Come on down to crazy Amal's flex-o-ramma-ramma!

There are no LF products like the NFC fingernail that I am aware of. LF antennas are able to just be printed like the HF ones afaik. It is why the flexEM is so chonky I believe.

Gotcha. Well, now I’ve planted the idea. Lights for function indicators! :joy:

It just keeps looking better by the day!

Amal, any chance of getting a FlexNext without the EM tag, and with a cutout in the middle? Or said another way, just the aluminum foil tag encased in biopolymer. Something like this:

The only body artist willing to undertake such an implant is coming to my town in 2 months from 400 mi away, and I’d like to use the opportunity of his visit to implant that thing. But I value flexibility and minimizing the area of detached skin more than I care for blinkies or dual-frequency.

Or possibly that thing with one blinky over the chip itself to protect it, is there’s added value.

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yeah i could do this… order a custom mod version of flexnext and i’ll one-off something for you… but after all the messing around with following the shapes etc i think the best approach for me to do this is to simply cut a single circle out of the center… i was able to make a little “map” of the interior, but then my expectation of simply being able to reduce size to cut the biopoly in the same shape was a bit dashed… angles didn’t line up and so it was a serious pain to try to re-map the smaller cut lines… so anyway… how about a 15mm diameter slightly offset circle cutout?

actually in testing the metal foil of the antenna where the chip is severely reduces performance of the LED to the point of it being basically pointless. I chose specific spots on the antenna trace to fit the 3 point LED pattern to avoid these issues. do you want me to put LEDs or no? Without them, I think this will be a very flexible implant since there will be no rigid structures inside and a nice big hole in the middle.

also, while working on flexnext inventory, i managed to pop out a few of these little things… just the nfc nail led only (in biopoly).

Because @Pilgrimsmaster asked in another thread, i’ll repost here;

It’s very hard to give a straight answer with range comparisons because the xLED has a fundamentally different antenna, so range will vary drastically depending on the reader you’re interacting with, as well as the normal orientation issues. For example, the ACR122U has a specific spot where xLEDs perform pretty well… but no such spot exists for basically any other readers or phones. The ACR122U has a very unique antenna design with ground planes built to constrain and shape the field… very strange, but effective. Take one apart and check the PCB, you’ll see what I mean.

Here’s my totally unfair and basically pointless comparison on the ACR122U;

xLED; 15mm
nfc nail; 30mm
nfc nail on flexnext; 55mm

These are the “light points” where the LED starts to light up, not max brightness… but it’s typically only a few less mm to achieve max brightness, depending on the LED characteristics involved.


Oh right okay. I thought that solid aluminum foil zone around the chip was functionally dead. Interesting…

Also, I didn’t realize you carefully chose the spots you put the blinkies at. On the photos, they look like they were thrown in there in a triangular pattern at random.

In that case, no blinkies then.

Let me guess: your largest punch is 15 mm in diameter? :slight_smile:

More seriously, that sounds okay. That means the widest “free floating” skin bridge between the outside of the implant and the inside cutout would be 16 / 17mm at the offset point. It sure beats 41mm. Assuming the skin reattaches at the center of course…

Yes that’s the appeal. On the other hand, I’m a bit worried it will be too flexible for the 4 “solder” joints - 2 to connect the chip, and 2 for the aluminum foil “jumper”. I mean at the end of the day, them tags were designed to be rolled and unrolled once, manipulated a bit once, then stuck to a solid surface forever. If those joints flex constantly day in and day out, they might come undone in the long run. Hmm…

I must be the only idiot in town to pay more to get less :slight_smile:

Okay, let me do some more photoshopping tomorrow to picture what I’m really looking at getting, and to trial-position a paper cutout here and there, to see where it will best implanted, then I’ll place my order.

One last question: do you think I could get it in Finland before Sept 5th? That’s the date the visiting body artist comes to town.

Thanks man!

kinda… the inlays use standard via tech used with flex pcbs, even those meant to flex and move. Also the NTAG216 chip (and most chips on printed wet inlays like this) are meant for “smart poster” applications, some of which to involve loose material that does bend. I might think the biggest concern would be if your flesh deformed significantly enough to surpass anything that these might be stuck to by design, and did so on a regular basis :slight_smile: Anyway, my point was that there wouldn’t be these rigid bits inside so if your hand had a lot of curve to the back of it, or if you wanted to place this on say, the side of the arm where there is a lot more curve but not a lot of modulation, the device should conform to the curve much more readily than a flexNExT.

