Scientists who introduced laser-induced graphene (LIG) enhanced their technique to produce what may become a new class of edible electronics.

The chemists, who once turned Girl Scout cookies into graphene, are investigating ways to write graphene patterns onto food and other materials to quickly embed conductive identification tags and sensors into the products themselves.

“This is not ink,” says James Tour, chair of chemistry and professor of computer science and of materials science and nanoengineering at Rice University. “This is taking the material itself and converting it into graphene.”

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GrapheneNew graphene printing technology can produce electronic circuits that are low-cost, flexible, highly conductive and water repellent, researchers report.

The nanotechnology “would lend enormous value to self-cleaning wearable/washable electronics that are resistant to stains, or ice and biofilm formation,” according to the new paper.

“We’re taking low-cost, inkjet-printed graphene and tuning it with a laser to make functional materials,” says Jonathan Claussen, an assistant professor of mechanical engineering at Iowa State University, an associate of the US Department of Energy’s Ames Laboratory, and the corresponding author of the paper in the journal Nanoscale.

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GrapheneAdding a little ultrathin hexagonal boron nitride to ceramics could give them outstanding properties, according to new research.

Rouzbeh Shahsavari, an assistant professor of civil and environmental engineering at Rice University, suggests the incorporation of ultrathin hBN sheets between layers of calcium-silicates would make an interesting bilayer crystal with multifunctional properties.

These could be suitable for construction and refractory materials and applications in the nuclear industry, oil and gas, aerospace, and other areas that require high-performance composites.

Combining the materials would make a ceramic that’s not only tough and durable but resistant to heat and radiation. By Shahsavari’s calculations, calcium-silicates with inserted layers of two-dimensional hBN could be hardened enough to serve as shielding in nuclear applications like power plants.

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PlantSensors on tape that attach to plants yield new kinds of data about water use for researchers and farmers.

“With a tool like this, we can begin to breed plants that are more efficient in using water,” says Patrick Schnable, plant scientist at Iowa State University. “That’s exciting. We couldn’t do this before. But, once we can measure something, we can begin to understand it.”

The tool making these water measurements possible is a tiny graphene sensor that can be taped to plants—researchers call it a “plant tattoo sensor.” Graphene is an atom-thick carbon honeycomb. It’s great at conducting electricity and heat, and is strong and stable. The graphene-on-tape technology in this study has also gone into wearable strain and pressure sensors, including sensors for a “smart glove” that measures hand movements.

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GraphenePillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, report engineers.

Materials scientist Rouzbeh Shahsavari of Rice University and alumnus Navid Sakhavand first built atom-level computer models of pillared graphene—sheets of graphene connected by covalently bonded carbon nanotubes—to discover their strength and electrical properties as well as their thermal conductivity.

In a new study, they found that manipulating the joints between the nanotubes and graphene has a significant impact on the material’s ability to direct heat. That could be important as electronic devices shrink and require more sophisticated heat sinks.

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GrapheneScientists have learned how to tame the unruly electrons in graphene.

Graphene is a nano-thin layer of the carbon-based graphite in pencils. It is far stronger than steel and a great conductor. But when electrons move through it, they do so in straight lines and their high velocity does not change. “If they hit a barrier, they can’t turn back, so they have to go through it,” says Eva Y. Andrei, professor in the Rutgers University-New Brunswick department of physics and astronomy and the study’s senior author.

“People have been looking at how to control or tame these electrons.”

Graphene is a better conductor than copper and is very promising for electronic devices.

The new research “shows we can electrically control the electrons in graphene,” says Andrei. “In the past, we couldn’t do it. This is the reason people thought that one could not make devices like transistors that require switching with graphene, because their electrons run wild.”

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GrapheneScientists have turned wood into an electrical conductor by making its surface graphene.

Chemist James Tour of Rice University and his colleagues used a laser to blacken a thin film pattern onto a block of pine. The pattern is laser-induced graphene (LIG), a form of the atom-thin carbon material discovered at Rice in 2014.

“It’s a union of the archaic with the newest nanomaterial into a single composite structure,” Tour says.

Previous iterations of LIG were made by heating the surface of a sheet of polyimide, an inexpensive plastic, with a laser. Rather than a flat sheet of hexagonal carbon atoms, LIG is a foam of graphene sheets with one edge attached to the underlying surface and chemically active edges exposed to the air.

Not just any polyimide would produce LIG, and some woods work better than others, Tour says. The research team tried birch and oak, but found that pine’s cross-linked lignocellulose structure made it better for the production of high-quality graphene than woods with a lower lignin content. Lignin is the complex organic polymer that forms rigid cell walls in wood.

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GrapheneScientists have created a durable catalyst for high-performance fuel cells by attaching single ruthenium atoms to graphene.

Catalysts that drive the oxygen reduction reaction that lets fuel cells turn chemical energy into electricity are usually made of platinum, which stands up to the acidic nature of the cell’s charge-carrying electrolyte. But platinum is expensive, and scientists have searched for decades for a suitable replacement.

The ruthenium-graphene combination may fit the bill, says chemist James Tour, a professor of computer science and of materials science and nanoengineering at Rice University, whose lab developed the material. In tests, its performance easily matched that of traditional platinum-based alloys and bested iron and nitrogen-doped graphene, another contender.

“Ruthenium is often a highly active catalyst when fixed between arrays of four nitrogen atoms, yet it is one-tenth the cost of traditional platinum,” Tour says. “And since we are using single atomic sites rather than small particles, there are no buried atoms that cannot react. All the atoms are available for reaction.”

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GrapheneA quantum probe based on an atomic-sized “color center” in diamonds has let researchers observe the flow of electric currents in graphene.

Made up of a lattice of carbon atoms only one atom thick, graphene is a key material for the electronics of the future. The thin carbon material is stronger than steel and due to its flexibility, transparency, and ability to conduct electricity, holds great promise for use in solar cells, touch panels, and flexible electronics.

No one has been able to see what is happening with electronic currents in graphene, says Lloyd Hollenberg, professor at the University of Melbourne and deputy director of the Centre for Quantum Computation and Communication Technology.

According to Hollenberg, this new technique overcomes significant limitations with existing methods for understanding electric currents in devices based on ultra-thin materials.

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GrapheneA team of researchers at the University of Manchester – where graphene was first discovered and won the Nobel Prize – created a graphene-oxide membrane for desalination. The newly developed sieve can turn seawater into drinking water, demonstrating graphene’s ability to filter common salts from water, leading to affordable desalination technology.

Prior to this research, graphene-oxide molecules have garnered significant attention from the scientific community, demonstrating their potential to filter our small nanoparticles, organic molecules, and even large salts. However, researchers have not been able to use a graphene-oxide membrane in desalination technologies, which require very small sieves, until this development.

This from the University of Manchester:

Previous research at The University of Manchester found that if immersed in water, graphene-oxide membranes become slightly swollen and smaller salts flow through the membrane along with water, but larger ions or molecules are blocked.

The Manchester-based group have now further developed these graphene membranes and found a strategy to avoid the swelling of the membrane when exposed to water. The pore size in the membrane can be precisely controlled which can sieve common salts out of salty water and make it safe to drink.

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