Biomedical sensing with free-standing complementary supercell terahertz metasurfaces

We present a free-standing terahertz metasurface supercell that consists of four complementary mirrored asymmetric split-rectangular resonators. The quality factor of the excited resonance of this supercell has been significantly improved by 250% when compared to its counterpart nonmirrored supercell. The mirroring of the resonators leads to an enhanced out-of-phase oscillating current in each neighboring resonators of the supercell. In turn, this leads to a suppression of the dipole moments and its corresponding scattered fields. Moreover, this design can be realized by utilizing a simple laser machining technique. Furthermore, we numerically evaluate the performance of this design as a label-free biosensor for thin-film analytes and biomolecules such as double-stranded DNA and single-stranded RNA viruses. A sensitivity level of 1.14 × 10⁵ nm/refractive index unit (RIU) can be achieved using this design. Therefore, this design has the potential to be used as an effective label-free biomedical sensor for in-situ detection of various biomolecules.