Measured transmission spectra via single-resonance nano-antenna sensing chip with a fundamental resonance frequency at 1.4 THz with and without three AI virus samples are shown in Fig. 2a. Each virus sample shows a distinct transmission change and a shift in the resonance frequency related to their different surfaces and inherent strains. Further analysis and comparison of THz optical characteristics for different subtype viruses were investigated through numerical simulations using the Finite-difference time-domain (FDTD) method (Fig. 2b) (details in Supplementary Information). In FDTD simulations calculating transmission spectra, virus samples are considered as 5 μm-thick, homogeneous dielectric clads possessing different complex refractive indices as illustrated in inset (see the methods). In Fig. 2, experimental results on transmittance characteristics of various samples are compared with numerical FDTD results showing a good agreement. The transmission value change is affected by the molecular absorption accompanying with the change of the imaginary part of the refractive index, κ of each sample. Also, the change of the real part of the refractive index, n is related to the composition of the virus samples. The spectral changes in transmission, therefore, can be confident evidences to define and identify the virus samples, as well presented in both experiments and simulations.