Transdermals

edited April 2011 in Everything else

Seems like the inability to get transdermals to work is a big pain in grinding's ass. It's something I'd like to try to fix. I'm even willing to do some experimentation on it.


What are the main problems associated with them? Does anyone have any ideas to overcome those problems?

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  • You're right, it is a total pain; L had to give up its thermistor idea partially because of the problem, and many of the other projects proposed here either require or would be much more convenient if we could do things transdermal.  Although the medical community hasn't done much in the way of figuring this out, it makes sense that the first one to do it successfully would be a group of grinders.

    After all, necessity is the mother of invention, and we've got plenty of necessity.  By a (rather weak) analogy, a model in physics called string theory is unsolvable, at least at the moment, because we haven't discovered the mathematics necessary to do so.  Some physicists, therefore, have suggested that, instead of waiting for mathematicians to figure that out, they should discover it for themselves.

    Saying that, @Unqualified did once hint at a research paper that included a potential method, which involved attaching the transdermal component to the bone.  I'll link to that paper as soon as I can find it.

    ~Ian
  • I've read that paper- I believe the thing you're talking about is an ITAP implant.

    via jbjs.org.uk (may not be the right one, but most of the ones I found wanted me to pay for access).

    animal use via fitzpatrickreferrals (detailed information)

    The way they've done it, or what I gather from reading that, is that layers of porous or biologically active material (hydroxyapatite / HA) on the outside of the implant bond with the skin to form a tough seal. They also talk about using flanges to give the skin a better hold.

    The analogy was good, but it's not that we can't do transdermal at all- we just can't do it with our level of equipment and funding. (yet).

    HA seems to be available for consumption from health food stores. It would probably stick to sugru... Do you think that would work?
  • I'll dig the paper up again (it's somewhere in the repository at home, so it'll be a few hours) and post it here; I think you have the rough details, though.
  • It wasn't me, and I didn't have it at home. All credit to Chase of the Sapiens Anonym comments: paper's here.
  • @Unqualified Awesome, thank you. That's a lot more informative than what I could find.
  • I've posted this link several times, but find it highly relevant here.
  • in that vid, the guy do has problems with infections, too. back to square one.
  • the problems involved with infections are basically cleanliness problems. Anytime you deal with cutting yourself open, you have a chance of infection- especially if you plan to surgically modify anything. Piercings and tattoos, done by the most experienced professional have the chances to get infected. And we're going a slight step further, and turning what is basically a piercing into something more borderline amateur surgery- increasing the danger.

    I'm not saying that infections are good, but its one of those things that you have to take care of. If you never changed your clothes and never bathed, you'd develop lesions that would quickly become infected. Even the best hospitals in the world have to deal with infections; and a perfect surgery can be ruined by poor aftercare on the patients part.. resulting in an infection.

    The reason I bring up that video is because it is an excellent place to start. A transdermal can be broken down into 3 parts- the part that your skin heals into, the part that is below the skin, and the part that is above the skin. The BME community has developed a working prototype that your skin can assimilate effectively. You can read their wiki entry here- http://wiki.bmezine.com/index.php/Transdermal_Implant
    And that is a damn good first step. Things still needing to be figured out are how to improve success rates, which are fairly low due to aftercare issues and possibly improper placement. 
  • You could go with surface piercings; http://en.wikipedia.org/wiki/Surface_piercing or dermal anchors; http://news.bmezine.com/2005/10/14/dermal-anchoring-the-dermal-anchor-piercing-procedure-the-publishers-ring/ If your tech is small enough. I'm not sure what the upper limit on size is on those things but you could certainly fit some kind of tech in that way :).
  • I guess the best way to deal with infections, besides (obviously) keeping the place clean, would be to seal over the junction as quickly as possible. That's where the binding effect of the HAP comes in.

    BMEzine is an awesome site, I'd been there before briefly but thanks for reminding me.

