156B Week 5 Progress

MAE 156B Project Update

Week 5: 04/26/15 - 5/02/15

Team 8:

Nerve Gripping

1. OVERVIEW AND PROJECT STATUS
  1. Tested Prototypes
    1. Clamp (3D Printed)
    2. Piercing wafers (3D Printed)\
    3. Clamping Mechanism -- In Progress
      1. Initial Setbacks: Fractured Snap Fit, Anomalous Delayed Curing, Uncompressed Cure Resulting in Lack of Suture Adherence
  2. Began Brainstorming Improvements
  3. Draft 01 Initialized
2. LATEST ACCOMPLISHMENTS

- 1. Received Laboratory Access Badges
  2. Received Consultation on Micromilling
    1. Rafaella - Calit2 nano3 Machine Shop
      1. Time is major issue - must start training ASAP
        Optimistic Forecast as per Machinist: 3 - 4 Weeks
      2. Upfront training costs - $240

- - - - Limited to 2 trainees

- 1. 1. 1. Must purchase own bits from vendor
  2. Contacted other Machine Shops with Micromills

- - 1. Kenneth - SIOMS
      1. Need to send drawings before meeting

- 1. Updated Team Webpage

- - 1. Placed emphasis on front page

- 1. First Draft of Final Report
  2. Gained Access to Microscope that Interfaces with Computer

- - 1. MAE 171A lab room
    2. Allows taking screenshots to use in reports/presentations

- 1. Results from Initial Prototype Testing

- - 1. Clamp works well, but difficult to tighten
      1. Found the force it takes to make the nerve slip on the clamp
    2. Microbarb layer worse than default surface roughness

- - - 1. Decrease density, but increase overall height

- - 1. Sutures had difficulty staying in place in composite wrap

- - - 1. Guidelines etched alongside of male component to secure sutures during compression.

1. GOALS FOR NEXT WEEK

- 1. Perform Tests on all Prototypes
    1. Compare tensile forces at various weave elongations for finger trap
    2. Compare tensile forces needed for slip with various strap down lengths/screw turns
    3. re-prototype the suture/PDMS polymer
  2. Develop a reusable, durable mold for replica nerves
  3. Narrow Down Material Considerations
  4. Purchase Required Materials
  5. Considerations for Attachment to Stainless Steel Backbone
  6. Get heat shrink sample

1. SPONSOR COMMENTS

- 1. Effect of Nerve’s Stickiness on Friction
  2. Make surface less fine, but rough
    1. Less microbarb density, but greater overall height
  3. Securing and Placement of sutures in composite wrap.

1. INSTRUCTOR COMMENTS

- 1. Method of Testing Compressive Force/Stress
    1. Decided to measure strain, then using Hooke’s Law to find stress
      1. Use image analysis to measure change in area of cross section
      2. or use difference in major/minor axes of cross section

1. CURRENT PROJECT RISKS

- 1. Need to Find Biocompatible High Friction Materials
  2. Methods to Bond Gripping Mechanism to Stainless-Steel Backbone
  3. Need to Find Biocompatible with slow transient property degradation (Stiffness)
  4. Consider Size and Feasibility for Surgeon

1. NEEDED RESOURCES AND INFORMATION

- 1. Micro-machining Information
    1. Need to find resources on how to machine on our small scale
  2. Accessibility of proposed materials
  3. How well can the body handle heat (for heat shrink)

1. UPCOMING MILESTONES

- 1. First Draft of Report (May 1st)
  2. Set-up Team Homepage with Graphics and Introductory Text (May 1st)
  3. Proof of Concept Presentation (May 7th)

1. BUDGET UPDATE

- 1. $995.86 Parts Budget Remaining ($1000 Starting Budget)
    1. 3D Printed Parts
      1. $100.00 spent for UHD 3D Printer ($100 provided)
        Rate: $0.30 for model material, $0.60 for support material (all per gram)
        Need to verify with Chris on latest printed part
      2. $9.72 spent for lower-res 3D Printer ($100 provided)

- - - - Rate: $5.20 per cubic inch of material combined

- 1. 1. Supplies

- - - 1. $5 spent for presentation printing ($401.33 provided by class)
      2. $ 1.14 spent for the screws and bolts

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