News from the NNI Community - Research Advances Funded by Agencies Participating in the NNI

Researchers from the University of Illinois Urbana-Champaign and the University of California, Irvine, have discovered that the friction on a graphene surface can be dynamically tuned using external electric fields. Surfaces coated in graphene films generally exhibit very low friction, but the new results demonstrate that friction on graphene-coated surfaces can be "turned on" by exposing the surface to an electric field under the proper conditions. The system can then be switched back to lower friction without applying large electrical biases between the surfaces in contact.

Researchers at the National Institute of Standards and Technology are working on an ambitious project, called Thermal Magnetic Imaging and Control (Thermal MagIC), that measures the magnetic responses of nanometer-sized spheres embedded in the object whose temperature is being measured. Thermal MagIC consists of two systems working together. The first part consists of the sensors themselves: nanometer-sized spheres whose magnetic signals change with temperature. The second part is the instrument that excites the tiny spheres magnetically and then reads out their signal.

Engineers at the University of California, San Diego, have developed nanoparticles, fashioned from plant viruses, that can deliver pesticide molecules to soil depths that were previously unreachable. This advance could potentially help farmers effectively combat parasitic nematodes that plague the root zones of crops while minimizing costs, pesticide use, and environmental toxicity. "We're developing a precision farming approach where we're creating nanoparticles for targeted pesticide delivery," said Nicole Steinmetz, the scientist leading this research effort.

Researchers from the University of Illinois at Urbana-Champaign and the University of Nebraska─Lincoln have developed a method of "wiring up" graphene nanoribbons, a class of one-dimensional materials that are of interest in the scaling of microelectronic devices. Using a direct-write scanning tunneling microscopy-based process, the nanometer-scale metal contacts were fabricated on individual graphene nanoribbons and could control their electronic character. The researchers say that this is the first demonstration of making metal contacts to specific graphene nanoribbons with certainty.

Researchers from Vanderbilt University Medical Center; the University of California, San Francisco; and the U.S. Department of Energy’s Lawrence Livermore National Laboratory have developed a new type of filter for kidney dialysis machines that can clean the blood more efficiently and improve patient care. The new filter uses carbon nanotubes – tiny tubes formed by a sheet of carbon atoms bonded in a hexagonal honeycomb mesh structure – that have very small, smooth channels. These channels make it easier to remove toxins and waste from the blood without letting important proteins escape, which can be a problem with traditional filters.

Late last year, researchers from Caltech revealed that they had developed a new fabrication technique for printing microsized metal parts containing features about as thick as three or four sheets of paper. Now, the Caltech team, along with researchers from the Agency for Science, Technology, and Research in Singapore, have reinvented the technique to allow for printing objects that are 150 nanometers in size. In doing so, the researchers also discovered that these objects can be three-to-five-times stronger than similarly sized structures.

Penn State researchers have developed a novel ultrasound imaging technique to view immune cells, called macrophages, continuously in mammal tissue. The researchers introduced nanoemulsion droplets to macrophages, which internalized them. A nanoemulsion is a mixture of oil droplets that are a few nanometers in diameter each. Under ultrasound, the nanoemulsion droplets turned into gas bubbles that helped to distinguish macrophages from other neighboring cells. 

Researchers from Caltech have created a new kind of drug delivery system that, they say, may give doctors the ability to treat cancer in a more targeted way. The system uses drugs that are activated by ultrasound only where they are needed in the body. The researchers combined air-filled protein nanostructures (found in some bacteria) and mechanophores (molecules that undergo a chemical change when subjected to a physical force). 

A study showing how electrons flow around sharp bends, such as those found in integrated circuits, has the potential to improve how these circuits, commonly used in electronic and optoelectronic devices, are designed. The research team, composed of scientists from the University of California, Riverside, and Nanyang Technological University in Singapore imaged streamlines of electric current by designing an "electrofoil" – a new type of device that allows for the contortion, compression, and expansion of streamlines of electric currents in the same way airplane wings contort, compress, and expand the flow of air. The scientists designed the electrofoils in the lab as little wing shapes in nanoscale devices that make the electrons flow around them, similar to how air molecules flow around an airplane wing.

Researchers from the University of Pennsylvania, the U.S. Department of Energy’s Brookhaven National Laboratory, the Air Force Research Laboratory, and KBR, Inc. (Beavercreek, OH) have grown a high-performing 2D semiconductor to a full-size, industrial-scale wafer. In addition, the semiconductor material, indium selenide, can be deposited at temperatures low enough to integrate with a silicon chip. Indium selenide has long shown promise as a 2D material for advanced computing chips, because it carries electrical charge exceptionally well. But producing large enough films of indium selenide has proven tricky because the chemistry of indium and selenium tends to combine in a few different molecular proportions, taking on chemical structures with varying ratios of each element and thus compromising its purity.