Brain activity detection technologies are disclosed. In some embodiments the technologies include a brain activity detection system that includes a sensor block including that includes at least one reference electrode and at least one sense electrode. The reference and sense electrodes are configured to produce analog reference and analog sense signals that are indicative of activity of a brain of a user. A signal processing block may also be included, and is configured to generate at least one digital differential signal based at least in part on the analog reference and analog sense signals. At least one processor may convert the digital differential signal(s) in said time domain to one or more frequency domain digital differential signals. Signal processing on the frequency domain digital differential signal may be performed to determine health information of a user. Devices, methods, and computer readable media utilizing such technologies are also disclosed.
