Engineers have developed the world’s first fully recyclable printed electronics

3D rendering of the first fully recyclable printed transistor.Credit: Duke University

The new technology regenerates almost 100% of all carbon-based transistors while preserving the future functionality of the material.

Duke University engineers have developed the world’s first fully recyclable printed electronics. Researchers are demonstrating transistors, an important and relatively complex computer component made of three carbon-based inks, to combat a new generation of recyclable e-waste epidemics. I want to stimulate electronic devices.

The work will be published in the journal online today (April 26, 2021) Nature Electronics..

Aaron Franklin, Adi’s professor of electrical and computer engineering at Duke, said: .. “But we hope that by creating new electronic devices that are completely recyclable and easy to print and show what they can do, they will become widely used in future applications.”

Insulated cellulose is printed on other carbon-based components to produce the first fully recyclable printed transistors. Researchers want to inspire a new generation of recyclable electronics to combat the global pandemic of e-waste.Credit: Duke University

As people around the world bring more electronics into their lives, there is an ever-growing pile of discarded devices that no longer work or are abandoned in favor of new models. The United Nations estimates that less than £ 250,000 of the millions of pounds of electronics that are discarded each year are recycled. And as the world upgrades to 5G devices and the Internet of Things (IoT) continues to expand, the problem will get worse.

Part of the problem is the difficulty of recycling electronic devices. Large factories employ hundreds of workers to hack bulky devices. However, while copper, aluminum, and steel scrap can be recycled, the silicon chip at the center of the device cannot.

In a new study, Franklin and his lab show a fully recyclable, fully functional transistor made of three carbon-based inks that can be easily printed on paper and other flexible, environmentally friendly surfaces. I will.With carbon nanotubes Graphene Ink is used for semiconductors and conductors, respectively. While these materials are not new to the world of printed electronics, Franklin says the path to recyclability was paved with the development of wood-derived insulating dielectric inks called nanocellulose.

Testing biosensor recyclable electronics

Researchers test biosensors made from fully recyclable printed electronics. In the recycling process, almost 100% of the material used is recovered and the performance of the material is hardly lost.Credit: Duke University

“Nanocellulose is biodegradable and has been used for years in applications such as packaging,” says Franklin. “And people have long known about its potential use as an insulator for electronic devices, but no one has ever understood how to use it with printable inks. , Is one of the keys to making these fully recyclable devices work. “

Researchers have developed a method for suspending nanocellulose crystals extracted from wood fibers. It sprinkles a small amount of table salt to produce an ink that works well as an insulator for printed transistors. The team has shown that the aerosol jet printer uses three inks at room temperature and is still powerful enough to be used in a variety of applications, even six months after the first print.

The team then shows how recyclable the design is. By submerging the device in a series of baths, gently vibrating it with sound waves, and centrifuging the resulting solution, carbon nanotubes and graphene are sequentially recovered in an average yield of nearly 100%. Both materials can then be reused in the same printing process, with little loss of performance viability. Also, because nanocellulose is made of wood, it can be easily recycled with printed paper.

Transistors are relatively complex computer components used in devices such as power controls, logic circuits, and various sensors compared to resistors and capacitors. Franklin explains that he hopes to take the first step towards commercially pursued technology for simple devices by first demonstrating a fully recyclable multifunction printed transistor. .. For example, Franklin can imagine the technology used in large buildings that require thousands of simple environmental sensors to monitor energy use and customized biosensing patches to track medical conditions. say.

“Such recyclable electronics have never replaced the $ 5 trillion industry as a whole and are far from printing on recyclable computer processors,” Franklin said. “But we hope that demonstrating these types of new materials and their capabilities will provide a foothold in the right direction for the new types of electronics lifecycle.”

See also: “Printable and Recyclable Carbon Electronics Using Crystalline Nanocellulose” by Nicholas X. Williams, George Bullard, Nathaniel Brooke, Michael J Therien, Aaron D. Franklin, April 26, 2021 Nature Electronics..
DOI: 10.1038 / s41928-021-00574-0

This work has been supported by the Department of Defense Parliamentary Medical Research Program (W81XWH-17-2-0045), National Institutes of Health (1R01HL146849), and Air Force Scientific Research Office (FA9550-18-1-0222). It was. Engineers have developed the world’s first fully recyclable printed electronics

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