A team from EPFL (Ecole Polytechnique Federale de Lausanne) in Switzerland, working with researchers from the University of Tokyo, used only household materials such as paper, pencil and a teflon tape to make a tiny device that can generate more than 3 volts of power- it could power a remote control.
Researchers say that the simple, eco-friendly and inexpensive system can produce the same current as two AA batteries just by pressing your finger on the cards at a rate of 1.5 times per second, for a short period of time; the capacitor will release the same amount of voltage as that supplied by two AA batteries.
This paper system could represent the next step, since it would remove the need for conventional batteries. Another advantage is that it does not generate waste, as it can simply be incinerated or left to decompose naturally.
How does this device work? This main principle at work here is static electricity. When two insulators like paper and teflon come into contact, they gain or lose electrons. The system is made up of two small cards, where one side of each card is covered in pencil, carbon serves as the electrode. By pressing down with your finger on the system, the two insulators come into contact. This creates a charge differential: positive for the paper, negative for the teflon, which is applied on the inner side of the two cards to make a sandwich of carbon and teflon in the middle. They are then taped together in such a way that cannot touch, giving the system a configuration that makes it electrically neutral.
When you release your finger and the cards separate, the charge passes to the carbon layers, which act as electrodes. A capacitor placed on the circuit absorbs the weak current that is generated. By pressing down with your finger on the system, the two insulators come into contact. This creates a charge differential: positive for the paper, negative for the teflon.
To boost the device's output, Xiao-Sheng Zhang, a postdoc at EPFL's Microsystems Laboratory found that pressing the sandpaper firmly against the cards gives them a rough surface, that increases the contact area and improves the system's output six times. This is enough to power micro- or nano-sensors, which need only a little electricity to run.
"The one that we developed in the framework of this European project is the first one to use natural, every day and environmentally friendly materials," said Jurgen Brugger, a professor at the Microsystems Laboratory. This device could have applications in the medical field where, ultra-low-cost sensors made of paper for various diagnostic purposes, which would be especially practical for developing countries, are already being tested.se their driving experience according to their track or country.