Development of nitrogen doped graphene based electrophysiological data electrode and feasibility study for its use in ECG, EMG measurements

As a result of rapidly advancing technology, the use of electronic devices has become quite widespread today. As a result, new technologies and new materials have been rapidly found and put into use in this field. One of these materials is graphene. Especially with the increase in nanotechnology today, the use of graphene in the field of electricity and electronics has increased even more. In this thesis, it is aimed to develop new Electro Physiological Study (EPS) electrodes and to compare the signals obtained from the developed electrodes depending on ionic/electrical conductivity. For this purpose, eight different electrodes were developed within the scope of the study and the electrode used in the current market was used as a control group. The developed electrodes are; 1-Electrode with carbon fiber fabric coated on the gel of the existing Ag/AgCl electrode, 2-Electrode with ionic liquid added on the gel of the existing commercial electrode, 3-Electrode with graphene powder coating on the gel of the existing commercial electrode, 4-Electrode with graphene and ionic liquid mixture coating on the gel of the commercial electrode, 5-Electrode with graphene polyurethane and ionic liquid mixture coating instead of removing the gel of the commercial electrode, 6-Electrode made by adding ionic liquid on graphene and polyurethane coated electrode prepared by removing the gel of commercial electrode, 7-Electrode made by adding ionic liquid on graphite and polyurethane coated electrode prepared by removing the gel of commercial electrode, 8-Electrode made by adding ionic liquid on graphene and polyurethane coated electrode prepared by removing the gel of commercial electrode. In terms of electrical conductivity, signals were obtained from newly developed electrodes and existing electrodes and experiments were carried out. Experiments were also carried out by adding ionic liquid to the mixtures. Thus, in the thesis, ionic conductivity studies were carried out by adding ionic liquid to the mixtures, doping on gel, doping with ionic liquid without gel. All electrical conductivity and ionic conductivity and signals obtained were recorded, compared and the results were compared. Arduino set was used for signal acquisition from the electrodes. At this stage, signal acquisition and processing were performed with Arduino using AD8232 sensor. The data obtained was read from the serial port and saved. These data were recorded for 1 minute with a sampling frequency of 200 Hz for each electrode type. The recorded data were converted into signals via Matlab and plotted and analyzed. For the comparison of coated and uncoated electrodes, the data recorded from the existing commercial electrode was taken as a reference and compared and evaluated sequentially with the signals obtained from 8 types of newly produced electrodes. In the comparison study, the dimensions of the data were first equalized and then the mean square error and cosine similarity were calculated. Then, peak-to-peak amplitude analysis was performed to compare the peak-to-peak amplitude values and cross-correlation values were calculated, the maximum correlation amount was found and graphs were drawn. In addition, simulation was developed in the Comsol Multiphysics® program, which is used in many fields of engineering today. The electrical analysis of the electrodes was simulated and evaluated in the Comsol Multiphysics program. Commercial Ag/AgCl electrode was used as a control group. In vivo experiments were conducted as part of the thesis study. For this purpose, signal measurements were performed with the assistance of stimulators and electrodes. The signal measurements were carried out repeatedly in the form of signal acquisition only. Two-dimensional and three-dimensional arm design and anode and cathode simulation were performed using Comsol software. The signal results obtained from eight electrodes were compared with the signal results obtained from commercial Ag/AgCl electrodes. Matlab analysis results of the signals obtained from all electrodes were evaluated. As a result, the electrical conductivity of nitrogen doped graphene is quite high. Therefore, a more readable signal was obtained from JelveTozGrafen3, the electrode created by using this material. Likewise, the electrical conductivity of ionic liquid is also high and more distinct signals were obtained from JelveİyonikSıvı2, the electrode obtained by applying ionic liquid to the existing electrode.