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New Project: Eyeboard Electrooculography (EOG) System

The Eyeboard is an open source eye tracking project that lets you interact with the computer and the real world.

New Project: Eyeboard Electrooculography (EOG) System

Note: Be sure to check out the Kickstarter campaign of the Eyeboard project.

This is an inexpensive yet reliable human-computer interface that detects eye movements using electrooculography (EOG), a biomedical technique based on picking up signals from electrodes placed around the eyes. EOG interfaces let users who can’t manipulate a mouse or trackpad with their hands move a cursor on a computer screen.

An Electrooculogram or EOG is the resulting signal of the potential difference caused by eye movements. The voltage difference is measured between the cornea and the retina. The resting potential ranges from 0.4mV to 1mV and a pair of electrodes are commonly used to detect this signal, but the voltage difference when there’s an eye movement can be as small as just some microvolts. Depending on the eyes’ position, an electrode is more positive or negative with respect to the ground electrode. Therefore, the recorded signal is either negative or positive when moving the eyes.

Due to the fact that an oscilloscope or a CPU cannot detect such small voltages, an EOG system must amplify those voltages in order to get a readable signal. However, other problems such as unwanted signal (noise) arise, such as the 60Hz signal (if you are in America) caused by the AC electrical devices. Therefore, electronic filters should be used in order to attenuate noise after amplification.

The system relies mostly in three important factors: the differential voltage from the electrodes, noise, and offset. In electronics, these three “power sources” can be summed in order to estimate the output voltage.

  • Luis Cruz

    The AVR microcontroller works with a voltage range of 0-5V. So if you are using a higher voltage before in the circuit (e.g using a -5V and +5V supply in the Op Amps) make sure that the signal going to the MCU is +5V or less.

    • kim

      hi luis, great work you have here. what type of electrodes and where did you buy them?

  • Luis Cruz

    Hi Greg,

    All the capacitors are ceramic 0.1uf capacitors. :)

  • Luis Cruz

    Kevin: Many instrumentation amplifiers would work just fine. Make sure it has a good enough CMRR and a high gain though.

    Gulshan: You can get all the electronics at any online store such as digikey, jameco etc…

  • narayan m narvekar

    where can i get the electrodes

  • Awanish

    After making the board and programming the controller the control will communicate through USB or RS 232 PORT (DB9) using max 232

  • http://gravatar.com/rovilsonm rovilsonm

    I cant Understod, two things: 1. The device are ready to sell?
    if the answer is yes, then
    2. How can I buy?

  • yuliana

    cuanto tiempo tardaria en llegar aqui en honduras ese proyecto

  • Bruce McConnell

    Intriguing. Can anyone tell me how to contact the author? I am very interested in making EOG or buying the setup. Thanks

  • http://www.likepeace.blogspot.com nurul

    hello..my research in this area..can i contact this person? how?

  • http://www.intelsath.com Luis Cruz

    Hi everyone,

    If you want to contact me for any questions regarding the eyeboard, visit our website at: http://www.intelsath.com. We have more information about this and other projects, as well as the DIY kits we have available at our site. Check the contact section if you would like to contact us for further information.

    Thanks for your interest.

    Luis Cruz

  • http://glazunov.eu Andrei

    Hi Luis, the link for schematic diagram (http://makeprojects.com/Project/Document/Meta/t3HBdGgrPCNNLdL6) gives 404 error. Could you please update?

  • Bruce

    After buying your kit, I fail to understand why pin 4 of the NA118 amp is sent to ground. According to the data sheets, this pin should be set to a negative voltage, e.g, -5V and pin 7 to +5V. Grounded, it is set to 0 volts, according to both the photos and the circuit diagrams presented in the tutorial. I’m totally ignorant of a roper rationale for this. Any dual voltage op amp i’ve ever seen needs -5 at pin 4 and +5 at pin 7, for example the 741.

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  • Wani Mubin

    hye..can i know the types of electrode used?

  • ROSEPETALS RPS

    I am interested in this.I want to do it as my project.So could you please help me by sharing the details regarding the electrode used here?

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