Tag Archives: US National Institute of Food and Agriculture

Treating graphene with lasers for paper-based electronics

Engineers at Iowa State University have found a way they hope will make it easier to commercialize graphene. A Sept. 1, 2016 news item on phys.org describes the research,

The researchers in Jonathan Claussen’s lab at Iowa State University (who like to call themselves nanoengineers) have been looking for ways to use graphene and its amazing properties in their sensors and other technologies.

Graphene is a wonder material: The carbon honeycomb is just an atom thick. It’s great at conducting electricity and heat; it’s strong and stable. But researchers have struggled to move beyond tiny lab samples for studying its material properties to larger pieces for real-world applications.

Recent projects that used inkjet printers to print multi-layer graphene circuits and electrodes had the engineers thinking about using it for flexible, wearable and low-cost electronics. For example, “Could we make graphene at scales large enough for glucose sensors?” asked Suprem Das, an Iowa State postdoctoral research associate in mechanical engineering and an associate of the U.S. Department of Energy’s Ames Laboratory.

But there were problems with the existing technology. Once printed, the graphene had to be treated to improve electrical conductivity and device performance. That usually meant high temperatures or chemicals – both could degrade flexible or disposable printing surfaces such as plastic films or even paper.

Das and Claussen came up with the idea of using lasers to treat the graphene. Claussen, an Iowa State assistant professor of mechanical engineering and an Ames Laboratory associate, worked with Gary Cheng, an associate professor at Purdue University’s School of Industrial Engineering, to develop and test the idea.

A Sept. 1, 2016 Iowa State University news release (also on EurekAlert), which originated the news item, provides more detail about the intellectual property, as well as, the technology,

… They found treating inkjet-printed, multi-layer graphene electric circuits and electrodes with a pulsed-laser process improves electrical conductivity without damaging paper, polymers or other fragile printing surfaces.

“This creates a way to commercialize and scale-up the manufacturing of graphene,” Claussen said.

Two major grants are supporting the project and related research: a three-year grant from the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 11901762 and a three-year grant from the Roy J. Carver Charitable Trust. Iowa State’s College of Engineering and department of mechanical engineering are also supporting the research.

The Iowa State Research Foundation Inc. has filed for a patent on the technology.

“The breakthrough of this project is transforming the inkjet-printed graphene into a conductive material capable of being used in new applications,” Claussen said.

Those applications could include sensors with biological applications, energy storage systems, electrical conducting components and even paper-based electronics.

To make all that possible, the engineers developed computer-controlled laser technology that selectively irradiates inkjet-printed graphene oxide. The treatment removes ink binders and reduces graphene oxide to graphene – physically stitching together millions of tiny graphene flakes. The process makes electrical conductivity more than a thousand times better.

“The laser works with a rapid pulse of high-energy photons that do not destroy the graphene or the substrate,” Das said. “They heat locally. They bombard locally. They process locally.”

That localized, laser processing also changes the shape and structure of the printed graphene from a flat surface to one with raised, 3-D nanostructures. The engineers say the 3-D structures are like tiny petals rising from the surface. The rough and ridged structure increases the electrochemical reactivity of the graphene, making it useful for chemical and biological sensors.

All of that, according to Claussen’s team of nanoengineers, could move graphene to commercial applications.

“This work paves the way for not only paper-based electronics with graphene circuits,” the researchers wrote in their paper, “it enables the creation of low-cost and disposable graphene-based electrochemical electrodes for myriad applications including sensors, biosensors, fuel cells and (medical) devices.”

Here’s a link to and a citation for the paper,

3D nanostructured inkjet printed graphene via UV-pulsed laser irradiation enables paper-based electronics and electrochemical devices by Suprem R. Das, Qiong Nian, Allison A. Cargill, John A. Hondred, Shaowei Ding, Mojib Saei, Gary J. Cheng, and   Jonathan C. Claussen. Nanoscale, 2016,8, 15870-15879 DOI: 10.1039/C6NR04310K First published online 12 Jul 2016

This paper is open access but you do need to have registered for your free account to access the material.

Citrus canker, Florida, and Zinkicide

Found in Florida orchards in 2005, a citrus canker, citrus greening, poses a serious threat to the US state’s fruit industry. An April 2, 2105 news item on phys.org describes a possible solution to the problem,

Since it was discovered in South Florida in 2005, the plague of citrus greening has spread to nearly every grove in the state, stoking fears among growers that the $10.7 billion-a-year industry may someday disappear.

