1. EEG Biofeedback Team: Cullen Rotroff, Andrew Eley,
Prakash Rao, Joseph Hippensteel
BME 400
October 27th, 2006

2. Client: Dan Mueller, Ph. D
Client: Dan Mueller, Ph.D. Medicine (Rheumatology) Institute on aging, Mind-body Center Advisor: Professor Willis Tompkins, Ph.D. Dept. of Biomedical Engineering University of Wisconsin

4. Overview Problem Statement Background Design Constraints
Proposed Designs
Future Work
Questions

5. Problem Statement To Design and build an inexpensive, portable
electroencephalogram (EEG - brain wave
monitor) that teaches meditation practitioners
to achieve optimal meditation by indicating
the presence of EEG alpha and theta waves.
This shall be achieved through a relatively
inexpensive, minimally distracting, and
potentially portable device intended for
commercial use.

6. What is Meditation
In pop culture/alternative medicine, meditation is a technique for achieving “inner peace”.
Allows access to a naturally-occurring rest state.
Different from sleep, in that rest via mediation is much deeper and happens more quickly.

7. Benefits of Meditation
Spiritual Enrichment
Facilitates Creative Awareness
Psychological Benefits
Increased Patience
Heightened Sensation
Reduced Stress (Kabat et al. 2001)
Improved Stress Recovery
Increased Response Time
Decreases Recovery Time from Illness

8. Physiological Response to Meditation
Decreased metabolic rate
Decrease oxygen consumption (up to 20% below normal level)
Lowered heart rate
2 less breaths per minute on average
Decreased levels of lactate (linked to anxiety symptoms), cortisol, and epinephrine
Raise skin resistance
Increased blood flow
Presence of Alpha (8-13 Hz) and Theta waves (4-7 Hz).

9. Brain Wave Frequencies
Brain-Wave Frequency
State of Consciousness
Brain Wave Sample
BETA: above 13 Hz
Fully-Awake, Alert, Excitement, Tension
ALPHA: 8 to 13 Hz
Deeply-Relaxed, Passive-Awareness, Composed
THETA: 4 to 7 Hz
Drowsiness, Unconscious, Deep-Tranquility. Optimal Meditative State
DELTA: Below 4 Hz
Sleep, Unaware, Deep-Unconsciousness

10. Product Requirements Small in size, simple in design (like an iPod)
Portable
Low cost (~ $100 - $200)
Provide auditory feedback that won’t disrupt meditative state
Long-term: Marketable

11. Competition Computer automated EEG biofeedback
Expensive (range from $1,200 - $6,000+)
Non-portable systems
Superfluous detection abilities
GSR (Galvanic Skin Response) biofeedback
Conductivity of skin to indicates stress level
Prices average ~$100.00
Less reliable than EEG
biofeedback

12. Competition AUTOGENIC AT62 PORTABLE EEG Alpha and theta filter
Dual audio feedback modes
Signal proportional Pitch change
On/off threshold verification
Visual ‘Lightbar’ display varies with brainwave state
Real Time EEG display
$1,550.00

13. Project Flowchart {
Primary Focus {
Future
Work

14. Electrode Design Passive Electrodes
Traditional EEG electrodes
Ag/AgCl Standard
Also available:
Tin, Silver, Gold
No amplification
Requires low impedance skin contact (Electrolyte gel)
Easy to clean
Price: ~$6 per unit (
a.com/product/ /Gold_EEG
_Large_Electrode_Cup.html

15. Electrode Design Active Electrodes
Use Ag/AgCl substrate
First stage amplification moved to electrode site
Tolerates higher impedances if desired
Shortens skin preparation time
Lessens potential for electric shock
Improves signal clarity
Diminishes 60 Hz noise
Reduces problems with capacitive coupling
Very expensive commercially (cost up to $395 per electrode)

16. Electrode Comparison Weight Active (Fabricated) Active (Purchased)
Passive
Cost 5 4 1
Production 3
Power Consumption 2
Safety
Noise Reduction
Maintenance
Total 95 80 74 75

17. voltage-controlled oscillator
Circuit Flow Diagram
q filter
(4-8 Hz)
rectifier+ averager
voltage-controlled oscillator
audio output
Amplifier/DRL
a filter
(8-13 Hz)
rectifier+ averager
Electrodes/amplify

18. Bio-Amplifier Raw signal is noisy and on the order of microvolts
Need great amplification and fine-tuned filtration
Typical specifications for EEG Amplifiers:
Gain: 4-5 dB
2nd order BP filter

19. Bio-Amplifier Amplification
Instrumentation Amplifier
High input impedance
High CMRR*
Gain: ~25
Driven Right-Leg
Used as “reference point”
Lowers common-mode voltage

20. Bio-Amplifier Filtering
Theta LP – fc = 8 Hz
Alpha BP – BW = Hz
Gain ~ 4500 for both channels, 5th order

21. Filter Frequency Response

22. Bio-Feedback Signal Conditioning
Rectify signal
Average signal
Voltage Controlled Oscillator (VCO)
Translate voltage to audible frequency

23. Future Work Validate bio-amplifier design
P-Spice Simulation
Bread-board prototype
Fabricate final bio-amplifier
Complete active electrodes
Finalize Bio-feedback design
Integrate all components
Clinical testing with subjects

24. Questions?

25. References
Aftanas LI and Golocheikine SA. “Human anterior and frontal midline theta and lower alpha reflect emotionally positive state and internalized attention: high-resolution EEG investigation of meditation.” Neuroscience Letters 2001;
Kabat-Zinn J, Massion AO, Kristelle J, Peterson LG, Fletcher KE, Pbert L, Lenderking WR, Santorelli SF. “Effectiveness of a meditation-based stress reduction program in the treatment of anxiety disorders.” Am J Psychiatry 1992;

26. Electrode Placement Primary activation during meditation Fp1/Fp2
F3/Fz/F4
O1/O2
(Aftanas and Golocheikine 2001)