A motion-artifact tracking and compensation technique for dry-contact EEG monitoring system

A digital online technique for motion artifact (MA) tracking and compensation is reported for electroencephalogram (EEG) monitoring using dry-contact electrodes. A safe, low-level pseudorandom noise (PN) signal is driven to the body through a reference electrode as a test signal to measure the bio-potential acquisition-path gain (APG) of the electrode-tissue interface (ETI). The measurement result is then utilized by a digital-domain gain compensator to act in the opposite way to the MA-induced APG variation, thereby compensating the multiplicative motion artifact (MMA) in real time. The remaining baseline wander or additive motion artifact (AMA) is treated by a digital high-pass filter (HPF). The interference of the test signal to the EEG signal acquisition is negligible in this technique due to the nearly white spectrum of the PN signal.