156B Week 7

Overview of Status of Analysis, Design, Fabrication, Tests, etc.

• • Previous nozzle design did not work because two drilled holes are not on the same plane, so gas did not flow through the nozzle. Also design has holes that were too far apart for a 1mm x 1mm sample.

  • New design of flow splitter is made and we decided to use this as the final design. The new design combines multiple parts (arm, needle, nozzle attachment) into one piece.

Accomplishments from Previous Week

• • Previous design tested and confirmed dysfunctional

  • New flow splitter design ready for machining

Goals for Next Week (list names after each item). Use specific and measurable objectives.

• • CAD design modifications and CFD analysis on the flow splitter - by Thursday (Kuanren)

    • Create space for diamond knife movements

    • Create slot for mounting screw for future adjustments on distance between channel openings and sample

    • Avoid extreme angle cuts for easy manufacturing

    • Bigger radius for fillet at the tip of the splitter to avoid collision with base stage

    • Possible reversed design (upside down) to reduce the thickness of the bottom wall

  • Improve the draft of final report (Haonan)

    • Make correction based on the comments received

    • Add more content based on our progress

    • Remove content about failed designs

    • Rewrite “Final Design” section to reflect new design

  • Manufacture new design - by Friday (Dylan)

    • Program CNC file

  • Test new design - as soon as manufacturing is done, latest by Tuesday 5/22 (Edwin)

    • Perform standard gas injection test on a rat (brain, liver, or testes) sample, and compare it to previous results

    • Test without the knife for now

Sponsor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)

• • Tristan (5/15/18, in person)

    • Two layer tip design

      • Maybe reverse the design upside down so that the screw will not obscure the back scatter

      • CFD simulation in progress

      • Try aluminum foil as sealing layer

    • May use spacer to adjust the height of manifold

    • Don’t worry about diamond knife operation right now

Instructor Comments from Last Meeting and Actions Taken to Address these Comments  (indicate date of comments and if via email or in person)

• • Try using EDM machine on fabricating Titanium manifold(5/9/18, in person)

  • Extensive comments given on report draft, we will be fixing all of these

Comments from Other Students in the Class (indicate date of comments and if via email or in person)

• • N/A

Risks and Areas of Concern

• • Difficulties in machining

    • Two layers assembly requires high precision and extensive time

    • High risk in gas leaking

  • Possible that new flow splitter does not converge flows and not improve the result, we won’t know until testing is done

  • Since the new flow splitter confines the gas over the sample, the ionized gas may interfere the image

Resources or Information Required but not Available

• • N/A

Schedule

• • CAD model of new two layer design by Wednesday night

  • Due by Friday:

    • Prototype of two layer design

    • Revising report draft and updating webpage

  • Be ready to test newest design by Tuesday 5/22

  • Update Gantt chart.

Budget (list amount spent and amount remaining)

• • PEEK, $200

  • Machining at CRMS, ~$400 (waiting for exact quote from Bob)

  • Grade 2 Titanium,  1 inch wide, 1 ft long, 1/4 in thick, ~$43 (McMaster)

  • $4357 remaining

  • Potential manufacturing service from CRMS - $600 (Heavy workload, can’t start until Week 9)

  • Potential manufacturing service from Zera development (Based in Berkeley, relatively faster service)

Progress on Report and Webpage

• • First draft report finished

    • Improvements in progress

  • First draft team website finished

    • Will be updated once second draft of report is done