Combined method for characterization of biological phantoms using optical coherence tomography and a fiber-optic refractive Index sensor
Liubov D. Zavalishina, Aleksandr A. Markvart, Uliana A. Makarenko, Leonid B. Liokumovich, Nikolai A. Ushakov
Peter the Great St.Petersburg Polytechnic University, St.Petersburg, Russia
Abstract
A novel biomedical diagnostic approach combines optical coherence tomography (OCT) with a fiber-optic refractive index (RI) sensor based on an intermodal interferometer incorporating a tapered few-mode section (SFT). Conventional OCT is limited to structural imaging. Osmotic OCT enables monitoring of solution absorption dynamics in biological tissues, allowing quantitative estimation of diffusion coefficients and assessment of tissue density and pathological progression.
Additional quantitative parameters enhance this approach. In particular, tissue RI is of diagnostic interest, as malignant transformation is known to be accompanied by an increase in RI. To obtain this complementary information, OCT is integrated with a fiber-optic SFT RI sensor, enabling direct measurement of the local RI and thereby estimation of the composition and concentration of the absorbed solution in the region of interest. This architecture was selected because its localized sensing region enables point measurements at the tissue site while maintaining spatial overlap with the OCT scanning area.
The approach was validated using multilayer gelatin phantoms. Aqueous glycerol solutions of different concentrations were applied dropwise onto the phantom surface, while changes in the phantom layers and absorption dynamics were continuously monitored using OCT A-scans. Simultaneously, the local RI in the measurement region was monitored using the SFT sensor. The results revealed that water and glycerol were absorbed at different rates, accompanied by swelling of the surface layer. These findings demonstrate that simultaneous OCT imaging and RI sensing provide complementary quantitative information, enabling characterization of tissue transport processes and estimation of diffusion coefficients in biological tissues.
Speaker
Zavalishina Liubov Dmitrievna
Peter the Great St.Petersburg Polytechnic University (SPbPU)
Russian Federation
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