Design Of 64 Lead EEG Acquisition System

We call the signals that collected from the brain is EEG signals,which can reflect the state of brain activity.It is the general response of the electrophysiological activity of brain nerve cells in the cerebral cortex or the surface of the scalp.At present,scientists attach great importance to the study of EEG signals.The first condition of studying EEG signals is to collect and store them from human body.Therefore,a high quality multi-lead EEG acquisition system is very important in the related research of brain science.In this paper,a 64-lead EEG acquisition device is developed and designed on the basis of the investigation of EEG acquisition products,based on the actual functional requirements of EEG acquisition and the technology that can realize the function.EEG acquisition equipment can generally expand the number of leads according to requirements.The mainstream EEG acquisition equipment is generally 32,64 or 128 leads.Compared with the lower 8-Lead and 16-lead EEG acquisition devices,32-lead EEG acquisition devices collect more EEG signals and are more flexible in the application of Brain-Computer Interface.However,with the progress of technology and in-depth research,higher requirements have been placed on the location and traceability of EEG signals,so 64-lead EEG acquisition devices will gradually become the mainstream.Higher 128-lead EEG acquisition equipment is more difficult to develop and the cost is multiplied.At the same time,in the process of EEG acquisition,128-lead EEG acquisition equipment needs 130 electrodes(128 recording electrodes and 2 reference electrodes)in the brain.It has higher requirements for the related performance of electrodes and the preparation work before EEG acquisition,and its practicability is far inferior to 64-lead EEG acquisition equipment.At present,most of the domestic EEG acquisition equipment are imported from abroad,and the price is expensive.It occupies a leading position in the field of EEG acquisition with 32 leads or more.Domestic manufacturers have gradually established their foothold in the field of low-lead EEG acquisition.There is a tendency to gradually challenge imported equipment.Many manufacturers have already provided acquisition equipment with 32 leads and 64 leads which are not inferior to imported equipment in performance.This design mainly aims at 64-lead EEG acquisition device.,which is divided into signal acquisition module and signal transmission module.Signal acquisition module uses preamplifier circuit and band-pass filter amplifier circuit to pre-process EEG signal and import it into sampling module.Sampling module uses high-precision A/D conversion chip to convert EEG signal into digital signal.Signal transmission module uses USB technology to transmit data to computer.The connection and communication between signal acquisition module and signal transmission module adopts optical fiber technology.Tested,the common mode rejection ratio of the system is 96 dB.The filtering circuit can filter the EEG signal from 0.5Hz to 40 Hz.The A/D conversion module can convert the analog EEG signal into 24-bit digital signal.The optical fiber technology can realize the electrical isolation and signal transmission function of the signal acquisition module and the signal transmission module.The communication speed of the signal transmission module is above 10 Mbps.The system can collect the EEG signals and store it.So the expected function can be basically realized.