An oil and water emulsion phantom for biomedical terahertz spectroscopy

In order to determine the ability of THz spectroscopy to analyse the composition of biological tissue, a phantom containing combinations of water and lipids was developed. Initially, the absorption coefficient and refractive index of five pure commercially available lipids was measured between 0 and 3 THz. A suitable lipid for phantom manufacture was then chosen and a series of oil-water emulsions were made using surfactants. The lipid content ranged from 0% to 100%. THz spectra of the absorption coefficient and refractive index of these emulsions were measured. Using spectral decomposition techniques based on the Beer Lambert law, the percentage of oil and water in the emulsion was determined. The results show good qualitative agreement with the known compositions. The absolute oil and water content showed a systematic error of 10%. These initial results demonstrate that THz spectroscopy has the potential to determine the composition of biological tissues