Skull Cap Requirements Skull Cap Requirements PresentationPresentation

Group 5

Engineering 4017 - Engineering Design

Project OverviewProject Overview

General DescriptionGeneral Description

What is EEG? Why is the

information being collected?

Refer to the following webpage http://www.epub.org.br/cm/n03/tecnologia/eeg.htm

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Mission StatementMission Statement

The reliable measurement over extended periods of scalp EEG

on consecutive occasions during mental function in everyday environments.

Existing SystemExisting System

Skull cap containing electrodes with wired connection.

Requires extensive preparation of scalp for usage.

System must be operated in a shielded environment.

Issues with Existing Issues with Existing SystemSystemLack of repeatabilityLack of mobilityLong setup timeShort length of experiment

before the results are affected by external factors

Requirement StructureRequirement Structure

Priority System– Essential - Match existing functionality

and/or core customer requirements– Highly Desirable - Extend the

functionality of the system and are achievable in the available time frame

– Desirable - May not be achievable in the available time frame & further research is required

Electrode PositioningElectrode Positioning

EssentialPosition 23 electrodes on the

skull according to the 10/20 positioning convention– 19 scalp electrodes– Two eye electrodes– Reference electrode– Isolated common

Signal ProcessingSignal Processing

EssentialProcess electrode signals to

make them suitable for input into customer’s existing computer system.

Experimental Experimental RepeatabilityRepeatabilityEssentialAbility to position system on

subject on subsequent occasions so that electrodes are within 1mm2 of original position.

Acceptable Noise LevelAcceptable Noise Level

EssentialNoise from external

electromagnetic fields and undesired physiological rhythms must be less than 1% of the recorded EEG signal.– E.g. power line hum, heart beats

Sampling SpecificationsSampling Specifications

EssentialRate: 1kHzResolution: better than .15VRange: ±400mV

Skull ImpedanceSkull Impedance

EssentialSkull impedance must be

reduced below 5k for the purposes of electrode measurement.

Scalp IrritationScalp Irritation

EssentialBased on ISO 10993-10,

irritation should be reduced to a level such that less than 2% of subjects experience irritation (as defined in the standard).

Highly DesirableHighly Desirable

Less than 1% deviation of data due to electrode polarisation.

Easily cleanable to medical grade cleanliness in accordance with Australian Standard AS 4187/1998.

Signal compensation for up to 0.05Hz of signal drift.

Highly Desirable, cont.Highly Desirable, cont.

Suitable for use on persons of different head dimensions, within the range of 53 to 60 centimetres head diameter as measured above the ears.

Possible to position system on subject's head within 15 minutes.

DesirableDesirable

Exist as a portable system that can operate for up to three hours without interruption.

Ability to transfer signals from the patient to a monitoring terminal without the need for physical connection.

Ability to select a subset of the EEG monitoring electrodes.

Desirable, cont.Desirable, cont.

Ability to select different sampling rates for data collection.

Suitable for use on wider range of adult head dimensions and extending to smaller sizes for children.

ConclusionConclusion

Requirements may be changed after consultation with the client

From these requirements, conceptual designs will be generated and evaluated, with the successful design being further refined into a final product design.

Refer to the Group’s Website - http://www.angelfire.com/il/skullcap/

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