Design and Implementation of Data Acquisition System for EEG Analysis

The Electroencephalogram (EEG) is a recording of the electrical activity of the brain from the scalp. The recorded waveforms reflect the cortical electrical activity. EEG activity is quite small, measured in microvolts (μV). EEG is a non-invasive method to record electrical activity of the brain. Most commonly it is used to identify the type and location of the abnormal activity in the brain during a seizure. It is also helpful in diagnosis of sleep disorders, encephalitis and brain dead. The main design aspect of this system is aimed to observe the behavior and analyze electrical activity of the brain. The Electroencephalography (EEG) signals are acquired by suitable signal conditioning designed exclusively. In order to analyze the behavior of the brain, the functioning of the brain must be studied. This is achieved by analyzing the electrical activity of the brain. The brain signals are very low voltage signals normally range from 0.5 to 100 μV in amplitude. Although the spectrum is continuous, the signal frequencies range from 0.65Hz to 65Hz. The results and the wave forms is compared with the threshold values to determine the disorders in the brain of the subject. The system has an amplification of 5000 and can be varied up to 10,000. The resultant output has been implemented using LabVIEW. Discrete Wavelet Transform (DWT) construction and reconstruction program has been developed in LabVIEW and output results are acquired through computer as well as Cathode ray oscilloscope (CRO) using offline data.