Archive for December 4th, 2012

Body Modification: Magnetic Sensor

Our Larval Engineer reports that the current techie-thing-to-do involves having a tattoo artist or other unlicensed medical technician implant a tiny bar magnet in one’s finger, a process that adds a sixth sense to one’s built-in repertoire after the anesthetic shot of whiskey wears off. Evidently, converting magnetic field variations into mechanical force tweaks those little nerve endings wonderfully well, provided that your finger doesn’t subsequently rot off.

I point out that a magnet epoxied to a fingernail would probably get you within a few dB of the same result, minus the back-alley surgery thing. She counters that’s tacky and lacks style.

I point out that her medical insurance (for which, harumph, we are currently paying) probably doesn’t cover self-inflicted damage. She counters that most victims people have no problems at all.

I point out that a steampunk-style wristband incorporating a Hall effect sensor, LEDs, and maybe a vibrating pager motor would be at least as cool and probably marketable, to boot. She returns broadside fire by observing such a device requires power and she knows how I feel about batteries.

Game, set, and match.

In the interest of science and so as to not be rendered completely obsolete, I’ve epoxied a small neodymium magnet to my left little finger to discover what the world feels like. It’s surrounded by epoxy, which ought to prevent corrosion & deterioration until it eventually falls off or the nail grows out. It came with a white ceramic layer on one pole, which means it’s completely encapsulated:

Neodymium magnet on fingernail

Neodymium magnet on fingernail

She’s absolutely right: it’s tacky and lacks style.

I used JB KwikWeld fast-setting epoxy. The magnet attracted a tendril of uncured epoxy, so the “steel filled” part of the description seems accurate, and the magnetic field produced a nice smooth coat over the entire side of the disk.

It buzzes gently inside a Sonicare toothbrush handle, snaps firmly to steel surfaces. and is otherwise inoffensive. I must run some calibration tests to figure out what sort of magnetic field intensity a fingernail can detect. I’m certain it’s less sensitive than an implanted magnet, but I’m down with that.

Memo to Self: If you should occasionally use your little finger to ream out your ear or nose, that’s just not going to work any more…