Novel passive ceramic based semi-dry electrodes for recordingelectroencephalography signals from the hairy scalp

Novel passive ceramic based semi-dry electrodes for recording electroencephalography signals from the hairy scalp

Guangli Lia, Dan Zhangb, Sizhe Wanga, Yanwen Y. Duana,∗
aCollege of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
bDepartment of Psychology, School of Social Sciences, Tsinghua University, Beijing 100084, China



This study reports on a novel passive ceramic-based semi-dry electrode prototype for electroencephalography (EEG) applications. With the help of capillary forces of the porous ceramics pillars, the semi-dry electrodes build a stable electrode/scalp interface by penetrating hair and releasing a small amount saline in a controlled and sustained manner. The semi-dry electrode/scalp impedance were low and stable(44.4 ± 16.9 k, n = 10), and the variation between nine different positions was less 5 k. The semi-dry electrodes have shown non-polarization characteristics and the maximum difference of equilibrium potential between eight electrodes was 579 V. The semi-dry electrodes demonstrated long-term stability, and the impedance only increased by 20 k within 8 h. EEG signals were simultaneously recorded using a 9-channel gel-based electrode and semi-dry electrode arrays setup on ten subjects. The aver-age temporal cross-correlation between them in the eyes open/closed and the steady state visually evoked potentials (SSVEPs) paradigm were 0.938 ± 0.037 and 0.937 ± 0.027 respectively. Spectral analyses revealed similar response patterns with expected functional responses. Together with the advantages of quick setup, self-application and cleanliness, the result suggests the semi-dry electrode is suitable for emerging real-world EEG applications, such as brain-computer interfaces and wearable EEGs.

© 2016 Published by Elsevier B.V.


Article information

Article history:

Received 29 March 2016
Received in revised form 25 May 2016
Accepted 6 June 2016
Available online 7 June 2016


Dry electrode
Dry sensor
Dry biopotential electrode
Electrode/scalp impedance
EEG recording