THz detection of virus samples. (a) Absorption spectra for pallet types of virus included a protein sample (H9N2) and a control sample without virus in it. (b) A conceptual schematic of THz detection of virus samples in liquid state using a nano slot-antenna array based sensing chip. (c) Optical images of dropped virus solutions onto the multi-resonance nano-antenna array before (top) and after (down) THz excitation. (d) Transmittance spectra through multi-resonance nano-antenna that have three resonance peaks, with and without H9N2 sample onto the antenna. (e) The difference in transmitted intensity (ΔT) and shifted resonance frequency from each fundamental resonance peak of multi-resonance nano-antenna (Δf) for H9N2 sample are represented.