Fig. 1. Schematic overview of THz biomedical detection applications. THz biomedical applications mainly focuses on three aspects：THz spectroscopy，THz imaging，and THz biological effects.

Fig. 2. THz spectroscopy detection techniques. （a） Schematic of the transmission mode. （b） THz absorption spectra of L-Tyr，D-Tyr and DL-Tyr samples in solid state. The spectra are offset along the vertical axis for the purpose of easier comparison. （c） Schematic of the reflection mode. （d） THz absorption spectra of tumor and normal regions of a rat brain tissue sample. （e） Schematic of the ATR mode. （f） THz absorption spectra of U87 cells treated with different concentrations of ginsenoside Rg3. Images reproduced with permission from Ref. ^［15］ （b），Ref. ^［41］ （d），and Ref. ^［48］ （f）.

Fig. 3. Conventional THz biomedical imaging techniques. （a） Schematic of ex vivo imaging detection. （b） Optical visual image and corresponding transmission-mode THz images of a mouse skin tissue sample containing melanoma. （c） Optical visual image （i，the tumor region is marked by the dotted line） and corresponding HE stained image （ii） and THz-ATR image of a mouse brain glioma tissue （iii）. （d） Schematic of in vivo imaging detection. （e） Reflection-mode THz images of a human skin scar measured at different times during the recovery period. （f） Reflection-mode THz images of the plantar region of a normal human being （left），and a typical diabetic foot patient （right）. Images reproduced with permission from Ref. ^［31］ （b），Ref. ^［61］ （c），Ref. ^［63］ （e），and Ref. ^［65］ （f）.

Fig. 4. THz near-field biomedical imaging. （a） Schematic of the micron-resolution THz-PCAM system. （b） The optical visual image of a single cell （i），and the THz-PCAM images of the cell during the dehydration process （ii-iv）. （c） Schematic of the nano-resolution THz s-SNOM system. （d） THz near-field images of IgG and ferritin measured by the s-SNOM，which include both atomic force microscopy （AFM） images （left） and THz images （right）. Images reproduced with permission from Ref. ^［70］ （b），and Ref. ^［77］ （d）.

Fig. 5. Effects of THz radiation on biomolecules. （a） Schematic of THz radiation on biomolecules. （b） Circular dichroism spectra of BSA solution before and after THz radiation. （c） After the exposure to THz radiation，the effect of dsDNA length on the fluorescence recovery in the strand exchange experiment，*p < 0.05. Images reproduced with permission from Ref. ^［79］ （b），and Ref. ^［81］ （c）.

Fig. 6. Effects of THz radiation on cells. （a） Schematic of THz radiation on nerve cells. （b） Statistical results for the effects of THz radiation on sperm motility. The experimental groups （E） received THz irradiation，while the control groups （C） did not. The results are presented as median with the standard error of the mean，“N” stands for results from normal patients，“Mi” stands for results from mild asthenospermia patients，and “Mo” stands for results from moderate asthenospermia patients，*p < 0.05. （c） Effects of THz radiation on the apoptosis of primary hippocampal neurons of rats analyzed by flow cytometry. The representative images are presented on the left while the statistical analysisis shown on the right，**p < 0.01. Images reproduced with permission from Ref. ^［89］ （b），and Ref. ^［90］ （c）.

Fig. 7. Effects of THz radiation on tumors in living organisms. （a） Schematic of THz radiation on a mouse. （b） Fluorescence images of neutrophil distribution in the ear skin of a live mouse before and after THz radiation. Red，green，and magenta colors indicate neutrophils，blood vessels，and hair follicles，respectively. （c） Temperature rise curves of the skin （left） and a HE stained image of a skin tissue slice （right） after THz radiation. Images reproduced with permission from Ref. ^［96］ （b），and Ref. ^［97］ （c）.