High-sensitivity biosensing of tryptophan based on a MoS ₂ -modified QBIC terahertz metasurface

-modified metasurfaces demonstrate that the modification significantly improves the limit of detection for tryptophan, achieving fivefold and fourfold enhancements for the QBIC (0.005 nmol/µL) and dipole (0.05 nmol/µL) modes, respectively. This performance gain is attributed to the suppression of the coffee-ring effect and enhanced analyte accumulation at electromagnetic hotspots. The proposed method offers a label-free and cost-effective solution for trace-molecule detection in biomedical and environmental applications.