Development Of Synchronous EEG Stimulation System

The brain is the most important organ of the human body.It deals with activities related to consciousness,spirit,language,learning and memory.It is the material basis of higher neural activities in the human body.Therefore,the study of human brain activity is of great significance to the development of human science.EEG is an important charac-teristic of neuron discharge in the brain,which can be indirectly understood by studying EEG signals.In recent years,some researchers have used weak direct current to stimu-late the brain,which can cause a biphasic,polarization-dependent change in the cerebral cortex,resulting in short-term changes in the brain.At the same time,micro-current stim-ulation technology is gradually used in clinical medicine to assist the treatment of related diseases.The electric stimulation technology also has the positive significance to the brain science research.At the same time,the study found that the electrical stimulation showed a post-effect mechanism,and the influence of the post-effect of electrical stimulation on the brain activity became weaker over time.Therefore,this paper designs and makes a synchronous EEG electrical stimulation system,which can complete EEG acquisition and stimulation tasks synchronously,or perform two tasks on a time-sharing basis.This paper finally designs and manufactures synchronous EEG electrical stimulation equipment,which has such basic functions as EEG acquisition,impedance detection and electrical stimulation.The EEG acquisition part was designed as an eight-channel syn-chronous EEG acquisition system with unipolar lead,and the EEG electrodes were wet Ag/AgCl electrodes.The EEG acquisition amplifier adopts the integrated simulation front end for data acquisition.The gain and sampling rate of the collector can be flexibly ad-justed through the program,and the sampling rate is up to 16 KHz.You can select one channel at a time to display and analyze the data on the LCD,and all the channel data will be saved in the TF card of the system,or can be uploaded to PC through bluetooth for sav-ing.Impedance measurement used the same interface with EEG collection,but it could not work at the same time.The impedance measurement part measured 8 active elec-trodes,1 reference electrode,1 ground electrode,10 electrodes in total.A threshold value can be set during impedance detection to facilitate the experimenter to conduct impedance processing.Electrical stimulation has a variety of stimulus types,including tDCS,tACS,tRNS,etc.The whole system makes electrical connection between EEG collection and impedance detection,and at the same time,it isolates the circuit directly contacted by hu-man body from the actual power supply,so as to ensure the safety performance during use.In order to ensure the performance of the system and to complete the manufacture of the synchronous EEG electrical stimulation system,this paper carried out the testing and experimental verification of various indicators.In this paper,the parameters such as common-mode rejection ratio,noise,system bandwidth and amplifier gain of EEG module are tested.At the same time,the accuracy of the resistance network of the impedance mea-surement system is tested.Secondly,we test the current output accuracy and load capacity of the current source.In addition,spontaneous and induced EEG signals were collected to verify the feasibility of the system.Finally,the synchronous EEG stimulation experiment based on P300 was carried out in this paper.The test results showed that the synchronous EEG stimulation system designed in this paper met the expected synchronous EEG stim-ulation system,and could effectively improve the efficiency of electrical stimulation and EEG collection.