I can say I’ve mistreated these things quite a bit, and the only thing that seems to kill them is a direct hit on the tiny chip… dislodges it from the flip pads… but, once encapsulated in biopoly (and under your tissue), it will have more than a fighting chance at keeping alive long term. Of course, anything is possible, but I’d be surprised if it became an issue.

Yep, I’ll try to get it out to you 5-7 biz days after you order.

Would a piece of stiff(ish) plastic above and below the chip protect it some more? You know, just so that area is stiffer.

Also, would it be better to implant the thing so the chip is directly above a bone, or above soft tissue?

yeah the biopoly serves this purpose pretty well as it molds around the z-height of the chip. Otherwise if you put bits of rigid plastic on either side, it becomes like a ball bearing between two rigid discs and ends up being the fulcrum for those plates, ultimately taking more force from a greater surface area of impact probability… basically it would make it worse… but you see my point… the biopoly works to help the situation but I would not want to add additional materials that would essentially remain rigid. … though it might make sense to put a protective ring around maybe? I’ll see if I can find something.

Hmm… I would say… probably irrelevant in this case. I’d say it’s more important to ensure it’s comfortable. The only reason I say this is that the tissue above the chip will be more important than the tissue under it. Unless you are getting stabbed with a flatblade screwdriver right on the chip, I think it won’t matter what’s under it so much.

PS, i have had a flexNT in my left middle finger directly over the second metacarpal… it also uses a flipchip’d NTAG216 and it’s survived plenty, including punches to the body bag and probably a couple harder surfaces.

I’m only concerned because I often work in my workshop, and I can’t count the number of hard blows I’ve sustained to my hands and (to a lesser degree) arms with machinery. I try to be careful, and most of the time nothing happens. But when it does, it really does.

Speaking of which, I asked you that in another thread: would implanting my FlexM1 there be an option? It’s tempting, but it looks less flat and less flexible than a FlexNT in the short dimension to be able to “wrap” around the finger.

It would only fit in the longest of fingers… the flexNT barely fits in mine and you definitely don’t want to go over the knuckle. The flexMT antenna wouldn’t mind but you might have complications with the knuckle. Finger surgery is very tricky… that’s why general surgeons refer you to a hand surgeon for stuff like this. One wrong move with a scalpel and you could lose all feeling in your finger, sever a tendon, or lose your finger all together.

Yeah okay. I thought so. My middle finger is okay for length, but again… it’s too often too close to machinery. And yes, it’s dangerous to cut stuff open there - I know that from experience.

I just “simulated” punching several overlapping holes with standard round punches. Here for instance, one 15mm punch hole smack at the center, one off to the left and down, and 2 smaller partial cutouts with a 6mm punch to the right and up:

Or I suppose you could also use an even smaller punch and follow the shape around inside to create a custom cutout with a standard tool.

Wouldn’t that work? Why make a custom-routed punch?

all I can think of are these

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So I made my FauxNext out of paper with a dozen layers of clear tape over it to simulate the stiffness of a Flex device.

I tried it on the back of my hand: it’ll work, and it doesn’t even feel that awkward at all. But the positioning needs to be surprisingly precise: too far forward and it’ll bend with the knuckles. Too far backwards and it’ll bend with the wrist. And since it’s already slightly bend left-to-right due to the curvature of the back of the hand, it’s not going to end well if it gets bent in the other direction. Also, I feel it should be contained entirely within the space of the metacarpals - i.e. no overhang on the blade or on the thenar area:


I tried it on my forearm too: it’d work, but good thing I don’t wear a watch :slight_smile: Also, again, it can’t be too close to the wrist to avoid bending in both directions:


I think the major problem with the back-of-the-hand placement is the risk of collision with something. For the wrist, the risk seems to be that it’s extremely easy to crumple. Hmm…

I’m gonna ponder some more, but I think I’ll end up pulling the ole credit card…

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really nice job simulating with the fauxnext :slight_smile:


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Yes I did try the forehead: it’s not working out all that well actually. The problem is, you’re trying to paste a flat, somewhat stiff disk onto a sphere. It doesn’t want to and it actually creates wrinkles if you insist. Definitely not good.

There is one perfect location for that implant: the temple. it’s truly flat, the skin is reasonably taut, it’s not soft underneath (well, for most people anyway…) The problems with that location are:

  • do you really want to tell people to bring their cellphone to your head to share whatever information is on the chip? Or headbutt the reader to log in?
  • I wear glasses. I’d have to take them off each time I want to read the implant.

And no, you ain’t getting a photo of my ugly mush :slight_smile: