Detection of Trace Dibutyl Phthalate Based on Multiresonant Terahertz Metamaterial Sensor

[] During the production process of plastic toys, plasticizers are added in a certain amount to facilitate molding. Phthalate esters (PAEs) are a widely used type of plasticizer in the processing of plastic toys. Long-term or high-concentration exposure to PAEs in the environment can cause endocrine disruption. Traditional methods for measuring PAEs, such as gas chromatography–mass spectrometry and fluorescence detection, have issues like complicated operation and complex sample preparation, so it is urgent to develop a simple, accurate, and fast PAE detection technology. The low photon energy and "fingerprint characteristics" of terahertz (THz) waves make them widely used in material detection. The characteristics of metamaterials that enhance the electromagnetic response of analytes to incident waves promote the application of metamaterial sensors in the THz band for detection. In this work, we used computer simulation technology microwave studio (CST MWS) electromagnetic simulation software to analyze a metamaterial sensor based on aluminum and polyimide and proposed the mechanism of the metamaterial producing multiple resonance peaks. The resonance frequency shifts of ${f}_{{1}}$ and ${f}_{{2}}$ on the surface of electromagnetically induced transparency (EIT) sensors with different dibutyl phthalate (DBP) droplet concentrations were obtained. The sensor was used to detect different concentrations of DBP solutions. The results show that the detection limit of the sensor for DBP is 0.02%, meeting the residual detection standard for DBP content in toys in the United States. The proposed metamaterial sensor has high sensing sensitivity and is expected to be applied to further sensing detection in biomedical and other fields.