Byunggik Kim 1* , Jongmin Jang 1* , Kisun Kim 1*` , Houngkyun Kim 1 , Jiyoon Kim 1 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