Highly Sensitive Metamaterial Refractometric Biosensor in the THz Spectrum

Some exceptional features of the THz spectrum, such as the non-ionizing character of radiation, have made it a promising wavelength range for refractometric and biomedical sensing applications. Nevertheless, the low performance of metals in terms of confining light on their flat surfaces is considered a main drawback at THz frequencies. The combination of graphene and metamaterials in the design of biosensors is an effective solution to enhance the sensitivity of the sensor. In this work, we report on a dual-band graphene-based metamaterial refractive index biosensor with a simple structure in the terahertz spectrum. The structure of the proposed biosensor includes four layers of gold, SiO2,graphene, and a thin gold film that is patterned according to a unit cell formed by four metamaterial elements. The absorption of the metamaterial exhibits two large peaks at 6.995 THz and 8.305 THz. By adjusting the chemical potential of graphene in the proposed biosensor, the absorption spectrum can be shifted aiming at optimizing the biosensor performance. The achieved preliminary results may pave the way for the realization of tunable graphene-based biosensors.