A breathalyzer distinguishes volatile organic compounds in the breath of COVID-positive people in less than 5 minutes. (Credit: Shi Xuan Leong and Yong Xiang Leong, Nanyang Technological University)

Researchers have developed a prototype “breathalyzer” that can sensitively and accurately diagnose COVID-19, even in asymptomatic individuals, in less than 5 minutes. The quick, convenient and accurate breathalyzer test would be suitable for on-site screening of large numbers of people.

The handheld breathalyzer contains a chip with three surface-enhanced Raman scattering (SERS) sensors attached to silver nanocubes. When a person exhales into the device for 10 seconds, compounds in their breath chemically interact with the sensors. Then, the researchers load the breathalyzer into a portable Raman spectrometer that characterizes the bound compounds based on changes to the molecular vibrations of the SERS sensors.

The team found that Raman spectra from COVID-positive and -negative people were different in regions responsive to ketones, alcohols and aldehydes, which they used to develop a statistical model for COVID diagnosis. The method had a 3.8 percent false-negative and 0.1 percent false-positive rate.

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