This 3D printer can figure out how to print with an unknown material

Researchers developed a 3D printer that can automatically identify the parameters of an unknown material on its own.
Photo Credit: Courtesy of the researchers
(CC BY-NC-ND 4.0 DEED)

While 3D printing has exploded in popularity, many of the plastic materials these printers use to create objects cannot be easily recycled. While new sustainable materials are emerging for use in 3D printing, they remain difficult to adopt because 3D printer settings need to be adjusted for each material, a process generally done by hand.

To print a new material from scratch, one must typically set up to 100 parameters in software that controls how the printer will extrude the material as it fabricates an object. Commonly used materials, like mass-manufactured polymers, have established sets of parameters that were perfected through tedious, trial-and-error processes.

But the properties of renewable and recyclable materials can fluctuate widely based on their composition, so fixed parameter sets are nearly impossible to create. In this case, users must come up with all these parameters by hand.

Researchers tackled this problem by developing a 3D printer that can automatically identify the parameters of an unknown material on its own.

Airy cellulose from a 3D printer

Complexity and lightness: Empa researchers have developed a 3D printing process for biodegradable cellulose aerogel.
Photo Credit: Empa

Ultra-light, thermally insulating and biodegradable: Cellulose-based aerogels are versatile. Empa researchers have succeeded in 3D printing the natural material into complex shapes that could one day serve as precision insulation in microelectronics or as personalized medical implants.

At first glance, biodegradable materials, inks for 3D printing and aerogels don't seem to have much in common. All three have great potential for the future, however: "green" materials do not pollute the environment, 3D printing can produce complex structures without waste, and ultra-light aerogels are excellent heat insulators. Empa researchers have now succeeded in combining all these advantages in a single material. And their cellulose-based, 3D-printable aerogel can do even more.

The miracle material was created under the leadership of Deeptanshu Sivaraman, Wim Malfait and Shanyu Zhao from Empa's Building Energy Materials and Components laboratory, in collaboration with the Cellulose & Wood Materials and Advanced Analytical Technologies laboratories as well as the Center for X-ray Analytics. Together with other researchers, Zhao and Malfait had already developed a process for printing silica aerogels in 2020. No trivial task: Silica aerogels are foam-like materials, highly open porous and brittle. Before the Empa development, shaping them into complex forms had been pretty much impossible. "It was the logical next step to apply our printing technology to mechanically more robust bio-based aerogels," says Zhao.

The researchers chose the most common biopolymer on Earth as their starting material: cellulose. Various nanoparticles can be obtained from this plant-based material using simple processing steps. Doctoral student Deeptanshu Sivaraman used two types of such nanoparticles – cellulose nanocrystals and cellulose nanofibers – to produce the "ink" for printing the bio-aerogel.

‘Frankenstein design’ enables 3D printed neutron collimator

Images of the 3D printed “Frankenstein design” collimator show the “scars” where the individual parts are joined, which are clearly visible at right.
Photo Credit: Genevieve Martin/ORNL, U.S. Dept. of Energy

The time-tested strategy of divide and conquer took on a new, high-tech meaning during neutron experiments by scientists at the Department of Energy’s Oak Ridge National Laboratory. They discovered that the problems they faced while attempting to 3D print a one-piece collimator could be solved by instead developing a “Frankenstein design” involving multiple body parts – and some rather obvious scars.

Collimators are important components used in neutron scattering. Similar to X-rays, neutrons are used to study energy and matter at the atomic scale. Neutron collimators can be thought of as funnels that help guide neutrons toward a detector after they interact with experimental sample materials. These funnels primarily serve to reduce the number of stray neutrons that interfere with data collection, for example, neutrons that scatter off sample holders, or from other apparatuses used in the experiment such as high-pressure cells. 

During this process, most of the unwanted neutrons, those scattering from features other than the sample, enter channels inside the collimators at odd angles and are absorbed by channel walls, also referred to as blades. The blades act like the gutters on a bowling lane, which capture bowling balls that are not headed toward the pins.

