Terahertz Impedance Spectroscopy of Biological Nanoparticles by a Resonant Metamaterial Chip for Breathalyzer-Based COVID-19 Prompt Tests

We propose a tested, sensitive, and prompt COVID-19 breath screening method that takes less than 1 min. The method is nonbiological and is based on the detection of a shift in the resonance frequency of a nanoengineered inductor-capacitor (LC) resonant metamaterial chip, caused by viruses and mainly related exhaled particles, when performing terahertz spectroscopy. The chip consists of thousands of microantennas arranged in an array and enclosed in a plastic breathalyzer-like disposable capsule kit. After an appreciable agreement between numerical simulations (COMSOL and CST) and experimental results was reached using our metamaterial design, low-scale clinical trials were conducted with asymptomatic and symptomatic coronavirus patients and healthy individuals. It is shown that coronavirus-positive individuals are effectively screened upon observation of a shift in the transmission resonance frequency of about 1.5-9 GHz, which is diagnostically different from the resonance shift of healthy individuals who display a 0-1.5 GHz shift. The initial results of screening coronavirus patients yielded 88% agreement with the real-time quantitative polymerase chain reaction (RT-qPCR) results (performed concurrently with the breath test) with an outcome of a positive predicted value of 87% and a negative predicted value of 88%.