Introduction

Functional Near-infrared spectroscopy (fNIRS) detects NIR backscattered photons passing through human brain tissues thus measuring their oxygenation level. The depth of the analysed tissue region depends on the source-detector distance (SDS). The patent uses silicon photomultipliers The high gain by adjusting the source optical power, a LED, in relation to the tissue characteristics and the SDS.

Technical features

The patent allows designing and fabricating fNIRS and diffuse optical tomography (DOT) systems having higher performances than commercial counterparts do. The hardware is based on the use of silicon photomultipliers having high gain, low operation voltage and small dimensions (allowing their positioning directly on the scalp), overpassing their major drawback, i.e. their relatively modest linearity range. The optical source is a two (or more) coloured LEDs in the wavelength range 700-900 nm, also placed on the scalp. The optimal performances are obtained through a “smart” modulation of the source optical power, by adding a feedback to optimize the signal as a function several factors: source-detector distance, hair presence and color, tissue color and properties, etc. The source/detector small dimensions allow obtaining a “wearable” system.

Possible Applications

Monitoring of neurological diseases manifesting as blood oxygenation related functional or metabolic alterations:

• Stroke;
• Epilepsy;
• Alzheimer’s disease;
• Autism spectrum disorder;
• Multiple sclerosis;
• Monitoring of rehabilitation terapies effects;
• Brain functioning study.

Advantages

• Reduced system footprint;
• Robust hardware; high signal-to-noise-ratio;
• High sensitivity;
• Improved spatial resolution (in fNIRS and DOT);
• Detection at larger depths (in fNIRS e DOT).