Design of a Wheelchair-Mounted Transfer Assist Device University of Pittsburgh Senior Design – BioE 1160/1161 Michael Anderson Andrew Feola Jill Marion Bryan Shelly April 18, 2006 Mentors: Alicia Koontz, PhD, RET Jeremy Puhlman, BSE

Wheelchair Patients Have trouble transferring from chair Bed, toilet, sofa, etc. Must carry bulky transfer boards, benches Background

Current Solutions Transfer boards, benches Wall and ceiling-mounted devices Portability Issues! Our goal To design a modified wheelchair armrest such that a transfer assist device is contained within the armrest

Market Analysis- Frost and Sullivan North American Mobility Aids Market Manual Wheelchairs 313,000 units in 2001(standard) 77,000 units in 2001 (lightweight) 313,000 units + 77,000 units = 390,000 units * $60 /unit= $23,400,000 market for our product to be used on manual wheelchairs Frost and Sullivan, 2001

Lightweight manual wheelchairs $102 million/ 77,000 units in 2001 $130 million in 2008 Sunrise Medical Quickie II 30% of market 0.3 * 77,000 = 23,100 units 23,100 units * $60/unit = $1,386,000 $1,386,000 market for our product to be used on the Quickie II model Market Analysis- Frost and Sullivan Frost and Sullivan, 2001

Home Healthcare Market (US) $2.03 billion-devices in homecare (2001) $1.23 billion- home durable medical equipment (1999) Market Analysis- Frost and Sullivan Frost and Sullivan, 1999, 2001

Growth rate of home healthcare market- 14% due to: Increasing number of elderly (baby boomers) Medicare moving toward covering at home treatments/devices more than in hospital Improvements in technology Allows greater number of medical procedures/monitoring to be done at home Frost and Sullivan, 2001 Market Analysis- Frost and Sullivan

Design Requirements Armrest converts into a transfer board Fit in space occupied by standard armrest Weight < 10 pounds Provides same comfort as standard armrest Able to support up to 250 pounds

Original Design

Final Design

Our Prototype

Prototype Fabrication Human Engineering Research Laboratory Wire EDM Aluminum 6061 Alloy (prototype) Mass Production Plastic Injection Molding High-density polyethylene

Finite Element Analysis Maximum displacement =.006 inches Minimum factor of safety = 3.2

Experimental Methods Validate FEA results Protocol – both ends supported Digitize a point (no load applied) Apply load Digitize same point (with load applied) Compute displacement

Experimental Testing

Experimental Results FEA testExp. test **All units are inches

High-density Polyethylene Maximum displacement =.37 inches Minimum factor of safety = 1.4

Standard Transfer Board Maximum displacement = 0.4 inches Minimum factor of safety = 1.1

Survey Results Eight (8) volunteers 7 use transfer boards 3.9 / 5 difficulty rating of current boards 4.75 / 5 aesthetic rating of our product All 7 would prefer a transfer board that does not need to be carried

Competitive Analysis Transfer bench Invacare transfer bench $120 Carex transfer bench $300 Standard transfer board Allegro Medical wooden board ~ $37 per unit Therafin Theraslide transfer board $100 per unit Our device Plastic Injection Molding $50-60

Competitive Analysis Strengths Price Comparable to current transfer boards Portability Minimal additional weight Weaknesses Limited armrest adjustability One sliding mechanism

Constraints—Testing Human factors Lack of human subject testing Falls, etc. Production Material availability Testing done on aluminum, not plastic Economic Cost of prototyping Only one prototype

Manufacturability Considerations Simple Design Ease of injection molding Standard shapes Lack of small, irregular pieces Ease of mass production

Human Factors Considerations Standard transfer material Patient can slide easily across board Cushioning consistent with standard armrests Handles in transfer board No sharp edges

FDA Regulation CDRH website Sec Wheelchair accessories Includes armrests, transfer boards Class I device

Individual Project Work Jill Marion Contact companies and patients Market Analysis Prototype testing DHF, SBIR Mike Anderson SolidWorks design Prototype testing COSMOSWorks analysis DHF, SBIR Andrew Feola SolidWorks design COSMOSWorks analysis Prototype testing DHF, SBIR Bryan Shelly Material selection DHF, SBIR Manufacturing

Project Timeline

Future Considerations Human subject testing Additional sliding mechanism Armrest height adjustability

Acknowledgements Alicia Koontz, PhD, RET Jeremy Puhlman, BSE Alexis Wickwire, BS Human Engineering Research Labs Pittsburgh Life Sciences Greenhouse University of Pittsburgh BioE Dept. A generous gift from Dr. Hal Wrigley and Dr. Linda Baker

Thank You Questions?