Sensitive detection of the concentrations for normal epithelial cells based on Fano resonance metamaterial biosensors in terahertz range

In this paper, we have cultured normal epithelial cells (HaCaT) as analytes to detect the sensitivity of a biosensor based on Fano resonance metamaterials (FRMMs). The frequency shift Delta f of the transmission spectrum was experimentally measured at three different concentrations (0.2 x 10(5), 0.5 x 10(5), and 5 x 10(5) cell/ml) of HaCaT cells. By employing the FRMMs-based biosensor, the detection concentration of HaCaT cells can approximately arrive at 0.2 x 10(5) cell/m1; further, the corresponding Delta f is 25 GHz, which reaches the measurement limit of the THz-TDS system. Additionally, the increase of HaCaT cell concentration causes a different redshift of Delta f from 24-50 GHz, and the maximum of Delta f can reach 50 GHz when the HaCaT cell concentration is at 5 x 10(5) cell/ml. Similarly, the simulated results show that the Delta f depends on the numbers of analytes with a semiball shape and the refractive index of analytes. The theoretical sensitivity was calculated to be 481 GHz/RIU. The proposed FRMMs-based biosensor paves a fascinating platform for biological and biomedical applications and may become a valuable complementary reference for traditional biological research. (C) 2019 Optical Society of America