ALS Breathing and Communication Suite

1. ALS Breathing and Communication Suite By: Alex Kim Alex Chirban Donald Ziems

2. Project Overview    Amyotrophic Lateral Sclerosis (ALS)     Degenerative Neurological Disease • Affects muscle control, voluntary and involuntary including muscles involved in respiration • Effects of ALS: • Loss of breathing control leads to eventual asphyxiation • Inability to communicate verbally • Loss of mobility     Proposed solutions: • Motorized vest to assist in breathing • Eye-tracking suite to enable communication and mobility • Text-to-speech by means of on-screen keyboard • Mobility by means of on-screen navigation controls

3. Currently Available Medical Solutions Iron Lung • Relies on negative pressure to expand and contract lungs • Patient confined to device for duration of "treatment" • Bulky and expensive • Requires wall power Hayek • Smaller and more portable than Iron Lung • Uncomfortable due to intense retching from extreme vacuum • Also very expensive  Medical Operations • Tracheotomy

4. Design Requirements Breathing Vest Mobile high efficiency negative pressure respiratory device which is more comfortable than available devices Monitoring of patient's vital signs in order to automate breathing control as well as integrate the ability to sigh and cough Eye-tracking Non-intrusive system with accurate controls Interface for user to communicate via text-to-speech and control wheelchair

5. Original Design • 4 - piece vest • Motors move pieces • Pieces press on chest • Based on Hayek

6. Original Design - Problems • Airtight seal not feasible • Extreme mechanical stress • Low margin for motion error • Uncomfortable • Complex mechanics

7. New Design • Central plate generates air pressure • Single motor operation • One moving part • Low mechanical stress • 3D printed - custom fit

8. What We Contributed • Motor Selection • Mobility • Breathing • Motor Driver • Safety • Eye Tracking • Pulse Oximeter • Power System

9. Motors • Stepper motors • Dual H-Bridge driver • 12V Lead-Acid Batteries for power • Lead screw linear actuation • Back-EMF slip detection • Controlled by Arduino • Speed, direction, and distance control • Only one motor needed • Two used to lessen load • 70W power consumed

10. Safety Pressure Monitoring • Constantly monitors pressure • Compares to ambient • Warning at 1.0 psi • Sounds audible alarm • Stops motors Battery Monitoring • Constantly monitors voltage • Passive components • Warning at 50% depletion • Calibrated to battery voltage under full load • Audible alarm sounds • Non-essential features shut down

11. Pulse Oximeter Development necessitated by lack of commercial pulse-oximeter option. Design based on traditional pulse oximetry. • Two LEDs (Red and IR) pulsed in alternation • Sensor detects intensity of light transmitted through deoxygenated and oxygenated blood • Blood-oxygen content dependent on relative intensities of transmitted light • Heart-rate resolved from calculation of time period between peaks of IR waveform

12. Pulse Oximeter Build • TSL230A Light Intensity to Frequency Converter IC used as sensor. • 940nm IR and 630nm Red LEDs • Repurposed potato chip-clip • Atmel ATMega328P • Processing.org software for interface

13. Pulse Oximeter Testing Tested for accuracy against commercially available Masimo pulse oximeter. Initial BPM tests found our oximeter to be within 10-12 BPM of the Masimo. Initial blood-oxygen content found to vary from 15% to 40% of the Masimo. Sensor initially exposed to ambient light which interfered with our readings After manufacture of clip, sensor was more isolated and gave us readings of BPM within 3-5 BPM and blood oxygen within 2-4%.

14. Mobility Control (Wheelchair unavailable) Dependent on eye-tracking for control. On-screen GUI provides user with options to move Forward or Reverse, turn Left or Right, and Stop. Design was never implemented due to lack of actual wheelchair.  However eye-tracking control scheme developed as proof of concept.

15. Inter-module Communication Arduino I2C library used to communicate between ATMega uControllers in a Master-Slave relationship. Data processed on laptop sent through serial over USB to master uController. Master acts as relay to the two slaves which control the breathing vest motor uController and wheelchair motor uController.

16. Communication Testing • Communication tested from master to each slave individually as well as to both slaves simultaneously. • Control signals monitored on oscilloscope to both devices. • Due to lack of wheelchair, LEDs used to simulate output of transmitted control signals to the wheelchair uController • Vest pump control (both rate and depth of stroke) successful with I2C communication from master uController • Failsafe included in message encoding in case of emergency or due to reception of invalid messages

17. Eye Tracking Image credit:  www.eyewriter.org PS3 Eye camera with custom lens and infrared filter Proper illumination provided by USB powered IR LED array Can be mounted on laptop Open source software for calibration, text-to-speech, and cursor control Custom user interface for navigation of motorized wheelchair Hardware based on low-cost design available at http://www.eyewriter.org

18. Challenges • Power Budget • Battery powered system • Energy efficient design needed • Timeline • Patient needed device sooner than anticipated • Patient Safety • Have to ensure patient will be safe • Many points of failure to be considered • Unanticipated changes/additions to design • Pulse Oximeter • Changes in Motor Control • Eye-tracking calibration issues • Limitations of uController (communication)

19. Successes and Future Recommendations Successes • Pulse Oximeter developed with no background • Eye-tracking calibration issues overcome • Communication achieved without extra hardware • Motors made to meet specifications of given design parameters Recommendations • Clear concept of design is crucial • Specifications for design necessary before selection of parts. • Further research of available options for pulse oximeter, eye-tracking, and emergency systems recommended

20. Experiences with Interdisciplinary Design Team Positive experiences: • Exposure to real-world design problems outside of ECE • Part fabrication • Evolution of design • Inter-group collaboration • Multiple perspectives add to robustness of design Challenges: • Communication between groups and team members • Differing levels of involvement and commitment between different teams • Different scheduling for different teams • ECE team underrepresented in weekly group meetings • Out-of-scope expectations

21. Questions?