Fig. 1. Schematic diagram of the three-dimensional structure for a double-F multifrequency resonant metamaterial sensor

Fig. 2. Schematic diagram of a unit structure for a double-F multifrequency resonant metamaterial sensor

Fig. 3. Schematic diagram of the steps to prepare a double-F multifrequency resonant metamaterial sensor

Fig. 4. Microscopic photograph of double-F multifrequency resonant metamaterial sensor

Fig. 5. Simulation and experimental transmission spectra of a double-F multifrequency resonant metamaterial sensor

Fig. 6. Electric field distribution and surface current distribution of a double-F multifrequency resonant metamaterial sensor. Electric field distribution at (a) 0.267 THz, (b) 0.364 THz, and (c) 0.649 THz; surface current distribution at (d) 0.267 THz, (e) 0.364 THz, and (f) 0.649 THz

Fig. 7. Transmissivity curves for different analyte thicknesses and their fitted curves. (a) Variation curves of transmissivity with the analyte thickness; (b) relationship between analyte thickness and frequency shift and their fitted curves

Fig. 8. Variation in transmissivity with different structural parameters. (a) Opening width; (b) line width

Fig. 9. Effect of refractive index on transmission spectra and fitted curves between resonant frequency and refractive index. (a) Effect of refractive index on transmission spectra; (b) fitted curves between resonant frequency and refractive index

Fig. 10. Schematic diagram for dropwise uric acid solution on a double-F multifrequency resonant metamaterial sensor

Fig. 11. Transmission spectra of a double-F multifrequency resonant metamaterial sensor dropwise with 1.000 g/L uric acid solution

Fig. 12. Transmission spectra of a double-F multifrequency resonant metamaterial sensor dropwise with different mass concentrations of uric acid solution, and amplification illustration of frequency shifts

Fig. 13. Variation in frequency shift of resonant peakswith mass concentration of uric acid