Electroencephalogram signal acquisition in unshielded noisy environment

Fatoorechi, Mohsen (2015) Electroencephalogram signal acquisition in unshielded noisy environment. Doctoral thesis (PhD), University of Sussex.

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Researchers have used electroencephalography (EEG) as a window into the activities of the
brain. High temporal resolution coupled with relatively low cost compares favourably to
other neuroimaging techniques such as magnetoencephalography (MEG). For many years
silver metal electrodes have been used for non-invasive monitoring electrical activities of
the brain. Although these electrodes provide a reliable method for recording EEG they
suffer from noise, such as offset potentials and drifts, and usability issues, e.g. skin prepa-
ration and short circuiting of adjacent electrodes due to gel running. Low frequency noise
performance is the key indicator in determining the signal to noise ratio of an EEG sensor.
In order to tackle these issues a prototype Electric Potential Sensor (EPS) device based on
an auto-zero operational amplifier has been developed and evaluated. The absence of 1/f
noise in these devices makes them ideal for use with signal frequencies ~10Hz or less. The
EPS is a novel active electrode electric potential sensor with ultrahigh input impedance.
The active electrodes are designed to be physically and electrically robust and chemically
and biochemically inert. They are electrically insulated (anodized) and scalable. These
sensors are designed to be immersed in alcohol for sterilization purposes. A comprehensive
study was undertaken to compare the results of EEG signals recorded by the EPS with
different commercial systems. These studies comprised measurements of both free running
EEG and Event Related Potentials. Strictly comparable signals were observed with cross
correlations of higher than 0.9 between the EPS and other systems.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Subjects: R Medicine > RC Internal medicine > RC0321 Neurosciences. Biological psychiatry. Neuropsychiatry > RC0346 Neurology. Diseases of the nervous system Including speech disorders
Depositing User: Library Cataloguing
Date Deposited: 28 Jul 2015 15:26
Last Modified: 28 Jul 2015 15:26
URI: http://sro.sussex.ac.uk/id/eprint/55034

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