I have reported on several advances in the area of printing electronic circuits on paper. One issue I did not touch upon is once you have that circuit on a piece of paper (or any surface) how can you power it?
The solutions so far called for some wiring to connect the circuit to a battery (or main line power source). And of course that wiring can be printed as well but then you need a bulky battery or a connection to the main to make it work (unless you are creating an RFID circuits that can be powered by an electromagnetic field -wirelessly).
Now researchers have managed to create a paper capacitor based on carbon nanotubes that can be printed on paper.
The resulting “battery” can be recharged up to 2,500 times keeping its capacity and this compares to the best lithium batteries around. Of course the capacity, the amount of power that can be stored, is much less, but it is good enough for many applications.