Scientists are always looking for ways to create flexible microchips that are also cost-efficient so as to be used for an ever growing number of applications in the electronics sector. The material of choice is generally plastics, but one of the biggest problems with flexible chips made of plastic or polymers is that they remain sensitive to heat.
This problem seems to have been solved, as researchers with the Max Planck Institute of Germany managed to create conductive graphite structures on paper. Surprisingly, carbon electronics created from paper can withstand temperatures of 800 degrees Celsius (1,472°F).
The idea is not new, as scientists have been trying to find ways to create functional flexible paper circuits for quite some time, given the lost costs and myriad applications of such a development. But the German team has found a simple, elegant method to actually create paper circuits.
Max Planck researchers, led by Cristina Giordano, used a conventional inkjet printer to print a catalyst – iron nitrate, on paper. The catalyst was printed in the shape of the head of Minerva, the Roman goddess of wisdom and Max Planck Institute’s logo.
The paper was then heated to 800 degrees in a nitrogen atmosphere, the absence of oxygen being probably why the paper does not burn in the process. The cellulose in the paper releases water until only pure carbon is left. Due to the iron nitrate catalyst, the printed areas are turned into conductive graphite, while the non-printed areas are just less conductive carbon.
Scientists than proved that the carbon electronics were conductive by electrolytically coating the paper with copper. The copper was deposited only on the Minerva printed design.
The research team used a similar method to create a 3D conductive structure. They immersed an origami paper crane into the catalyst and heated it until it turned into graphite. The form of the crane was maintained and unlike the 2D design, the entire structure had turned into conductive carbon during the process.
Carbon electronics created from paper can have a wide range of applications and could be easily integrated in the production of electronic devices, due to the fact that they can withstand high temperatures. Furthermore, paper-made circuit boards would be a very cost-efficient alternative to traditional circuitry and a lot easier to integrate with 3D structures.