Poly(3,4-ethylenedioxythiophene) (PEDOT) as interface material for improving electrochemical performance of microneedles array-based dry electrode

As a promising alternative for conventional wet electrode made from silver/silver chloride (Ag/AgCl), micro-needles array (MNA)-based dry electrode has gained extensive attention. The low contact impedance between the MNA-based dry electrode and skin interfaces is pivotal for the acquisition of high quality biopotential, especially for long-term monitoring. In this report, we study, for the first time, the use of organic conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) as the interface material of MNA-based dry electrode to improve its electrochemical performance. The interface performance of PEDOT coated dry electrode was characterized by electrochemical impedance spectroscopy and cyclic voltammetry. The mean impedance magnitudes (measured from skin) of PEDOT dry electrode are around 7.5 ± 3.2 kΩ at 2 Hz and 2.7 ± 1.2 kΩ at 100 Hz, while the values are 274.2 ± 54.6 kΩ and 31.8 ± 9.6 kΩ for gold dry electrode, and 547.1 ± 374.2 kΩ and 79.9 ± 10.3 kΩ for commercial electroencephalography (EEG) wet electrode. The charge storage capacity (measured on rat skin sample) of PEDOT and gold was 461.48 μC and 1.8296 μC, respectively. These improvements provided by PEDOT interface material can significantly contribute to MNA-based dry electrode for recording or electrostimulation. Compared with commercial EEG wet electrode, similar biopotential signals can be acquired with our PEDOT-coated MNA-based dry electrodes.