Fig. 1. 7-methylguanine. (a) Molecular structure; (b) THz characteristic spectra (gray, white, red, and blue represent the C, H, O, and N atoms, respectively)

Fig. 2. Unit structure diagram of resonant ring

Fig. 3. Terahertz resonance ring chip parameters. (a) Schematic diagram of chip testing principle device; (b) microscopic photographs of partial structure of metamaterial chip (200×); (c) terahertz spectrum of this chip

Fig. 4. Spectral tests with different concentrations.(a) Spectra of superstructures covered by different amounts of 7-methylguanine; (b) dependence of resonance peak shifting on the amount of 7-methylguanine

Fig. 5. Spectral tests at different concentrations. (a) Spectra of superstructures covered by different amounts of guanine; (b) dependence of resonance peak shifting on the amount of guanine

Fig. 6. THz spectra of binary mixture. (a) Spectra of the metamaterial chip covered by the binary mixture with different mixing ratios (G∶7-MG); (b) relationship between the total frequency shift of the binary mixture and individual frequency shift from the components in the binary mixture

Fig. 7. Terahertz spectra of the mixture before and after mixing with 7-MG. (a) Spectra of the metamaterial chip covered by the multicomponent mixture before and after the addition of 23.35 μg 7-MG; (b) relationship between the total frequency shift and individual frequency shift in a multicomponent mixture

Table 1. Guanine and 7-MG with different mixing ratios

Table 2. Adenine(A), G, thymine(T) cytosine(C), and 7-MG with different mixing ratios

Table 3. Comparison of 7-MG mass between the experimental and theoretical results and the corresponding relative error