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Pink (boron) and blue (nitrogen) pillars serve as spacers for carbon graphene sheets (grey). The researchers showed the material worked best when doped with oxygen atoms (red), which enhanced its ability to adsorb and desorb hydrogen (white).

Graphene-Nanotube Combo Exceeds Benchmarks for Hydrogen Storage in Fuel Cells

With lithium-ion (Li-ion) batteries becoming the de-facto energy source for next-generation vehicles, some of us remember that there was a time when fuel cells were thought to be the most viable solution for powering vehicles after the internal combustion engine.

Of course, this is only a perception based on how companies like Tesla have made the Li-ion battery seem to be the best option. However, the US Department of Energy (DoE) has set benchmarks for what storage materials will need to deliver in order to compete for a place in post-fossil fuel vehicles.

Now researchers at Rice University have developed a nanomaterial for fuel cells that consists of layers of graphene separated by nanotube pillars of boron nitride. The material might tick all the boxes established by the DoE for next-generation vehicles.

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Introducing lithium ions between layers of molybdenum sulfide can tune the thermal conductivity of the material.

New Way to Control Heat in 2D Materials

Two-dimensional (2D) materials such as those made from transition metal dichalcogenides (TMDs) are  layered one on top of another to create devices that could potentially be used for electronics. In fact, how these materials are layered determines to a large extent the electronic properties of the final device.

One property that engineers have kept in mind when plotting the layering of TMDs and other 2D materials is how they dissipate heat. Researchers at North Carolina State University, the University of Illinois at Urbana-Champaign (UI) and the Toyota Research Institute of North America (TRINA) have discovered an almost counterintuitive phenomenon in the layering of 2D materials that should help them to dissipate heat when they are fabricated into electronic devices.

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Dendrites growing in a lithium-metal battery

Video Microscopy Technique Reveals How Battery-Killing Dendrites Grow

While the exact cause of the recent fires experienced with Samsung’s Galaxy Note 7 smartphones have not yet been precisely determined, it appears that these incidents are in some way related to the batteries.

One known problem for both the lithium-ion (Li-ion) batteries used in today’s mobile phones as well as next-generation lithium metal batteries is that they are susceptible to the growth of finger-like deposits of lithium called dendrites inside the battery. These dendrites grow so long that they pierce the barrier between the two sides of the battery and cause a short circuit, possibly leading to a fire.

Now researchers at the University of Michigan—inspired by the potential of next-generation lithium metal batteries to store 10 times more charge than conventional Li-ion batteries—have peered into lithium metal batteries to observe the growth of dendrites. They leveraged a novel microscopy tool that enables them to watch how the lithium changes inside the battery during cycling to create conditions conducive to dendrite growth.

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Reflection spectra in air of the red, green, and blue samples for different angles

Flexible and Colorful Electronic Paper Promises a New Look for E-books

Plasmonic nanostructures leverage the oscillations in the density of electrons that are generated when photons hit a metal surface. Researchers have used these structures for applications including increasing the light absorption of solar cells and creating colors without the need for dyes. As a demonstration of how effective these nanostructures are as a replacement for color dyes, a the technology has been used to produce a miniature copy of the Mona Lisa in a space smaller than the footprint taken up by a single pixel on an iPhone Retina display.

It has also been shown that if you combine these plasmonic nanostructures with electrochromic polymers that change color when a voltage is applied—the kind used in windows that can be turned from clear to opaque with a flip of a switch—you can make a display.

Now researchers at Chalmers University of Technology, in Göteborg, Sweden, have used these plasmonic nanostructures in combination with a electrochromic polymer to create a micrometer-thin display capable of rendering all the colors of traditional light-emitting diode (LED) displays. What’s more, it does so on one-tenth the energy needed to run a Kindle.

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Three gold nanoparticles supported by a DNA scaffold

DNA Scaffold Self-Assembles Into Single-Electron Device

To organize nanoparticles into structures that are useful in electronics, researchers have turned to DNA scaffolds that self-assemble into patterns and attract the nanoparticles into functional arrangements.

Now researchers at the Nanoscience Center (NSC) of the University of Jyväskylä and BioMediTech (BMT) of the University of Tampere, both in Finland, have used these DNA scaffolds to organize three gold nanoparticles into a single-electron transistor. DNA scaffolds have previously been used to organize gold nanoparticles into patterns. But this work represents the first time that these DNA scaffolds have been used to construct precise, controllable DNA-based assemblies that are fully electrically characterized for use in single-electron nanoelectronics. The immediate benefit: There’s no longer a need to keep these structures at cryogenic temperatures in order for them to work.

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Mirkó Palla (left) and P. Benjamin Stranges (right) who performed the work at the Wyss Institute

Personalized Medicine Draws Closer With Cheap and Accurate DNA Sequencer

Sequencing-by-synthesis (SBS) technology currently dominates the gene sequencing market. The process involves dividing a DNA molecule into many pieces of single-stranded templates that are put into millions of tiny wells on a substrate inside a machine that washes them through millions of cycles. Even though prices have dropped five orders of magnitude in the last decade for this technology, it’s still complicated and expensive. 