New Material Can Be Used as a Membrane in Nuclear Reactors

The development can be used to accumulate deuterium and tritium for reuse.
Photo Credit: Rodion Narudinov

The new proton conductor developed by Ural scientists can be used as a separation membrane for hydrogen isotopes. This will make it possible to extract deuterium and tritium from the gas mixture and then use them for their intended purpose - either to recycle or to use. The scientists' development can be used in nuclear power plants (NPPs) to improve the efficiency of chemical separation. The scientists have published detailed information about the new conductor and its benefits in Ceramics International.

"Our material can be used as a functional material in nuclear energy. The fact is that during the operation of a nuclear reactor, a radioactive isotope of hydrogen, tritium, is released, which needs to be properly utilized. Our material can act as a membrane capable of electrochemically pumping the tritium out of the supplied gas mixture. This makes it possible to use the tritium as a fuel for fusion reactors, depending on the task", explains George Starostin, Junior Researcher at the Hydrogen Energy Research Laboratory of UrFU.

A separation membrane has been created to separate individual components and, in the case of proton-conducting membranes, to separate hydrogen isotopes. According to the scientists, a membrane made of the created material will make it possible to optimize the separation process and obtain pure isotopes that can be used in thermonuclear reactions.

Magnetic Avalanche Triggered by Quantum Effects

Christopher Simon holds a crystal of lithium holmium yttrium fluoride.
Photo Credit: Lance Hayashida/Caltech

Iron screws and other so-called ferromagnetic materials are made up of atoms with electrons that act like little magnets. Normally, the orientations of the magnets are aligned within one region of the material but are not aligned from one region to the next. Think of groups of tourists in Times Square pointing to different billboards all around them. But when a magnetic field is applied, the orientations of the magnets, or spins, in the different regions line up and the material becomes fully magnetized. This would be like the packs of tourists all turning to point at the same sign.

The process of spins lining up, however, does not happen all at once. Rather, when the magnetic field is applied, different regions, or so-called domains, influence others nearby, and the changes spread across the material in a clumpy fashion. Scientists often compare this effect to an avalanche of snow, where one small lump of snow starts falling, pushing on other nearby lumps, until the entire mountainside of snow is tumbling down in the same direction.

Unleashing Disordered Rocksalt Oxides as Cathodes for Rechargeable Magnesium Batteries

Schematics of the battery and present cathode material. The present material contains many metal elements as cations thanks to the effect of the high configurational entropy.
Illustration Credit: ©Tohoku University

Researchers at Tohoku University have made a groundbreaking advancement in battery technology, developing a novel cathode material for rechargeable magnesium batteries (RMBs) that enables efficient charging and discharging even at low temperatures. This innovative material, leveraging an enhanced rock-salt structure, promises to usher in a new era of energy storage solutions that are more affordable, safer, and higher in capacity.

Details of the findings were published in the Journal of Materials Chemistry. 

The study showcases a considerable improvement in magnesium (Mg) diffusion within a rock-salt structure, a critical advancement since the denseness of atoms in this configuration had previously impeded Mg migration. By introducing a strategic mixture of seven different metallic elements, the research team created a crystal structure abundant in stable cation vacancies, facilitating easier Mg insertion and extraction.

This represents the first utilization of rocksalt oxide as a cathode material for RMBs. The high-entropy strategy employed by the researchers allowed the cation defects to activate the rocksalt oxide cathode.

New Method Developed to Isolate HIV Particles

The image shows PNF-coated magnetic microbeads that bind HIV particles to their surface.
Image Credit: Torsten John

Researchers at Leipzig University and Ulm University have developed a new method to isolate HIV from samples more easily, potentially making it easier to detect infection with the virus. They focus on peptide nanofibrils (PNFs) on magnetic microparticles, a promising tool and hybrid material for targeted binding and separation of viral particles. They have published their new findings in the journal Advanced Functional Materials.

