Fiber-Based Raman Spectroscopy towards Label-Free Hemodynamic Monitoring in deep brain tissue

Neural activity is closely linked to blood oxygenation dynamics through neurovascular coupling, a relationship widely exploited by established functional optical neuroimaging techniques to reconstruct brain activity, such as functional Near Infrared Spectroscopy (fNIRS). However, while this strategy provides a robust overview of global hemodynamic patterns, it relies on a differential measurement and it lacks molecular specificity. Raman spectroscopy has recently emerged as a powerful complementary tool to overcome this limitation, offering biochemical selectivity and the ability to resolve the specific vibrational signatures of distinct states of haemoglobin oxygenation. This thesis focuses on the experimental validation and characterization of a fiber-based approach designed to monitor haemoglobin oxygenation dynamics using Raman spectroscopy. The implementation of a flexible fiber-optic configuration enables versatile light delivery and collection geometries, including localized measurements within deep tissue structures. The experimental setup was validated using human red blood cells, successfully identifying the characteristic Raman peaks of both oxy- and deoxy-haemoglobin. The measurements were validated using a custom-made UV-VIS absorbance system. Overall, these results demonstrate a promising step toward a minimally invasive approach for molecular-specific hemodynamic monitoring that can complement fNIRS in preclinical research.