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

Abstract

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%.

Sensitivity Enhancement of THz Metamaterial by Decoupling its Resonance from the Substrate's Fabry–Pérot Oscillations

“…In order to discover and understand the relationship between FP oscillations and MM resonance, we are using a cross‐arrowhead polarization, independent, LC resonant MM structure, [ 34 ] as shown in Figure a, with some nanoparticles in the capacitor gap depicting the dielectric. We simulated the THz transmission spectra [ 34 ] shown in Figure 1b using a numerical simulation tool from the CST Studio Suite.…”

“…In order to discover and understand the relationship between FP oscillations and MM resonance, we are using a cross‐arrowhead polarization, independent, LC resonant MM structure, [ 34 ] as shown in Figure a, with some nanoparticles in the capacitor gap depicting the dielectric. We simulated the THz transmission spectra [ 34 ] shown in Figure 1b using a numerical simulation tool from the CST Studio Suite. The dashed black line in Figure 1b represents the transmission parameters of the bare Si substrate without any MM structure fabricated on its surface, and shows the FP oscillations varying between 0 and −5.4 dB.…”

“…[28,32] In our previous work using 725 μm thick chips made from 8 in. Si wafers, [33,34] we enhanced the dielectric sensitivity in a completely different way. We increased the probability of nanoparticles falling within the capacitive gap by introducing a new LC resonant metastructure with capacitor gaps on the diagonals of a square SRR.…”

Ultra-wideband terahertz fingerprint enhancement sensing and inversion model supported by single-pixel reconfigurable graphene metasurface

“…Fortunately, the proposed optical metasurfaces in recent years provide the possibility to overcome this obstacle, which can confine the incident light in their resonant cavities and form a strong local near-field, thus greatly promoting the light-matter interaction [11][12][13][14][15][16]. Some reported metasurface-based THz sensing methods can obtain the refractive index frequency shift or absorption amplitude change caused by the analyte through the resonance detection peak, so as to realize the detection of samples such as cells [17][18][19], proteins [20][21][22][23], DNA [24,25] and viruses [26]. However, the material and structure of previous metallic or dielectric metasurfaces are difficult to adjust after fabrication.…”

Hydrogenated Boron Phosphide THz-Metamaterial-Based Biosensor for Diagnosing COVID-19: A DFT Coupled FEM Study

“…A published study has clearly shown that asymptomatic infections exhibit a high percentage in the tested individuals, which means a potential risk of transmission of asymptomatic infections in the community [2]. In addition, asymptomatic patients as a major source of COVID-19 transmission have been a mainstream point [3]. Therefore, there is an urgent need for rapid, accurate, large-scale, and cost-effective detection methods or techniques for COVID- 19.…”