Fig. 1. Schematic diagram of evanescent wave generated by ATR prism

Fig. 2. (a) Verification model of milk fat, total solid and somatic cells^[29] ; (b) THz spectra of glucose solutions with different concentrations and scatter plot between actual and predicted glucose concentrations^[30]

Fig. 3. (a) Complex dielectric constant of sucrose aqueous solutions with different concentrations ^[31]; (b) Polarizability of bulk water and hydrated water ^[31]; (c) THz spectra of nifedipine crystals and mixtures at different concentrations ^[32]; (d) THz-ATR spectra of nifedipine crystals and nifedipine suspensions with different concentrations ^[32]

Fig. 4. (a) Real and imaginary parts of dielectric coefficients of distilled water, HeLa, DLD-1 and HEK293^[33];(b) Average absorption spectra of ASF and FET ^[34]

Fig. 5. (a) The ATR amplitude |RP| and phase arg (Rp) of human skin at different times (0, 45, 90 min) after ingesting the glucosesolution ^[35]; (b) Relationship between THz- ATR spectral reflectance and theophylline concentration at 0.164 THz^[36]; (c) THz timedomainwaveform, frequency spectra, dielectric constant and dielectric loss of LCIS culture solution, MCF10A cells and referenceATR prism without samples^[37]; (d) The dielectric constant and dielectric loss of MCF10A living cells exposed andunexposed to 10 mmol/L H2O2 after 0, 1, 2 h were compared ^[37]

Fig. 6. (a) Refractive index and absorption coefficient and complex permittivity of artificial normal skin and melanoma samples ^[38] ;(b) THz absorption spectra of two short-chain oligonucleotides and two long-chain oligonucleotides withconcentrations of 5.0 g/ L and 0.5 g/L^[39]

Fig. 7. (a) Time variation of absorption coefficient at 0.4, 1.0, 1.6 THz ^[40]; (b) Complex refractive index and extinction coefficient of SVG P12, HMO6 and U87 cells ^[41]

Fig. 8. (a) THz absorption spectra of colon cancer cell lines DLD-1 and HT-29 in different concentration solutions ^[42];(b) THz- ATR spectra of tyrosine (Tyr) enantiomers (L- and D-Tyr) and racemate (DL-Tyr) in aqueous solution ^[43]

Fig. 9. (a) Comparison of the absorption spectra of the glucose pellet, aqueous glucose (0 mg/dL versus 80 mg/dL) and smart hydrogels before and after reaching swelling equilibrium in aqueous glucose (80 mg/dL) ^[44]; (b) THz absorption coefficient of U87 cells treated with different concentrations of G-Rg3 for 24 hand THz absorption coefficient of U87 cells at a specific frequency ^[45]

Fig. 10. High-power THz-ATR spectra of α-lactose samples with different concentrations^{[46, 47]}. (a) Time-domain spectra; (b) The corresponding frequency-domain spectra; (c) Characteristic absorption spectra; (d) The change rate of absorption peak position with different concentrations of α-lactose solution