Absorption Enhancement Mechanism of Multifrequency Resonant Terahertz Metamaterial Absorber and Detection of Forchlorfenuron

The abuse of high concentrations of forchlorfenuron can lead to malformed fruits and pose risks to human health, highlighting the need for effective detection methods. In this study, a flexible multi-frequency resonant terahertz metamaterial sensor is designed and validated both theoretically and experimentally. The sensor exhibits magnetic dipole resonances at 0.53 THz and 2.30 THz, and the physical enhancement mechanism of the magnetic dipole resonances is analyzed through the distributions of electric field, magnetic field, and surface current. Simulation results reveal that the metamaterial sensor achieves a maximum detection sensitivity of 440 GHz/RIU, with multi-frequency resonance maintained across a polarization angle range of 0°– 90°. Experimental detection reveals that the designed multi-frequency resonant metamaterial sensor successfully detects different concentrations of forchlorfenuron, with a minimum detectable concentration of 0.01 mg/L. These theoretical and experimental results confirm the feasibility of a multi-frequency resonant terahertz metamaterial sensor for forchlorfenuron detection.