A better RFID implant

edited November 2015 in RFID/NFC
As everyone one knows, one of the main issues with current RFID/NFC implants is their read distance. For some of us this probably isn't an issue as you use more powerful readers other than just a planer coil on a smartphone.

Personally, I would like my implant to become another seamless interface in my smartphone experience. Much in the same way that an on screen button or gesture would be used. For example, instead of swiping down my status bar and tapping a button to access the flashlight, it would be much cooler to put my phone over the back of my had for a quick second and have it turn on. Turning on your phone's flashlight with your implant can already be done to a degree, but it is just a little to finicky for my taste.

(Admittedly this is a pretty narrow minded example, but bear with me)

Regardless, I think they key to a better read distance is simply location and form factor. 

The idea that I have had rolling around in my head is this:
  • A flexible RFID that sits under the skin on the back of one's hand
  • Could be rolled up inside of a syringe, injected, and then unfurled
  • No bigger than a U.S. quarter.
  • Cheaper perhaps(???)
Some issues that I see with this are:
  • The material in which we could coat the implant in (The age old question) that would be able to be thin, flexible, and tough enough.
  • The idea of unfurling under the skin. I am pretty sure I have seen this technique in plastic surgery, but I am no surgeon.
  • The connections between the coil and the chip inside of the chip eventually breaking due to repeated flexing. 

Any insights in terms of advantages and disadvantages? What about materials and how it could be made? Implant procedure?



  • I'm not at all sure how "unfurling" would work... i.e. how would it push the tissue out of the way of the implant?

    aside from that, I could probably make a flexible U.S. quarter size NFC implant. Though without testing I'm not sure long it would last for, e.g. the flexing would eventually break the antenna wire, but it may last for many years before that happens.
  • I think the implant method would work but your read distance isn't going to be increased as dramatically as you might hope. Inexpensive NFC tags you find on shopping sites are already flat and their read distance is not much better than the tag in my hand. Plus, like you said, flexing will ultimately destroy them while the glass tags are not susceptible to movement.
    Skin doesn't just fit over our bones and muscle like a latex glove. It's connected. If you start making lots of areas where those connections can't function I suspect your skin isn't going to be happy.
    If read distance is important, it's a good goal, consider active implants which broadcast the desired commands. Check out the Misfit Link.
  • @McStuff personally I have gotten my tag to read though my phone once or twice. So the read distance may not be the whole issue, but rather the read angle. Now I am sure that with more practice I will be able to read it on command.
    With a flat tag though this would not be an issue, it would be much easier to align.

    As far as the issue with skin and bone connection. If feel that if people are implanting devices like the Northstar, this should be too much of an issue.

    @AlexSmith I suppose you could just make a small incision and create a pocket for the tag to sit in. How much would something like that cost? I feel like this method could be a viable replacement for the rather pricey glass tags, but at the expense of longevity.
  • @ChrisBot It is a bummer that you aren't getting reliable reads through your phone. My tag unlocks my phone and used to be scanned 30 times per day. Unfortunately my phone has been failing so I have to press hard in order to read my tag now.

    The difference between implanting one Northstar and a "polka-a-dot" array of tags should be obvious. You can cut a few fibers of a rope but when you cut many it loses integrity.

    If you want a variety of functions wouldn't it make more sense to have a single tag display a menu of your "Quick Options" on your screen? Every time you open your skin you're risking infection while a software change to your phone is non-invasive. I shouldn't try to draw that line for you so I'll stop myself here.
  • @McSTUFF My intention is definitely NOT to polk-a-dot myself. It was just a silly thought.. (I didn't make that too clear). I am very aware of the risks involved with these procedures.

    In terms of price however, 85-100 dollars for an nfc tag is a bit steep for most people. This could be a lower cost alternative.
  • Haha, I'm glad you're not going to Swiss cheese your innards. But it does bring up a good point, current implants only allow a single action to be repeated. I suppose you could do something like, "If the phone is held there for 1 second turn on the flashlight. If the phone is held there for 2 seconds launch the email program."

    Or, if you involved the magnetometer and an implanted magnet you could change the angle of your phone in relation to your hand to perform different actions. When the phone is held perpendicular to your thumb it turns on the flashlight, when it's held at an acute angle it launches email, and when it is held at an obtuse angle it launches a browser to this forum. It would require an app to differentiate so it would only work on your phone. I'm off topic.

