Half a croissant, on a plate, with a sign in front of it saying '50c'
h a l f b a k e r y
Cogito, ergo sumthin'

idea: add, search, annotate, link, view, overview, recent, by name, random

meta: news, help, about, links, report a problem

account: browse anonymously, or get an account and write.



Human Sweat Electrolyte Powered Watch

Make the watch back out of striped copper/zinc and get free power!
  (+5, -3)
(+5, -3)
  [vote for,

Quartz watches require very little power for normal operation and no-one likes replacing batteries in watches. Either you spend a surprising amount of money or risk compromising the sealing of the watch. So, let's power the watch with a much larger if less sophisticated battery.

Many people have taken a couple of nails, plunged them into a lemon or potato and used the output to run a clock. These kits are common <link>. They rely on the redox mid points of two metals. This is usually copper (~+0.3V) and the zinc coating of a galvanized nail (~-0.7V). When inserted into a fruit/vegetable/tuber, the salty liquid allows movement of ions between the two dissimilar metals. This will rapidly reach an equilibrium unless you allow electrons to move from one to the other, this is where you can make the electron flow do work such as powering a clock.

Now, for a watch, lets replace the lemon/potato with a slightly sweaty human wrist. This is essentially the same thing, a vaguely acidic ion rich aqueous solution. The watch back is striped copper/zinc with insulation between the stripes. Each pair is ~1V so 2/3 pairs would probably be optimal to avoid a lossy boost circuit. Now when wearing your watch and it gets a bit clammy, at least you know it's doing something useful.

bs0u0155, Jul 17 2023

Potato Clock https://www.amazon....Clock/dp/B001T8OFQM
[bs0u0155, Jul 17 2023]

Sweat-powered battery for wearable tech https://www.science...08/210816102548.htm
Printed silver flake electrodes generate electricity in the presence of sweat. 2x2 cm, paper thin, affixed to a flexible and sweat absorbent textile that can serve as watchband, armband, etc. [a1, Jul 17 2023]

Sweat fuel cell https://spectrum.ie...-your-next-wearable
[scad mientist, Jul 17 2023]


       The nails might hurt a little bit but we all have to do our part to save energy. [+]
doctorremulac3, Jul 17 2023

       As long as zinc disks are free, we have free power! [+]
Voice, Jul 17 2023

       //The nails might hurt//   

       The Romans were close to Christian-derived electricity!
bs0u0155, Jul 17 2023

       See link "sweat powered battery" - it's been done, but with different electrode material.
a1, Jul 17 2023

       //The Romans were close to Christian-derived electricity!//   

       Well, if I wasn't going to Hell before I am after laughing at that.
doctorremulac3, Jul 17 2023


       Bless yourself repeatedly (without sneezing first) [doc] and perhaps you'll merely end up in Purgatory with the rest of us.
whatrock, Jul 17 2023

       I’ll bring the whiskey and cigarettes. Which I’ll start enjoying again ‘cause I’m already dead.
doctorremulac3, Jul 17 2023

       Um... Aren't the electrodes consumed or plated (depending on the chemistry) during the process of generating electricity? Having a free source of electrolyte (sweat) is fine, but the other two-thirds of the cell (the two electrodes) will need to be refreshed as well.   

       Personally I'm happy with my solar powered watch that I've been using since 2011. It's got some kind of battery or capacitor for running at night. I don't remember it reporting less than a full charge since taking it out of the box. During the winter I usually wear a fleece jacket all day that often covers the watch. I was worried about that initially, but it doesn't seem to be a problem.
scad mientist, Jul 17 2023

       A more realistic approach to getting power from sweat is a fuel cell that burns the lactate in sweat. See link.
scad mientist, Jul 17 2023

       Though personally I'm not sure I want to have to sweat to keep my devices going. In the fuel cell article, they talk about how to deal with intermittent power. My thought was, if you put a piece of plastic over my skin, it generally gets sweaty whether or not I'm exerting myself, but I can't imagine that it would smell great after a day or two.
scad mientist, Jul 17 2023


back: main index

business  computer  culture  fashion  food  halfbakery  home  other  product  public  science  sport  vehicle