In-vivo EEG Signal Extraction, Noise Analysis And The Optimization To The In-vitro Biomembrane Electrical Impedance Testing Platform

The electrophysiological signal of human nerve,refers to the electrical activity of an individual or an isolated organs,tissues,cells and others.In practice,electrodes,patch clamps and other devices can be used to record or measure such signals for the research of function and mechanism.In the laboratory research and clinical application,use nerve electrophysiological techniques through the study of electrical signals in vitro and other parts of the human body to research the role and function of human part in the hole body,measure the isolated tissue,cell electrophysiological signal of the specific region in vivo to study its structure and function.EEG signals are obtained from the brain's scalp or cerebral cortex to through contact electrodes in a specific mode of electrical activity signals to study the role the brain play in the entire individual;in order to research the functions of some specific regions,use the brain slices,brain cell population or single neuronal cell as the study object.EEG acquisition vivo is to use electrode to acquire EEG signals and process it in the computer,then response to consistent reaction which includes the operation of the arm,the cursor movement on the display and so on.As for the research of electrophysiological signals in vitro,usually use the electrodes to collect the electrical signals of isolated neuronal cells and tissues,analyze their electrochemical parameters to study their functions and physiological activity state as well as comparison and analysis.In this paper,aimed at the EEG signals,they were sampled from an experimenter's scalp when the experimenter was reading different kinds of books(closing eyes,reading English books,reading poems and reading modern Chinese).Then HHT transform(Hilbert-Huang Transform,HHT)and Support Vector Machine method were used to train and distinguish the model of closing eyes and other three kinds of reading patterns.Finally,the algorithm is optimized because of its frequent phenomenon-end issue that occurred during the Empirical Mode Decomposition and the results were analyzed.There are two methods to acquire EEG signals which are in vivo and vitro.Before establishing the EEG signals analyzing mode base on big data,it needs data acquisition and analysis of feature point data of electrophysiology test including specific neuron group or brain slices.The advantages of electrophysiology signal test is that it is separated from the individual organism and experiments are conducted in the unit of tissues or cells.Also,in vitro they can be cultured,expanded the number,which can make the sample of data is enough to collect useful information.But the biggest problem is that the contact distance between electrodes and brain slices or neuron will be limited by the electrodes' material,the characteristics,the way of surface treatment and others.So,in the study of vivo electrophysiology,we firstly need to evaluate a quantitative model of contact between the vivo electrode and the biomembranes.Therefore,for the important medium of EEG signal acquisition-electrodes,the paper used the electrochemical methods including cyclic voltammetry,chronoamperometry,Ac impedance method of the bare gold electrode and evaluated the electrodes' characteristics.Then research the efficient area of attachment between the electrodes and biomembranes during measurement.According to the simulation of attachment state of electrodes and biomembranes,measured the electrochemical impedance and established the equivalent circuit from the effect of electrodes in the measurement system.After that fit the impedance parameters and established a model of Support Vector Regression whose input is impedance parameters,output is electrode radius to study quantitatively the attachment area and the biomembranes and evaluate the attachment between electrodes.Above all,in order to evaluate the attachment state between the real cell membranes and electrodes,nerve cells were cultured on the NC membrane,and electrochemical impedance experiments were carried out by using different area electrodes with electrodes to make the structure of cell-NC membrane-electrode structure.And analyzed and compared relationship between different electrochemical impedance plots whose electrodes is different.The final results validated the effectiveness of the simulated electrode-nerve cell attachment experiment,and the possibility of using electrochemical methods to study isolated brain cells,tissue in vitro.The experiment result and theory can provide the basis for point model in vitro after EEG signal processing in vivo with analysis of quantitative parameters.