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EEG Monitoring System The EEG Porto-Cap Team 5 ENGN4017 - Engineering Design Autumn 1999.

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Presentation on theme: "EEG Monitoring System The EEG Porto-Cap Team 5 ENGN4017 - Engineering Design Autumn 1999."— Presentation transcript:

1 EEG Monitoring System The EEG Porto-Cap Team 5 ENGN Engineering Design Autumn 1999

2 Design Process Examine project domain –EEG measurement systems Meet with intended customer –Dr Richard Clark, Flinders University SA Identifying problems with existing skull cap system –Requirements for new system were formulated Develop conceptual solutions to problems –Brainstorming Project Decomposition –Sub-system groups focussing on specific problems Integration –System integration Presentation, Final Report March June

3 What is EEG? EEG = Electroencephalogram Measurement of brain wave patterns in hopes of understanding the mysteries of the mind.

4 Problem Statement The reliable measurement, over extended periods, of scalp EEG on consecutive occasions, during mental functions in everyday environments.

5 Key Problem Areas Lack of repeatability Different Head Sizes Long setup times Difficulty with lengthy experiments Use of conductive gels Scalp abrasion Noise in signal Lack of portability/environmental constraints Issues that needed to be addressed in any new system developed by the group: In finding a solution, we have taken an ambitious approach to solving these problems in a medical research application

6 Problem Decomposition

7 Key Requirements M e c h a n i c a l

8 Cap Design M e c h a n i c a l

9 Positioning Nasion/Ear reference points Adjustable straps for different head dimensions (53cm - 66cm) Electrodes retractable to suit M e c h a n i c a l Nathan in an early model. Current model.

10 Demonstration of Skull Cap Setup... M e c h a n i c a l

11 Key Requirements E l e c t r o d e

12 Electrode Selection Silver/silver chloride selected –Minimal polarisation characteristic Dry electrode used (no gel required) –Uses local impedance converting amplifier Pellet electrode, 2mm diameter –Small electrode size ensures good hair penetration and contact with scalp 2mm E l e c t r o d e

13 Irritation Issues Initial model- helmet supported by electrodes Prototype - straps support the load –allows smaller electrodes to be used without increasing irritation –straps allow for more comfortable fit No preparation or abrasion of skin surface required E l e c t r o d e

14 Cleaning Electrodes detachable for cleaning Cleaning processes include disinfecting and sterilisation via autoclave Use of two sets of electrodes allows continuous use E l e c t r o d e

15 Key Requirements S i g n a l s

16 Components S i g n a l s

17 Signal Flow S i g n a l s

18 Signal Flow S i g n a l s

19 Signal Flow S i g n a l s

20 Signal Flow S i g n a l s

21 Signal Flow S i g n a l s

22 Other Features EMF Shielding –Faraday cage –Cable shielding Auto-Zero Function –Remove constant DC offset introduce by electronic components S i g n a l s

23 Areas of Further Research Gauging depth of electrodes Improving setup time Ag/AgCl dry electrodes Electrode polarisation Effectiveness of Faraday cage Noise analysis Artifacts from physiological rhythms

24 Manufacturing Materials Cost Total - around US$4k –Mechanical - US$100 –Electrode - US$2300 –Signals - US$1800 Prototype materials - estimated US$50k

25 Why you should upgrade to the Porto-Cap... Wireless communication – no huge cables to lug around, you are free to walk around the house just like with a cordless phone. Data recorded from each different electrode is clocked at exactly the same instant – at last, a device which accurately maps which bits of your brain that werent working during that embarrassing moment. No scalp preparation required – the feeling of blunt needles scraping your scalp will only be remembered in your nightmares. Porto-Cap uses dry electrodes only – that gooey conducting paste can now be used as axle grease. Zero signal drift – the amplifier and filter package has been hand picked so that the only interruptions during a testing period will involve rubble entering your building. Eight selectable sampling frequencies – if flexible data rates is you, then you wont die hungry when wearing the Porto-Cap.

26 Conclusion The EEG Porto-Cap successfully enables repeatable and reliable measurements of EEG signals. It achieves this with little discomfort, no paste or gel and in conventional environments.

27 Thank you for coming, we would like to take this opportunity to answer any questions you may have. Team 5 ENGN Engineering Design Autumn 1999

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