Two Cornell University electrical engineering students, Chuck Moyes and Mengxiang Jiang, developed a way to play Pong using brain waves on a $75 budget. The students constructed an EEG helmet consisting of an old baseball cap modified to contain EEG electrodes. The electrodes were then connected to a computer. The results, breathtaking.
Their goal was to build a brain-computer interface using an AVR microcontroller. They decided that the least invasive way of measuring brain waves would be using electroencephalography (EEG) to record microvolt-range potential differences across locations on the user’s scalp. In order to accomplish this, they constructed a two-stage amplification and filtering circuit.
You can read their full research paper here.
You won’t rack up a high score while napping (or with a teammate narrating over your shoulder), but with a budget under $75, it’s hard to find fault. You can grab the source code on their website, and check out a video of Jiang and Moyes’ work after the break.