Few people who have taken a nasopharyngeal swab to test for coronavirus could describe taking this test as a pleasant experience. The procedure involves pushing a long swab into the nose to take a sample from the back of the nose and throat, which is then analyzed for SARS-CoV-2 RNA using reverse transcription-polymerase chain reaction (RT-PCR). The researchers reported in an article for ACS Nano that they have developed a prototype device that non-invasively detects COVID-19 in the exhaled air of infected patients.
The current gold standard for COVID-19 testing is not only inconvenient but also requires PCR – a laborious laboratory procedure. Due to delays, it may take several days to get the result. To reduce transmission and mortality rates, health systems need tests that are fast, inexpensive, and easy to use. Hossam Haick, Hu Liu, Yueyin Pan, and colleagues wanted to develop a nanomaterial-based sensor that could detect COVID-19 in a manner similar to a breathalyzer so that a person only had to exhale. Previous research has shown that viruses and cells infected with them release volatile organic compounds (VOCs) that can be exhaled.
The researchers created an array of gold nanoparticles bound to molecules sensitive to various VOCs. When VOCs interact with nanoparticle molecules, the electrical resistance changes. Researchers trained the sensor to detect COVID-19 using machine learning to compare the breathing patterns of 49 confirmed COVID-19 patients with 58 healthy controls and 33 non-COVID-19 lung infections in Wuhan, China.
Each study participant blew into the device for 2-3 seconds from a distance of 1-2 cm. Once machine learning identified a potential COVID-19 signature, the team tested the device’s accuracy on a subset of participants. In the test set, the device showed 76% accuracy in distinguishing COVID-19 cases from controls and 95% accuracy in distinguishing COVID-19 cases from lung infections. The sensor can also distinguish with an accuracy of 88% of sick and recovered patients with COVID-19. However, the test needs to be tested on more patients, the scientists conclude.