E-paper electronic tattoo implant

Projects
#1

Hello,

I have this crazy idea I would like to share with some people to see if it actually makes sense to build and if it would even work the way I intend it to.
Recently I found this flexible E-paper display with 4-tone grayscales.
It is really thin and flexible, that’s why I’m wondering if it would be possible to implant such a display under the skin on for example your arm.
I already wrote my own driver for it, and I tested it on several microcontrollers.
I also found a suiting storage solution for all the uploaded images, and I think it would be possible to use an NTAG I2C to write new images to the implant.

My background is mainly in microcontrollers, so I would like to know if this idea is even doable and if the displayed image would even be visable through the skin.

Any feedback or suggestions are greatly appriciated, thank you in advance!
Hugo

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#2

Can you link to the display? Do you load new images onto it via I2C, or are you thinking the implant will have an integral microcontroller that will interpret the I2C commands and translate them into an image and force it onto the display?

Also did you try to cover the display with a skin analogue to see if you would even be able to see it under the skin?

#3

Can you link to the display?

2.9 Flexible 296x128 Monochrome eInk / ePaper Display [UC8151D Chipset] : ID 4262 : $24.95 : Adafruit Industries, Unique & fun DIY electronics and kits I got the display itself from a different source, but this one from Adafruit is the same one as I have right here.

Do you load new images onto it via I2C, or are you thinking the implant will have an integral microcontroller that will interpret the I2C commands and translate them into an image and force it onto the display?

The display uses SPI to change its content, I already wrote a driver to put a byte array image onto the display with succes. Now I’m just wondering what would be the best way to get those images onto the microchip. I was thinking about having a small memory module on there as well to have some pre-saved images on there to easily switch to. Images would then be flashed to the microcontroller using the NTAG I2C, the chip would store it onto the storage chip, and then the user can select a pre loaded image by sending a command to the NTAG I2C.

Also did you try to cover the display with a skin analogue to see if you would even be able to see it under the skin?

I was looking for this, but I couldn’t find it. Do you have any suggestions where to order some material that really simulates the look/feel/behaviour of human skin? When I was searching the web I found some strange website where I could buy real donor skin for scientific purposes… no thank you, I don’t want to be on any watchlist.

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#4

Just a shot in the dark,

Deli chicken breast as damn thin as then can get it?
Lol

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#5

That could work. The NTAG 5 could also do it but with a “transparent I2C Master” channel which could add more features but be more complex to setup. I have experience with both of those chips and flex PCB designs for implants if you want help.

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#6

I have experience with both of those chips and flex PCB designs for implants if you want help.

I would love to receive your help. I already have an idea on which parts I want to use, but I have never designed NFC antennas or flex PCBs. I do have plenty of experience with normal PCBs and I have basic embedded systems knowledge. Is there any way to contact you directly so we could maybe discuss a few things?

#7

I love the idea, but I’m afraid that, once implanted, you will not see the grayscale art.

In the last few decades the bodmod community implanted various colored objects: the first 3d implants were steel and titaniun and I saw a few anodyzed titanium implanta too. No color visible through the skin, even with bulky implants on thin skin (i.e. back of the hand).

My understanding is that the right place for an implant to sit is simply too deep for the skin to let the color of an opaque object through.

I really want an implanted display, o please prove me wrong :slight_smile:

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#8

This is a good looking Idea!

I just got to ask… do you plan on having it “permanently on” or only light up when paired through wireless charging?

Because the main hurdle to be crossed with the “permanently on” approach is… energy source. (see below)

Also, some other thoughts:

Not really.

We have a bunch of experiments proving even a dim light emission can be seen through the skin.
From implanted LED displays to glow in the dark subdermals.

There are issues to be considered, though:

  • Colour will be “tinted towards orange”
  • any veins/vases will show up as shadows across thedisplay
  • dark patches on the skin might affect this.
  • a good chunk of the light will be absorbed, so you need to spend more energy to light it up (higher brightness) under the skin than to do so in the open.

And ultimately, you will need some “backlight”, which consumes a lot more energy.

So back to the first concern: power source!
There are some pretty thin solid state batteries, but I’m not so convinced the technology is ready for “permanently under the skin”.

  • Some cells fail over time.
  • Some vent noxious gases (or bloat and explode if prevented from venting).
  • Some of those thin solid state batteries can burst into flames if damaged by force (so immagine being hit by something or being in an accident, and then having to deal with fire coming from under your skin?)
  • some of those overheat and could cause burns

That said, it has been a short while since I last checked batteries, so maybe there is a new product I’m unaware.

Lastly, the other issue which should be considered is durability.

I’m pretty sure you can find ways to solve it, but we shouldn’t forget that the e-paper would need to whitstand a ton of punishment!
constantly being bent, pulled, stretched, compressed… not to mention it should take a good beating from external sourced bashing against it because… all that happens to our skin on a daily basis!

And not only the e-paper screen, but all the connections to controller, ntag and power source would need to be insane resilient as well.

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#9

Sure, light makes all the difference. I was referring to a non backlit epaper display.

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#10

Thank you all for sharing your thoughts and concerns. I was actually not planning on putting any backlighting around the display. I has hoping that the colour changing of the display would be enough to see through the skin. My next step would be to test the visibility through skin without… actually placing it under my own already. If anyone has some suggestions on what material to use please let me know.

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#11

Try chicken skin to start.

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#12

I do like this:

But mostly as a “sanity check”.

Chicken skin is less than 1mm thick.

The depth you’ll end up placing that e-paper will probably be between 1 and 4mm deep.

