Electrical engineers at Duke University have unveiled a groundbreaking technique capable of printing fully functional and recyclable electronics at sub-micrometer scales. This innovation could significantly impact the electronic display industry, valued at over $150 billion, by reducing its environmental footprint and providing a competitive edge for U.S. manufacturing. The research was published on October 17 in the journal Nature Electronics.
“If we want to seriously increase U.S.-based manufacturing in areas dominated by global competitors, we need transformational technologies,” said Aaron Franklin, the Edmund T. Pratt, Jr. Distinguished Professor of Electrical & Computer Engineering and Chemistry at Duke. “Our process prints carbon-based transistors that can be fully recycled and provide comparable performance to industry standards. It’s too promising of a result not to be given further attention.”
Environmental and Economic Impacts
Electronic displays are integral to numerous industries, from televisions and computer screens to watch faces and car displays. Currently, most of these displays are manufactured overseas, predominantly in South Korea, China, and Taiwan. The traditional manufacturing process is environmentally taxing, contributing significantly to greenhouse gas emissions and energy consumption. Alarmingly, a United Nations estimate suggests that less than 25% of the millions of pounds of discarded electronics are recycled each year.
Several years ago, Franklin’s team pioneered the world’s first fully recyclable printed electronics. However, the initial method, which utilized aerosol jet printing, was limited to creating features no smaller than 10 micrometers, restricting its application in consumer electronics.
Breakthrough in Printing Technology
In collaboration with Hummink Technologies, Franklin and his colleagues have overcome this limitation with their “high precision capillary printing” machines. These devices leverage natural competing surface energies to extract minute quantities of ink from tiny pipettes, akin to how paper towels absorb liquid.
“We sent Hummink some of our inks and had some promising results,” Franklin explained. “But it wasn’t until we got one of their printers here at Duke that my group could harness its real potential.”
The researchers employed three carbon-based inks—carbon nanotubes, graphene, and nanocellulose—suitable for printing on both rigid substrates like glass and silicon, as well as flexible substrates like paper. These inks, originally developed in Franklin’s earlier work, have been refined to function with Hummink’s printers.
Potential Applications and Future Prospects
The team’s demonstration showcased the ability to print features tens of micrometers long with submicrometer-sized gaps, forming the channel length of carbon-based thin-film transistors (TFTs). These transistors are crucial for the backplane control of flat-panel displays.
“These types of fabrication approaches will never replace silicon-based, high-performance computer chips, but there are other markets where we think they could be competitive—and even transformative,” Franklin noted.
Behind every digital display lies a vast array of microscopic TFTs controlling each pixel. While OLED displays require more current and at least two transistors per pixel, LCD displays need only one. Franklin’s team previously demonstrated their printed, recyclable transistors powering a few LCD display pixels. The new submicrometer printed TFTs are nearing the performance required for OLED displays.
Franklin believes digital displays are the most promising application for this technology. Besides being fully recyclable, the printing process is energy-efficient and emits fewer greenhouse gases compared to traditional methods.
“Displays being fabricated with something similar to this technique is the most feasible large-scale application I’ve ever had come out of my lab,” Franklin stated. “The only real obstacle, to me, is getting sufficient investment and interest in addressing the remaining obstacles to realizing the considerable potential.”
Challenges and Future Directions
Despite the promise of this technology, challenges remain. “Unfortunately, the National Science Foundation program that we were pursuing funding from to continue working on this, called the Future Manufacturing program, was cut earlier this year. But we’re hoping to find a fit in a different program in the near future,” Franklin mentioned.
This research was supported by the National Institutes of Health (1R01HL146849) and the National Science Foundation (CMMI 2245265, ECCS-1542015). The study, titled “Capillary flow printing of submicrometre carbon nanotube transistors,” was authored by Brittany N. Smith, Faris M. Albarghouthi, James L. Doherty, Xuancheng Pei, Quentin Macfarlane, Matthew Salfity, Daniel Badia, Marc Pascual, Pascal Boncenne, Nathan Bigan, Amin M’Barki, and Aaron D. Franklin, and published in Nature Electronics, 2025 (DOI: 10.1038/s41928-025-01470-7).
