Prototype design of low cost four channels digital electroencephalograph for sleep monitoring

The electrical activity in brain or known as electroencephalogram (EEG) signal is being used in the diagnosis of sleep quality. Based on EEG signal, power of brain wave that related with a sleep quality could be obtained by analysis of power spectral density. The problem in developing countries, for example in Indonesia, EEG instrument is not widely available in each region of the country. This project designed and implemented four channels digital EEG, in which the design of hardware and software concepts was adopted from OpenEEG project. A four channels EEG amplifier operated by battery with average gain magnitude of 6100 times, bandwidth 0.05-60Hz and slope gradient of -60.00 dB/decade is developed. Digital board consists of AT-mega8 and serial interface with optocoupler is used to interface and viewed EEG signal on notebook. The prototype has successfully detected patterns of cardiac signal simultaneously with good SNR. In EEG measurement through monitoring the brain wave sleep, the data generated by PSD (Power Spectral Density) graph show the dominance of the brain signals at 7-9Hz (alpha) and 3-5Hz (theta). From several tests and measurements, this research concludes that the prototype of low cost EEG 4 channels is capable of acquiring satisfactory brain wave monitoring during sleep from healthy volunteer.