Brain Monitoring Via an Innovative CW-FNIRS System

Abstract

Functional Near InfraRed Spectroscopy (fNIRS) is an imaging technique mainly devoted to human brain monitoring. It is used as a non-invasive technique, in medical field, in order to measure the oxygen concentration of blood. This because the relatively good transparency of biological materials in the near infrared allows sufficient photon transmission through tissues. Within the so-called fNIRS range (650-900 nm), the main absorbers are blood chromophores, in particular the oxygenated and deoxygenated haemoglobin (HbO2 and Hb, respectively). When two or more wavelengths are used, changes of such chromophores can be computed by employing the modified Beer-Lambert law, thus providing important information about the brain activity. The main hardware novelty consists in the employment of Silicon PhotoMultiplier (SiPM) showing different advantages towards PhotoMultiplier Tubes, Avalanche PhotoDiodes, PIN or Single Photon Avalanche photodiodes. SiPMs are ideal candidates for CW-fNIRS applications and, furthermore, they could potentially increase the spatial resolution.