By Mark Waghorn
A cheap air sensor has been developed that can detect Covid in a room in just five minutes.
It can differentiate between coronavirus, flu or other infections – in about the time it takes to boil a kettle.
The monitor detects their presence at much lower levels and much more quickly than conventional tests.
It opens the door to surveilling indoor environments – including schools and hospitals – in real-time for viruses.
The device is compact at about one foot wide and 10 inches tall. It lights up when a virus is detected – alerting administrators to increase airflow or circulation.
Project member Dr. John Cirrito said: “There’s nothing at the moment that tells us how safe a room is.
“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 five minutes, if there is a live virus.”
The team tested the monitor in the apartments of two Covid-positive patients – comparing PCR results of air samples from the bedrooms with those from a virus-free control room.
The devices identified bits of DNA called RNA of the virus in the air samples from the bedrooms – but not in the others.
In laboratory experiments the biosensor were able to detect varying levels of airborne virus concentrations after only a few minutes of sampling.
Scientists fear pandemics will become more frequent in future years owing to global warming.
The device combines aerosol sampling technology and an ultrasensitive biosensing technique
It could be used in hospitals and health care facilities, schools and public places – and potentially monitor for other respiratory bugs.
The team at Washington University in St. Louis had previously developed a biosensor that detects rogue proteins that cause Alzheimer’s disease.
So they decided to build an instrument that can also measure the toxicity of air.
The researchers exchanged the antibody that recognizes amyloid beta for a nanobody from llamas that recognizes the spike protein from the SARS-CoV-2 virus that causes Covid.
It’s small, easy to reproduce and modify and inexpensive to make, they explained.
Co-author Dr. Carla Yuede said: “The nanobody-based electrochemical approach is faster at detecting the virus because it doesn’t need a reagent or a lot of processing steps.
“SARS-CoV-2 binds to the nanobodies on the surface, and we can induce oxidation of chemicals on the surface of the virus using a technique called square wave voltammetry to get a measurement of the amount of virus in the sample.”
Air enters the device at very high velocities and gets mixed centrifugally with the fluid that lines the walls to create a surface vortex – trapping virus aerosols.
An automated pump collects the fluid and sends it to the biosensor for seamless detection of the virus using electro-chemistry.
Co-author Dr. Rajan Chakrabarty said: “The challenge with airborne aerosol detectors is that the level of virus in the indoor air is so diluted that it even pushes toward the limit of detection of polymerase chain reaction (PCR) and is like finding a needle in a haystack.
“The high virus recovery by the wet cyclone can be attributed to its extremely high flow rate, which allows it to sample a larger volume of air over a five-minute sample collection compared with commercially available samplers.”
The monitor has a flow rate of about 1,000 liters per minute – much higher than commercially available alternatives.
Dr. Cirrito said: “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.
“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.”
Produced in association with SWNS Talker
Edited by Saba Fatima and Asad Ali