Parylene deposition, diy feasible?
  • ThomasEgiThomasEgi October 2016
    Hi folks!

    after reading a lot about parylene used for magnet coatings (which apparently had mixed results) and it's general use in medical applications I was wondering about the difficulties to do parylene deposition in a DIY way.

    From what I read up it involves heating a granual base chemical so it sublimates, then heating the resulting gas to perform pyrolysis  followed by guiding the gas into the deposition chamber. Everything done in a somewhat moderate vacuum environment.

    Some surfaces apparently need priming for proper adhesion of the deposited parylene but other than that, the process seems reasonably straight forward. A vacuum pump, 3 chambers heated at different temperatures and a single chemical don't appear like rocket science to me.

    So did I miss something important? Are there any common pitfalls? Does anyone have the equipment to hack up something like that?

    Having a working deposition process may allow for fun ways to coat magnets. For example having the magnet suspended free floating in the chamber to get seamless and uniform coating. Or for coating other implants too. Like smallish electronics, which could be sealed with epoxy which qualify only for short-term implantation (as safeguard) and a parylene coat on top of it.
  • CassoxCassox October 2016
    Thomas I intend to come back to this so I'm bumping it.
  • It's been a while and I've been more or less silently been working on stuff.
    First of all it seems that not only parylene but also certain epoxy types from AtomicAdhesives are potential candidates for a diy coating process (as I learned from others on the IRC channel)

    One of the apparent difficulties is to get an even and thin coating free of seams and defects.

    I took some inspiration from youtube and hacked together a prototype for levitating the the sort of tiny magnets we deal with (levitating bigger ones is comparebly easy).

    Picture of the first prototype can be found  HERE  (sry for the imgpaste but my webhoster decided to terminate services after 16 years of free operation).

    The control circuitry is not shown in the pic (it's boring anyway and needs improvement). I still need to fix a couple of shortcommings to make it easier to set up and operate. But it can keep the magnet floating in mid air for indefinite time. The disc magnet in the picture is about 3.5mm diameter and 0.8mm  thick.

    With this we could already get a seam-free coating for parylene. Epoxy is a bit more difficult to apply evenly without dripping/noses. My initial idea was to produce epoxy mist using ultrasonic spray nozzles and expose the levitated magnet to it for a defined period of time. Those do exist for industrial processes but they are prohibitively expensive.

    More ideas on getting coatings on the magnet would be welcome. The magnet levitation works in full vacuum and slight air motion is not a problem (gently blowing against it makes the magnet swing a bit but it won't fall). Strong and/or rapidly changing magnetic fields would be problematic as it would interfere with the elevation control. 

    ps: i am building a less frankensteiny version of the hardware these days.