In some aspects, the present disclosure relates to devices, systems, and methods for collecting brain activity data. In some embodiments, a head-worn device collects EEG data using a plurality of sensors that are positioned at multiple points across the scalp of the subject. Each of the sensors can be constructed with a housing having an absorbent portion that can be moistened with the conductive fluid. The sensors can be held in position at a subject's head through the use of a framework of flexible bands that are adjustable to accommodate different head sizes.
