Gastrointestinal cancer diagnostics by terahertz time domain spectroscopy

Abstract Samples of fresh excised tissues obtained from patients who had undergone gastric cancer have been investigated. Samples consisted of cancer zone, normal zone and pathologically changed zone. Their optical properties and spectral features were investigated by terahertz time-domain spectroscopy (THz-TDS) in reflection mode. It was found that waveforms of reflected signals from normal and cancer tissues and their optical properties were well distinguished, so it can be concluded that it is possible to discriminate gastric cancer tissue from normal by using THz-TDS

Towards non-invasive reflection measurement of water content in biotissue by means of terahertz timedomain spectroscopy

Abstract We apply terahertz time-domain spectroscopy for the quantitative non-invasive assessment of water content in biological samples: tree leafs and pork muscles. The Landau-Looyenga-Lifshitz-based model is used for the calculation of water concentration within the samples. The obtained results show that water content in biological samples can be measured utilizing terahertz waves in transmission and reflection modes

Investigation of water-free biotissue-mimicking phantoms in terahertz frequency range

Abstract PVC-based water-free phantoms with silicon and zinc oxide nanoparticles were fabricated for mimicking biotissues in the terahertz frequency range. Terahertz time-domain spectroscopy (TDS) was used to obtain the refractive indices and absorption coefficients of the phantoms. Their optical properties were compared with those of real biotissues from published data. The results show that the phantoms are able to mimic human skin, paraffin-embedded glioma and paraffin-embedded healthy brain tissue by their optical properties. The refractive index of the phantoms can be controlled by changing the concentration of the nanoparticles

Multi-layered graphene based optically tunable terahertz absorber

Abstract We present a broadband tunable terahertz (THz) absorber, which consists of cross-shaped multi-layered graphene (MLG) resonators. The proposed absorber possesses almost perfect absorption over the range 0.4—0.8 THz and can be easily fabricated. Dynamical tuning of absorption band is achieved by external optical pumping of modest intensity. This multi-layered graphene-based absorber has high potential for various THz applications

Investigation of terahertz radiation influence on rat glial cells

Abstract We studied an influence of continuous terahertz (THz) radiation (0.12–0.18 THz, average power density of 3.2 mW/cm²) on a rat glial cell line. A dose-dependent cytotoxic effect of THz radiation is demonstrated. After 1 minute of THz radiation exposure a relative number of apoptotic cells increased in 1.5 times, after 3 minutes it doubled. This result confirms the concept of biological hazard of intense THz radiation. Diagnostic applications of THz radiation can be restricted by the radiation power density and exposure time

Optical activity of graphene-based chiral metasurface in THz frequency range

Abstract In this paper the optical activity of two types of graphene-based chiral metasurfaces with two different variations of graphene inclusion positions was studied. The gammadion resonators of the unit cell were partly made of graphene. Three resonant frequencies of the metasurfaces in the frequency range of 0.1—0.5 THz were found. It is shown that the value of optical activity expressed in azimuth polarization rotation angle strongly depends on the chemical potential of graphene petals, as well as on the position of graphene inclusions

Graphene-based optically tunable structure for terahertz polarization control

Abstract We present a theoretical model of optically tunable graphene-based structure for polarization characteristics control of transmitted terahertz (THz) wave. The experimental verification was performed using a THz time-domain polarimetry setup. The tunability is achieved by applying an external optical pumping and magnetic field. The structure shows the possibility for dynamical control of ellipticity and azimuth angles of polarization state of THz radiation in a transmission mode. This study indicates a strong potential for using graphene-based structures for polarization sensitive applications such as THz wireless communications and biomedical research

Terahertz time-domain polarimetry of carbon nanomaterials

Abstract Terahertz time-domain spectroscopic polarimetry (THz-TDSP) method was used to study of polarization properties of a few-layer graphene (FLG) and a randomly oriented single-walled carbon nanotube (SWCNT) thin film on silicon (Si) substrates in terahertz (THz) frequency range under an external optical pumping (OP) and an external static magnetic field (MF). Frequency dependencies of azimuth and ellipticity angles of a polarization ellipse of the samples were obtained experimentally. The results confirm the fact that, based on carbon nanomaterials, it is possible to devise tunable THz polarization modulators for use in the latest security and telecommunication systems

Terahertz-to-infrared converters for imaging the human skin cancer:challenges and feasibility

Abstract Purpose: Terahertz (THz) medical imaging is a promising noninvasive technique for monitoring the skin’s conditions, early detection of the human skin cancer, and recovery from burns and wounds. It can be applied for visualization of the healing process directly through clinical dressings and restorative ointments, minimizing the frequency of dressing changes. The THz imaging technique is cost effective, as compared to the magnetic resonance method. Our aim was to develop an approach capable of providing better image resolution than the commercially available THz imaging cameras. Approach: The terahertz-to-infrared (THz-to-IR) converters can visualize the human skin cancer by converting the latter’s specific contrast patterns recognizable in THz radiation range into IR patterns, detectable by a standard IR imaging camera. At the core of suggested THz-to-IR converters are flat matrices transparent both in the THz range to be visualized and in the operating range of the IR camera, these matrices contain embedded metal nanoparticles (NPs), which, when irradiated with THz rays, convert the energy of THz photons into heat and become nanosources of IR radiation detectable by an IR camera. Results: The ways of creating the simplest converter, as well as a more complex converter with wider capabilities, are considered. The first converter is a gelatin matrix with gold 8.5-nm diameter NPs, and the second is a polystyrene matrix with 2-nm diameter NPs from copper–nickel MONEL® alloy 404. Conclusions: An approach with a THz-to-IR converter equipped with an IR camera is promising in that it could provide a better image of oncological pathology than the commercially available THz imaging cameras do