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Multi-Chamber Programmable Air Cushion (MC-PAC)

Multi-Chamber Programmable Air Cushion (MC-PAC). Joli-A Kabamba Masahiro Ohno Scott Paik Joe Suarez. Pressure Ulcer (Bedsore). Tissue damage caused by restricted blood flow, friction, and shear force.

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Multi-Chamber Programmable Air Cushion (MC-PAC)

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  1. Multi-Chamber Programmable Air Cushion (MC-PAC) Joli-A Kabamba Masahiro Ohno Scott Paik Joe Suarez

  2. Pressure Ulcer (Bedsore) • Tissue damage caused by restricted blood flow, friction, and shear force. • Affect ~500,000 people in US hospitals. When combined with other conditions, mortality is two to five times higher than patients without pressure ulcers. • Prolonged hospital stay up to 5 times longer than patients without pressure sores. Stage 2 Pressure Ulcer Stage 4 Pressure Ulcer [1] http://www.hcup-us.ahrq.gov/reports/statbriefs/sb64.jsp Picture courtesy of the National Pressure Ulcer Advisory Panel (NPUAP)

  3. Pressure Ulcer (Bedsore) Christopher Reeve died in 2004 from heart failure due to the septicemia caused by the pressure ulcer. [2] Septicemia – A condition in which the bloodstream is overwhelmed by bacteria. Symptoms include organ failure and blood pressure drop. [2] http://www.apparelyzed.com/pressuresores.html

  4. Project Summary • The cushion with automatic distribution of individual air cell pressure • Based on the suggestion from Shepherd Spinal Center to reduce occurrence of pressure ulcers on paraplegic patients in wheelchairs • Sponsored by Texas Instruments Analog University Design Competition • Expected cost of $2,000.00

  5. Technical Objectives

  6. Example System Packaging • System is compact enough to be packaged on motorized and unmotorized wheelchairs 14” 14”

  7. Project Photo Air control block Pressure Cushion Power Supply Air Pump UI Board Pump Driver Pressure Sensing Amplifier Display Module Switch Board Debug Interface MSP430F1612 MCU

  8. MSP430 CPU Peripherals

  9. Valve Selection and Description Valve cartridge Manifold and fitting Servo motor Original Valve NOT used • Integrated Air control and Sensor Manifold saves space and reduces number of electrical components

  10. Pump Selection Ryobi portable air compressor

  11. Pressure Cushion Sealing We welded the channels shut using a re-flow station from the lab Original cushion had passages Interconnecting cells

  12. Sealing Improvisation Reflow station was used with small tip @ 200°C and then passage was clamped shut until bonded

  13. Pressure Cushion Intakes

  14. Pressure Sensing • Freescale MPX2202 Sensors are used to monitor pressure readings from the individual cushions • Typical air cell pressure is shown to be about 10-20 psi. • Set Gain = 100 to read up to 50psi using Texas Instruments INA333 Precision Instrumentation Amplifiers • At 10 psi, +/- 20% reading accuracy • High inaccuracy possibly caused by sensor grounding issue. Currently troubleshooting to obtain higher accuracy

  15. Algorithm Description • Two main state: Manual and Autopilot • Manual mode • Enable control buttons • Allowing to Inflate /deflate on each cell • Autopilot mode • Disable control buttons • Load Configuration every period

  16. Control System Flow START Toggle SW? H Manual Mode SW Read L Open valves Autopilot Pressure read Pump ON Open valves Pump ON Pressure Read

  17. User Interface Implementation • Debug and tracking purpose • TeraTerm – Terminal emulator • Log and track instructions and data • ASCII data TxD from MSP430 • AVR 8-bit MCU controlled16x2 LCD • Same function as TeraTerm • But simpler for user

  18. User Interface in Prototype • TeraTerm • Console • 16x2 LCD • AVR controlled

  19. Portability and Battery Life • Portability • Cushion can be installed on the wheelchair seat, with control elements mounted on the frame • Device weight is under 20lbs without the 12V battery • 12V car battery weighs approximately 40 lbs. • Battery Life • Current draw with pump ON : 2 – 5 Amps • Current draw with pump OFF : 40 mA • Using 100Ah battery, Usage life is expected to be 60 hours

  20. Portability and Battery Life 5 A 40mA

  21. System Performance Testing • Short Term Testing • Individual components tested and functioning • User comfort testing, to be done • Long Term Testing • Pressure mapping to test performance of different operating modes • Long term efficacy in pressure sore reduction / prevention

  22. Manual/ Auto Demo

  23. Problems and Solutions

  24. Development Cost

  25. Production Run Cost • 5,000 units for 5 years

  26. Recommended Future Work • Pump: Select low noise pump, and small in size that can fit in the cushion package • Improve UI display, use touch / tongue control or eye track • Cushion material resilient to damage • Add moisture and temperature sensors to increase device capability • Select light material when designing cushion to reduce weight • Add air cooler to the system to keep the skin dry

  27. Questions?

  28. Appendix 1

  29. Appendix 2

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