Programmable Chip EEG

The Programmable Chip EEG is a dual channel electroencephalograph that could be a brain-computer interface.

The Programmable Chip EEG is programmable because it uses Digitally Programmable Potentiometers. They are used to set the Gain, frequency range, and can calibrate multiple analog boards for different EEG tests.

Parts used in the PCEEG:

• LT1168 Programmable-Gain Precision Instrumentation Amplifier is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc.
• Several LT1114 Low Power Precision OP-Amps are used for amplification and filtering of the signal
• The AD5204 4-Channel Digitally Controlled Potentiometer is used to make calibration of this device easier. (Historically, a weak point of homebrew designs has been their sensitivity to component value; tolerance and drift have made them require constant tweaking for good results.)

To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

The resulting analog signals will be passed into a digital circuit, based on the Cypress PSoC microcontrollers, which will digitize the signals, further process them, and provide an interface to a computer.