Abstract In this Phase II project, we will build a complete high-density wearable full-head MEG system using our micro-OPM sensors and to cross-validate our system against current SQUID-based MEG systems. A complete system consists of (1) the sensor system - an array of 128 sensors and their control electronics that performs synchronous data collection and control; (2) a MEG cap that conforms to the shape of the head and holds the sensor array; (3) an integrated sensor scanning system to localize the position and orientation of each sensor relative to the head; (4) an integrated active coil system to compensate for the background field gradients using feedback from the sensor array during recording; and (5) a user interface software seamlessly controls and collects signals and metadata from all the sub-systems. The system will be delivered to our collaborators at the Children’s Hospital of Philadelphia (CHOP) for cross- validation against the current SQUID MEG system in adults and children. We will also evaluate its performance in paradigms that are impossible with current technology, which could open services to patient groups currently denied, and broaden the range of applications for such systems.