Colon project

Discussion in 'Show off' started by Henry feldman, Nov 4, 2016.

  1. Henry feldman

    Henry feldman Well-Known Member

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    So I am working on making a colon. No not the 2 dots, the thing that bring poop from your small intestine out. No this isn't some weird fetish, (well it is but that's my job) as we are working on a rapid turnaround surgical practice mannequin for practicing surgical techniques. So step one was figuring out how we can mold a complete colon, so given that it is a complex folded tube with really thin walls, we decided on cast silicone (plus we have mastered all the different tissue types out of silicone). So step one was making a mold with a center that could dissolve, so made the core of the colon out of Scaffold. Printed like a dream, and the piece is super smooth. The molds are printing now, and will add those to the thread when ready (and then the cast piece)

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  2. R Design

    R Design Well-Known Member

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    That's one giant turd you printed!
     
  3. mike01hu

    mike01hu Well-Known Member

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    Scatology aside, that is impressive. Who is it modelled on, not Mr Trump is it? :D
     
  4. Henry feldman

    Henry feldman Well-Known Member

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    Update: Here is the mold outside (PLA/PHA) with the inside piece from above (Scaffold) in place. @mike01hu this is just a test of the mold. Next we will use a "virtual colonoscopy" (which is a specific 3D reconstruction our PACS system does with CT scans of the abdomen) and will do it for sections of the colon (A real colon is way, way to big for the printer since it is about 60-70cm long)

    [​IMG]
     
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  5. mike01hu

    mike01hu Well-Known Member

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    A really lateral thinking exercise for using scaffold. I suspect there are many other out there who will be interested in the outcome.
     
  6. Spoon Unit

    Spoon Unit Well-Known Member

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    Once set, won't the silcone just roll up over an off the inner core without having to dissolve it?
     
  7. Henry feldman

    Henry feldman Well-Known Member

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    For a straight section that might be sort of possible, although your colon has Haustra which are partial walls that stick out perpendicular into the middle, and some sections like the sigmoid are a loop.

    Our real goal is to print interlocking sections and pour as one giant single piece (otherwise if you wanted to put in a colonoscope the sections would come apart)
     
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  8. Henry feldman

    Henry feldman Well-Known Member

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    So massive progress today on the tech proof of concept: Sorry a lot of pics, but this was pretty cool:


    Molds ready to go (ended up using some crayola mold clay to caulk around the bottom opening). Dark gray = scaffold, light gray = PLA/PHA. In the future the mold locator pins need to be big blocky things, not 5mm pins which are easily stuck together.
    [​IMG]

    Filled the molds with skin tinted silicone (this one in "very fast") using a feeding-tip syringe
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    Cracking the mold (a little lube might have helped here, pretty tacky onto PLA) using a malleable retractor and a scalpel
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    Melt the core out using hot tap water (yes in this test we could clearly have just rolled it down, but when the tube is 60cm long with curves, no way), Softened in about 30 seconds, and the infill dissolved in about 2 minutes, then we were able to crush the tube and pull it out)
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    Looked amazing out of the mold (the frilly stuff is actually intentional, although we need to make it slightly thicker - that's the mesentery which is filmy between the loops of bowel). I real life it tears easily too, but this probably needs to be twice as thick
    [​IMG]

    We then put a colonoscope into it to see how it looked and how it moved relative to how we expected
    [​IMG]

    And on the screen looked pretty good (not anatomically correct, but this was not a model of a real colon yet)
    [​IMG]
     
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