Rapid Fabrication of Sterile Medical Nasopharyngeal Swabs by Stereolithography for Widespread Testing in a Pandemic

Abstract

The 3D printing of nasopharyngeal swabs during the COVID‐19 pandemic presents a central case of how to efficiently address a break in the global supply chain of medical equipment. Herein a comprehensive study of swab design considerations for mass production by stereolithography is presented. The retention and comfort performance of a range of novel designs of 3D‐printed swabs are compared with the standard flocked‐head swab used in clinical environments. Sample retention of the 3D swab is governed by the volume, porosity density, and void fraction of the head as well as by the pore geometry. 3D‐printed swabs outperform conventional flock‐head swabs in terms of sample retention. It is argued that mechanically functional designs of the swab head, such as corkscrew‐shaped heads and negative Poisson ratio heads, maximize sample retention and improve patient comfort. In addition, available designs of swab shafts for an optimized sample collection procedure are characterized. The study is conducted in vitro, using artificial mucus, covering the full range of human mucus viscosities in a 3D‐printed model of a nasal cavity. The work sets the path for the resilient supply of widespread sterile testing equipment as a rapid response to the current and future pandemics.

On‐Site, On‐Demand 3D‐Printed Nasopharyngeal Swabs to Improve the Access of Coronavirus Disease‐19 Testing

“…Based on this swab architecture, we developed two new prototype designs, one with porcupine‐like bristles (BU bristle) and the other with a smooth, honeycomb‐like structure (BU honeycomb) on the swab head for increased surface area and sites for viral deposition (Figure 1a ). Compared to the designs shown in van der Elst et al., [ 29 ] the BU honeycomb has circular cut‐outs on the swab head as opposed to hexagon‐shaped windows. We designed the swab head to ensure a high surface area for sample collection, similar to the nylon fiber flock on commercial swabs.…”

“…[ 13 , 14 , 15 , 16 , 17 , 18 ] Several institutions, including Boston University, initiated internal research and 3D fabrication programs to print nasopharyngeal swabs and to evaluate performance with clinical samples. [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ] In this study, we describe two new 3D‐printed nasopharyngeal swab designs fabricated using a biocompatible and sterilizable material, and we evaluate their functional performance to collect nasopharyngeal samples during autopsies.…”

Establishing a point-of-care additive manufacturing workflow for clinical use

“…Finally, nasopharyngeal swabs used for analytical testing remain important not only to monitor the progression of COVID-19 throughout the world, but also to determine when restrictions on daily living may be alleviated. 3-D-printed nasal swabs not only were able to help ease the burden and lack of supply, but outperformed conventional swabs with regard to sample retention while improving patient comfort [ 136 ]. Similarly, another study noted improved comfort with the 3-D-printed nasal swabs, engineering each swab to shrink while under axial tension, and thus better navigate through the nares [ 137 ].…”

CFD based analysis of 3D printed nasopharyngeal swabs for COVID-19 diagnostics

“…3D printing of NP swabs can be thought of as a local rapid short-term response to resolve the swab shortage crisis and meet supply chain needs. The key advantages of design and 3D printing of NP swabs are: (a) simplicity (if the multistep process of applying flock is avoided), (b) the widespread availability and use of 3D printing capacity in biomedical devices and biocompatible material applications, and (c) ability to rapidly iterate prototypes [ 8 , 9 ]. Once the NP swab has been produced using 3D printing technology, it still needs to go through a rigorous clinical trial process to demonstrate its efficacy.…”

“…Once the NP swab has been produced using 3D printing technology, it still needs to go through a rigorous clinical trial process to demonstrate its efficacy. Some of the preliminary results of 3D printed NP swabs are quite discouraging, which suggests that conventional swabs outperform the 3D printed swabs [ 8 , 9 ]. The current limitations of the 3D printed NP swabs include inferior quality of the collected samples, inadequate clinical specimens, inappropriate materials (e.g., too sticky or brittle), inappropriate designs (e.g., sharp heads), patient discomfort particularly among kids, and limited mechanical stability, to name a few [ 4 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ].…”