Make Functional Electronic Circuits on Paper Using Silver Ink Pen
We are used to making a closed conducting circuit diagram on PCB’s and Vera Boards. The same process can now be done by drawing on a paper with a silver coloured liquid metal ink. This whole basic process has been named 3-D Handwriting by its inventors – researchers at the University of Illinois at Urbana-Champaign.
The device consists of a normal looking pen in which an ink with conducting property is filled. This pen is then used to draw the closed electronic circuit on the paper. This circuit is then powered with the help of a battery.
In the image shown below, an LED display with the university initials, UIUC was made through this method. A flexible array of colourful LED’s are mounted on a sheet of paper, where some interconnected lines are drawn between the LED’s with the help of silver ink. The whole circuit is made conducting by connecting it to an external power.
Researchers had to make a detailed study on making the property of the ink suitable for its purpose. The ink must have some characteristics like; it should stay as a liquid as long as it is kept inside the pen. When drawn with it on any surface like wood or paper, it should dry off quickly. To make this possible, the ink was made from silver nanoparticles and its size was further decreased using an acid. To provide more viscosity and smoothness, the ink was modified with cellulose.
When a line is drawn with it, a silver wire with conducting property is obtained. An image below shows a sketch designed by them consisting of a home and surrounding trees. The ink wiring is provided for the LED placed n the top of the roof. This LED is powered with the help of a 5 volt battery kept at the edge of the painting.
Some of the main advantages of this method is that it is easy to use, cheap (as soon as it is marketed abundantly), and portable. There is no need of any special software to design the electronic circuit. It can be drawn on any surface. All you need is a steady hand.
To know how much wear and tear the ink can withstand, the paper was folded many times. After about a 1000 folding, the ink lines were seen to be broken.
Some of the applications of such a device are that electronic circuits and displays can be made more flexible and can also be used to make 3D objects.