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Parylene deposition, diy feasible?
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.
Comments
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Thomas I intend to come back to this so I'm bumping it.
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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.
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Hi Thomas-I'm interested in building a parylene coating system. Do you have any plans/clues on this?Thanks!Nick
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@nellens i have no such plans nor any knowledge on how to practically do it.
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since it's levitating, why not just spray coat with PDMS? way easier than trying to mess around with parylene
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Guessing not, but is the magnet able to rotate in its levitating bubble? :o
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it can rotate around its vertical axis. There's some minor roll/pitch vibration but you usually try to dampen it with a metal cage.
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That sounds perfect! ;0; Any chance you'd be willing to share your design? (Novice to electrical working, but good at following directions >~<) I'd love to start experimenting with trying to contribute to this stuff myself... But completely lost with how to get started on the electrical end of his application.
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just info on how to coat things in paraylene for anyone who interestedparaylene is something that's vapor deposited the video above explains how that works below is the Wikipedia page on CVD (chemical vapor deposition).gen info:
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@Zerbula just google for magnetic levitation devices. Look for the type with two analog output hall-effect sensors. They give the best/most stable results. For small magnets you need to add a metal cage (aluminum/copper) to stabelize the magnet. The rest is setting up the PD controll parameters and you'r done.@chironex if PDMS is safe to implant and easy to spraycoat, why not. Guess treating the magnet's surface to make it properly wet would be critical.
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I am already talking to third party manufacturers and attempting to get my magnet coated in a layer of epoxy before the TiN layer however if any of you are interested in contributing to assisting in the development of high quality magnets send me a message.I am not looking to make profit off of the magnets, instead I am intending on using this project to fund biotechnology projects stemming from this one (I am researching a method of sensing anything with that's measurable or detectable) and because of this I am willing to give a healthy commission to anybody interested. The magnets will be sold for considerably under current market prices however I will make the commission large.
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..Why are you doing epoxy before TiN?
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Misslitty if you go on my thread and read my conversation with Cassox you'll get a basic explanation of galvanic corrosion. The epoxy layer is dielectric, meaning it is an incredibly efficient electric current insulator. This dielectric layer is required between TiN (Titanium + Nitrate) and the nickel layer so the magnet doesn't corrode from the inside out.Galvanic corrosion also occurs between the neodymium and the nickel however the iron and boron are close enough in nobility to not cause allot of corrosion. This is also a long term concern for magnets coated in any material that can cause galvanic corrosion including TiN.
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@thermalwinter um, what. where did you hear this? The main issue with the plain TiN coating is that it's near impossible to get a perfect TiN coating on a magnet. You'd be far better served by going for a secondary coating like parylene ontop of the TiN than trying to add a layer in between. that's asking for trouble in something that's already difficult to get right. Or if you're that worried about a galvanic reaction, do nickle-gold-TiN-parylene.
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@thomasegi ya it's biocompatible. @glims was doing some work with spray coating it onto stuff a while ago. your floating rig would make the process way cleaner. Also, as someone very familair with vacuum systems and chemical vapour deposition, I don't even want to try to do parylene cause the system is a pain to build. Unless you've got a tube furnace lying around that can take a vacuum, in which case, go ham. Also, it's pretty hot, which may demagnetize the magnet and make it fall. Generally when magnets are coated, they're heated and demagnetized first, coated, then remagnetized afterwords. leads to seam issues, but that's only because most coating are hot. if you go with spray coating you can skip that
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i am a medicine student from india
an uk based company is already selling biocompatible, hypoallergenic, titanium encased 12000-14000 gauss neodymium magnets but, they are big in size and cannot be implanted in fingers but, they can be implanted in palm or wrist or some other suitable area in body
we can contact this company to make biocompatible magnet encased in implant grade titanium or i would prefer the magnets to be coated in titanium gold because titanium gold is even more biocompatible beside that titanium gold is a magnetic material it can be magnetised it is attracted to magnets so it will protect the magnet from loosing its propertyhttp://www.healthandcare.co.uk/magnet-and-press-pellet-therapy/medimag-titanium-11mm-15mm-spot-magnets.html
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