A sensor has been developed that can diagnose Covid in just 10 seconds. It can differentiate between coronavirus, flu or other infections - in about the time it takes to sneeze. The device detects their presence at much lower levels and much more quickly than conventional tests.
Only a square inch in size, its key component is a tiny nano-material - no thicker than an atom. Symptoms of both flu and Covid overlap considerably - making them difficult to distinguish, said project leader Dr Deji Akinwande. He explained: "When both of these viruses are circulating together as they did earlier this winter, it would be immensely useful to have a sensor that can simultaneously detect whether you have Covid, flu, none of the above or both."
The University of Texas at Austin team say the device could be modified to test for other infections as well. It was constructed using graphene, a single layer of carbon atoms arranged in a hexagonal lattice pattern. Its extreme thinness renders it highly sensitive to any electrical changes in its environment.
The breakthrough opens the door to create sensors for a range of applications. Dr Akinwande said: "These ultra-thin nanomaterials generally hold the record for best sensitivity, even down to the detection of single atoms. They can improve the ability to detect very small quantities of basically anything that needs to be sensed, whether it Is bacteria or viruses, in gas or in blood."
His group has previously designed a graphene-based temporary tattoo that could monitor blood pressure. It consists of pairs of sensors placed along the arteries of the arm. One sends out an electrical current that its partner detects - determining blood flow.
The infection sensor responds to the presence of viral proteins produced by the immune system. The researchers linked antibodies against SARS-CoV-2, the virus that causes Covid, and flu to graphene. When a sample from an infected person is placed on the device they bind to their target proteins, prompting a change in the electrical current.
For satey reasons the researchers tested it using virus proteins delivered in fluid resembling saliva. Results indicated it identified their presence - even at extremely low quantities. The high sensitivity suggested the sensor could be used for detecting the much more sparse viral particles found in breath, said Dr Akinwande.
He added: "It also worked quickly, returning results within about 10 seconds of dropping in a sample."
By comparison, conventional Covid tests can take minutes or hours, depending on the type. A dual Covid and flu test recently authorised by the US Food and Drug Administration takes about half an hour. The researchers are working to improve its performance further, including by expanding the slate of viruses it can detect.
They are developing a sensor designed to test for SARS-CoV-2 variants, such as omicron and delta. While they are currently focusing on a two-variant design, the test could be adapted to simultaneously identify even more. The findings were presented at a meeting of the American Chemical Society in Indianapolis.