Now the U.S. Department of Agriculture has awarded the University of Florida a $4.6 million grant aimed at testing a potential new weapon in the fight against citrus greening: Zinkicide, a bactericide invented by a nanoparticle researcher at the University of Central Florida.

An April 2, 2015 University of Central Florida news release by Mark Schlueb (also on EurekAlert), which originated the news item, describes the problem and the solution (Zinkicide),

Citrus greening – also known by its Chinese name, Huanglongbing, or HLB – causes orange, grapefruit and other citrus trees to produce small, bitter fruit that drop prematurely and is unsuitable for sale or juice. Eventually, infected trees die. Florida has lost tens of thousands of acres to the disease.

“It’s a hundred-year-old disease, but to date there is no cure. It’s a killer, a true killer for the citrus industry,” said Swadeshmukul Santra, associate professor in the NanoScience Technology Center at UCF.

The bacteria that causes HLB is carried by the Asian citrus psyllid, a tiny insect that  feeds on leaves and stems of infected citrus trees, then carries the bacteria to healthy trees.

Zinkicide, developed by Santra, is designed to kill the bacteria.

The $4.6 million grant is the largest of five totaling $23 million that were recently announced by the USDA’s National Institute of Food and Agriculture.

The evaluation of Zinkicide is a multi-institute project involving 13 investigators from six institutions. Evan Johnson of UF’s [University of Florida] Citrus Research and Education Center at Lake Alfred is the project director, and there are a dozen co-principal investigators from UF, UCF, Oak Ridge National Laboratory (ORNL), Auburn University, New Mexico State University and The Ohio State University.

”Managing systemic diseases like HLB is a difficult challenge that has faced plant pathologists for many years,” said Johnson “It is a privilege to work with an excellent team of researchers from many different disciplines with the goal of developing new tools that are both effective and safe.”

A portion of the grant money, $1.4 million, flows to UCF, where Santra leads a team that also includes Andre Gesquiere, Laurene Tetard and the Oak Ridge National Laboratory collaborator, Loukas Petridis.

HLB control is difficult because current bactericidal sprays, such as copper, simply leave a protective film on the outside of a plant. The insect-transmitted bacteria bypasses that barrier and lives inside a tree’s fruit, stems and roots, in the vascular tissue known as the phloem. There, it deprives the tree of carbohydrate and nutrients, causing root loss and ultimately death. For a bactericide to be effective against HLB, it must be able to move within the plant, too.

Zinkicide is a nanoparticle smaller than a single microscopic cell, and researchers are cautiously optimistic it will be able to move systemically from cell to cell to kill the bacteria that cause HLB.

“The bacteria hide inside the plant in the phloem region,” Santra said. “If you spray and your compound doesn’t travel to the phloem region, then you cannot treat HLB.”

Zinkicide is derived from ingredients which are found in plants, and is designed to break down and be metabolized after its job is done. [emphasis mine]

It’s the first step in a years-long process to bring a treatment to market. UF will lead five years of greenhouse and field trials on grapefruit and sweet orange to determine the effectiveness of Zinkicide and the best method and timing of application.

The project also includes research to study where the nanoparticles travel within the plant, understand how they interact with plant tissue and how long they remain before breaking down. [emphasis mine]

If effective, the bactericide could have a substantial role in combatting HLB in Florida, and in other citrus-producing states and countries. It would also likely be useful for control of other bacterial pathogens infecting other crops.

The Zinkicide project builds as a spinoff from previous collaborations between Santra and UF’s Jim Graham, at the Citrus Research and Education Center to develop alternatives to copper for citrus canker control.

The previous Citrus Research and Education Foundation (CRDF)-funded Zinkicide project has issued three reports, for June 30, 2014, Sept. 30, 2014, and Dec. 31, 2014. This project’s completion date is May 2015. The reports which are remarkably succinct, consisting of two paragraphs, can be found here.

Oddly, the UCF news release doesn’t mention that Zinkicide (although it can be inferred) is a zinc particulate (I’m guessing they mean zinc nanoparticle) as noted on the CRDF project webpage. Happily, they are researching what happens after the bactericide has done its work on the infection. It’s good to see a life cycle approach to this research.