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Proof of Concept Presentation

Group 12: Development of Cutting Edge Instrumentation for Vision Preserving Surgery

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Hans Chen

Joanne Low

Quinn Mullineaux

Hanieh Seilsepour

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Overview & Problem Definition

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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Vision Preserving Surgery

Image Sources:

[1] Xue, X., Zhou, C., Gao, Y., Ji, X., & Zhang, X. (2023, January 6). Optic nerve sheath fenestration for visual impairment in cerebral venous diseases. Frontiers. https://www.frontiersin.org/articles/10.3389/fneur.2023.1065315/full

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1) Procedure - Optic Nerve Sheath Fenestration

Figure 1 : Step- by Step illustration of optic nerve sheath fenestration

Presenter: Hanieh

Team 12

3-4X

incision

Eye

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Current Status

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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Presenter: Quinn

Team 12

First Prototypes & Iterative refinements

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Sponsor Feedback and Cadaver Lab Results

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Design for Manufacturing

Image Source: Adobe Stock, Medical Images https://stock.adobe.com/search?k=clipart+medical

Progress - Iterative Refinement Method

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High Risk Components

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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Presenter: Hans

Team 12

  • Snap-on Configuration
    • Manufacturing/ injection molding risk
    • Functionality

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  • Head of Tool
    • Material
      • Moldable
      • Biocompatible and meets standards
    • Size constrained by orbital bone

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Figure 2: Snap in head model

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Key Decisions

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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Presenter: Hans

Team 12

  • Material Choice
    • Pebax
    • Nylon

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  • Placement of Light Source
    • LED light source placed near base
    • Fiber optics transmits light to head

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  • Type of Snap-On Configuration

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Proof of Concept Results

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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Presenter: Joanne

Team 12

Current Design

Tested in Cadaver Lab

  • Fits within geometric constraints of eye socket and surgical slit
  • Can retract eye fat

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Sponsor Feedback

  • Handle angle optimizes visibility
  • 2-part design good for size variation

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Analytical Methods Used

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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Presenter: Quinn

Team 12

Main Areas of Analysis

Numerical Methods: Stress Concentration

Goal: Quantify stress & strain fields

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Assumptions:

1) Static Loading

2) 11.7 N load (applied in -y) at tip

  • From: “as hard as you can push with a pencil grip”

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Analytical Method:

Finite Element Analysis via Ansys Simulation

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Goal: Quantify Snap Force

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Assumptions:

1) Deflection only in tool “head”

2) Cantilever style snap joint

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Analytical Method:

Standardized Analytical approximations of deflection and engagement force

Areas of concern

Analytical Methods: Snap Fit Engagement Stress

Equations:

h

y

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l

Permissible Deflection (y):

Engagement Force (W):

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Results

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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Presenter: Hans

Team 12

Permissible Deflection (y):

PEBAX Property

Value

Permissible Strain (ε)

15%

Deflection Force (P)

9N

Friction Coefficient (𝜇)

0.23

Interface angle(𝞪)

45°

Secant Modulus (Es)

700 Mpa

Engagement Force (W) from deflection force (P):

Source: Pebax in Medical Applications, PEBAX https://www.fostercomp.com/wp-content/uploads/2018/11/Pebax-in-Medical-Applications.pdf

ANSYS Simulation→

Snap-in Force Calculation ↓

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Remaining Questions and Unresolved Issues

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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  • Eyelid incision creates functional limitations

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  • Fiber Optics Implementation

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Presenter: Hanieh

Team 12

Image source: https://www.snexplores.org/article/scientists-say-fiber-optic-cable-definition-pronunciation

Figure (3): ONSF process

https://link.springer.com/chapter/10.1007/978-3-030-13558-4_12

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Purchasing Timeline for Major Components

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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Purchase Handle Material

Purchase Light Source Component

Presenter: Joanne

Team 12

Purchase Pebax

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Manufacturing Timeline for Major Components

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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Injection Mold Head (Pebax)

Manufacture Handle (316 SS)

Presenter: Joanne

Team 12

Implement Light Source

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Gantt Chart

JACOBS SCHOOL OF ENGINEERING | Mechanical and Aerospace Engineering

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Presenter: Hanieh

Team 12

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Acknowledgements

UC San Diego Health - Shiley Eye Institute

Dr. Bobby Korn

Eman Al-Sharif

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Department of Mechanical and Aerospace Engineering, UC San Diego Prof. Jerry Tustaniwskyj

Prof. Nicholas Gravish

Prof. David Gillett

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