Manotech Associates Initial Prototypes April 5, 2006 Jina Kim Forrest Liau David Lin Teresa Wang
Presentation Overview Project goals (review) Current prototype Next steps
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
The Four-Step Process
Materials Initial Mold Solid Hand Reversible Mold Wax Plaster of Paris Brushable latex rubber Prosthetic Hand Silicone rubber Polyurethane foam
Schedule & Prototype TODAY
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
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
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
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 nm
Testing Result
Costs
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
Questions? Manotech Associates