Byunggik Kim1*, Jongmin Jang1*, Kisun Kim1*`, Houngkyun Kim1, Jiyoon Kim1

1 Ybrain Research Institute * These authors contributed equally to this work

Here we introduce soft constructs, low impedance, low noise, advanced Ag/AgCl composite coated dry EEG sensor (A3C), designed to perform

practical applications of electroencephalography (EEG).

• Sensor fabricated in chemical reaction between advanced Ag/AgCl composite and conductive polymer, for minimal polarization.[1], polymer coating [2]

Introduction

• Standard EEG acquisition began with acquisition of data on multiple objects on 10-20 system to measure ERP, alpha rhythms, and eye blink artifacts.

Then, the result was compared to commercial wet EEG system (Geodesic EEG System 300, EGI, U.S.). (Fig. 2 B, C, D, E)

A Novel Soft Dry Electrode with Advanced Ag/AgCl Composite Coating

for High-Quality EEG Recording Applications

• Demonstrated SSVEP, setup visual stimuli flickering at 10Hz for 60 seconds. A single male volunteers with normal vision participated. The participant

was asked to perform 5 trials and EEG recorded during the course of each trials. The experiment began with acquisition of baseline data, referenced to

Fz and averaging in same weight with O1 and O2, averaged PSD in each trial is shown as topographic map.

The alpha activity is clearly distinguished by PSD (Fig. 2C) of alpha

band with average peak 17.4 dB/ Hz and 17.8 dB/ Hz for wet and the

A3C respectively. Spectrograms for EEG signal measured on Fp1 with

A3C sensor (Fig. 2D, E) clearly show alpha rhythms and eye blink

artifact.

The impedance exhibited average electrochemical impedance of

0.1kΩ and average phase shift -20 degree angle across frequency sweep

1Hz ~ 1kHz. The soft dry EEG electrode showed no significant

difference with conventional wet electrode. (Fig. 2A, B)

Figure 1. Schematic of soft dry EEG electrode coated with

advanced Ag/AgCl composite material

Figure 2. Electrical characteristics of soft dry EEG electrode and

standard EEG measurement

Figure 3. Steady-State Visual Evoked Potential(SSVEP) Measurement

Fig. 3A shows an SSVEP from our developed dry sensor, compares it

with baseline data. The results exhibit clear rendered information on a

set of visually evoked stimuli. Fig. 3B shows its corresponding

topographic mapping on the area of visual cortex for visual stimuli at

10Hz and its harmonic components.

Conclusion & Discussion

Reference

[1] Chi, Y. M., Jung, T., & Cauwenberghs, G. (2010). Dry-Contact and

Noncontact Biopotential Electrodes: Methodological Review. IEEE Rev.

Biomed. Eng. IEEE Reviews in Biomedical Engineering, 3, 106-119.

doi:10.1109/rbme.2010.2084078

[2] Voronkov, M. G., & Deich, A. Y. (1965). The donor-acceptor

properties of the siloxane bond. J Struct Chem Journal of Structural

Chemistry, 5(3), 443-448. doi:10.1007/bf00748884

The collection of results presented here illustrates that the soft-dry A3C

sensor provides flexibility even on demanding surface of the head as

well as successful various applications on clinical EEG recording. The

chemically coated advanced Ag/AgCl composite ensures stable

electrochemical characteristics as conventional wet electrodes.

Beyond basic electrical approach, the operation and enhancement of

polymer coating such as washability and long-time usability would be

further studied along with advanced clinical practices with the soft dry

sensor. We conclude that the A3C sensor as shown here hold the

promise to enable new forms of EEG acquisition and analysis in the

field of neuroscience.

Method

Results

A

A

C

D

B

A