EMG Biofeedback Device

1. EMG Biofeedback Device BME 200/300 Fall 2003 Department of Biomedical Engineering University of Wisconsin-Madison

2. Introduction • Team Members: Tom Chia Jason Ethington Tim Rand Kim Treml Brent Geiger

3. Introduction • Client: Arleigh Birchler MDiv, BSN • Advisor: Professor John Webster

4. Presentation Overview • Problem statement/description • Background • Client requirements • Subgroup Presentations -Proposed designs -Final design solution -Potential Problems

5. Problem Statement • The goal of the project is to design an EMG biofeedback device to allow a patient with Lissencephaly to exhibit some physical control over their life • Measure, amplify, and process EMG signal to provide physical and cognitive stimulation

6. Background Lissencephaly Malformation of the Brain Causes Vary Symptoms Severe Mental Retardation Poor Control of Movement Frequent Seizers Pneumonia

7. Background • Description of Child • Occasional C-posturing • Responsive to tactile stimuli (touch/vibration/heat) • Very limited muscle control • Fully developed limbic system -Full range of emotions -Ability for operant and/or classical conditioning • Confined to chair

8. Background The Chair • Padded guards stabilize the child’s chest. • Shoulders above the guards, arms on either side

9. Client Requirements Feedback triggered by EMG signal Vibration triggered by only voluntary muscle contractions Timer to control duration of vibration Vibrating pad comfortable for continuous use Processor to record activity of device

10. Proposed Design Solutions • Subgroup Presentations

11. EMG Biofeedback Device Proposed Design Solution Brent Geiger Jason Ethington

12. Basic Circuitry Analog vs. Digital Advantages: Advantages: • Programmable • Memory/data storage • Allows for logic/learning operations • Ideal for more complex circuit operations • Simple • Inexpensive • Easy to build and test • Ideal for simple activation and deactivation of massage pad

13. Basic Circuitry Analog vs. Digital Disadvantages: Disadvantages: • Complex • Require programming experience and expertise to design and build • No memory • Perform only one function • No logic/learning applications

14. Basic Circuitry • Simple analog circuit design chosen -Time Constraints -Limited experience with digital circuitry • Digital Circuit basis for future work

15. Analog Circuit Design • Function - Detect Voluntary EMG Signal - Activate massage pad for set time period - Terminate massage after period expires

16. Analog Circuit Design

17. Analog Circuit Design • EMG Amplifier – Common biosignal amplifier • Rectifier – Passes only positive signal component • Low Pass Filter – Outputs steady DC signal • Comparator – Compares signal with prescribed reference voltage • Timer – Terminates massage after set time period • Triac – Activates massage pad

18. Design Variables • Placement of Electrodes - Detect only Voluntary Movement - Large Muscle - Easy to apply • Options - Thigh muscle - Bicep - Calf

19. Design Variables • Massage Pad - Fit in child’s chair - Cause no discomfort/irritation - Easy to maintain • Options - Purchase commercial pad - Design and construct own pad

20. Final Design • Analog Circuit • Electrodes on Thigh • Build our own Pad AnalogCircuitry Vibrating Pad Electrodes

21. Potential Problems • Pending agreement of child’s mother to allow testing • Irregular EMG signal

22. Future Work • Design Circuit Schematic • Select and order circuit components • Build and test circuit on breadboard • Buy massage pad and modify • After circuit test order and build design on circuit board