High Sensitivity Metamaterial Sensor Based on Electromagnetically Induced Transparency Effect for the Detection of Chlortetracycline Hydrochloride

ABSTRACT In this paper, we propose a high‐sensitivity metallic EIT‐like terahertz metamaterial sensor for antibiotic detection, featuring a split‐ring resonator coupled with a rectangular resonator. Numerical refractive‐index simulations yield a sensitivity of 259 GHz/RIU. Based on the simulated EIT transparency peak, the corresponding quality factor ( Q ) is 7.6 and the figure of merit (FOM) is approximately 2.57. Its transparency window is strategically centered near 0.76 THz, corresponding to a reported characteristic absorption frequency of chlortetracycline, to enhance the interaction between the target analyte and the EIT‐like resonance. Through systematic fabrication and characterization, we employed laser direct writing technology to manufacture the EIT‐like terahertz sensor and evaluated its performance using terahertz frequency‐domain spectroscopy. For quantitative chlortetracycline hydrochloride detection, we prepared concentration gradients in both aqueous and milk matrices. Within the tested concentration range, experimentally distinguishable spectral responses were observed down to 0.1 mg/L in aqueous solution and 1 mg/L in the milk matrix. Detailed analysis of the transmission spectra revealed distinct concentration‐dependent spectral responses in both media, advancing the application of metamaterial sensors in biochemical detection and food safety monitoring. The observed concentration‐dependent spectral responses in aqueous and milk matrices demonstrate the potential of the proposed platform for rapid antibiotic sensing in food‐related environments. These findings significantly contribute to the development of practical metamaterial‐based sensing platforms for food safety applications.