    @Firedust I'm interested in figuring this out mainly because it's one of the most obvious obstacles. For my own tech, I'd probably use it for chargers or data transfer- it seems like a preferable alternative to induction.

    You could use the screw hole on a skin diver to mount something, definitely. Something larger if you had multiple of them.
  • Turns out the HAP from legitimate biotech suppliers is very, very expensive, and besides they wouldn't sell it to me because we come across like serial killers. I managed to get a small amount of pure HAP from a health food store. It should be here within the week.

    I'm going to test similar to the way that the ITAP people did it, by using short pegs with different coatings and shapes. @Hughligen has given me free use of his leg. (If everything works, he can have it back when I'm finished too :D)
  • @SixEcho:  odd; my computer claims you posted just now on September 15...wtf?!?!

    That's great; let us know how well it goes, and if @Hughligen still has a leg to loan when you're done.

    ~Ian

    P.S.  It looks like the activity is slowly starting to run back into this forum.  That's good to know :-D
  • @Ian: It bears out one hypothesis of mine - a whole lot of odd things on the internet slow down when college is out. ",)
  • @Unqualified:  that makes sense enough.  Perhaps internet time also suddenly jolts backwards when college starts, which would explain why my computer at first claimed that @SixEcho posted on the 15th XD

    ~Ian
  • does anyone have any microdermal's or think they may be useful in some sort? I could see some thermistor probe or some kind of temperature sensing device that could easily be screwed in. the microdermals have a much better chance of not being rejected. although it still would need external power.
  • edited October 2011

    Okay so I made a couple pegs, using different mixes and coatings. Turns out the HAP won't just stick to sugru, what with it being such a fine powder, so I opted for a 50/50 mixture. The peg is pretty tiny so if it does fuck up, I don't get too bad of an infection, and I can cut it out easily.

    If this doesn't work I'd like to spend a little time and cash finding out how to make the HAP form more of a coating, perhaps have it clump a little so it can adhere to the sugru.

    implant procedure was standard, disinfect everything with isopropyl alcohol, cut a hole with a 6ga and stick it half way in. It sits flat on the skin to minimise knocks, and because it's over my shin bone.

    I'm getting fairly used to this, actually, I don't mind the pain and I don't feel queasy when I do it.

    I've done it in my leg because @Hughligen has no end of prior commitments, and I want to get this out of the way so I can move up to bigger, better things.


    @Ian time stops when college goes out. That's why, if you ask us, the things we've done on break never actually happened ;)

  • @SixEcho: what kind of form does the HAP come in? A light enough powder can be given a light static charge and blown at the implant, which should cause it to stick to it fairly evenly. (It's how factories paint bike frames and stuff - molecules in the paint cloud even reverse direction after passing the chassis and stick to the back.)
  • It's a nanopowder, so that would definitely work, maybe in conjunction with biocompatible glue. Worth chasing up.

    Anyway, I've tried a few other mixes and materials, and I've had some success with Gore-tex. It's already used for internal stuff in legitimate medicine so it seemed like a fairly intuitive choice.
    I've had a short rod wrapped in the stuff (I used a fabric repair kit, convenient size, has a sticky side.) sitting in my vivo for about a week.

    It didn't form a particularly strong bond, but the skin sealed to it around the join and showed a good resistance to infection. There was a small amount of discolouration, mostly when I bumped it, or went running, but it faded slowly during the week.

    Ripping it out, while incredibly painful, wasn't too hard. If anyone else decides to use this method in their devices, I suggest using a porous flange to anchor it in like the ITAP people did. I also suggest keeping the protruding part of the device as small as possible, and having a 90º angle between the transdermal and the skin surface. Mine stuck up at about thirty degrees from the skin surface, making the underside harder to keep clean. The underside also developed a weaker seal.
  • Yikes! Better you than me, boss. ",)
    The 90º -> promote better healing makes intuitive sense; I'll try and formalize it and post back why that is, if I can.
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