Revolutionary Device Detects Airborne SARS-CoV-2 in Minutes, Paving the Way for Rapid COVID-19 Surveillance
Scientists at Washington University in St. Louis have developed a compact device, slightly larger than a toaster, capable of quickly detecting airborne SARS-CoV-2, the virus responsible for COVID-19. The researchers achieved a remarkable sensitivity level by detecting as few as seven to 35 viral particles per liter of air in just five minutes, comparable to PCR nasal swab tests. The team, led by aerosol scientist Rajan Chakrabarty, spent three years working tirelessly to create this innovative detector.
The main challenge in sampling airborne viruses lies in collecting a sufficient amount of air to concentrate viral particles for detectable levels. Previous attempts typically involved sampling between 2 and 8 liters of air per minute. However, the new detector developed by Chakrabarty’s team can pull in an impressive 1,000 liters of air per minute.
To capture the virus effectively, the researchers implemented an artificial cyclone mechanism inside the sampler. By swirling liquid at high speed, the viruses become trapped in the cyclone’s wall and are subsequently concentrated for analysis. Any remaining viruses not captured in the liquid are filtered out of the air using a HEPA filter attached to the device. After a five-minute collection period, the liquid is pumped to a biosensor for further analysis.
The biosensor consists of an electrode attached to a llama nanobody, a specialized protein derived from llamas that functions similarly to antibodies, but with smaller size and potentially greater resilience. The nanobody binds to the coronavirus spike protein, and when electricity passes through the nanobody-spike protein interaction, tyrosine amino acids in the spike protein oxidize, resulting in an electron loss. Another component attached to the electrode detects this oxidation as a voltage change, indicating the presence of SARS-CoV-2 in the air.
The biosensor technology is based on a detector developed by Chakrabarty’s colleagues, Carla Yuede and John Cirrito, for amyloid-beta protein fragments associated with Alzheimer’s disease plaques.
In tests conducted by the researchers, the device successfully detected trace amounts of the virus shed by two individuals with COVID-19 infections in their respective apartments. Conversely, air collected from an empty, well-ventilated conference room showed no signs of the virus.
Aerosol scientist Linsey Marr from Virginia Tech, who specializes in virus spread, praises the device’s capability to detect the virus at low levels, expressing confidence in its effectiveness. Although some challenges remain, such as the device’s noise level, similar to that of a vacuum cleaner or ringing phone, Marr suggests it could be tolerable if operated for shorter durations, like 10 minutes.
The cost of building these detectors in research labs ranges from $1,400 to $1,900. While commercial versions may initially be too expensive for home use, they could find utility in hospitals, airports, and other public areas for virus surveillance. Furthermore, integrating the devices into HVAC systems could enable increased ventilation and filtration if the virus is detected, according to suggestions by Marr and Chakrabarty.
Chakrabarty envisions expanding the device’s capabilities to detect other respiratory viruses, such as influenza or respiratory syncytial virus, by incorporating additional llama nanobodies in the future.