Sensing Avian Influenza Viruses Using Terahertz Metamaterial Reflector

We numerically demonstrate a highly sensitive detection of three subtypes of Avian Influenza (AI) viruses, namely, H1N1, H5N2, and H9N2 viruses, using terahertz (THz) biosensing metamaterial (MM) that composed of an H-shaped graphene resonator located on a semiconductor film. Three subtypes of AI viruses with different complex refractive indexes (CRIs) were detected at the THz frequency regime. The optical properties of the viruses in the THz frequency range were first measured, and the real and imaginary parts of their CRI are also plotted to investigate the sensing/detecting applications. We observed the resonance frequency shift of the THz MM following the deposition of the viruses on the surface of the proposed design. As an RI sensing application, we show that, with placing different sensing materials in vicinity of the nano sensor/detector device, the reflected resonance frequency changes, which, in turn, leads to measuring the sensitivity of the nano sensor/detector to detect the AI viruses. We investigate the detection of three subtypes of AI viruses with different protein concentrations and different RI values. We observed the resonance-frequency shift of the THz nano bio-sensor/detector following the RI changing of the detected viruses. The resonance shift is higher for the H9N2 virus, which has a relatively large amount of real part of the RI. Thus, the frequency shift decreases with lower amount of the RI real part. Additionally, we show that the magnitude of the reflection spectrum will be enhanced in larger amount of imaginary parts of the RI. This results from a combination of size-related factors, leading to field enhancement accompanying strong field localization.