Fig. 6: Real-time contact impedance and N170 mood evocation experiments with hydrogel electrodes.

a Pictures of subjects measuring real-time contact impedance in a sonic darkroom. b Pictures of reference and working electrodes used for EEG measurements (GND and CPz are the reference electrodes, and the rest are the working electrodes). c Real-time contact impedance of the wet electrodes and the hydrogel electrodes in the area of less hair. d Real-time contact impedance of the wet electrodes and the water gel electrodes in areas with normal hair. e Schematic of N170 test. f Signal-to-noise ratios of dry, wet, and hydrogel electrodes. g Generation of N170 waves at O1 and O2 using dry, wet, and hydrogel electrodes. h Generation of N170 waves at O1 using hydrogel electrodes for 21 days (worn for 2 h per day). i Variation of signal-to-noise ratios of hydrogel electrodes for 21 consecutive days