156B Week 1 Progress

MAE 156B Project Update

Week 1: 03/29/15 - 4/04/15

Team 8:

Nerve Gripping

1. OVERVIEW AND PROJECT STATUS
  1. List of different concepts for two design mechanisms
  2. List of materials
  3. Some strain data of the tested PDMS for the phantom nerve
  4. Refined Gantt Chart/Timing for deliverables
2. LATEST ACCOMPLISHMENTS

- 1. Completed Individual Component Analysis
    1. Aileen - Nerve clamp mechanism designs
    2. Johnathan - Potential materials for nerve clamp concept
    3. Daniel - Finger trap mechanism designs
    4. Fabian - Potential materials for finger trap concept

1. GOALS FOR NEXT WEEK

- 1. Mix and test more PDMS for the phantom nerve
  2. Complete Nerve Surrogate
    1. Identify PDMS ratio most resembling nerve material properties
    2. Construct nerve-shaped mold for PDMS curing
    3. Perform analysis to estimate coefficient of friction of live nerve
  3. Narrow Down Nerve Gripping Designs

- - 1. ~2 “nerve clamp” concepts
    2. ~2 “finger trap” concepts
    3. Possible combinations of the two concepts
    4. FBD’s for all concepts
    5. Plan for determining all forces in designs

- 1. Create Friction Testing Process

1. SPONSOR COMMENTS

- 1. Presentation Remarks
    1. Introduce key statistics to show severity of problem
    2. Show pictures of severed nerve
    3. More clearly define what the challenge is
      1. Slide on Wallerian degeneration
    4. Reds and Yellows project poorly for presentations
    5. Compare current nerve repair solutions (grafts) to Dr. Shah’s solution
  2. Other Remarks

- - 1. Data on Poisson's ratio of nerves can be found in available research

1. INSTRUCTOR COMMENTS

- 1. Unclear Presentation Aspects
    1. Nerve growth objective: Pull severed proximal end of nerve stump a certain amount each day to stimulate nerve growth.
    2. Status of treatment: Currently tested on lab rat sciatic nerves
    3. Problem of current approach (grafts): Costly, require removal of existing tissue from somewhere else in the body
    4. Viscoelastic model: During experimentation, the nerve strain and strain rate (compute rate) was low, so the nerve was assumed to be linear
    5. Friction test: Plan on fabricating friction testing device
    6. Tapered design: Explain how this design works
  2. Deliverables and Fundamental Requirements Clarification

- - 1. Deliverables
      1. A nerve gripping mechanism that interfaces with the current stainless-steel backbone and can reliably grip on the proximal stump of a severed nerve
    2. Fundamental Requirements

- - - 1. Grip nerve with enough compressive force for no slip
      2. Distribute compressive load so compressive stresses do not "kill" the nerve
      3. Must be biocompatible and fit within injury setting

- 1. Project Definition Clarification

- - 1. What Is Already Completed
      1. Stainless steel backbone to support the gripping mechanism
      2. Stainless steel hypotube for gripping mechanism to slide along backbone
    2. What Needs to be Improved

- - - 1. Current gripping device is a spiral cuff and suffers from a telescoping effect when being tugged
      2. Need to design a better gripping mechanism than current cuff

1. CURRENT PROJECT RISKS

- 1. Must find biocompatible materials
  2. Size constraints
  3. Friction considerations and testing

1. NEEDED RESOURCES AND INFORMATION

- 1. Other materials needs to be researched for gripping mechanism

1. UPCOMING MILESTONES

- 1. Week 2 - Finish identifying nerve substitute
  2. Week 3 - Create nerve substitute
  3. Week 3 - Narrow down to designs we’ll try to analyze/prototype

1. BUDGET UPDATE

- 1. Remaining budget:
    1. Equipment & parts: $1000
    2. Machine shop: $500
      1. Nothing has been purchased

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