In this paper, a wideband terahertz (THz) metasurface is proposed for sensing of cancerous cells. The sensing device is based on the mechanism of reflective cross-polarization conversion. The polarization converter comprises of a modified Jerusalem cross-shaped resonator. The lengths of the diagonal metallic strips of the resonator are chosen unequally to achieve the anisotropic property. The proposed metasurface achieved a wide operating bandwidth with high polarization conversion ratio (PCR) of \(\ge \) 96% from 1.85 to 5.31 THz. The sensitivity of the converter to dielectric changes allows it to detect cancerous cells, and its wideband operation enhances the detection across multiple frequencies. By this way, a highly sensitive metasurface is designed that has the highest sensitivity of 5 THz/RIU compared to the existing polarization conversion-based sensors. The highest sensitivity was achieved for MCF-7 cancer cell for the refractive index change from 1.387 to 1.401. The sensitivity and figure of merit (FOM) for MCF-7, basal, PC12, Jurkat, MDA-MB231, and HeLa cancer cells are extracted from the spectral characteristics of the polarization converter. The polarization converter maintains the sensing characteristics over the entire operating frequency band owing to the anisotropic design of the modified Jerusalem cross-shaped resonator that provides stable performance. This allows the converter to consistently detect variations in dielectric properties across the entire range and exhibits accurate biosensing over a broad spectrum. The proposed biosensor finds applications in clinical applications where high sensitivity, stable response, and miniaturized device area are important.
