Design of a Wheelchair-Mounted Transfer Assist Device

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

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

3. 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

4. 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

5. Market Analysis- Frost and Sullivan • 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 Frost and Sullivan, 2001

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

7. Market Analysis- Frost and Sullivan • 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

8. 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

9. Original Design

10. Final Design

11. Our Prototype

12. Our Prototype

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

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

15. 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

16. Experimental Testing

17. Experimental Results **All units are inches

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

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

20. 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

21. 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

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

23. 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

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

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

26. FDA Regulation • CDRH website • Sec. 890.3910 Wheelchair accessories • Includes armrests, transfer boards • Class I device http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPCD/classification.cfm

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

28. Project Timeline

29. Future Considerations • Human subject testing • Additional sliding mechanism • Armrest height adjustability

30. 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

31. Thank You • Questions?