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Category: nanotechnology

Carbon nanotubes are closing the gap on copper conductivity

Carbon nanotubes are one technology that many observers believe hasn’t quite lived up to the extreme hype that surrounded them when they first appeared on the scene in the late 1990s. At that time, much was made of their extraordinary electrical, thermal, and mechanical properties, with predictions that they would revolutionize materials science, electronics, and daily life. But could we be closer to realizing some of that promise?

In a paper published in the journal Science, researchers describe a method for adding a chemical to carbon nanotube bundles that brings them closer to copper’s ability to conduct electricity.

Carbon nanotubes are nanoscale hollow cylinders of carbon atoms, a structure that allows electricity to flow through them with very low resistance. However, when you bundle millions of them together, as you would need for practical applications like power lines and electrical wiring, they lose some of their exceptional conductivity. Electrons move easily along individual nanotubes, but transferring charge between neighboring tubes in a bundle is much less efficient.

High-resolution imaging shines light on nanoscale nuclear organization

Researchers at the Indian Institute of Science (IISc) have implemented an advanced microscopy technique to visualize multiple biomolecules inside the nucleus of a cancer cell simultaneously at incredibly high resolution. The biomolecules they visualized include critical components of the cell’s transcription machinery and proteins that provide structural support to the nucleus—providing one of the first detailed maps of nuclear organization.

The human body is composed of trillions of cells. Each cell is an intricately organized meshwork of millions of proteins, nucleic acids, and many other molecules vital for the cell’s health. “Building novel technologies to visualize many biomolecules in individual cells is crucial to push the boundaries of biological research,” says Mahipal Ganji, Assistant Professor at the Department of Biochemistry (BC) and corresponding author of the study published in Nature Communications. Conventional imaging techniques, however, allow scientists to visualize only two or three biomolecules in each cell at a time.

In the study, the researchers turned to a microscopy technique called DNA-Points Accumulation for Imaging in Nanoscale Topography (DNA-PAINT), which allows for the visualization of biomolecules inside cells at incredible detail—far beyond the limits of conventional microscopes. It uses small fluorescent DNA fragments or tags that briefly attach to specific targets inside the cell and light up like tiny, blinking signals when a laser beam is shined on them.

Light near surface of ultra-thin optical fibers can sort twisted nanoparticles

Many important objects in the world can be divided into two categories based on their chirality or handedness, including molecules important for life such as amino acids. Such chiral objects (formally defined as objects which are not identical to their mirror images) are often characterized by a structure which twists in a given direction.

An everyday example of a chiral object is a screw. A right-handed screw moves into a material when rotated clockwise, but its mirror image (i.e., a left-handed screw) moves out.

Just as right-and left-handed screws behave differently when turned, chiral particles behave differently when exposed to light with a circular polarization. This fact allows them to be sorted in principle, which is expected to be important for applications such as drug development, where the handedness of a chiral molecule determines how it interacts with biological systems.

How electron structure affects light responses in moiré materials

In materials science, if you can understand the “texture” of a material—how its internal patterns form and shift—you can begin to design how it behaves. That’s the focus of the work of Zhenglu Li, assistant professor in the Mork Family Department of Chemical Engineering and Materials Science at USC Viterbi School of Engineering. Li’s recently published paper in PNAS, titled “Moiré excitons in generalized Wigner crystals,” demonstrates that the way electrons organize themselves inside a material determines how that material responds to light—and how this organization can be engineered.

“Moiré” is a word that will be familiar to anyone who follows fashion. In the context of textiles, it refers to a larger-scale interference pattern that appears when two repeating patterns are slightly misaligned. Imagine brushing a swatch of velvet in different directions; the material reveals different properties depending on how it is ruffled.

Likewise, in the context of nanoscale materials science, an independent, shimmering or wavelike pattern is formed when two overlapping atomically thin layers are overlaid at an acute angle. The new pattern, moiré superlattice, changes how electrons move, which can give the material unusual properties.

First direct nanomagnet measurement finds switching attempts far slower than long-assumed

A compass always points north—or does it? Magnets normally maintain a stable direction of magnetization, pointing from south to north (S→N). However, this direction can change under strong magnetic fields or heat. For example, a compass placed near a strong magnet may no longer point in the right direction.

Magnets can also lose their magnetism when exposed to high levels of heat. This isn’t just relevant to wayfinding during your camping trips—if the magnets in hard drives and memory storage devices are affected, it could mean losing all of your precious data.

