Making a model for testing nose-swap skills for COVID19 sampling

This guide elaborates on how to manufacture the model for assessing nose swap skills concerning upper respiratory tract (URT) COVID-19 testing. There is a published paper by Todsen et al. describing the validation of the test available here (https://doi.org/10.3390/diagnostics11111987)

Diagnostics 2021, 11(11), 1987; https://doi.org/10.3390/diagnostics11111987

A summary of the process:

• Downloading the models
• Preparing the models for printing on a 3D printer
• Assembling the models

Downloading the models

We cannot make the print-ready files available for licensing reasons, as the Nose Anatomy model does not allow this. Therefore you will get this guide instead.

So now you are about to download the models,

Nose Anatomy, and a

frame with ears to follow the sampling guidelines.

Both are available in STL (Standard Tessellation Language) format.

Nose Anatomy:
The nose anatomy can be obtained from Bone3D, as the FDM NP-Swab-Simulator.

Landing page (use the FDM NP-Swab-Simulator): https://landing.bone3d.com/np-swab-simulator — Direct link and License

Please see the following link for more information Sananès N et al. 3D-printed simulator for nasopharyngeal swab collection for COVID-19. Eur Arch Otorhinolaryngol. 2021;278:2649–2651

Frame with ears:
The frame with ears ensures that the trainees/candidates for assessment can use the earlobe as the target direction when sampling.

The frame can be downloaded from CAMES Engineering GitHub repository.

Direct download https://github.com/CAMES-Engineering/Upper-Respiratory-Tract-Sampling-Simulator/raw/main/Share/resized.stl

Preparing the models for printing on a 3D printer

Before you can print the models available in STL format. The models need to be sliced, which infers a translation from the digital models into the motion and paths of your available 3D printer. The resulting file(s) will be in .gcode. Depending on your setup, these files can be printed on your printer using an SD-card ( e.g., Prusa) or sent directly. This guide will demonstrate how to slice the models using PrusaSlicer. I find the fastest and most straightforward, if you have a Prusa printer, is using PrusaSlicer.

PrusaSlicer and Prusa 3

All models could fit the build plate, but the chance of a bad print increases when placing objects in the periphery of the plate. So I recommend printing the models in 2 sessions.

Figure 1: Printing the frame. Red arrows indicate actions — mouse clicks or attention

Session1: Ear frame, see figure 1

#1->2: Drag and drop STL file onto Slicer software window
#3: Arrange model for printing. Press the button at the arrow, and after that, click on the back of the model so that it arranges itself as in #4

#4: Arrows from top to bottom.
Print settings indicate the layer height. Larger numbers infer faster printing but also more visible layers.
Support: Select “on built plate only”
Infill: smaller numbers infer less fill and more air inside the model. Smaller is faster but also less robust.
Brim: Prints brim; I think it makes the model catch the plate better. So I always add it.

Press: Slice Now

#5: The sliced model is now shown. Press export to save it -> #6.

The gcode file can be placed on an SD card, and the print started

Figure 2: Printing the nose. Red arrows indicate actions — mouse clicks or attention

Session 2: Nose model, see figure 2

1,2: Drag and drop to slice software window
3,4: Arrange model to lay on its lateral side
5: Drag and drop the other part to the software window. Arrange to the lateral side
6: Auto arrange models on plate
7,8: Add support on build plate only. Add brim.
9: Inspect model and export ->10

Assembling the models

When the models are printed, remove the brim and support material. The Nose model parts can be pushed together, and the frame should fit tightly around them.