A hardware design for brain electrical activity mapping

Abstract

In this thesis a hardware was developed for Brain Electrical Activity Mappingand also for standard EEG and EP recording. The study involves design andimplementation of 32 bipolar, high CMRR, low noise and low cost biopotentialamplifiers for EEG and EP measurements, and an analog to digital converter system,a digital opto-isolation unit, and an interface card to communicate the system to anIBM compatible Pc. Digital opto-isolation is advantageous since it is immune tononlinearity and gain instability effects with which analog isolation suffers. The systemdeveloped has electrode impedance check and calibration check utilities. Twoselectable analog low pass filters and a 50 Hz notch filter has been employed in eachanalog channel. The CMRR of the analog amplifiers was measured and found to bevery high, which is very adventageous for EEG and EP recording. The system wastested as a whole by recording real EEG and EP data from a normal subject.