Schematic diagram of the COVID-19 biosensor operation procedure. Source: Giwan Seo et al.

Testing for the diagnosis of COVID-19 currently relies on reverse transcription polymerase chain reaction (RT-PCR), a technology that requires at least three hours to return results. A faster diagnostic technique recently devised by researchers in South Korea relies on a field-effect transistor-based biosensor that generates results in less than a minute.

The graphene-based sensor detects SARS-CoV-2, the virus causing COVID-19, from nasopharyngeal swabs. Graphene sheets embedded in the transistor are coated with antibodies against the SARS-CoV-2 spike protein to the graphene. Addition of purified spike protein or cultured SARS-CoV-2 virus to the sensor bind to the antibody and alter the electrical current, signaling the presence of the target virus.

The method, which requires no sample preparation, was tested with nasopharyngeal swabs collected from patients with COVID-19 or healthy controls and was shown to distinguish between samples from sick and healthy patients. The sensor platform quickly and effectively detected SARS-CoV-2 in clinical samples at a concentration of 242 copies per ml and greater.

While two to four times less sensitive than the RT-PCR gold standard, different materials could be explored to improve the signal-to-noise ratio. Researchers from Korea Basic Science Institute, Korea Research Institute of Chemical Technology and Jeonbuk National University Medical School contributed to this development, which is reported in ACS Nano.