Design and Implementation of a Multi-Channel EEG Acquisition System

[[abstract]]Brain Computer Interface (BCI) provides a novel communication method for patients with neuromuscular disorders or amyotrophic lateral sclerosis to directly control external devices with their brain activities, without pass conventional motor output pathways of nerves and muscles. However, the BCI relevant equipment is expensive and bulky, it is hard to be popularized. The objective of this research is to design and implement a multi-channel, low cost, small-volume and modularized Electro-Encephalo-Gram (EEG) acquisition system. The system consists of fundamental circuits, the programmable gain amplifiers, the switch capacity filter modules and the LabVIEW-based application software. Concerning the design of hardware, the Drive Right Leg (DRL) is adopted to reduce the common-mode noise. The switch capacity filter is used to replace the traditional active RC filter to reduce the drift of frequency. The digital potentiometer is used to replace traditional rheostat to increase the accuracy and reduce the error caused by artificial adjustment. The concept of module is introduced into the layout of Printed Circuit Board (PCB) to increase the numbers of channel through circuit stacking. After the system is developed, the measurement performance of the system is compared with the NuAmp which is a professional instrument of BCI. The results show that the average error and the standard deviation are 0.1809 volts and 0.1153, respectively. In frequency domain, the average error and the standard deviation are 0.0606 volts and 0.167, respectively. The average of trend similarity is 83.25%. The correlation coefficient is larger than 0.8. According to the experiment results, the system is feasible. In the future, the system can be integrated with an embedded system for benefits disabled persons.