Design and development of a continuous wave functional near infrared spectroscopy system

Functional Near InfraRed Spectroscopy uses light sources and optical detectors for human brain monitoring. In this paper, a portable, low cost, battery-operated, multi-channel, continuous wave fNIRS embedded system, hosting up to 64 LED sources and 128 Silicon PhotoMultiplier optical detectors, is reported on. The designed system is based on a scalable architecture, in which each probe consists of 8 modular and flexible stands, able to host 4 bi-color LEDs as light sources, 16 silicon photomultipliers as photodetectors and a temperature sensor. The hardware structure allows to easily set up several relevant parameters: the timing of the LEDs, the optical power emitted by the LEDs; the acquisition of the photodetectors, the bias voltage of each SiPM; the portion of cerebral cortex that has to be analyzed by programming the suitable source photodetector couples that will be involved in the measurement. Several preliminary functional tests were successfully carried out, thus achieving very encouraging results.