Terahertz metamaterial-prism hybrid sensors for the detection of microorganisms

In this study, we developed terahertz (THz) metamaterial devices with attenuated total reflection (ATR) geometries for biosensing applications. This was achieved by transferring the metamaterial patterns fabricated on a polyimide film to a prism-top surface. We characterized the resonance characteristics of metasurfaces for different THz wave polarizations and gap structure orientations in the metamaterials. The metamaterial resonances exhibited a sharp resonance compared to the normal incidence case; the quality factor increased from 3.3 to 6.0. For biosensing applications, we measured the resonant-frequency shift of the hybrid device by depositing yeast cells. The sensitivity in terms of the yeast number density increased 3.4 times compared to that of the Si substrate under normal incidence, which presented a 4.1-fold increase in the figure of merit. The resonance characteristics based on finite-difference time-domain simulations successfully reproduced our experimental results, including the enhanced sensitivity of our hybrid devices.