Fig. 1. Schematic diagram of metamaterial structure. (a) Metal structure unit; (b) metal array and detection principle; (c) actual photography; (d) partial structure under optical microscope

Fig. 2. Properties and principles of metamaterials. (a) Simulated and experimental resonant peaks; (b) surface current distribution at resonant frequency; (c) electric field distribution at resonant frequency; (d) magnetic field distribution at resonant frequency; (e) equivalent circuit

Fig. 3. Terahertz spectra of different mass concentrations of Isocarbophos

Fig. 4. Response of metamaterials to Isocarbophos. (a) Frequency shift of resonant peak at different mass concentrations; (b) mass concentration sensitivity coefficient S_n: (Ⅰ) response at low mass concentrations and (Ⅱ) response at high mass concentrations (saturation phenomenon)