A Preliminary Study On The Biological Tissue Of Terahertz Time Domain Spectroscopy

Objective:To investigate the difference of absorption coefficient and refractive index at the beginning and end of the dehydration among three biological tissue samples, further explore what causes the response differences to THz radiation between different biological tissue to occur and find out the mechanism of interaction between THz radiation and biological tissueMethods:①The continuous dehydration processes of adipose, muscle and skin from pork were investigated by using transmitted terahertz time-domain spectroscopy (THz-TDS), the changes of terahertz spectroscopy during the dehydration have been observed.② The regular change of the optical properties of the different concentrations of aqueous solutions of sucrose in the THz frequency range were investigated by using transmitted THz-TDS, and the dielectric properties of the solvent system was modeled theoretically by using double Debye theory, and the dielectric parameters of sucrose solution were calculated.Result: ①Terahertz spectroscopy was sensitive to the change of water content in the fresh tissues. ②There was a significant difference in the terahertz spectroscopy absorption between different tissues, specifically, the absorption coefficient of muscle tissue was the highest, and adipose tissue was the minimum.③The difference among three tissues in absorption coefficient was significantly reduced after the dehydration. ④ With increasing concentration, the absorption coefficient and refractive index of sucrose solution were decreased.⑤ The fitting results of the Debye model showed that the dielectric relaxation time of water molecules in solution was delayed when the concentration of sucrose increased.Conclusion:①Water content was the primary factor to influence the absorption coefficient of fresh tissues, the component of tissue was the key influence factor of spectrum under dry condition.②The transmitted THz-TDS enable to distinguish different biological tissues.③The relaxation process of water was slowed due to the sugar, along with increasing concentration, this effect of restriction will be more prominent, thereby resulting the decreases of the absorption coefficient and refractive index of the solution on a macro-scale in the THz frequency range. It is suggested that the changes of content of the hydrophilic biomacromolecule is a important factors that lead to the response differences to THz radiation between different biological tissue.④This research laid a theoretical foundations for further understand the interaction of biological tissue with THz radiation and helps for the further application of terahertz technology in the fields of biology and medicine.