Sourcing silicone and using it as a bioproof coating.

The title sort of says it all, has anyone found any good source of silicone to use on implants?  Applied silicone has a $250 1 lb jar of a long-term implant type IIRC, but a pound seems like a lot for our purposes and that is a bit spendy, anybody know a more fitting solution?  I've seen some sources indicating that the main difference between temporary implant grade silicone and the long-term stuff is the liability structure of the companies selling them, does anyone have more knowledge of this?  I've even heard of peroxide curing silicones working well for implants at grinder definitions of 'well' (which fall short of medical definitions slightly) before platinum curing silicones were widely available.

So, does anyone have any thoughts?  What does Steve Hawarth use?


  • What is your setup? Buying silicone is easy. Applying it is more difficult. Spincoating, spray coating, drop casting? Do you have a vacuum oven? you need one of those.

    Personally, I believe silicone is inferior to many coatings. It just happens to be easy and got approval early. I know lots of people use it, but I work in a material science lab, different standards...

    That being said, the advice I can give you is that when you are sourcing your coating, you are not looking for silicone, you are looking for PDMS. Same thing, but how retailers refer to their product often denotes how good it is. Silicone is for tits and boats. PDMS is a medical coating. The most inert PDMS is the one that is just a simple backbone, a crosslinker, and an initiator. Most of the Silicone that you see has had other things added to it to give it other qualities. This is why we never do butt implants with silicone caulk...
    Of course, once you know this, you could in theory, just get the ingredients for PDMS and make your own custom batch, with the precise mechanical properties you want. But again, if you can do that, you probably know how to make something better than PDMS for implants...
  • doesn't PDMS belong into the group of silicone,too?
    And whether or not it's a good idea to use silicone for coating highly depends on the object to coat, the desired thickness etc. No reason to exclude this option just like that.
  • PDMS is silicone. It's just what people call it when they are being chemists instead of talking to the lay person. Searching for PDMS will get you a much different product than searching for silicone. Same thing, different classification metric...ish.. thing

    I disagree with your statement on silicone. I can't actually think of situation where silicon is an ideal coating compared to the other options available. That is, there are many better things than silicone in almost every situation that I can think of. It is, of course, not the worst thing that people could be using, but being mediocre is hardly a good metric to use... Even in situations where PDMS is used, people are moving towards using block co-polymers or hybrids in place of standard PDMS. I think it is important that we use the highest quality materials possible. I mean, it is going inside the body....
  • i very much agree on having the best quality possible is a good idea. Compared to options like hot-glue or suguru, the Applied silicone products could be at least an option to think about, given it's easy to obtain and work with.
  • what is the best/cheapest/most accesible coating?
  • The best, cheapest, and most accessible coatings are not the same thing. Also, it depends on what type of material you are implanting and where it is going. 

    Do you mean for magnets, or electronics, or tubing, or...?
  • i ment best bang for buck, i realize best, is gonna be more expensive, and cheepest is gonna be poor quality.

    as for what its covering i ment electronics, my bad
  • the industry (read: medical) standard for implanted electronics is a hermetically sealed titanium case.

    things that need to communicate with the outside world (rfids, near field, charging, etc) usually end up in biosafe glass if they are small or in a metal casing with a biosafe glass or sapphire window.

    prolly not the answer you are looking for, but putting electronics in something that can tear is not a good idea in the long run.

    smacking silicone on something and saying go is not actually a good idea. 
  • I have a question, Can you coat something like a RFID chip on silicone and it would work? (I know it is not good to coat it on silicone because the electrinics would tear it, my question is hipotetical)
  • it would

  • Like Jack, and Ansamech, i'm trying to figure out an accessible coating or encapsulation... and digging through old threads...
    i'm trying to get something i could put an rfid-powered light under the skin. (hypothetically). they are small, less than a fingernail's terrain and just an mm or two thick.

    I'm not equipped to build a mould injection kit in my appt, $250 for a pound of silicone sounds a bit much, and am leaning on borosilicate, but am not sure of the grade nor tools to heat and seal it without damaging it, myself, or the chip.

    Any tips would be appreciated! (even on where to start looking if i'm not super technical)

  • What type of cure are you looking for? I've been testing a lot of coatings. Silicones have great biocompatibility but are mechanically weak and very permiable. Whatever you coat in it will basically be wet.

  • @Cassox sorry slow reply, been working with mcstuff on the electronic parts actually.
    I'm looking at a project to make an led that powers by rfid. I know i've been beaten to the punch by Alex already, but my enthousiasm isn't dented yet.

    So basically some high shoreA silicone that will be enough to encapsulate some rfid antenna components, some wire potentially, and led.
    I've contacted MasterBond but this would be a small order, and i'm not sure they would want to go through with it. Waiting for follow up email from them.
    I've also been in contact with Schottel for some glass options. Problem is; don't know size that i want to go with yet, like how big we can go without risking breakage too much, and how to seal.

    If it comes down to epoxy, i'm thinking even that could work if cast small and implanted hard.

    Optimally i'd love to find a company that sells the damn RFID encapsulation (two sides, like a gelatin pill), but nuuuuuuuuu... spent houuuurs on google.


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