This obviously depends on where in the body you’ll set that and a bunch of other factors…

This diagram gives you an Idea:

Superficial-and-deep-adipose-layers-separated-by-subcutaneous-fascia-in-abdominal
Superficial-and-deep-adipose-layers-separated-by-subcutaneous-fascia-in-abdominal850×458 159 KB

Between Epidermis and Dermis you would end up with wounds that are trying to close themselves. Think the body Identifying a foreign body and actively fighting to push it out.

So for a large implant the highest surface level you want to target would be the “Subcutaneous Fascia”, in blue above.

That region allows for a pocket to be formed which should reduce the risk of rejection.

Another consideration is blood flow. Given that you have a large surface implant you need either to set it deep enough that new blood vessels might form on top of it (which might even mean the actual muscle fascia, in black above, depending on placement and implant), or you need to add in some strategical holes, such as these:

micro
That’s a default microdermal /dermal hook piercing. those holes are designed so that the 2 layers of skin can reconnect, helping both circulation and locking the piercing in place.

also, using the opportunity, if you have an implant which is very thin and very flat… it will probably act like a knife and just keep on migrating and separating the skin tissues, especially if implanted in the muscle fascia, where the loose connectivity tissue is really easy to come undone.
So one way or another we should include some hooking surfaces/holes as part of the screen design.

Ok, why was I saying all that?

A: because I talk too much
but also…
B: because the chicken skin might be a great first attempt, but it’s still only 0,5mm thick at most, while implanting on your shoulder might mean you got around 2,5mm of skin there.

So if the chicken skin works, I would try and get a slice of pork belly with skin and give that a go.

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#13

also, using the opportunity, if you have an implant which is very thin and very flat… it will probably act like a knife and just keep on migrating and separating the skin tissues, especially if implanted in the muscle fascia, where the loose connectivity tissue is really easy to come undone.

That is something I haven’t thought about yet… That actually sounds a bit scary. I have some basic biology knowledge but I’m nothing like an expert. How would the implantation process even work for such a large implant? Would it even be possible to implant something of this size without causing permanent obvious scars?

#14

That’s the thing… We don’t have anything similar.

The implants like that I’ve read about were all temporary placements.

The next best things are either bone plates, where a metal plate is bolted to the bone, or subcutaneous “piercings”.

But those have holes, usually in the middle, and rounded larger edges, both designed to help keep them in place.

If I were designing this implant I would layer it with the battery solution and the backlight emmitter, so they are at least a couple mm thick, and round the edges with the resin encapsulation.
On top of that, I would place a few holes in the structure so skin could reconnect there, helping keep it in place.
Finally, I would immobilise completely the implanted area for the initial healing period and study “herding” it in place with a slightly pressure applied around it by a compressing bandage during sleep.

Would not be an easy implant.
But it’s still a potentially doable one…

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#15

I think I have some more explaining to do about my actual idea. I was not planning on using backlighting, I was hoping that the display would be visible through skin no matter what. Other than that I don’t want it to use batteries. I want it to be passively powered over an NFC connection. You could then use some app to turn images into grayscale images, and upload it to a small memory module on the implant. After this you could tell the microcontroller to fetch the image from storage, and push it to the display. The microcontroller I use pulls a total of 3mA while idle and 5mA while refreshing the display. That’s why I think it would be possible to power the whole thing over just NFC.

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#16

Run the tests on chicken first. If it’s quite nitid you got a shot (try the pig then).

gut feeling (since I haven’t checked that display in person) is that unless you have some light emission from the display, even if small, the combo of Sub Surface Scattering and Light Absorption from the skin will kill the visibility.

not relying on batteries helps with feasibility. :+1:

Sounds fairly doable via nfc.

Might want to also think of something to help with pairing since if the field loses stability (arm moves, etc) it might interrupt the supply for long enough for the screen to reset.

This makes me think of a test to see how well the microcontroler handles multiple successive power source interruptions.

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#17

My biggest concern is still visibility, especially after reading confirmation that no backlight is involved (I agree the whole reasonof epaper is to avoid constant power)

One thing still to be addressed in the thread is the biocompatible encasing for the electronics: this is where you can add round corners to help minimize migration, but it’s also a challenge in its own. Something like what we have on the DT flex implants would probably work, but it should be tested for robusteness on the final electronics.

Implantation per se is not super problematic: you make a cut, you carve a pocket using a dermal elevator, you insert the implant and stitch. Similar to 3d implants in the bodmod world (or -if you want- to a supersimplofied version of a pacemaker implant procedure).
The real challenge is seeing the b/w art thru the skin and, in case you see something, see if it’s just a blurred dark blob, or something intelligible

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#18

The fact that I can’t read the next page of a book through the current page tells me that without active light you won’t be able to see it.

Also those displays can only flex on one axis at a time. It wouldn’t do well around a more complex shape like any body part.

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#19

Paper and skin are distinct mediums and absorb/scatter light differently.

Take a thin enough piece of paper… or even a bright enough environment, and you can actually read the next page.

Actually, that made me think of another test you can do, @hugovantriet :
Check it both on a dark room and on an overlit room.

This is a good question, though… any flex implant would require either 8-directional flexibility or a very specific implant surface (qhich I can’t even think of).

Amal’s goop is brilliant! but I believe it had a maximum height it could be applied to. (or am I mixing resins in my head?)
Think I remember a post in which @amal mentioned something about that. :thinking:

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#20

I did not have any chicken skin on hand so I went for a slice of ham.
I hoped that it would have been a bit more visible, but looking at this I would still argue that this might be possible to pull off.
There is not a very clear difference between black and dark gray, but there is a very clear difference between black, white and light gray.
Knowing this it might actually be better to have the display operate in monochrome mode, this also allows for double the amount of stored images since you then only need one bit per pixel.

Please let me know what you think of these results, this is what the display was showing without it being covered:

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