    Price is obviously a consideration. A year ago the thought of spending $100 on an NFC implant was abhorrent to me. It's simply not in some people's budget and that's that. Now that I'm gainfully employed the thought of making an implant when a proven commercial alternative is available seems foolhardy. Expanding the functionality, read range in this case, seems like a worthy pursuit. I would encourage you to buy some ordinary RFID tags: glass ampoules, flat stickers, keychains, and the credit card size ones. Buy a cheap reader and map, in 3 dimensions, what kind of detection field you're getting. You want to answer a few questions. Does the size of the loop affect the read range and by how much? Does the shape affect reading distance or only scannable area? What kind of range is available from the edge of flat tags? What kind of range is available from the top of flat tags? Do the corners of square cards affect the read range?

    There are probably papers written on this sort of thing too. I prefer a hands on approach and I like amassing hardware.
  • @McSTUFF I actually just bought some on Amazon, and they should be here on monday. I'm still very young (high school junior) and am employed so I have a decent amount of disposable income.

    I have made some basic android apps so it would be a fun challenge to tackle nfc. I'll do some experiments once I get home with magnets and the magnetometer on my phone once I have time. Im not too sure if a m31 would effect the magnetometer all that much but I could be wrong.

    I'll post what I find out eventually(even though I am sure you could for fire it out your own)

    Hopefully @AlexSmith will provide me with some more information too.
  • I COULD answer all my own questions but I've got my plate full. Constantly. If you want to take this to a level where it is valuable and usabe it will require some serious hours. I'm an engineer and the most important thing I've found is knowing which questions to ask and finding how to answer them. Hopefully you can device a way to accurately measure and record the read distance from different styles of tags. The rest is a matter of sitting down and DOING it. If you have the USB RFID reader I purchased you'll hear a beep every time you get a good scan and I bet you'll want to rip that beeper out before too long, haha.
    I would also be curious what kind of readings your phone's magnetometer gets from an m31. Maybe that has to be positioned right under the phone by a couple millimeters. That might make it impossible since different phones have their magnetometers in different places and no one wants to be tied to a single phone model forever.
    Keep accurate records!
  • Since I've been meaning to get into app dev for a project, this could be fun.
    My phone's magnetometer picks up the magnetic ring I have quite strongly, could you download this app https://play.google.com/store/apps/details?id=com.chrystianvieyra.android.physicstoolboxmagnetometer and tell me how your magnets show up? If they show up decently, I might see about making a gesture recognition module for an implanted magnet, something that lets you swipe with your magnet to unlock or something like that.
  • ChrisBot I doubt these type of chips would be much cheaper than existing ones. Also, while I could knock out a prototype pretty easily, there would be a lot of development and testing costs before I'd be willing to say they were safe.

    @ElectricFeelI tried that app, it works with my magnet implant, but I have to have the sensor right over the implant site for it to detect it.

  • @ElectricFeel due to the shortage of bio-safe m31's from dangerousthings, I have yet to get a magnet implanted. Fortunately I had a neodymium for similar size that I just super glued to my finger nail. The readings that I got were definitely encouraging, they would fluctuate a considerable amount. The magno' on my phone is near the top left corner of the screen (OnePlus One) so I may have gotten a better reading than those with their sensors in other places. 

    @AlexSmith I am fairly reckless, so if you would be willing to enlighten me with your thoughts on the production of a prototype I could attempt to produce one for myself. Or I supposed that I would be willing to pay you for a commission. As far as the antenna shape, I don't see why the existing circular tag antenna wouldn't suffice. 

    Also in term of flexing and bending, an alternate implant sight could help decrease the amount of flexing experienced by the implant. Perhaps on the top of the forearm? Towards the wrist? Any thoughts?
  • edited November 2015
    ChrisBot  in general terms, I would buy some of the partially flexible NFC stickers and then paint them with a few layers of soft implant grade silicone, such as this

    I wouldn't say such a device was safe, but I'd feel it was good enough to try implanting as a proof of concept, but I would recommend not leaving it implanted long term.

    To move from a prototype like this to something I'll feel happy having implanted in myself long term, I'd want to get extra flexible tags made, which didn't contain any toxic materials, then I'd find someone to professionally coat them, then have toxicity and fouling tests done. Then do a test implant and have it removed and examined for coating degradation.

