A nanomaterials-based sensor detects flu and COVID-19 much more quickly than conventional tests. (Credit: Dmitry Keeriv)

Scientists have used a single-atom-thick nanomaterial to build a device that can simultaneously detect the presence of the viruses that cause COVID-19 and the flu — at much lower levels and much more quickly than conventional tests for either.

The symptoms of both flu and COVID-19 overlap considerably, making it difficult to distinguish between them. The device could be modified to test for other infections as well.

The group constructed the COVID-19 and flu sensor using graphene, a single layer of carbon atoms arranged in a hexagonal lattice pattern. Its extreme thinness renders graphene highly sensitive to any electrical changes in its environment. The researchers see enormous potential in using it and other, similar nanomaterials to create sensors for many different applications.

To build the infection sensor, the researchers had to make graphene respond to the presence of viral protein. To do so, they looked to the immune system, which produces antibodies that are fine-tuned to recognize and latch onto particular pathogens. The researchers linked antibodies against SARS-CoV-2, the virus that causes COVID-19, and against the flu virus to graphene. When a sample from an infected person is placed on the sensor, these antibodies bind to their target proteins, prompting a change in the electrical current.

The researchers used proteins from these viruses delivered in fluid intended to resemble saliva. Their results indicated that not only could the sensor detect the presence of the proteins, but it could also do so when they were present at extremely low quantities. This sensitivity suggested the sensor could be used for detecting the much sparser viral particles found in breath, Akinwande says.

The sensor also worked quickly, returning results within about 10 seconds of dropping in a sample.