The system desing for acquiring EEG signal

In this study, it is aimed to perform an analog portable EEG (electroencephalogram) signal acquistion system design. A portable biomedical signal recorder is significant for the detection of symptoms which are encephalitis, brain neoplasms, epilepsy etc. By using an EEG recorder, investigators and clinicians have more opportunity to analyze symptoms from the long-duration recorded signals. This thesis is further divided into three parts which are the acquisition, gain and filtering. For an EEG amplifier, it consists of an instrumentation amplifier (IA) followed by a low pass filter, high pass filter, and a notch filter. Firstly, EEG signals are acquired from the patient by means of probes and these signals are transmited to amplifier. EEG signals are amplified by use of AD620 which is an instrumentation amplifier (IA). After, amplified EEG signals pass into low pass filter and the signal will be filtered to eliminate signal noise. Then the signals entered high pass filter and notch filter which have been used in the past for applications like elimination of 50 Hz hum components, respectively. Finally, analog EEG signals are digitized by an AD7715 analog-digital converter. The digitized signals are transmitted to a PC by a wired serial port by usuing Arduino kit and the signals are viwed with an interface programming. The system made reliable results in a short time for real-time applications because these signals are controlled from users and this method will be very useful for control systems.