Advancing Dry Electroencephalography With Scalable, Soft, and Transcranial Magnetic Stimulation-Compatible Ti₃C₂T_x...

Electroencephalography (EEG), essential for diagnosing and researching neurological disorders, utilizes gelled electrodes, which present limitations in safety, comfort, stability, and usability, particularly in long-term applications. We introduce a novel dry EEG technology using soft, porous, low-impedance, Ti₃C₂T_x MXene electrodes. The 10 Hz impedance of these electrodes across scalp locations is 2.1 ± 1.8 kΩ, comparable to gelled Ag/AgCl electrodes and below clinical thresholds. Ti₃C₂T_x electrodes maintain stable impedance over 4.5 h on agarose phantoms and retain structure after 50 cycles of 80% axial compression. These electrodes are suitable for simultaneous EEG and transcranial magnetic stimulation (TMS), exhibiting no significant displacement, heating, or unsafe charge densities under TMS fields. We benchmarked dry electrodes across recording scenarios and hair types against gelled electrodes. In full-scalp steady-state visual evoked potential (SSVEP) recordings, gelled and Ti₃C₂T_x electrodes were highly correlated (R > 0.89). Clinical EEG with Ti₃C₂T_x electrodes captured all features observed with gelled electrodes (R > 0.84) and was rated for clinical quality by neurologists. Furthermore, dry MXene EEG electrode recorded high-quality EEG for over 4 h. In mobile EEG, Ti₃C₂T_x electrodes did not induce signal distortions and enabled task-specific feature detection with a comparable signal-to-noise ratio to gelled electrodes. These findings establish dry Ti₃C₂T_x electrodes as an alternative to gel-based systems, with broad potential in clinical diagnostics and research.