[HN Gopher] Paper batteries on the cards to power IoT and smart ...
       ___________________________________________________________________
        
       Paper batteries on the cards to power IoT and smart labels
        
       Author : LinuxBender
       Score  : 38 points
       Date   : 2022-07-31 15:05 UTC (2 days ago)
        
 (HTM) web link (www.theregister.com)
 (TXT) w3m dump (www.theregister.com)
        
       | mrsteveman1 wrote:
       | 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.
        
       | Pasorrijer wrote:
       | 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!!
        
         | sandworm101 wrote:
         | But there are already a hundred different methods for doing
         | this. Saltwater batteries, the type that power emergency lights
         | in life rafts, activate upon contact with water. You just need
         | any two dry electrodes that, when in contact with not-pure
         | water, result in a current. I'm not sure that the novelty of
         | making them out of ink would change things.
         | 
         | https://en.wikipedia.org/wiki/Water-activated_battery
        
       | stevenjgarner wrote:
       | > 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"?
        
         | moffkalast wrote:
         | Also what happens if you enclose it in a ziploc bag full of
         | water? This adding of water thing seems weird to demand from
         | the end user.
        
           | stevenjgarner wrote:
           | Yes or a small amount of water that is released when a user
           | pulls a release tab.
        
         | Clent wrote:
         | Alternatively, what are the availability of the materials to
         | make these labels?
         | 
         | I assume these are meant to be disposable like a package label.
        
       | ravenstine wrote:
       | 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.
        
         | adolph wrote:
         | > operator must introduce a small amount of water dissolving
         | the salt in the paper and thereby releasing charged ions which
         | disperse through the paper causing the zinc ink anode to
         | release electrons
         | 
         | My impression is that the process of oxidizing the zinc is what
         | is releasing the electrons. It isn't intended to be recharged.
         | 
         | Source paper:
         | https://www.nature.com/articles/s41598-022-15900-5
         | 
         | Previous work:
         | https://onlinelibrary.wiley.com/doi/full/10.1002/adma.201004...
        
       ___________________________________________________________________
       (page generated 2022-08-02 23:01 UTC)