Flexible electrodes with enhancement of electronic-ionic conductivity for electrophysiological signal monitoring

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The transmission of electrophysiological signals to the skin is subject to decay, which renders them challenging to detect. To improve the signal-to-noise ratio, we need electrodes with low skin impedance that are also flexible to avoid movement artifacts. Low skin impedance requires not only low resistivity but also high ionic conductivity to accommodate electrophysiological signals of different frequencies. By blending two electronic-ionic conductors, i.e., PEDOT:PSS and Ti3C2Tx MXene, we reported a film electrode with high conductivity (∼2780 S/cm) and high volumetric capacitance (31.3 F/cm3). Low electrochemical impedance was thereby achieved (41.2 Ω cm² at 100 Hz) with the film thickness of approximately 60 nm. Such an excellent mixed conductivity, enables the accurate monitoring of electrophysiology signals that can be used in wearable electronic devices.