Thesis

Design and Implementation of Electroencephalogram System

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Thesis

Design and Implementation of Electroencephalogram System

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Abstract

The EEG is important in the medical field. The EEG used to record the brain activities that are used in diagnoses strokes. Recently, the advancement in technology of the brain signals enabled the control of equipment that could help the disabled in their daily life such as wheelchair and robots. Now, mindwave and emotive epock are used in EEG Systems. The EEG recording systems play a major role in the Brain-Computer Interface machines where the brainwave signals are given as controls. There is development in transmission of these signals into different platforms based on the portability of applications. This thesis presents a virtual electronic system for measuring the EEG signals. The system consists of electrodes, instrumentation amplifier, filters and a DAQ card with LabVIEW application on a personal computer. The system is developed for displaying, measuring, analyzing and recording the EEG signals. The system is practically implemented with success where the experimental results are verified with simulation results. Hence, the EEG system is developed in order to be portable. The portability is in the first step is based utilizing a data acquisition card DAQ and laptop. Our own system is a low cost system, since the LabVIEW plotter application is developed the EEG system. So, our main target is to design and implement a light weight EEG system with three electrodes. These electrodes are used to sense the signals on human brain which are produced by neurons. The main problems with the brain electrical signals are that they are very small. So, they have to be amplified with special amplifiers. Such amplifiers are called instrumentation amplifiers. These amplifiers are characterized by high gain and common mode rejection ratio in addition to high input impedance. With these specifications, human brain signals can be amplified to get the EEG signal. The filter circuits are also required to clean the contamination and artifacts in EEG signal. The EEG system is developed based on our design with DAQ card and computer. The system is a simple and low cost for acquiring the EEG signals. Chapter One: This chapter explains the importance of electroencephalogram and the development of medical instrumentation systems. Also, the evolution of smart systems is expressed in the medical instrumentation field. This chapter presents electronic system for measuring brain signals. The system consists of electrodes, amplifiers and filters with EEG plotter application is developed on a computer for displaying and measuring the EEG signals. A circuit was developed to amplify the low amplitude brainwave signals and a band pass filter to eliminate the unwanted frequencies. A DAQ card was used to convert the analog signals to digital signals and transmit them into the computer by using USB interface. Chapter Two: provides an overview of the previous researches in the EEG systems. Chapter Three: this chapter explains the design of the EEG circuit and Data Acquisition. Hence, a circuit is designed to amplify the EEG signals and to remove the noise. The EEG circuit consists of electrodes, amplifiers and filters, DAQ card for A/D conversion .A LabVIEW graphical user interface design which are interfaced to develop the prototype electroencephalogram system. Chapter Four: this chapter introduces implementation of EEG circuit on a PCB to reduce some noise in the EEG system and allow for smaller product. Only four resistors, two capacitors, two integrated circuits and three electrodes are used in our EEG circuit implementation. Also, a LabVIEW software is presented implementation where a LabVIEW application is developed for acquiring, controlling, measuring, analyzing, processing and saving the EEG signals on the computer. Finally, the thesis ends by extracting conclusions and stating future work that might be done based on this work. Keywords: Electroencephalogram (EEG), Data Acquisition (DAQ), Laboratory Virtual Instruments Engineering Workbench (LabVIEW).

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