Terahertz toroidal dipole metamaterial sensors for detection of aflatoxin B1

Terahertz metamaterial biosensors have attracted significant attention in the biological field due to their advantages of label-free, real-time and in situ detection. In this paper, a highly sensitive metamaterial sensor with semi-ring mirror symmetry based on toroidal dipole resonance is designed for a new metamaterial biosensor. It is shown that a refractive index sensitivity of 337.5 GHz per refractive index unit can be achieved under an analyte of saturated thickness near a 1.33 THz transmission dip. For biosensor samples where aflatoxin B1 is dropped on the metamaterial surface in our experiment, dip amplitudes of transmission varying from 0.1904 to 0.203 and 0.2093 are observed as aflatoxin B1 concentrations are altered from 0 to 0.001 μg ⋅ml −1 and to 0.01 μg ⋅ml −1 , respectively. Furthermore, when aflatoxin B1 concentrations are 0.1 μg ⋅ml −1 , 1 μg ⋅ml −1 , 10 μg ⋅ml −1 and 100 μg ⋅ml −1 , dip amplitudes of 0.2179, 0.226, 0.2384 and 0.2527 and dip redshifts of 10.1 GHz, 20.1 GHz, 27.7 GHz and 37.6 GHz are respectively observed. These results illustrate high-sensitivity, label-free detection of aflatoxin B1, enriching the applications of sensors in the terahertz domain.