1. Manotech Associates Initial Prototypes April 5, 2006 Jina Kim Forrest Liau David Lin Teresa Wang

2. Presentation Overview Project goals (review) Current prototype Next steps

3. Vision & Mission Vision: Provide a method for producing an anatomically user-matched prosthetic hand for low-income communities Mission: Design a prosthesis fabrication process that a) creates a shape-matched hand and b) uses materials that are inexpensive and processable by the community

4. The Four-Step Process

5. Materials Initial Mold Solid Hand Reversible Mold  Wax  Plaster of Paris  Brushable latex rubber Prosthetic Hand Silicone rubber Polyurethane foam

6. Schedule & Prototype TODAY

7. Prototyping Process 1. Make plaster solid hand from wax mold 2. Lubricate solid hand 3. Brush layers of latex rubber 4. Lubricate reversible mold 5. Reverse reversible mold 6. Patch defects using superglue 7. Reinforce reversible mold by filling with water and then dipping into wax 8. Reshape reversible mold as needed 9. Pour-in prosthesis underlayer material

8. Improvements Needed Increase space between fingers Improve latex brushing technique Wait until layer is dry before applying new layer Apply thin, even layers Adjust orientation to compensate for gravity Use deeper wax-heating container Find method for holding molds with minimum distortion

9. Key Challenges Securing the solid hand and adjusting its position continuously while applying latex rubber Applying uniform layers of latex rubber Preventing distortions during mold reversal

10. Test Observation and Setup Load Cell = 1000lb = 5kN Rate Grip Separation = 50 mm/min High extension = 200 mm Problems: -Slipping -Bubbles -Making the samples Break Detection-Load level= 0.02 kN Gauge length ~60mm Break at 171.23 nm

11. Testing Result

12. Costs

13. Next Steps Tensile testing of latex rubber Do layers and brush techniques affect mechanical properties? Hardness test of prosthesis material Method for attaching prosthesis to arm Instruction manual Final prototypes Field test Survey general population for feedback

14. Questions? Manotech Associates manotech@mit.edu http://web.mit.edu/3.042/team2_06/