How many of us, as children, put our hands on the table and pretended to play the piano with our fingers? Our imagination was enough for us to give life to all the objects we had available and so every surface became magically interactive. What if today we could put our fingers on a sheet of paper and type numbers on a monitor? To tell the truth, the "if" in this case must be set aside, because today this can be done: the paper pocket keyboard has arrived!
Engineer Marina Sala de Medeiros, together with the research group of Purdue University – in West Lafayette, in the state of Indiana – worked on the development of an electronic paper keyboard, not powered by batteries but by the touch of the finger of the user . There are certainly several research groups dedicated to the development of electronic technologies on paper, but never before has anyone tried to make them resistant to water and dust .
How is this paper keyboard made?
The prerogatives for the realization of this device were different. It had to be accessible to everyone, to all intents and purposes look like a simple sheet of paper, to be impermeable to water, not to get dirty easily and small enough to “fit in your pocket”, says the engineer. The first idea was to use perfluorinated compounds – (PFC), which have exceptional hydrophobicity .
With no small surprise, however, the keyboard produced in this way was greatly affected by the attack of water molecules and was completely impregnated with it. Something was definitely not right, so the engineering team went to work trying to figure out what had gone wrong.
After careful analysis, they realized that the compound under analysis reacted when exposed to air.
Once the problem was found, the solution was found: use more chemicals and special equipment that would not allow air to enter the tubes.
Et voila! The small paper pocket keyboard is ready.
How does it power itself without using the battery?
The electronic circuit was made on the back of the sheet, through several layers of material, two of which containing tiny nickel particles. The last layer, on the other hand, was designed with a material very similar to Teflon. Once the circuit was completed, the engineering team flipped the sheet over so they could print the numeric keyboard and finally added a small Bluetooth chip to allow the device to communicate with a computer.
At the touch of the keypad with a finger, a triboelectric energy is generated, that is a phenomenon that consists in the generation of a voltage when two different materials rub each other. To be clear, it is the same phenomenon that generates static adherence in clothes. In this case, however, the pressure of the fingers and its rubbing on the layers of material generates an amount of energy equal to about 20 volts , just enough to be able to transfer the information to the Bluetooth chip and display the number typed on the monitor of the computer.
What can we expect in the future?
This type of innovation can only be a turning point in several areas. Just think that with paper electronics it will be possible to develop sensors capable of being printed on banknotes in order to prevent counterfeiting. The same can be done to monitor the temperature of drugs and foods and determine if they are still safe to use.
There is still a lot to discover but the possibility of actively interacting with a “simple” sheet of paper leaves room for a field of imagination that is difficult to contain.
And it is the imagination that we need, the one that makes everyone go back to being a little child in a world that sometimes lets us forget its magic.
Article by Nicole Rinaldi