Passive Time-telling, Magnetic Watches and more
I think that being able to make a method, with which a person can tell the time passively i.e. without having to look at their watch/phone/sundail would allow us to investigate the limits of brain plasticity, circadian rhythms and also being pretty cool thing to do
My main ideas were to either use some sort of electromagnet to stimulate a magnet inside the body at the end of every hour. More esoterically you could stimulate it with a different frequency every hour (although I don't have an implant yet so I dunno how well you can perceive frequencies etc).
My other idea was to use a thermo-electric generator, to produce a shifting heat pattern with an "N" shaped wave - so it peaks at every hour then slowly decreases till the 1/2 hour mark etc, although more experimentation into how well the ambient heat from the peak dissapates and if the body can actually notice and make a "time map" of past peaks and stuff to actually give you a passive perception of time.
Both of those methods could be conceivably housed in a watch-sized assembly, probably even much smaller for the electromagnet
Comments
i'd also recommend a fully implantable version with electrodes. it's about the most basic,yet useful implant one can build that contains all major components like power supply, microcontroller ,electrode-output and communication with the device.
even with only one electrode one could output a lot of useful information. like a pulse every few seconds and the full time every minute using morse-code or so.
and given my just created biohacking-idea-evaluation-flowchart this would be a wearable gadget.
i am all in favor of saumanahaii's idea. electrodes are pretty much the best idea to interface the body. doesn't really matter if you fire off a whole bunch of nerves, your brain won't care that much. i have no worries the brain will make sense from the input. i mean your tactile sense isn't going numb either and it's permanently active.
if you just want a wristwatch that gives you haptic feedback, that's rather easy to build. small RTC, an attiny, a very small vibration motor and a battery. and you'r ready to rumble
Also, I don't understand the implication that using Bluetooth implies "You won't see it built anytime soon." That's not the case, unless by "anytime soon" you mean "less than two months from now, assuming we can make sure it's properly bioproof before then."
the flowchart is to be read with a good portion of humor. it's not intended to always provide you with an actual choice for entertainment purpose.
@Ben having 12 electrodes 12x the problems and powerdemand. i'd start with one.