Preliminary Research On The Quantitative Control And Application Of Tissue Optical Clearing Effects

In the field of Biomedical Photonics, it is necessary to get optical information within tissue in order to improve the application of non-invasive optical technologies. However, the light penetration depth is seriously limited due to high scattering effects of biological tissues, which restricts light-based non-invasive diagonostic and therapeutic techniques in clinical application. Tissue optical clearing technique is one of the effective approaches to reduce the scattering effect and improve the light penetration depth into biological tissues. Therefore, this thesis has introduced tissue-like phantoms to probe how to quantitatively control the optical clearing effects. And furtherfore, its preliminary application in non-invasive optical blood glucose sensing has been performed in order to improve measurement precision.In order to quantify tissue optical clearing effects, tissue-like phantoms were firstly prepared according to the quantitative correlation between optical properties and the content of each component in tissue-like phantoms. And the optical properties of the customized phantoms were similar to that of human skin tissue. Then the optical properties of tissue-like phantoms with different concentration of optical clearing agents(OCAs) were determined by double integrating spheres system, and the mathematical models were built to quantitatively describe the relationship between the dose of OCAs and the optical clearing effects of tissue-like phantoms at 632.8nm. The results have shown that with the increase of OCAs'concentration in tissue-like phantoms, the scattering effect reduced effectively, as well as the light penetration depth increased, up to about 2.51mm. Furthermore, the calculated value based on mathematical models was consistent with that of experimental measurement within accepted error range, which indicates that the optical clearing effects in customized tissue-like phatoms could be quantitatively controlled by the mathematical models.On the basis of the conclusion that OCAs such as glycerol could alter the optical properties of tissue-like phantoms to some degree, the root mean square error of prediction(RMSEP) in optical glucose sensing has been studied by Monte Carlo simulation, in which Intralipid and different concentrations of glycerol were taken into account. And then experiments were performed. Both the results of simulation and experiment proved that the RMSEP decreased as the glycerol concentration increased in phantom solutions. RMSEP has improved by 30.91% and 39.08% respectively in simulation and experiment, which showed the great potential of tissue optical clearing could effectively improve the predicting precision of non-invasive blood glucose sensing.