An Australian research group has investigated a number of terahertz application areas including liquid Tray spectroscopy, bioaffinity sensing, image rendering, tomography, microwire Tray transmission, and detection through plastic layers.

We present a study of how residual hydration in fresh rat tissue samples can vastly alter their extracted terahertz (THz) optical properties and influence their health assessment. Fresh (as opposed to preserved) tissue most closely mimics in vivo conditions, but high water content creates many challenges for tissue handling and THz measurement. Our THz measurements of fresh tissue over time highlight the effect of tissue hydration on tissue texture and dimension, the latter directly influencing the accuracy of calculated optical properties. We then introduce lyophilization (freeze drying) as a viable solution for overcoming hydration and freshness problems. Lyophilization removes large amounts of water while retaining sample freshness. In addition, lyophilized tissue samples are easy to handle and their textures and dimensions do not vary over time, allowing for consistent and stable THz measurements. A comparison of lyophilized and fresh tissue shows for the first time that freeze drying may be one way of overcoming tissue hydration issues while preserving tissue cellular structure. Finally, we compare THz measurements from fresh tissue against necrotic tissue to verify freshness over time. Indeed, THz measurements from fresh and necrotic tissues show marked differences.

A report is presented of a novel study on the use of terahertz (THz) spectroscopy to distinguish between healthy and diseased snapfrozen tissue samples obtained from three regions of the human brain. The diseased tissue samples are neuropathologically diagnosed as containing abnormally high numbers of protein plaques consistent with Alzheimer's disease. As protein structures have been successfully probed elsewhere using THz radiation, it is expected that the collective vibrational modes of protein plaques can be detected in the THz frequency range. Furthermore, measurements of frozen samples assist in removing uncertainties caused by the presence of water in the sample. Results show some distinction in the THz absorption spectra, which could be attributed to pathological changes in the diseased tissue.

We demonstrate that terahertz (THz) spectroscopy can be used to differentiate soft protein microstructures. Differentiation of soft microstructures in gels has to date been performed using optical imaging techniques (e.g. electron microscope), but a non-destructive differentiation tool is lacking. Particulate and fine-stranded (fibrillar) soft protein microstructures are of interest, particularly to medical researchers, because they form from naturally occurring proteins that are thought to be involved in several human diseases, such as Alzheimer's disease. In this study, globular beta-lactoglobulin structures with diameters of 2 microm, and fibrillar structures with diameters less than 0.03 microm are observed between 0.8 and 1.5 THz. Results show that the globular structures have a decline in THz transmission when compared to the fibrillar ones. The cause of this decline is possibly due to Rayleigh scattering from the globular microstructures.

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