Biofeedback and Stress Management John Harrison – Leader Albert Kwansa – Communicator Eric Lee – BSAC Brenton Nelson – BWIG Dr. Daniel Muller – Client Dr. William Murphy - Advisor

Client Introduction Dr. Daniel Muller from the Institute of Aging, Mind Body Center. Dr. Daniel Muller from the Institute of Aging, Mind Body Center. Meditation - anything that keeps attention in the present Meditation - anything that keeps attention in the present Meditation as an alternative medicine Meditation as an alternative medicine –Epilepsy –Addictions –Mood disorders –Stress reduction

Background Information Beta waves Beta waves –Alert Alpha waves Alpha waves –Relaxed Theta waves Theta waves –Drowsy Delta waves Delta waves –Sleep Last updated: 3/6/05 Hevern, Vincent W. PhD 10µV

Problem Learning to meditate can be difficult Learning to meditate can be difficult –Meditation is a learned practice –Learning can be difficult with no feedback Learning device that provides brain state feedback to aid learning Learning device that provides brain state feedback to aid learning –Measure brain waves to provide brain state feedback

Design Overview Detection of brain wave with electrodes Amplification and filtration of the brain waves Converting the amplified/filtered waves into user feedback signal

Project History Electrode selection and placement Electrode selection and placement Output up to ~5V Output up to ~5V Audio or visual feedback Audio or visual feedback *Signal interference *Signal interference

Problem Design Statement This semester, the group will focus on the amplification and filtration of the raw signal obtained by the detection electrodes designed by previous semesters’ groups.

Client Specifications Biofeedback Biofeedback Recreational use Recreational use Simple Simple Inexpensive Inexpensive Portable Portable

Device Parameters Amplification Amplification –Gain 100,000 (10  V –> 1V) –Low # of parts Filtering Filtering –Band-pass filter –Alpha and theta waves

Circuit Design Preliminary Amplification Preliminary Amplification –Small amplification –Manipulatable voltage Filtration Filtration –High-pass and Low-pass filters->Band-pass filter Main Amplification Main Amplification –Interpretable voltage

Preliminary Amplification Common-Mode-Rejection Ratio (CMRR) Common-Mode-Rejection Ratio (CMRR) Differential Signal attenuation Instrumentation Electrocardiogram (ECG) OP AMP Electrode 1 Electrode 2 Electrode 3 R1 R2 R3 R4 R5 R6 R Electrode 1 Electrode 2 Electrode 3 OP AMP 1K5K 1K 500 1K

Filtration (Band-pass filter) First-order Filter Simple Low fall-off value Second-order Filter Complex High fall-off value 15.9K 159K F F + - R2 C1C2 R1 R3 1 0f1f1 f2f2 f (Hz) Gain 1 0f (Hz) Gain f1f1 f2f2 OP AMP

Main Amplification Non-inverting Amplifier Non-inverting Amplifier –Provides remaining gain required + - 4M1K OP AMP

Proposed Circuit Electrode 1 Electrode 2 Electrode 3 OP AMP 1K5K 1K OP AMP Total Gain = 100,000 Alpha Signal Theta Signal F159K 15.9K F 265K OP AMP 1K4M F 26.5K 1K4M 1K Preliminary AmplificationBand-pass FiltersMain Amplification Gain = 25Gain = 4000Alpha = 10 Hz Theta = 6 Hz F

Testing Build circuit and test with signal generator Build circuit and test with signal generator Test on heart with gel electrodes (ECG signals) Test on heart with gel electrodes (ECG signals) Test on brain with gel electrodes (EEG signals) Test on brain with gel electrodes (EEG signals) Compare the obtained data to professionally accepted data Compare the obtained data to professionally accepted data Integrate circuit with previous semesters prototype Integrate circuit with previous semesters prototype

Future Work Move on to signal processing Move on to signal processing Biofeedback Device Biofeedback Device Final Testing Final Testing Q u e s t i o n s ?