Silicone coating for subdermal implant? | Connect | Forum
June 4, 2013
Hi. I am planning to implant a RFID password key into my forearm and am looking for a way to bioproof it. It's about the size of a small USB flash drive and encased in hard plastic. I would like to coat the entire thing with silicone, but I don't know which type of silicone to get. Is food grade silicone good enough or do I need to get implant grade? Where can I buy this on the Internet? Also, what type of sterile precautions do I need to observe while applying the coating and prior to implanting? I appreciate any suggestions you all might have.
I've been researching this myself lately.
The problem you have is that to make silicone bio-proof it really needs to be injection molded. You can replicate this to a degree by using a pressure pot and setting it in a vacuum chamber, but that's pretty expensive to get set up for a single use.
As for sourcing silicone, you will not be able to purchase any certified as implant grade. Even reputable subdermal implants are not certified for this use due to stringent requirements to get this status. The grading system is highly complex, not just food or implant grade, varies from country to country, and i know enough after some reading to realise i don't know what is safe or not. (Check out hepatic silicosis if anyone with implants wants a fright. Anyone Google it before their implant?)
I guess the question becomes how far are you willing to compromise on safety? You will have to at some point i'm afraid, or change your plans. You may be fine, you may not, it's an educated gamble.
Some people have reported successful implants using silicone sealant, but i'm pretty certain that is highly toxic and strongly urge people to stay away from it. I've also heard biohacker types are using Sugru, but i have no idea as to it's safety, and as a material it seems to fall short of ideal needs for implants.
Sorry if that's seemed a downer. Good luck and keep us posted!
Preparing it you need to keep it free of any contaminants and sterilise it. That also restricts the materials you can use, assume you are using an ultrasonic, enzymatic cleaner and autoclave, as not many materials are suitable with all these.
June 4, 2013
I have Googled sugru quite a bit and it appears that it eventually breaks down, making it unsuitable for a long-term implant. I don't have much equipment on hand, so injection molding and autoclaving are both out of the question for me. I'm looking for something that's doable at home. Thanks for the advice @Oakbear. It's not a downer to me. I'd rather err on the side of caution than do something on impulse that I'll regret later.
February 3, 2014
OakBear why do you say 'to really be bio-proof silicone needs to be injection molded?'
I've implanted a number of devices that were encapsulated in silicone by just using a two part mold (plaster in a two half metal flask)
Although medical grade silicone is ideal (and it is not difficult to buy) people have told me that most 2 part (platimum cured) silicones are fairly pure anyway and tolerated fine.
The only problem with a two part mold is you need to burr off the flash edge which comes in the join plane of the two mold halves
As you metion, a few minutes in water in an ultrasonic cleaner helps remove debris and 5 minutes in an autoclave at 130 degrees C will ensure sterility. Silcione is fine at those temps, but if your electronics can't withstand that you may have to consider other methods of sterilisation.
Also you want to raise a pocket of skin and push the implant in far enough so the scar does not lie over the implant. Skin wounds on a non-vascular bed do not heal well.
Hi matmat, welcome to the forum.
I'm not against DIY or experimentation, but i think it is important to research as fully as you can before doing so. Everyone draws their own line as to what they are happy with, but for me there simply isn't enough good data yet regards long term silicone implantation to make a decision which does not carry potentially serious risk. As long as people know that it's fine by me what they choose. My worry is some people don't consider the risk, and make rash decisions.
My understanding is that to achieve medical accreditation for implantation injection molding is necessary. I know that is unlikely to be high on the agenda for those keen on DIY, but it's food for thought. Bio-proof is an unrealistic absolute tbh, the question is how bio-resistant is enough?
You also point out that casting leaves a seam. In understand that this can be filed to shape, however this leaves room for error regards a person doing it. Carving silicone in an appropriate manner is pretty tricky, although of course it can be done.
In a similar vein casting silicone is fairly difficult, and there is the possibility of flaws in the material, especially when doing this at home without experience or decent equipment.
Can i ask where you are able to obtain medical grade silicone? My understanding is that medical implantation grade silicone (suitable for bio-implantation) is expensive, very hard to source and has strict criteria about it's handling and use.
As such educated compromises are made by even the highly regarded and experienced artists supplying the public with ready made implants. (If i'm wrong and there is a good source, i know a lot of artists who will be delighted!).
I have read quite a bit into silicone grading and bio-compatibility, and understand enough to know that i am unable to make a good judgement about where the line should be drawn. Perhaps all those artists and all their consumers have a better understanding than I, but i suspect much of this runs on trust.
"Fairly pure" and "tolerated" seem relatively low standards for materials imho. Heck there are people out there who have tolerated aquarium sealant. Then there are horror stories from South America about people who go into organ failure from massive injections of diy silicone. Reason suggests that in the short term the amount of toxins the body can handle means small quantities can be tolerated. Long term though? Who knows, the data just isn't there.
As regards the 2 part platinum, again i don't have enough knowledge to make a judgement. If i was implanting it i'd want to have a huge degree of trust that the person telling me it was safe did have enough knowledge, and what their definition of safe was.
I also know that mechanical properties of types of silicone are very important, not just potential toxicity, and again don't know enough about those products to make a call.
That is not to say it can't be done DIY, but as i mentioned there will be compromises in safety as opposed to certified medical methods. Even then of course there is limited long term data, and what is emerging suggests that silicone is less bio-compatible than originally supposed.
Looking back at the original topic, a much easier option for RFID is ready made glass encapsulated RFIDs, similar to those used for pets. They seem to have become much more readily available in recent times, and avoid the whole silicone debate. There are also purpose made injectors for these too.
The compromise is placement and fragility, although that is a consideration with silicone too of course.
There also seem to be grades and differences between them, so, as ever, research.
If anyone is serious about doing this after reading all this, then just take the time to research, including methods. There's no rush, especially when your safety and health is on the line. I'm not advocating DIY, and i'm not a doctor or even a body modification artist, but would prefer if people didn't do stupid things and hurt themselves, so giving info might help.
There's a thread here about magnets http://uscobm.com/forum/general-discussion/magnet-implant-questions/ worth reading too. As matmat mentioned, you need to form a pocket. If you don't understand why, you need to read more.
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