Non-Contact EEG Active Multielectrode Hardware Design

Author: Scheina Yelena Gonzalez Duran

Gonzalez Duran, Scheina Yelena, 2018 Non-Contact EEG Active Multielectrode Hardware Design, Flinders University, College of Science and Engineering

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Abstract

The electroencephalogram (EEG) is a widely employed method of measuring electrical activity

of the brain for medical diagnosis and research. This electrical activity is generated a few

centimetres below the electrode employed in the measurement. As a result of this, the cortical

current must travel across different resistive levels causing a blurring effect of brain activity at

the scalp. Furthermore, spatial smearing occurs from the necessary use of a reference electrode

to measure the potential difference. An important method utilised to improve EEG spatial

resolution is the surface Laplacian. There are various methods that have been used to improve

EEG poor spatial resolution in the past. The tripolar concentric ring electrode (TCRE), is an

electrode that was developed to improve the surface Laplacian and consequently improve poor

spatial resolution. The first part of this thesis involves the design and assembly of a non-contact

segmented capacitive TCRE. This new design seeks to improve not only the surface Laplacian

and the noise ratio also seeks to increase the communication rate of the EEG and detect and

distinguishing of motor and sensory input from the body. For verification a filter stage was

designed and tested the reliability of the signal acquired. Some problems occurred during the

experiment showing that there was an analogue floating input that affected the signal acquisition.

The second stage of the thesis was dedicated to designing the digitalisation, control, and

communication system of a BCI. To achieve this, the circuits and PCBs of this stage including

AFE and BLE were designed. It was not possible to test this design as time constraints of the

project did not allow for its assembly.

Keywords: Non-Contact, EEG, Active Electrode, Capacitive electrode, Tripolar segmented active electrodes

Subject: Engineering thesis

Thesis type: Masters
Completed: 2018
School: College of Science and Engineering
Supervisor: Professor David Powers