Honduran teenager Luis Cruz, whose low-cost homebrew embedded video game system was featured in MAKE Vol 23, wrote in to let us know about his most recent project, a similarly low-cost prototype electrooculography (EOG) system, based on the ATmega328P, that allows people with motor disabilities to write text on a screen using only eye movements. Luis explains:
The human eye is polarized, with the front of the eye being positive and the back of the eye being negative. This is caused by a concentration of negatively charged nerves in the retina on the back of the eye. As the eye moves the negative pole moves relative to the face and this change in the dipole potential can be measured on the skin in micro volts. To translate this voltage into a position, two sets of electrodes are used to measure the differential voltage in the vertical and horizontal direction, on this project, however, just horizontal movements are recorded.
The embedded videos show the evolution of Luis’s prototype from bare-skin electrodes to a glasses-mountable system. [Thanks, Luis!]
From the pages of MAKE Volume 23:
MAKE Volume 23, Gadgets
This special issue is devoted to machines that do delightful and surprising things. In it, we show you how to make a miniature electronic Whac-a-Mole arcade game, a tiny but mighty see-through audio amp, a magic mirror that contains an animated soothsayer, a self-balancing one-wheeled Gyrocar, and the Most Useless Machine (as seen on The Colbert Report!). Plus we go behind the scenes and show you how Intellectual Ventures made their incredible laser targeting mosquito zapper — yes, it’s real, and you wish you had one for your patio barbecue. All this and much, much more.