| This master thesis describes the implementation and validation of a novel instrumentation able to acquire biosignals from two brain imaging technologies: electroencephalography (EEG) and near-infrared spectroscopy (NIRS). The first one directly measures electrical variations on scalp, while the other one can detect the blood oxygenation variations, which can be correlated with cerebral activities. Contrary to others brain imaging modalities, the both described here have potential to be portable, relatively inexpensive, with high temporal resolution and allow to image the whole cortex in real time.;This work is part of a multidisciplinary team collaboration within the IMAGINC research group, one of the goals being the development of a real-time, noninvasive and portable NIRS-EEG signal acquisition system, able to communicate wirelessly with a computer, gathering data from 32 EEG channels, 32 light sources and 32 light detectors, to image the whole cortex. Existing commercial or research devices do not gather all of these features. The built prototype fully meets the expected characteristics: composed of a helmet able to maintain every optodes and electrodes on scalp, the wireless system can be attached to the belt and transmit to an user interface the data provided by 128 NIRS and 32 EEG channels, as well as additional modules like an accelerometer or auxiliary channel acquisition circuits, useful in a clinical context.;The instrument has been validated on around forty subjects, during cognitive tests, the results of which showed expected induced brain activities on acquired data, through the calculation of haemodynamic variations, similar to those described in literature. We are also conducting studies to statistically compare the prototype and evaluate the reproductibility of biosignals, to confirm the qualitative validation developed here. In the future, the device should allow to monitor epileptic patients on long periods of time, while improving comfort, for preoperative studies, or patients undergoing open heart surgery, procedure in which the cerebral oxygenation needs to be controlled, but no existing commercial devices currently is operating-room friendly. |
