Sensitive Detection of Aspartame and Vanillin by Combining Terahertz Fingerprinting With a Metamaterial

In this study, a terahertz (THz) metamaterial based on THz fingerprint is proposed for simultaneous measurement of aspartame and vanillin. The metamaterial consists of an array of concentric aluminum rings on a polyimide substrate. A three-dimensional full-wave electromagnetic field simulation is performed using the finite integral method. The metamaterial transmission spectrum contains two dips at 0.39 THz and 0.61 THz. These two frequencies correspond to the characteristic absorption peaks of aspartame and vanillin in the THz band. According to the hybrid induced transparency (HIT) principle, introducing an additive on the metamaterial surface results in the appearance of a narrow transmission peak at the corresponding transmission dip, where the peak intensity increases with the additive thickness. The calculated sensitivity of the proposed metamaterial sensor is 30.76 dB/(ng/mm ² ) for aspartame and 63.91 dB/(ng/mm ² ) for vanillin. Specific detection is realized because the characteristic absorption peaks of different additives appear at different positions in the transmission spectrum. Therefore, the proposed THz metamaterial sensor has high application value in the field of food additive detection.