Development of a Portable Electroencephalogram with Display

In this experiment, the goal was to design, build, and test an Electroencephalogram (EEG) circuit that would then be paired with a touchscreen display as a portable unit for use in Schizophrenic research at East Tennessee State University at the Quillen College of Medicine. The requirements for this prototype denoted that the device had to be able to obtain a signal from two electrodes placed on the head of an individual with a third attached to the ankle as a ground, amplify and filter the signal, and display the results on a touchscreen display for recording and analyzing. The circuit design was approached using a basic three stage breakdown structure: Acquire, Amplify, Filter. This experiment outlines various lowpass and bandpass active filters used in conjunction with instrumentation amplifiers for signal acquisition and amplification. The final design is a 5th-order 25Hz Lowpass Filter EEG Circuit with variable Gain and Quality Factor.