Application of Graphene Dry Electrode in 512-Lead EEG Cap and Real-Time Monitoring EEG System

Dry electroencephalography (EEG) electrodes with low noise and minimal potential drift are crucial for daily wearable and high-density noninvasive brain-computer interfaces. In this study, a Na-doped vertical graphene dry electrode with a diameter of 2.8 mm was prepared to construct a 512-lead ultrahigh-density EEG cap and wireless 8- and 32-lead EEG headbands. The Na-doped vertical graphene layer has a three-dimensional architectural structure that absorbs sweat from the scalp and converts it into an Na⁺-mediated solid electrolyte, electrically connecting the device to the scalp. The optimized graphene dry electrodes exhibited low scalp-contact resistance (dry: 3.8-6.5 kΩ, H₂O: 4.5 kΩ), self-noise (11.1 μV), DC offset voltage (15.6 mV), and potential drift (189.9 μV). The EEG cap, composed of 512 dry graphene electrodes, recorded different rhythm signals with a high signal-to-noise ratio, demonstrating excellent repeatability and long-term stability over 103 days. In addition, a task-state strategy was designed that combined the intensity ratio of fast and slow waves with frequency-domain event-related potentials, demonstrating the reliability of dry electrode headband systems for rapid attention analysis during daily wear. This wearable metal-doped vertical graphene dry-electrode device, especially the 512-lead ultrahigh-density dry-electrode EEG cap, holds promise for applications in brain function research, neuroimaging, and brain-computer interface control.