Transdermals breach the skin barrier and require a lot of care to keep clean and free of infection. Not great.
Subdermally-implanted magnets don’t breach the skin barrier, but anything stuck to them pinches the skin and causes anoxia and necrosis. Not an option.
So here’s an idea I’ve been thinking about for quite some time. I’m submitting it to those in the know, to figure out if maybe it’s been done already, or if it’s flawed for a reason that escapes me.
Here’s the cross-section of a natural, unmodified wrist:
Now here’s where a traditional transdermal implant would sit:
Instead of doing that, imagine implanting a titanium rod subdermally (say, Ø6 mm or something) and letting it heal and settle for a few weeks. It would look like this eventually:
Finally, to anchor something to it, a sort of hollow clamp with “claws” would grab it from underneath like so:
Crucially, the anchoring clamp would not pinch the skin, but rather trap the rod and surrounding skin inside a hollow cavity. The "claws’ would be suitably thick and rounded off to avoid cutting through the taught skin.
Or, instead of a rod, the titanium implant could be a ring, and the clamp’s “claws’” would spread outwards and trap the ring from the inside, lifting the entire ring off the arm.
Of course the anchored device would not sit flush against the limb, so it would possibly not be a good idea for smart-looking jewelry. But I’m more thinking about watch-like devices.
Bear in ming that the above illustrations are rather poor photoshopped jpegs. None of them are to scale, and I expect the final outcome to look significantly less terrible. But they illustrate the basic idea.
This seems too simple and too obvious. So what’s the catch in my idea, before I start getting more serious with it? 
