Week 10

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

• • Casted two PDMS devices so far.

  • Testing done to validate seal integrity and as per Murphy's Law, nothing works. 

  • Printed out seals to test using water pressure method. Found out Ian Seals from week 1 works. 

  • There was uncured PDMS on the surface that were in contact with our mold. There is a problem with the PDMS cure, even though we left it in the oven for hours at high temperatures. They only cure when it's in contact with air. 

  • Emailed Dr. Monica Kim from UCI about this issue and she said it may be cure inhibition from our molds. The material the mold is made out of prevents the PDMS catalyst from working on the surfaces touching the mold. She said that this is a common issue with resin based printer, which is what our molds were made on, but it doesn't happen with filament based printers. This agrees with what we have observed. Our first test mold was made from PLA and it molded perfectly.

  • Emailed Dow Cowning where we bought the Sylgard 194 PDMS resin and they emailed back documents about cure inhibition and how to troubleshoot it. 

  • Solutions include spraying a primer, preheating the mold to get rid of the materials, or a surface treatment with some material that is compatible with PDMS. Some materials included Polyvinyl Alcohol (PVA).

  • Went to the submarine team cage to borrow PVA mold release and smeared it all over the molds to prevent cure inhibition. 

  • Casted a third PDMS device. 

Accomplishments from Previous Weekout

• • Printed final design mold out

  • Casted PDMS device from mold during the weekend.

  • Mold had wrong dimensions for the inner seal, and so a new part had to be printed out.

  • The casted part had a bad cure on the surface even though it was in the oven for a long time.

  • Decided with Dr. Kalmaz to go with pig testing in order to get the patent process done quicker instead of waiting for the IRB. 

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

• • Hopefully fix the cure inhibition problem. Otherwise, may have to print the inside rod that makes our cavity inside our device out of PLA. 

  • Get pig testing from hospital done.

  • Deliver as many devices as we could.

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

• • Dr. Kalmaz wants 10 devices on hand so she can test them whenever the opportunity arises with pig testing or cadavers. That way, she can prove to the patent department our device works and can be marketed.

  • We have casted 3 of them so far. Each cast is getting better. Still trying to prevent the cure inhibition problem.

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

• • Pig testing is a possibility and Mr. Gillet will look into pig testing from his friend in Philadelphia.

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

• • Cure inhibition problem. Need to fix it for a good finish.

  • Seals need to be fixed or else the device won't work.

Resources or Information Required but not Available

• • n/a

Schedule

• • fix cure inhibition

  • cast more devices properly

  • fix seal

  • all done next week.

Budget (list amount spent and amount remaining)

Progress on Report and Webpage