    I could make a prototype for you if you want... while you are probably not willing to pay me enough to really make it worthwhile, I would be interested in seeing how well it works.

    With regard to the antennas: There are a bunch of things at play, such as loop count, wire thickness, resonance frequency etc, which I'm not really an expert on. But if you are ok with the read range of those existing tags, then lets not worry about that, we can just use existing antennas.
  • My 2 EE cents about rfid tags.
    Loop area does increase reading range. Shape itself doesn't really matter that much. Just fiddling with antennas is unlikely to get you best results. The resonating usually need to be well-tuned. Changing loop area or loop count will have tremendous effect on the resonating frequency and thus range. This may happen unintentionally when you deal with flexible tags. Make sure you design them to not deform too much, or at least keep the area somewhat constant.
    Thicker wires and well tuned systems can lead to a slight increase in reading range, it's effect is nowhere close to that of the loop-area tho.
  • Could you possibly use the human body as the "antenna loop"?
  • edited November 2015
    ThomasEgi  thanks for the input.

    TheGreyKnight  there are some frequencies and antenna types where the human body works quite well, but not for this type of resonant inductive coupling.
  • @AlexSmith Could you give a few examples of these antenna and frequency types?
  • TheGreyKnight  again, not really my field of expertise, but people have done experiments etc, I know the body works reasonably well (though not as well as a properly design metal antenna) for frequencies in the 300MHz-500MHz range .
  • @AlexSmith, yikes, that stuff is pretty steep. Am I correct in assuming that all bio-safe silicone is just as expensive? Do you know of any other retailers that may sell it in smaller quantities?

    I would be willing to do a group buy if anyone is interested.
  • edited November 2015
    ChrisBot yeah, it is pretty expensive eh, I don't really know of other suppliers, I think most suppliers don't sell in such small quantities, so while they are probably cheaper, you'd need to order a lot...

    But I already have this silicone for a different implantable project.
  • @AlexSmith, what would a prototype cost me?
  • ChrisBot  ummm not really sure, say $20? I can get a few stickers and do the coating next time I'm doing one of my other coatings, probably sometime next month.
  • edited November 2015
    @AlexSmith, Fantastic! Take your time, I am not exactly in a rush.

    Just give me a heads up when you are getting ready to coat them. I am interested in your process.

     Are you good with PayPal when the time comes?
  • ChrisBot Cool, I'll order some stickers and take pictures of the coating process. yeah, paypal is fine.
  • Well, looking forward then....

    What method would you use to implant? Should I make an incision and then suture it up, or does the method of rolling it up in a syringe hold any promise?

    What about location? would the back of the hand work the best, or another location? Scaring?
  • I mentioned why I don't think the "unfurling" idea will work, no one has explained how it would work, so I still think it won't. The only way I can think of is to cut a line in the skin and then create a pocket to one side of it, you may not need to make the incision as long as the diameter of the tag though, since it is flexible, you could probably partially fold it when inserting it. But I think the pocket will need to be the full size, otherwise the tag will stay bunched up and not lay flat. Then suture the incision with a few stitches. 

    I imagine the procedure will be similar to how they implanted the NorthStars, i.e. there is no way you can do it yourself, will need a body mod artist to help you. If I were doing it, I would go for back of the hand, but it's totally up to you. There will be some scaring, how much really depends on how good your surgeon and after care is.

  • Yeah, "unfurling" implants work in animals like dogs because their skin isn't attached throughout like a human's. On a human, that method would only work someplace with similar anatomy, like...the shaft of the penis. Have fun. Otherwise, pocketing is the way you do it.
  • @zombiegristle, thanks that clears things up actually. I suppose that is why they can shake off water when they are wet.

    ...looks like I am going to be doing a pocket...
  • Yup, it's also why the "scruff" is a thing. Lot of animals (most? all?) are like that, it's key to how skinning works - it basically just slides off like a glove once you cut through a few key areas where it's attached like ours is almost everywhere.
  • This tag may be along the lines of what you're looking for in terms of the physical product but the protocol might be too much trouble.
  • McSTUFF  they tag is pretty cool, and has an amazing read range, but it won't work in this situation because it uses a different frequency, so it can't be read with a phone.
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