EEG Biofeedback Team Cullen Rotroff Andrew Eley Prakash Rao Joseph Hippensteel BME 400 October 27th 2006 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 Overview Problem Statement Background Design Constraints Proposed Designs Future Work Questions 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 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 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 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 Brain Wave Frequencies Brain Wave Frequency State of Consciousness 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 DeepTranquility Optimal Meditative State DELTA Below 4 Hz Sleep Unaware DeepUnconsciousness Brain Wave Sample 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 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 http www sciencekit com category asp Q c E 737808 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 Project Flowchart Primary Focus Future Work Electrodes Pre Amplifier Active Electrodes Bio Amplifier Main Stage Bio Amplifier and Filtering Voltage Controlled Oscillator Biofeedback Headphones 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 http bhgcoleman1 trustpass alibab a com product 10948731 Gold EEG Large Electrode Cup html http www rochestermed com Electrodes htm Electrode Design Active Electrodes Use Ag AgCl substrate First stage amplification moved to electrode site http electrodesales stores yahoo net tsd150a h tml 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 Electrode Comparison Weight Active Fabricated Active Purchased Passive Cost 5 4 1 5 Production 3 3 5 5 Power Consumption 2 4 3 5 Safety 2 4 4 5 Noise Reduction 5 4 5 0 Maintenance 3 5 5 5 Total 95 80 74 75 Circuit Flow Diagram filter Amplifier DRL 4 8 Hz filter 8 13 Hz Electrodes amplify rectifier averager rectifier averager voltagecontrolled oscillator audio output 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 Bio Amplifier Amplification Instrumentation Amplifier High input impedance High CMRR Gain 25 Driven Right Leg Used as reference point Lowers commonmode voltage Bio Amplifier Filtering Theta LP fc 8 Hz Alpha BP BW 9 7 12Hz Gain 4500 for both channels 5th order Filter Frequency Response Bio Feedback Signal Conditioning Rectify signal Average signal Voltage Controlled Oscillator VCO Translate voltage to audible frequency 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 Questions 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 310 57 60 Kabat Zinn J Massion AO Kristelle J Peterson LG Fletcher KE Pbert L Lenderking WR Santorelli SF Effectiveness of a meditationbased stress reduction program in the treatment of anxiety disorders Am J Psychiatry 1992 149 936 943 Electrode Placement Primary activation during meditation Fp1 Fp2 F3 Fz F4 O1 O2 Aftanas and Golocheikine 2001
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