Researchers at Tohoku University sought to better understand the intricate ways in which this thermally-activated switching occurs in nanomagnets, and successfully measured it experimentally for the very first time. The results are published in Communications Materials.

Scientists invent artificial neurons that ‘talk’ to real brain cells, paving way to better brain implants

Engineers have printed tiny, artificial neurons that can “talk” to mouse brain cells, and the development could pave the way to innovations in computing and medicine.

The work, published April 15 in the journal Nature Nanotechnology, adds to a growing field that aims to build computers that mimic the inner workings of the brain.

Quasiparticles reveal a magneto-optical transport phenomenon

Excitons are being explored in materials science and information technology as a means of storing light. These luminous quasiparticles move through individual layers of quantum materials and can absorb and emit light with high efficiency. They form when a laser pulse excites an electron, leaving behind a positively charged “hole.” The electron and hole attract each other and behave together like a new, independent particle. When the quasiparticle recombines, it emits light and can be detected in high-tech laboratories.

Excitons in ultrathin quantum materials have been intensively studied for more than a decade, including by Alexey Chernikov and his team. At the Cluster of Excellence ctd.qmat—Complexity, Topology and Dynamics in Quantum Matter—at the Universities of Würzburg and Dresden, Chernikov and an international research team based in Dresden have now made a surprising discovery: excitons can be carried along by the magnetic excitations of a quantum material and, as a result, accelerated to ultrahigh speeds. The findings are published in the journal Nature Nanotechnology.

“The fact that the motion of optical particles can be controlled by magnetism is new. Until now, we only knew that the transport of electrons could be controlled by the magnetic order in a quantum material—this is how some sensors in smartphones work, for example. This newly discovered link between optics and magnetism could open up entirely new technological possibilities,” explains Florian Dirnberger, head of an Emmy Noether Junior Research Group at the Technical University of Munich and formerly a postdoctoral researcher in Alexey Chernikov’s Chair of Ultrafast Microscopy and Photonics, where he was responsible for carrying out the research project.

Why does life prefer one ‘hand’ over the other? New study points to electron spin

A team of scientists has identified a new physical mechanism that could help explain one of the most persistent mysteries in science: why life consistently uses one “handed” version of its molecules and not the other. In a new study led by Prof. Yossi Paltiel of the Center for Nanoscience and Nanotechnology at Hebrew University and Prof. Ron Naaman of the Weizmann Institute, researchers show that electron spin, a fundamental quantum property, can cause mirror-image molecules to behave differently during dynamic processes, even though they are otherwise identical. The work appears in Science Advances.

Many molecules essential to life come in two mirror-image forms, known as enantiomers. Chemically, these forms are nearly indistinguishable. Yet in living systems, only one version is typically used: amino acids are almost exclusively one type, while sugars follow the opposite pattern.

This phenomenon, known as homochirality, has puzzled scientists for more than a century. Existing explanations have struggled to account for why one specific version was selected globally.

Put a nanodiamond under intense pressure and it becomes flexible

Diamond is among the hardest naturally occurring substances on Earth, but if you shrink it down to the nanoscale, it is surprisingly elastic. And that could be useful for a host of applications such as quantum computing. In a paper published in the journal Physical Review X, Chongxin Shan at Zhengzhou University in China and colleagues studied diamonds as small as four nanometers across to see how they respond to pressure.

Scientists already know that nanodiamonds, which are thousands of times smaller than a grain of sand, can survive being stretched or squeezed in ways that destroy a regular diamond. But nobody knew how.

So the team placed individual nanodiamonds (ranging from 4 to 13 nanometers across) inside a transmission electron microscope between two diamond indenters and compressed them. These were connected to a sensor that measured how strongly each nanodiamond resisted being squeezed while a high-resolution camera imaged diamond atoms as they moved. The researchers backed up their observations with computer simulations.

Tiny ‘light-concentrating’ particles boost terahertz technology, study shows

Scientists have found a way to boost terahertz technology using particles thousands of times smaller than a grain of sand. Research published in Scientific Reports by Loughborough University’s Emergent Photonics Research Center shows how a sparse layer of nanoparticles can make materials that produce terahertz radiation more efficient.

Terahertz radiation sits between microwaves and infrared on the electromagnetic spectrum and has a range of potential uses. It can “see” through materials like clothing or plastic and detect chemical fingerprints, with applications in security screening, medical imaging, materials testing, and wireless communications.

But existing devices are limited by how efficiently they can generate terahertz waves.

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