Design and implementation of EEG measuring system

Electroencephalographs (EEG) is a technique commonly used in medical and research fields to record the electrical activities of the brain. The EEG signals are recorded from the surface of the scalp using Ag/AgCl electrodes (locally made) according to the 10–20 international system. Measurements are usually difficult due to small signal magnitude and large DC offset. The signal is amplified in multistage amplifier and digitized using 24-bit analog to digital convertor (ADC). The DC-offset was treated using auto-zeroing technique, along with the use of high precision electronic components. The theoretical design was first simulated using TINA-TI software, then the PCB's were designed using Eagle software, and implemented practically. EEG signals were acquired and recorded for different people and it seems satisfactory for the diagnosis by doctors.