Terahertz Nanophotonic Hybrid-Metal Biosensor for Ultrasensitive, Noninvasive Cancer Detection Via Exosome Biomarkers

Abstract Early and accurate detection of cancer remains a global medical challenge, as conventional diagnostic tools such as magnetic resonance imaging (MRI), computed tomography (CT), and histopathology often suffer from limited sensitivity and specificity. Recent studies have identified extracellular vesicles (EVs), particularly exosomes, as reliable biomarkers for early cancer diagnosis due to their critical role in tumor progression. In this study, we present an ultrasensitive nanophotonic terahertz biosensor designed for the noninvasive detection of cancer-related exosomes. The proposed device integrates heterogeneous metal resonators composed of nickel (Ni) and silver (Ag), separated by a silicon dioxide (SiO 2 ) dielectric layer, forming a compact three-layer architecture with overall dimensions of 100 × 100 nm 2 and a thickness of 20 nm. Full-wave electromagnetic simulations were performed to analyze its optical response, including absorption spectra, electric and magnetic field distributions, and surface current behavior. The biosensor achieves perfect absorption exceeding 99% across the 0–30 THz range, exhibiting remarkable angular stability and polarization insensitivity. Comparative analysis demonstrates that the proposed structure outperforms existing terahertz biosensors in terms of bandwidth and absorption uniformity. Furthermore, the sensor effectively differentiates between normal and cancerous exosomes by detecting variations in dielectric properties associated with differences in protein composition and morphology. These results confirm the biosensor’s potential as a compact, label-free, and highly efficient platform for terahertz-based noninvasive early cancer diagnostics.