drastically improve the existing concepts in nasopharyngeal swabs using the principles of digital fabrication and meta-materials.

“The opportunity to digitally conceive and 3D print swabs allows for the incorporation of geometrical features that can potentially reduce patient discomfort.

“In this regard, our research expertise in additive manufacturing and meta-materials led to the development of auxetic nasopharyngeal swabs that can shrink under axial resistance.

“This allows the swab to navigate through the nasal cavity with significantly less stress on the surrounding tissues. In comparison, a traditional material will tend to expand under axial load causing discomfort and stress in surrounding tissues.

“When it comes to the additive manufacturing of functional materials, one of the areas of research at the School of Engineering focuses on is the development of 3D printed meta-materials and meta-biomaterials which is the foundation of this study. ‘Meta’ indicates that the characteristics of the material are beyond what is commonly seen in nature.”

Currently the swabbing process can be very uncomfortable as the swab must be inserted several inches deep. The swab head cannot account for the variation in the nasal cavity, increasing discomfort for children and the elderly.

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 the production of these nasal swabs has become paramount. This research will make the full data and design publicly available so that any institution or country will be able to manufacture them on demand.

On the next steps for the project, Dr Arjunan added: “We have now validated the concept at the laboratory scale. Next, we need to complete extensive mechanical and biological characterisation of the swab to ensure safety. This data will be used to further enhance the swab design and optimise it for the 3D printing process for efficient mass production.

“This will be followed by real-world testing of swab collection which will be in collaboration with healthcare partners.

“The study is likely to take another six months before it can be used in test centres, however the benefits of the swab go beyond the COVID crisis as these smart swabs are superior to traditional swabs because they significantly reduce patient discomfort and can be printed on demand.”