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

The Pressure Ulcer Problem Tissue damage caused by restricted blood flow, friction, and shear force Found on 12.3% of all hospitalized patients. 4% of patients die from it Prolonged hospital stay up to 5 times longer than patients without pressure sores Picture courtesy of the National Pressure Ulcer Advisory Panel (NPUAP)

MC-PAC Programmed system to control distribution of individual air cell pressure in the cushion Based on 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 price: $2,000.00

Design Objectives Provide automated means of pressure relief for wheelchair bound Minimize risk of friction, shear force on skin Maximize user comfort Easy to use Operate on 12V battery

Technical Objectives Maintain pressure in air cells at set levels Remap contact pressure distribution on cushion periodically, as suggested by NPUAP Use microcontroller to display status of each air chamber Pressure configuration changeable by user via intuitive user interface (UI)

MC-PAC Block Diagram Microcontroller (TI MSP-430) User Interface Cell Pressure Sensors Air Pump 5x5 Air Valves 5x5 Air Cells Air Release Air Intake Signal Air

PRESS? HI LOW OK Pressure Regulation Algorithm Algorithm is programmed to maintain set pressure in individual air cells CHECK SENSOR (X,Y) DELAY PRESS HI LOW OK DUMP SOME AIR ADVANCE (X,Y) COUNT HI LOW OK DONE LOW START

Sequential Control

Control Panel User Interface consists of three switches and one knob User can stop/switch cycle, or change cycle time Control panel displays cell status Display PowerHold Next Cycle Timer

Parts Acquired for Project Build Pressure sensors 5x5 Air Cushion Air Valve Air Pump MSP430 Launchpad MOSFET Switches

Design Challenges / Alternatives Number of Cells More cells better for user comfort Up to 25 cells controllable by single MSP430 microcontroller Difficulty to construct custom cushion Cell sealing challenges Project time constraints

Development Cost Project Component Labor Hours Labor Costs Equip. Costs Total Cost Algorithm Coding160$6, Simulation160$6, Code Debugging80$3, Pressure Control Device Design50$2,000.00$200.00$2, Cushion Design150$6,000.00$300.00$6, Prototype Product Design (Tech Demo)200$8,000.00$1,407.97$9, Final Product Design (Improved Prototype)200$8,000.00$1,500.00$9, Testing, Demo Preparation160$6, Lecture / Group Meetings300$12, Total Labor1460$58, Fringe Benefits and Overhead $113, Total Parts Cost ($) $3, Project Total $175,621.97

Production Run Cost Production ItemCost Development Cost per Unit$35.00 Assembly Labor (2 hr)$40.00 Testing Labor (1 hr)$20.00 Customer Support (5 hr)$ Fringe Benefits (30% of Labor)$48.00 Production Equipment ($500,000)$ Material Cost$ Overhead and Sales Expense$ Selling Price$ Profit Per Unit$ ,000 units for 5 years

Components Selected, Tested, Integrated Semiconductor switches (TI) Air compressor (Ryobi) Pressure transducer (MSP-2202-ASX) Solenoid Valves (GEMS-M-SERIES) Air Cushion (ROHO MOSAIC) MCU (Texas Instruments MSP430)

Project Milestones March 25 th : Modify ROHO seat cushion. March 28 th : Mount the sensors and valves to the air regulation block. April 4 th : Complete circuits and wiring harnesses April 18 th : Develop and calibrate the MCU algorithm. –Control inflation and deflation of cells.

Future Improvement Graphical Display Touchscreen. More air cells, moisture control, and temperature control. Custom user pressure mapping interface. MC-PAC for car seats and beds. Make profile smaller, quieter, lighter, and more efficient.

Questions