How to track eye movements with electrodes? I'm an Information Technology student (bachelor's degree) and as a summer project, I'd like to develop a small "alarm" system for ALS patients in case of emergency situations.

I thought about tracking the eye movements of the patients via electrodes and then send the eye movement signals to the software system which I'm going to develop and then process the data. I'm planning to use Python programming language since I already have some experience on.

However, I don't have any experience with using electrodes, processing the signals to detect eye movements. Do you know any good and simple online sources for the beginners like me? I can't afford to buy books so I'd be grateful if you can suggest me free online sources.
I believe this tutorial covers exactly what you are looking for. It describes how to use a relatively cheap kit ($150) to detect eye movements and eye blinks. It includes software and hardware information.