New subdural electrode contacts for intracerebral electroencephalographic recordings: Comparative studies on neural signal recording in vivo

In this paper, we propose new subdural electrode contacts to improve signal-to-noise ratio (SNR) for intracerebral electroencephalographic (icEEG) recording. We describe the proposed electrodes material composition, fabrication process, electro-chemical impedance spectroscopy analyses, and in vitro comparative studies with commercial electrodes (micro-electrodes-MRE, depth electrodes -DPE, and subdural electrodes -SDE). The proposed subdural electrode contacts are made of Platinum (Pt) or Gold (Au). Compared to the DPE/SDE and MRE, the proposed Pt or Au electrodes feature reduced impedances of ~116 kΩ and ~8.89 MΩ respectively. In vivo icEEG recordings for three weeks in an adult Sprague Dawley rat demonstrated signal stability, 50% noise reduction and up to 3 dB SNR improvement. Following the long-term icEEG recording, brain histological result showed no abnormal tissue reaction in underlying cortex.