Paper batteries on the cards to power IoT and smart labels

> Twenty seconds after adding two drops of water the battery reaches a stable 1.2 volts, a little less than 1.5 volt AA battery. The charge lasts about an hour, after which the paper dries out. Users can get another hour at 0.5 volts by adding a couple more drops of water.

This is so great. How many times can it be "recharged"?

In terms of practical use cases, if you're watering a plant anyway then splashing some of that water onto the "recharging" port of a nutrient/moisture/light sensor would work out quite well.

Same deal for sensors that are likely to be exposed to rain or other sources of water outdoors, certainly allows for fewer power components compared to a solar cell + battery + MPPT circuit.

So interesting. You could tie this to a sensor in areas that are supposed to be dry. If they get wet, they trigger the battery and a pulse or an alarm. So much potential!!

How long would this kind of battery last before unrecoverable failure? From what I can tell, this is essentially a potato battery where the paper is the potato and the penny and nail are printed on the paper. Eventually the printed zinc and graphite terminals are going to corrode completely (well maybe not so much the graphite). Once all the zinc is oxidized, that's it.