Many experts thought the key to cheaper DNA sequencers was going to be performing the SBS process in nanopore-based DNA sequencers. Here, the strands of the DNA are pulled through nanometer-scale pores in a membrane and the electric field variations of the four nucleic acids—A, C, G, T—are measured. While a number of companies have launched businesses around this technology, it remains costly enough to delay the revolution in medical care known as personalized medicine.

Now researchers at Wyss Institute for Biologically Inspired Engineering at Harvard University believe that they have developed a way to make these nanopore-SBS DNA sequencers fast, accurate, and, most importantly, cheaper than what is currently on the market. The trick was to biologically engineer the nanopore structure. If they can further develop the technology, they could enable doctors to quickly discern changes in your specific DNA sequence signaling a disease.

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Microscope image of a quantum LED device shows bright quantum emitter generating a stream of single photons.

Two-Dimensional Materials Combined to Produce “Quantum LED”

One of the many scientific and engineering challenges to realizing the prospects of quantum computing—which involves the use of quantum phenomena, like entanglement, to perform complex calculations—is  creating a device that can electrically generate a single photon to be used for carrying data in a quantum network. One method for producing these single photons is the use of complex multiple laser arrangements that have been precisely set up with optical components to produce these single photons. Lately, layered materials that serve as quantum emitters have begun to show a way forward. But even these layered materials require some kind of light source to trigger the emission of a single photon.

Now researchers at the University of Cambridge in England have constructed devices made from thin layers of graphene, boron nitride, and transition metal dichalcogenides (TMDs) that generate a single photon entirely electrically.  The combination of these three types of two-dimensional (2D) materials produces devices that are essentially all-electrical ultrathin quantum light-emitting diodes (LEDs).

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Schematic of a transistor with a molybdenum disulfide channel and 1-nanometer carbon nanotube gate.

One-Nanometer Gate Dimensions for Transistors Have Been Achieved

While there may be some quibbling about what really is the smallest transistor ever fabricated, an all-star lineup of U.S.-based researchers has laid a legitimate claim to having fabricated one that is at, or at least very near, the top of the list. And this one enjoys the relatively rare quality of having the potential to become more than just a lab curiosity.

With a physical gate length of only one nanometer, this latest transistor, made from a combination of molybdenum disulfide and carbon nanotubes, not only shatters the 20-nm gate length of state-of-the-art transistors currently on the market, but also surpasses the theoretical limit of five nanometers for the gate length of silicon-based transistors. While silicon transistors may stop shrinking by 2021, this research shows that transistors based on nanomaterials may still have some way to go in their miniaturization journey.

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Jean-Pierre Sauvage, Fraser Stoddart and Bernard Feringa have been awarded the Nobel chemistry prize.

Molecular Machine Makers Win Nobel Prize in Chemistry

In what seems to have come both as a shock to some of the recipients and a confirmation to all those who envision molecular nanotechnology as the true future of nanotechnology, Bernard Feringa, Jean-Pierre Sauvage, and Sir J. Fraser Stoddart have been awarded the 2016 Nobel Prize in Chemistry for their development of molecular machines.

The Nobel Prize was awarded to all three of the scientists based on their complementary work over nearly three decades. First, in 1983, Sauvage (currently at Strasbourg University in France) was able to link two ring-shaped molecules to form a chain. Then, eight years later, Stoddart, a professor at Northwestern University in Evanston, Ill., demonstrated that a molecular ring could turn on a thin molecular axle. Then, eight years after that, Feringa, a professor at the University of Groningen, in the Netherlands, built on Stoddardt’s work and fabricated a molecular rotor blade that could spin continually in the same direction.

The world of molecular nanotechnology is probably most familiar with Feringa’s work. He’s the one credited with being the first person to develop an actual molecular motor. In fact, IEEE Spectrum covered some of Feringa’s more recent work in 2011, when he and his team constructed a molecule that looks and seems to move like a four-wheeled car.

Of course, these molecular machines are far from having any practical, real-world applications. Despite nods in the press to nanoparticles moving through someone’s blood stream to deliver drugs, the nanogears, nanocars, and nanomachines developed by this year’s Nobel Laureates in Chemistry remain a long way from bringing to reality the primary hope of molecular nanotechnology (MNT): that these machines will work in unison to build macroscale devices. However, this Nobel Prize is as much a spur to future research as it is a recognition of what has already been achieved.

Speaking of the Nobel committee’s selection, Donna Nelson, a chemist and president of the American Chemical Society told Scientific American: “I think this topic is going to be fabulous for science. When the Nobel Prize is given, it inspires a lot of interest in the topic by other researchers. It will also increase funding.” Nelson added that this line of research will be fascinating for kids. “They can visualize it, and imagine a nanocar. This comes at a great time, when we need to inspire the next generation of scientists.”

Indeed, nanomachines do capture our imagination and have played a role in an increasing number of sci-fi movies and novels. However, experimental research in adapting these nanogears and nanomachines into the kind of MNT manufacturing that is envisioned in these works of fiction seems to still be lacking. MNT supporters have identified a lack of funding as one of the main obstacles. Whether this latest Nobel Prize will spur some funding bodies to open up the purse strings to realize the broader potential that this initial work seems to promise remains a question that only time can answer.



IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

Dexter Johnson
Madrid, Spain
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