# Engineering, feasibility, and safety of force-controlled oropharyngeal swabs with a 3D-printed feedback system FCCSS (force controlled COVID-19 swab study) – a preliminary study

## TL;DR

This study introduces a 3D-printed device to ensure proper force is applied during oropharyngeal swab collection to improve diagnostic accuracy for viral infections like SARS-CoV-2.

## Contribution

The novel contribution is a force-controlled swab system with haptic, acoustic, and visual feedback to optimize sample collection.

## Key findings

- Swabs generally fail at a maximum force of 5 N.
- The developed device can apply and indicate force with a mean accuracy of 0.05 N.
- An average force of 2.4±1.0 N was observed in 20 volunteers.

## Abstract

Errors in laboratory diagnostics of viral infections primarily occur during the preanalytical phase, which is especially observed in sample collection. Hitherto, no efforts have been made to optimize oropharyngeal smears. An accurate method to analyze the necessary conditions for a valid oropharyngeal smear test is required, especially to avoid false negative results, which can lead to promotion of the spread of viruses such as SARS-CoV-2.

In this study, a maximum-force failure analysis was performed on a swab, and the highest tolerable force was then measured on 20 healthy volunteers to obtain the dimensions of the possible force to be applied on a swab. Subsequently, a device which can validate and reproducibly indicate this force during swab collection was developed.

The study demonstrated that swabs generally fail at a maximum force of 5 N. Furthermore, an average force of 2.4±1.0 N was observed for the 20 volunteers. Lastly, this study described the development of a device which presents the selected force with a mean accuracy of 0.05 N (Force applied by Device 1: 0.46±0.05 N, Device 2: 1.55±0.11 N, Device 3: 2.57±0.18 N) and provides feedback via haptic and acoustic clicks as well as with a visual indicator. In the future, the swab will be analyzed for the presence of viral pathogens to determine its diagnostic performance corresponding to the force (German Clinical Trials Register Number 00024455).