In-vivo monitoring of tissue oxygen saturation in deep brain structures using a single fiber optical system

We propose a single fiber optical system for monitoring tissue oxygen saturation (sO₂) based on continuous-wave reflectance spectroscopy in the visible wavelengths. The system is designed for measurements in deep brain structures by stereotaxically implanting the 200 μm-core fiber probe into the tissue of interest. Monte Carlo (MC) simulations were used to estimate the measurement tissue volume between 0.02-0.03 mm³. Experiments in an optical phantom indicated the system had a root mean squared error (RMSE) of 4.21% compared with a commercial fluorescence-based tissue oxygen partial pressure measuring system. Finally, we used the system for continuously monitoring tissue sO₂ from a highly-localized volume in anesthetized mice.