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

When materials are created on a nanometer scale, even the thermal energy present at room temperature can cause structural ripples. How these ripples affect the mechanical properties of these thin materials can limit their use in electronics and other key systems. Now, using a semiconductor manufacturing process, researchers from Binghamton University, Harvard University, Princeton University, Penn State, and the U.S. Department of Energy’s Argonne National Laboratory have created alumina structures that are 28 nanometers thick on a silicon wafer with thermal-like static ripples, and then tested these ripples with lasers to measure their behavior. The results match with theories proposed about such structural ripples. 

Researchers from Northwestern University and the University of California, San Diego, have developed new technology that could lead to the creation of a rapid point-of-care test for HIV infection. The technology uses a nanomechanical platform and tiny cantilevers to detect multiple HIV antigens at high sensitivity in a matter of minutes. Built into a solar-powered device, this technology could be taken to hard-to-reach parts of the world, where early detection remains a challenge to deliver fast interventions to vulnerable populations without waiting for lab results.

Engineers at Harvard University have created a bilayer metasurface made of two stacked layers of titanium dioxide nanostructures. Almost a decade ago, the engineers had unveiled the world’s first visible-spectrum metasurfaces – ultra-thin, flat devices patterned with nanostructures that could precisely control the behavior of light and enable applications in imaging systems, augmented reality, and communications. But the single-layer nanostructure design has been in some ways limiting. For example, previous metasurfaces put specific requirements on the manipulation of light’s polarization in order to control the light’s behavior. Using the facilities of the Center for Nanoscale Systems at Harvard, the engineers came up with a fabrication process for freestanding, sturdy structures of two metasurfaces that hold strongly together but do not affect each other chemically.

An international team led by Rutgers University-New Brunswick researchers has merged two lab-synthesized two-dimensional materials into a synthetic quantum structure once thought impossible to exist and produced an exotic structure expected to provide insights that could lead to new materials at the core of quantum computing. One slice of the quantum structure is made of dysprosium titanate, an inorganic compound used in nuclear reactors, while the other is composed of pyrochlore iridate, a new magnetic semimetal. The specific electronic and magnetic properties of the material developed by the researchers can help in creating very unusual yet stable quantum states, which are essential for quantum computing. 

The shape of nanoparticles depends on the choice of solvent and temperature during their growth. But the tiny seed particles that form first and that guide the formation of final nanoparticle shapes are too small to measure accurately. With the help of a supercomputer, Penn State researchers have developed computer simulations to model seed particles with 100 to 200 atoms. They found that the shapes of the tiny particles depend on the solvent composition and temperature in unexpected ways. Surprisingly, in some cases the shape of the seed particle changes dramatically when only a single atom is added or removed. 

Researchers from The University of Texas at Dallas; Texas State University in San Marcos, TX; and Lintec of America in Plano, TX, as well as international collaborators,  have invented a new, inexpensive method in which fibers are coiled to make springlike artificial muscles. What’s unique about this method is that it doesn’t make use of a mandrel – a spindle that serves to support or shape the artificial muscles. The mandrel-free fabrication process involves inserting twist into individual fibers, causing them to coil back on themselves, and then plying the twisted fibers to create springlike coils. The researchers used the mandrel-free method to make high-spring-index carbon nanotube yarns, which could be used to harvest mechanical energy or as self-powered strain sensors.

Researchers from Lehigh University, the U.S. Army Research Laboratory, Arizona State University, and Louisiana State University have developed a nanostructured copper alloy with exceptional thermal stability and mechanical strength, making it one of the most resilient copper-based materials ever created. The breakthrough comes from the formation of copper-lithium precipitates, stabilized by a tantalum-rich atomic bilayer complexion. Unlike typical grain boundaries that migrate over time at high temperatures, this complexion acts as a structural stabilizer, maintaining the nanocrystalline structure, preventing grain growth and dramatically improving high-temperature performance. The U.S. Army Research Laboratory was awarded a U.S. patent for the alloy. 

In a Perspective article published in Nature Materials, two engineers at the Massachusetts Institute of Technology, Carlos Portela and James Surjadi, discuss key hurdles, opportunities, and future applications in the field of mechanical metamaterials. Metamaterials are artificially structured materials with properties not easily found in nature. With engineered three-dimensional geometries at the micro- and nanoscale, metamaterials achieve unique mechanical and physical properties with capabilities beyond those of conventional materials. Over the past decade, metamaterials have emerged as a promising way to address engineering challenges for which other existing materials have lacked success.

Researchers from the California NanoSystems Institute at the University of California, Los Angeles, have developed a sensor technology based on natural biochemical processes that can continuously and reliably measure multiple metabolites at once. The sensors are built onto electrodes made of tiny cylinders called single-wall carbon nanotubes. These electrodes use enzymes and other molecules to perform reactions that mirror the body’s metabolic processes. Depending on the target metabolite, the sensors either detect it directly or first convert it into a detectable form through a chain of intermediary enzymatic reactions. The team measured metabolites in sweat and saliva samples from patients receiving treatment for epilepsy and detected a gut bacteria-derived metabolite in the brain that could cause neurological disorders if it accumulates.

Researchers at the University of Pennsylvania have developed a new process that transports DNA into cells using lipid nanoparticles. Unlike messenger RNA (mRNA), DNA remains active in cells for months, or even years, and can be programmed to work only in targeted cells. But past attempts to use lipid nanoparticles to deliver DNA failed, because DNA can trigger severe immune reactions. The researchers discovered that by adding a natural anti-inflammatory molecule, called nitro-oleic acid, to the lipid nanoparticles, these immune reactions could be eliminated. With this advancement, treated cells produced intended therapeutic proteins for about six months from a single dose – much longer than the few hours seen with mRNA therapies.