Highly sensitive detection of glycerol proportion using asymmetric terahertz metamaterial

Metamaterials are artificial materials with unique electromagnetic properties not found in nature and could exhibit a strong electromagnetic resonance with frequency. These characteristics depending on the geometry, dimensions, compositions of the structure, and even the symmetry. In this study, we demonstrated a highly sensitive detection method of glycerol-water solutions using terahertz metamaterials fabricated on silicon substrate with metal arrays of the asymmetric double split-ring resonator structure. We measured the transmitted spectra of the metamaterial to detect the water-glycerol solutions at different concentrations by the terahertz time-domain spectroscopy system. With the increasing of glycerol concentration, resonant dips of metamaterial exhibit the blue-shift phenomena and transmittance at the resonance frequency simultaneously enhance. The movement of resonant dips and the change of transmittance shows that these resonators are sensitive to the variation of glycerol concentration. The finite-difference time-domain simulation agree well with the experimental data, and the simulation of surface current and electric field distribution at resonance dips can further understand the resonance modes in transmission spectra. Our study provides new prospect into the application of terahertz metamaterials in detecting glycerol proportions of solution.