Specific detection of tartaric acid chiral isomers based on centrosymmetric terahertz metamaterial sensors
Xujun Xu, Zhenxu Sun, Guocui Liu, Jianjun Liu, Yong Du
Abstract
• A highly sensitive centrosymmetric terahertz metamaterial with EIT-like effects has been designed. • Detailed principle analysis was conducted on centrosymmetric terahertz metamaterials, and theoretical calculations were performed on the slow light effect. • Theoretical simulation of TACIs unit cells was calculated using density functional theory in the quantum chemistry software Gaussian. • Specific recognition was performed on L −, D-tartaric acids, with limits of detection of 0.001 g/ml and 0.002 g/ml, respectively. Tartaric acid (C 4 H 6 O 6 ) is a common food additive with two mutually symmetrical chiral carbons, which is a very important class of four-carbon organic chiral sources. L-, D-, DL-tartaric acids have different uses in food additives and pharmaceutical fields. Traditional detection methods, such as fluorescence detection, have problems such as destructive and non-specific characters. Thus, the development of a simple, accurate, and rapid detection technique for tartaric acid chiral isomers (TACIs) is imminent. In this work, we designed a terahertz metamaterial sensor with central symmetry for detecting TACIs. Centrosymmetric metamaterial sensors based on aluminum and polyimide were simulated using computer simulation technology (CST) electromagnetic software. This metamaterial is composed of a trapezoidal structure with a hole and its rotation of 180 degrees, with three resonance peaks. The sensing properties of terahertz metamaterials and the slow light effect are further discussed. The minimum detection concentrations of D-tartaric acid and L-tartaric acid measured in the experiment were 0.002 g/ml and 0.001 g/ml respectively. In addition, theoretical simulations of the crystalline cells of TACIs were also calculated using the density functional theory. The terahertz absorption peak of the TACIs simulation results was obtained, and the data obtained by comparison with experimental measurements were basically the same. Experimental results indicate that the metamaterial designed in this article can distinguish small differences TACIs.