Electroencephalography makes use of sensors to capture time varying magnitude of electric fields originating from the brain. These fields result from synchronous activities of billions of neurons present in the brain. These fields are measured from scalp through sensors using different techniques developed over the time so that measurement can be precise, which in turn relies on direct and low resistance contact between the sensor and scalp. Recent advancement in EEG monitoring devices has extended its usage into the domains of lifestyle and entertainment. This paper discusses all such techniques used for the acquisition of EEG signal with the help of various sensors available such as wet electrodes, dry electrodes, wireless EEG system etc.

1. J. C. Chiou, Li-Wei Ko, Chin-Teng Lin, Chao-Ting Hong,Tzyy-Ping Jung, "Using Novel MEMS EEG Sensors in Detecting Drowsiness Application," IEEE Biomedical Circuits and Systems Conference, 2006.
2. Spence, Alexander P. , "Basic human anatomy", Redwood City, CA. The Benjamin Cumming Publishing Co. , 1990.
3. T. Sullivan, S. Deiss, T. P. Jung, and G. Cauwenberghs, "A Low-Noise, Low-Power EEG Acquisition Node for Scalable Brain-Machine Interfaces", In Proceedings of the SPIE Conference on Bioengineered and Bioinspired Systems III, May 2-4 2007.
4. T. Sullivan, S. Deiss, and G. Cauwenberghs, "A Low-Noise, Non-Contact EEG/ECG Sensor", IEEE Biomedical Circuits and Systems Conf. , 2007. 1989
5. Jovanov E, Raskovic D, Price J, Chapman J, Moore A,Krishnamurthy A. , "Patient monitoring using personal area networks of wireless intelligent sensors," Biomed. Sci. Instrum. , 37, 373-8, 2001
6. [Online]. Available: http://www. ebme. co. uk/
7. Roehrs T, Roth T. , " Sleep disorders: an overview," Clin Cornerstone, 6 Suppl 1C, S6-16, 2004.
8. Lindsay Brown, Jef van de Molengraft, Refet Firat Yazicioglu, Tom Torfs, Julien Penders and Chris Van Hoof," A low-power, wireless, 8-channel EEG monitoring headset",In 32nd Annual International Conference of the IEEE EMBS Buenos Aires, Argentina, August 31 - September 4, 2010
9. Ji Jun1, Yu MengSun1, Zhou YuBin2, Jin ZhangRui2," A Wireless EEG Sensors System for Computer Assisted Detection of Alpha Wave in Sleep",in proceedings of the 2005 IEEE engineering in medicine and biology 27th annual conference shanghai, china, September 1-4,2005
10. Sun M, Mickle M, Liang W, Liu Q, Sclabassi RJ. , "Data Communication between brain implants and computer," IEEE Trans. Neural. Syst. Rehabil. Eng. , 11(2), 189-92, 2003
11. Jovanov E, Raskovic D, Price J, Chapman J, Moore A, Krishnamurthy A. , "Patient monitoring using personal area networks of wireless intelligent sensors," Biomed. Sci. Instrum. , 37, 373-8, 2001
12. Tatum, W. O. , Husain, A. M. , Benbadis, S. R. (2008) Handbook of EEG Interpretation" Demos Medical Publishing.
13. [Online]. Available: mildpdf. com/result-standard-international-10-20-electrode-placement-pdf. html

Wet Electrodes