Highly Sensitive Terahertz Electromagnetically Induced Transparency-like Metasurface for Refractive Index Biosensing

In this research, we presented an electromagnetically induced transparency-like (EIT-like) metasurface. The structure is composed of pairs of L-shaped resonators, and by increasing the asymmetry between the coupled resonators, the dark mode has been excited with a transparency peak at 2.84 THz. The transmission spectra based on various asymmetry degree shows the intensifying trend of EIT-like resonance. The distribution of the electromagnetic field and the surface current were also examined to demonstrate the dark mode excitation. The sensing performance of the biosensor was studied based on various refractive index and thicknesses of the sample, and a total theoretical sensitivity of 800 GHZ/RIU based on a narrow line width of 230 GHz was achieved. The results also were compared with similar research works and proved a massive enhancement in sensitivity and Q-factor. The proposed structure can be served as an ultra-sensitive, inexpensive, and label-free biosensor for applications including biological sensing.