Duke University scientists have developed the world’s first fully recyclable printed electronics, utilizing a new technique that can reclaim nearly 100% of all-carbon-based transistors.
According to Duke professor Aaron Franklin and his team, their completely recyclable, fully functional transistor is made out of three carbon-based inks that can be easily printed onto paper or other flexible, environmentally friendly surfaces.
They hope their work will inspire a new generation of recyclable electronics to help fight the growing global epidemic of electronic waste.
According to a UN estimate, less than a quarter of the millions of pounds of electronics thrown away each year is recycled.
This is because electronic devices are difficult to recycle; large plants employ hundreds of workers who hack at bulky devices.
But while scraps of copper, aluminum and steel can be recycled, the silicon chips at the heart of the devices cannot.
The Duke path to recyclability is based on a wood-derived insulating dielectric ink called nanocellulose.
Franklin’s team developed a method for suspending crystals of nanocellulose that were extracted from wood fibers that – with the sprinkling of a little table salt – yields an ink that performs admirably as an insulator in their printed transistors.
Using the three inks in an aerosol jet printer at room temperature, the team shows that their all-carbon transistors perform well enough for use in a wide variety of applications, even six months after the initial printing.
To recycle their design, the scientists submerged their devices in a series of baths, gently vibrating them with sound waves and centrifuging the resulting solution.
Through this, they were able to sequentially recover carbon nanotubes and graphene with an average yield of nearly 100%.
Both materials can then be reused in the same printing process while losing very little of their performance viability.
And because the nanocellulose is made from wood, it can simply be recycled along with the paper it was printed on.
Image and content: Duke University via SciTechDaily