Washington University Scientists Develop An Air Monitor That Can Detect Covid-19 Virus

A team of researchers at Washington University in St. Louis has developed a real-time air monitor that can detect any of the SARS-CoV-2 virus variants that are present in a room in about 5 minutes.

The proof-of-concept device was created by researchers from the McKelvey School of Engineering and the School of Medicine at Washington University. The team includes Rajan Chakrabarty, the Harold D. Jolley Career Development Associate Professor of energy, environmental and chemical engineering in McKelvey Engineering; Joseph Puthussery, a postdoctoral research associate in Chakrabarty’s lab; John Cirrito, professor of neurology at the School of Medicine; and Carla Yuede, associate professor of psychiatry at the School of Medicine.

The results are contained in a July 10 publication in Nature Communications that provides details about how the technology works.

The device holds promise as a breakthrough that – when commercially available – could be used in hospitals and health care facilities, schools, congregate living quarters, and other public places to help detect not only the SARS-CoV-2 virus, but other other respiratory virus aerosol such as influenza and respiratory syncytial virus (RSV) as well.

“There is nothing at the moment that tells us how safe a room is,” Cirrito said, in the university’s news release. “If you are in a room with 100 people, you don’t want to find out five days later whether you could be sick or not. The idea with this device is that you can know essentially in real time, or every 5 minutes, if there is a live virus in the air.”

The team combined expertise in biosensing with knowhow in designing instruments that measure the toxicity of air. The resulting device is an air sampler that operates based on what’s called “wet cyclone technology.” Air is sucked into the sampler at very high speeds and is then mixed centrifugally with a fluid containing a nanobody that recognizes the spike protein from the SARS-CoV-2 virus. That fluid, which lines the walls of the sampler, creates a surface vortex that traps the virus aerosols. The wet cyclone sampler has a pump that collects the fluid and sends it to the biosensor for detection of the virus using electrochemistry.

The success of the instrument is linked to the extremely high velocity it generates – the monitor has a flow rate of about 1,000 liters per minute – allowing it to sample a much larger volume of air over a 5-minute collection period than what is possible with currently available commercial samplers. It’s also compact – about one foot wide and 10 inches tall – and lights up when a virus is detected, alerting users to increase airflow or circulation in the room.

To test the monitor, the team placed it in the apartments of two Covid-positive patients. The real-time air samples from the bedrooms were then compared with air samples collected from a virus-free control room. The device detected the RNA of the virus in the air samples from the bedrooms but did not detect any in the control air samples.

In laboratory experiments that aerosolized SARS-CoV-2 into a room-sized chamber, the wet cyclone and biosensor were able to detect varying levels of airborne virus concentrations after only a few minutes of sampling, according to the study.

“We are starting with SARS-CoV-2, but there are plans to also measure influenza, RSV, rhinovirus and other top pathogens that routinely infect people,” Cirrito said. “In a hospital setting, the monitor could be used to measure for staph or strep, which cause all kinds of complications for patients. This could really have a major impact on people’s health.”

The Washington University team is now working to commercialize the air quality monitor.