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

By using computer simulations, researchers at the University of Michigan have shown that cage structures made with nanoparticles could be a route toward creating organized nanostructures with mixed materials. The finding could open new avenues for photonic materials that manipulate light in ways that natural crystals can't. "We are developing new ways to structure matter across scales, discovering the possibilities and what forces we can use," said Sharon Glotzer, the scientist who led this study. 

A team of engineers at the University of Massachusetts Amherst has shown that nearly any material can be turned into a device that continuously harvests electricity from humidity in the air. The secret lies in being able to pepper the material with nanopores less than 100 nanometers in diameter. “What we've done is to create a human-built, small-scale cloud that produces electricity for us predictably and continuously so that we can harvest it," says Jun Yao, one of the four engineers involved in this study. 

Researchers from the National Institute of Standards and Technology, the University of Colorado Boulder, and Beijing Institute of Technology have fabricated a novel device that could dramatically boost the conversion of heat into electricity. The new fabrication technique involves depositing hundreds of thousands of nanopillars of gallium nitride atop a silicon wafer. Layers of silicon are then removed from the underside of the wafer until only a thin sheet of the material remains. The interaction between the pillars and the silicon sheet slows the transport of heat in the silicon, enabling more of the heat to convert to electric current. 

Scientists at Stanford University and SLAC National Accelerator Laboratory have invented a low-cost, recyclable powder that kills thousands of waterborne bacteria per second when exposed to ordinary sunlight. The powder consists of nano-size flakes of aluminum oxide, molybdenum sulfide, copper, and iron oxide. After absorbing photons from the sun, the molybdenum sulfide/copper catalyst performs like a semiconductor/metal junction, enabling the photons to dislodge electrons. The freed electrons then react with the surrounding water, generating hydrogen peroxide and hydroxyl radicals, which quickly kill the bacteria by damaging their cell membranes.

Researchers from Stanford University and Gyeongsang National University in South Korea have produced soft integrated circuits that convert sensed pressure or temperature to electrical signals, similar to the nerve impulses, to communicate with the brain. The skin-like material consists of three layers, one of which is nitrile, the same rubber that is used in surgical gloves. Integrated in each layer are networks of organic nanostructures that transmit electrical signals, even when stretched. These networks can be engineered to sense pressure, temperature, strain, and chemicals.

Researchers from the City College of New York, the Air Force Research Laboratory, and the Australian National University (Canberra, Australia) have created structured light on a silicon chip and used this added structure to gain new functionalities and control not available before. The scientists created two-dimensional optical metamaterials, or metasurfaces, that hosted a special kind of structured light spinning around just like vortex beams. The researchers also created waveguides for structured light – metal tubes that guide optical signals while preserving the internal structure of light.

Researchers from the National Institute of Standards and Technology, the U.S. Department of Energy’s Idaho National Laboratory, the University of Notre Dame, the University of California Los Angeles, and Indiana University−Purdue University Indianapolis have created a novel 3D printing method that produces materials in ways that conventional manufacturing can’t match. The new process mixes multiple aerosolized nanomaterial inks in a single printing nozzle, varying the ink mixing ratio on the fly during the printing process. This method controls both the printed materials’ 3D architectures and local compositions and produces materials with gradient compositions and properties at microscale spatial resolution.

Physicist Stephen Whitelam, of the Department of Energy’s Lawrence Berkeley National Laboratory, has used neural networks – a type of machine learning model that mimics human brain processes – to train nanosystems to work with greater energy efficiency. Whitelam modeled a so-called “optical trap,” in which laser beams, acting like tweezers of light, can hold and move a nanoscale bead around. He also simulated flipping the state of a nanomagnetic bit between 0 and 1, which is a basic information-erasure/information-copying operation in computing.

Scientists from Brown University, Michigan State University, Columbia University, the U.S. Department of Energy’s Sandia National Laboratories, the University of Innsbruck in Austria, and the National Institute for Materials Science in Japan have described what they believe to be the first measurement showing direct interaction between electrons spinning in a 2D material and photons coming from microwave radiation. The researchers made the measurements on a relatively new 2D material called "magic-angle" twisted bilayer graphene. This graphene-based material is created when two sheets of ultrathin layers of carbon are stacked and twisted to just the right angle.

Northwestern University engineers have developed a new nanoparticle-coated sponge that can remove metals – including toxic heavy metals and critical metals – from contaminated water, leaving safe, drinkable water behind. In proof-of-concept experiments, the researchers tested their new sponge on a highly contaminated sample of tap water, containing more than 1 part per million of lead. With one use, the sponge filtered lead to below detectable levels. The project builds on the team’s previous work to develop highly porous sponges for various aspects of environmental remediation.