Sensing magnet musing

So if I understand correctly, magnet implants for haptic feedback work best when their “dead” (non-magnetized) mass is kept to a minimum - which is why the glass-encapsulated xG3 isn’t considered all that great for sensing EM fields.

But wouldn’t a free-floating magnet inside a glass casing work? That is, a magnet that is slightly undersized compared to the inner diameter of the glass tube. You would essentially feel it rattling inside the tube.


That is an interesting thought. Although, if the glass casing has any hollowness to it, to allow for the magnet to rattle, I would imagine that the strength of the overall implant would be much less than if the implant was solid…or without hollowness.

Just a thought…as I have broken/damaged a couple implants in my lifetime. I am an artistic welder, so I work with heavy and sharp objects at times and it is not uncommon to have small scrapes or cuts when the day is over. The two implants that have been broken or damaged were both in my left hand.

The first implant to be damaged was a flexNT that I had in my middle finger. A large gas cylinder fell over with my left hand ending up between the cylinder and the ground. …my middle finger, the one containing the flexNT, ended up crushed and exposed in a dirty environment and then infected. So I removed the flexNT and was put on IV antibiotics.

The second implant that was broken was in between my thumb and pointer finger, an xNT, also on my left hand. I do not know exactly when or how it broke…but I had it programmed to the front door of my house and when it one day failed to open the front door I knew something was not right. I had minimal pain if any at all…even when I pushed on top of the implant site. I then used a 4 gauge needle to make a small incision above the implant… What I found out in the end, was that one of the ends of the implant had broken and my body began to grow around and inside the broken implant. It took some work to get the entire implant and bits of glass out but was totally doable! No antibiotics needed, no infection.

What if you fill the dead space with a gel? So it can wiggle?

That’s very interesting. When did you purchase that xNT?

That’s an interesting concept. EM fields interacting with a magnet isn’t really a sudden movement, unless it was a large pulse of current like when machinery initially starts up. It’s more like a low hum, which wouldn’t translate well through the thick glass capsule. You could try it out with some cheap glass and some Neodymium magnets, see how it goes.

I agree that it’s going to make the implant more likely to break. Voids are a real problem. That’s why the x series implants have resin fill. I’ve seen other that don’t and they’re pretty susceptible to crushing force.

I’ve been wanting to pursue an idea regarding this! I was thinking of using two teflon “endcaps” around a spherical magnet that isn’t balanced. I’d drill a hole in the magnet slightly off center so it would shift its mass as it moved sandwiched between the teflon cups.

I know Cassox did an experiment with this, but his goal was to generate sound. In the end it didn’t seem to provide much benefit over direct implantation of a magnet, and he had concerns about repeated force impacts of the magnet into the glass causing chipping over time and eventually cracking the glass. Adding teflon cups or shock absorbers sorta moots the point, which is to convey maximum kinetic force to the glass in hopes of stimulating nearby tactile nerve corpuscles.

Yeah, that was my worry. That’s why I was hoping for it to roll instead and have the off balance magnet shake it. It would be neat to see one filled with a tiny magnet and some biosafe lubricant.

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I gotcha… yeah… it could be interested if the magnet was magnetized along the long axis… and off balance as you said… but the lube would also be viscous and likely slow it down too… or maybe use dry graphite or something that it can roll in… lots of fun ideas.

Isn’t graphite mildly magnetic? How would that affect things?

Graphite is diamagnetic, which is different, but also weird. Probably wouldn’t matter

Ya I just read an article about it, before that I had never heard the term diamagnetic, for some reason I just had it stuck in my head that it was magnetic. Thats why I love this place it makes me look up things I would never think to research.


it might be better actually since the material would “stick” to the magnet and still provide lubrication and maybe some amount of “cushioning” without being overzealous.

The only information I can find regarding when I purchased the xNT is some time around october 2018.