Specific detection of tartaric acid chiral isomers based on centrosymmetric terahertz metamaterial sensors

Abstract

Tartaric acid (C4H6O6) 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.

Keywords

• Metamaterial sensors
• Terahertz spectroscopy
• Tartaric acid chiral isomers
• Specific detection