Antigen rapid tests are faster but have higher negatives and false positives. Scientists have also developed compressed air type tests for COVID-19, based on differences in concentrations of volatile organic compounds exhaled by people infected with the coronavirus, but most All require bulky, immovable equipment for analysis.
Xing Yi Ling and colleagues wanted to develop a fast, convenient, and accurate ventilator testing method suitable for on-site screening of large numbers of people.
The researchers designed a portable gas dispersion device that contains a chip with three surface-enhanced Raman scattering sensors (SERS) attached to silver nanotubes.
When a person exhales into the device for 10 seconds, the compounds in their breath interact chemically with the sensors. The researchers then loaded the vapor disperser into a portable Raman spectrometer, which characterized the bound compounds based on changes to the molecular vibrations of the SERS sensor.
The team found that the Raman spectra of COVID-positive and negative individuals were different in the reaction regions for ketones, alcohols and aldehydes, which they used to develop a statistical model for the diagnosis. COVID.
They tested the ventilator on 501 people at hospitals and airports in Singapore, who RT-PCR showed negative (85.2%), positive and symptomatic (8.6%), or positive. positive and asymptomatic (6.2%) for coronavirus.
The method has a 3.8% false-negative and 0.1% false-positive rate, comparable to RT-PCR tests, but it can be completed on-site in less than 5 minutes. Researchers say that respirators could one day be a new tool to reduce the silent spread of COVID-19 in the community.
The authors acknowledge funding from the National Medical Research Council, Singapore, A*STAR Singapore, the Max Planck Institute-Linked Laboratory of Nanyang Technological University and Nanyang Technological University.