The field of disability aids has seen many devices controlled by computers that visually track the eye movements of paralysed people, but none that reads the electricity given off by swivelling eyeballs [subscription link].
Research by NTT DoCoMo Research Laboratories has shown that the human pupil carries a slight positive charge, compared to the more negative white part of the eye.
DoCoMo chief scientist Masao Fukumoto explains the seemingly odd phenomenon, saying, "The human eye has the properties of a battery." Measuring how the electrical balance shifts as the eye moves is key to a more accurate eye-based control system.
Naturally, a multimedia company (as are all modern phone firms) like DoCoMo has plans beyond creating a disability aid. The Japanese giant plans to build the technology into headphones that can control music players with a mere sideways glance. Just be careful when using them on the night bus home.