A dry and flexible electrode for continuous-EEG monitoring using silver balls based polydimethylsiloxane (PDMS)

Purpose: Continuous-electroencephalograph (cEEG) monitoring has become one of the hottest issues in the neurology field. However, the conventional EEG electrode is unsuitable for EEG monitoring because drying conductive paste leads to increase in impedance and skin trouble. Therefore, we manufactured and tested a new dry and flexible surface electrode for cEEG monitoring. Methods: The electrode was constructed using a nontoxic, nonflammable polydimethylsiloxane (PDMS) substrate and a contacting silver balls electrode. A patient in a comatose state due to subarachnoid hemorrhage in the intensive care unit was studied over 48 h, and EEG data were recorded for 10 minutes every hour. The proposed electrode was evaluated using impedance, power spectral density, and coherence. Results: The fabricated electrode is sufficiently flexible and biocompatible. Impedance of the dry and flexible electrode (10. 6±2. 7 kΩ) was higher than that of the conventional Ag/ AgCl electrode (2. 8±0. 4 kΩ). However, the power spectral characteristics of the developed dry and flexible electrode and conventional Ag/AgCl electrode are similar throughout 36 h of recording. Conclusions: Our dry and flexible electrode, compared with a conventional wet electrode, showed comparable data quality in terms of impedance, visual interpretation, and spectral characteristics during cEEG monitoring.