Concert venues, international airports and even restaurants are increasingly asking patrons for a recent negative COVID-19 test before entering their premises. Some organizations offer to test people on the spot as they enter.
But current COVID-19 testing options aren't convenient enough for the kind of mass daily screening that some businesses would like to implement. Rapid antigen tests take about 15 minutes and are in short supply. Molecular test results—the gold standard—often take days to become available. Both typically require twirling a swab up the nose—not exactly something people like to do as they head for a cocktail.
This has led many scientists to develop super-rapid testing methods using breath samples. Such devices are less socially awkward and can deliver results in under a minute—fast enough to feasibly screen large crowds as they pass through hubs.
Here, IEEE Spectrum has selected five different approaches to analyzing breath for SARS-CoV-2, the virus that causes COVID-19. Some of these technologies can sense the virus directly. Others pick up indirect indicators, such as volatile organic compounds (VOCs). These molecules are present in healthy breath, but change in ratio when a person is infected with the virus.
The technologies come from companies working in a wide range of applications that pivoted to COVID-19 when the pandemic hit. Steradian Technologies in the United States, for example, was building a product for human supersight, and managed to turn its optics technology into a diagnostic.
No COVID-19 breathalyzer is widely available yet, but we might soon see them popping up in select settings globally. In May, Singapore provisionally approved a breath-based device from Breathonix and may use it to test travelers at a Singapore-Malaysia checkpoint, according to the company. A device from similarly named Breathomix, in the Netherlands, was recently used by a port company in Rotterdam to check about 3,500 employees daily.
After more clinical validation, COVID-19 breath-based tests might finally give the world a more convenient and comfortable testing option.
Steradian Technologies, Houston
Time to results: 30 seconds
The user blows into a tube, and if the virus is present, its protein receptors will bind with a chemically reactive biosensor. The binding causes the biosensor to emit light in the form of photons. Mirrors inside the handheld device concentrate the light emissions to a single focal point, amplifying the signal and allowing a measurement to be made. Light emissions indicate a positive sample.
About the size of: A glue gun
Good for: Screening people before entering a business, concert, or school
Breathomix, Leiden, Netherlands
Time to results: <1 minute
A cylindrical electronic nose containing seven different biosensors detects exhaled VOCs in breath. The sensors, made of metal oxide semiconductors, react with compounds in the breath. The reactions cause measurable changes in the flow of electrons and indicate the presence of certain compounds. Pattern-recognition algorithms then compare the readings from the sample to those of healthy and infected sample profiles in its database. The device either delivers a negative result, or it recommends further testing. It does not, by itself, definitively provide a positive COVID-19 diagnosis.
About the size of: A 500-milliliter water bottleGood for: Screening students in school or employees at large companies
BreFence Go COVID-19 Breath Test System
Time to results: <1 minute
In this "time-of-flight" mass spectrometry approach, VOCs in a breath sample are fragmented, given an electric charge and subjected to magnetic fields. This causes the fragments to take different trajectories depending on their mass-to-charge ratios. A detector records their abundance in a mass spectrum based on these ratios and the time it takes for the molecules to travel a known distance through the machine. The data helps identify the VOCs present in the sample.
About the size of: A dishwasher
Good for: hospitals, clinical laboratories, and point-of-care settings with trained operators
RAM Group DE, Zweibrücken, Germany
ThEA Terahertz Express Analyzer
Time to results: 2 minutes
A metamaterial nanoantenna deposited on glass creates resonances at specific points in the 1-to-2-terahertz range. These waves uniquely interact with SARS-CoV-2 and its protein structure. When the virus is present in a person's breath or throat-swab sample, it is drawn to the minuscule structures on the antenna. The presence of this viral matter generates disturbances in the resonances while interacting with the terahertz wave, creating a change in the spectrum. Detection of this signal indicates a positive result.
About the size of: A large microwave ovenGood for: Screening people coming through transportation hubs and commercial centers
Gas Chromatography—Ion Mobility Spectrometry
Imspex Diagnostics, Abercynon, Wales
Time to results: 8 minutes
A breath sample moves through a gas-chromatography column, which separates particles based on their size. Molecules then enter an ion-mobility spectrometry chamber where they are ionized, accelerated across the chamber, and hit a Faraday plate. This results in a current that is specific to each molecule and is used to produce a 3D chromatogram that can be analyzed using machine learning algorithms. For COVID screening, the system looks for specific changes in the ratio of VOCs present in breath samples compared with those found in healthy breath.
About the size of: A microwave ovenGood for: Testing travelers at airports, crowds at cultural festivals, staff at large companies
This article appears in the October 2021 print issue as "Five COVID Breathalyzers."