Analog EEG Amp

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(initial draft)

Revision as of 18:48, 11 May 2012

The analog EEG amp.

This analog EEG amplifier was donated to Noisebridge a couple of years ago. It is a medical-grade amp, probably used for clinical monitoring purposes. Since we've currently only tested the output by looking at noise through the fairly rudimentary electrodes shown, we don't have a good idea, at present, of the signal quality, but it should be in reasonably good shape. Electrodes die quickly in EEG and amps usually live substantially longer, but it's definitely possible that some of the channels will have artifacts or noise issues. Probably it will still amplify EEG signal sufficiently well to serve as an actuator for other projects.

Goals and Milestones

The current working goal is to accomplish analog to digital conversion of the amp's output with a reasonably consistent sampling rate, and to output this to USB. Then we should get one of the NB desktops set up with software to process and interpret the signal in real time so it can be used as an actuator. The test task will be using some EEG signal (probably beta power) to buzz open the door to noisebridge. The API for the door is already in place. Here are some steps along the way.

  1. Verify that amp outputs signal and that this signal is correctly modulated by the hardware controls.
    • Check signal amplification levels and multipliers
    • Check high and low pass filters
    • Connect a human with properly gelled electrodes and check to make sure blink artifacts are clearly visible in the amp signal.
    • Connect a human with properly gelled electrodes and check to make sure basic EEG signal comes through.
      • Alpha power would be a good first test
      • We could also test the photic stimulator and do some SSVEP.
  2. Build and program a microcontroller that correctly interprets and digitizes the analog signal output.
    • The analog signal consists of both positive and negative voltages and we need both.
    • There is a voltage range and accuracy requirement for this signal. We should determine what that is.
  3. Ensure that the ADC process includes a stable sampling rate.
    • I have been told this will require oscillators. Any specific proposals? --Hurtstotouchfire 01:48, 12 May 2012 (UTC)
  4. Pipe digital signal into real time EEG software.
    • Suggestions for software? Must run on linux.
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