Project: EEG

The semester just ended, and as my final project for EE40 (circuits), I created an EEG device to measure voltage changes from a person's brain. The signals are on the order of microvolts and contain a lot of noise, so the device basically had to amplify the signal to the order of volts and remove as much noise as possible. The circuit was designed, prototyped on breadboards, and then the PCB was fabricated and stuffed. It consists of an instrumentation amp, DC block (high pass filter with really low cutoff frequency), active low pass filter, and two cascaded 60 Hz notch filters. It is powered by 2 9V batteries and has adjustable gain. My partner and I tested it on our professor's head and it worked! Anyways, it was a pretty fun project; I plan on experimenting with more of this stuff later on. If you want to get into EEG projects yourself, a good resource is OpenEEG: http://openeeg.sourceforge.net/doc/
Thanks to my partner Eugene for his work on the project, and thanks to TI for free op amps!