Identifying phenotypes of colorectal malignant tumors using the quasi-bound state in the continuum of a terahertz metasurface biosensor.

A rapid and non-invasive method to identify phenotypes of colorectal malignant tumors is of vital importance for oncological surgery and further development of corresponding anti-tumor drugs. Herein, we demonstrate an approach to detect colorectal adenocarcinoma and colorectal cancer using the quasi-bound state in the continuum (q-BIC) resonance of a metasurface-based terahertz biosensor. We found that the colorectal adenocarcinoma leads to a 40 GHz q-BIC resonance shift compared to healthy colorectal cells. In addition, we found that colorectal cancer results in a q-BIC resonance red-shift of about 60 to 80 GHz. Both colorectal adenocarcinoma and cancer increase the linewidth of q-BIC resonance compared to healthy colorectal cells. The electric permittivity change confirms the aforementioned frequency shift, which is attributed to the water content of different colorectal malignant tumor cells. Our results highlight that the q-BIC resonance of a terahertz photonic biosensor offers a rapid and non-invasive methodology for identifying different colorectal malignant tumors, which accelerates oncological diagnosis.