Functional Near-Infrared Imaging for Biomedical Applications

Abstract

Functional near-infrared spectroscopy (fNIRS) is utilized as an optical approach for biomedical applications, especially for the brain-computer-interfaces (BCIs) applications due to their absorption contrast between oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb). In this chapter, we first make a brief introduction about the research background of fNIRS; then, the basic work principle of the fNIRS instrument was also reviewed, the performance of which was greatly affected by the light source (LEDs and lasers) and detectors (pin photodetector, avalanche photodiodes, and photomultiplier tube); afterward, we thoroughly introduce the fNIRS and hybrid fNIRS-EEG BCIs with a focus on the data classification methods, for instance, machine-learning (ML) algorithms and deep-learning (DL) algorithms, thereby forming better classification accuracies; lastly, challenges of fNIRS were pointed out, and an outlook was also made to foster the rapid research and development of this technology toward neuroscience and clinical applications.