Design of a Dual-Band Metasurface Cross-Polarization Converter for Cancer Detection in the Terahertz Band

We present the design of a metasurface-based, cross-polarization converter as a sensor for label-free detection of cancerous cells in the terahertz (THz) band. The device is designed to work on the principle of refractive index (RI) sensing wherein the frequency shift of the maximum polarization conversion peak in the presence of the target analyte is measured. This shift is proportional to the RI difference between healthy and cancerous cells thereby enabling classification with high sensitivity. Our metasurface is designed to support two resonances which significantly reduces the measurement errors, thereby increasing the detection accuracy. We report sensitivities of 155 and 350 GHz/RIU at the first and second resonant frequencies, respectively. The proposed structure is simulated using a finite element method (FEM) and validated with an equivalent circuit model.