Electrical and thermo-mechanical properties of styrene-ethylene-butylene-styrene/carbon nanotube and styrene-ethylene-butylene-styrene/carbon black multipin electrodes for electroencephalography

Flexible electroencephalography (EEG) electrodes have attracted increasing attention due to their potential applications in mobile health monitoring. However, balancing electrical conductivity, flexibility, stretchability, and EEG signal recording remains challenging. Here, we fabricated polystyrene-block-poly(ethylene butylene)-block-polystyrene (SEBS) composites with carbon nanotubes (CNT) and carbon black (CB) via solvent dissolution. The percolation threshold was approximately 12 wt% for SEBS/CB composites and approximately 2 wt% for SEBS/CNT composites. At 20 wt%, SEBS/CB composite conductivity plateaued at 0.01 S/m, whereas SEBS/CNT composite conductivity reached 1.26 S/m at 16 wt%. Contact impedance was 4.2 ± 0.45 kΩ for SEBS/16 wt%CNT and 5.4 ± 0.9 kΩ for SEBS/20 wt%CB. SEBS/CNT was slightly stiffer than SEBS/CB. The electrodes reliably recorded EEG signals, demonstrating their potential for health monitoring and long-term EEG measurements. • Flexible EEG electrodes made from SEBS with CNT or CB fillers. • CNT composites reached 1.26 S/m at 16 wt%, outperforming CB at 0.01 S/m. • Percolation: ∼2 wt% for CNT vs ∼12 wt% for CB. • CNT electrodes: lower impedance (4.2 kΩ) and higher EEG signal quality. • CB offers more comfort but lower electrical performance.