“The presented method makes it possible to efficiently capture, isolate and concentrate virus particles, which may improve the sensitivity of existing diagnostic tools and analytical tests,” says Professor Bernd Abel of the Institute of Technical Chemistry at Leipzig University. The nanofibrils used – small, needle-like structures – are based on the EF-C peptide, which was first described in 2013 by Professor Jan Münch from Ulm University and Ulm University Medical Center. EF-C is a peptide consisting of twelve amino acids that forms nanoscale fibrils almost instantaneously when dissolved in polar solvents. These can also be applied to magnetic particles. “Using the EF-C peptide as an example, our work shows how peptide fibrils on magnetic particles can have a completely new functionality – the more or less selective binding of viruses. Originally, fibrils of this kind were more likely to be associated with neurodegenerative diseases,” adds Dr Torsten John, co-first author of the study and former doctoral researcher under Professor Abel at Leipzig University. He is now a junior researcher at the Max Planck Institute for Polymer Research in Mainz, Germany.

New Nanoceramics Could Help Improve Smartphone and TV Displays

Nanoceramics are strong because they are made under high pressure.
Photo Credit: Anna Marinovich

Scientists from the Ural Federal University, together with colleagues from India and the Ural Branch of the Russian Academy of Sciences, have developed a nanoceramic that glows in three main colors - red, green, and blue. The new material is extremely strong because it is created under high pressure. Scientists believe that the characteristics of the new nanoceramics - luminescence, strength, and transparency - will be useful for creating screens with improved brightness and detail for smartphones, televisions, and other devices. The scientists published detailed information about the new nanoceramics and their properties in the journal Applied Materials Today. 

"We obtained optically transparent nanoceramics capable of luminescing in red, green, and blue colors. This was made possible by adding carbon particles that act as carbon nanodots. During the synthesis process, the carbon components are encapsulated between the ceramic particles, creating defects on their surface. We believe that these defects create several energy levels in the carbon nanodots, allowing the material to glow in different colors in the visible spectrum", explains Arseny Kiryakov, the co-author of the work, Associate Professor of the UrFU Department of Physical Techniques and Devices for Quality Control.

Elusive 3D printed nanoparticles could lead to new shapeshifting materials

Optical images of truncated tetrahedrons forming two large hexagonal grains at an anti-phase boundary (left), and transforming into a quasi-diamond phase that initiated at the anti-phase boundary (right). Scale bars are 25 um.
Image Credit: David Doan & John Kulikowski

Stanford materials engineers have 3D printed tens of thousands of hard-to-manufacture nanoparticles long predicted to yield promising new materials that change form in an instant.

In nanomaterials, shape is destiny. That is, the geometry of the particle in the material defines the physical characteristics of the resulting material.

“A crystal made of nano-ball bearings will arrange themselves differently than a crystal made of nano-dice and these arrangements will produce very different physical properties,” said Wendy Gu, an assistant professor of mechanical engineering at Stanford University, introducing her latest paper which appears in the journal Nature Communications. “We’ve used a 3D nanoprinting technique to produce one of the most promising shapes known – Archimedean truncated tetrahedrons. They are micron-scale tetrahedrons with the tips lopped off.”

In the paper, Gu and her co-authors describe how they nanoprinted tens of thousands of these challenging nanoparticles, stirred them into a solution, and then watched as they self-assembled into various promising crystal structures. More critically, these materials can shift between states in minutes simply by rearranging the particles into new geometric patterns.

This ability to change “phases,” as materials engineers refer to the shapeshifting quality, is similar to the atomic rearrangement that turns iron into tempered steel, or in materials that allow computers to store terabytes of valuable data in digital form.

“If we can learn to control these phase shifts in materials made of these Archimedean truncated tetrahedrons it could lead in many promising engineering directions,” she said.

Novel electrochemical sensor detects dangerous bacteria

By using a customized surface to bait the targeted pathogens, they separate by themselves from a mixture of many different bacteria. This makes it easy to detect them electrochemically.
Illustration Credit: Sebastian Balser, Andreas Terfort Research Group, Goethe University Frankfurt

Researchers at Goethe University Frankfurt and Kiel University have developed a novel sensor for the detection of bacteria. It is based on a chip with an innovative surface coating. This ensures that only very specific microorganisms adhere to the sensor – such as certain pathogens. The larger the number of organisms, the stronger the electric signal generated by the chip. In this way, the sensor is able not only to detect dangerous bacteria with a high level of sensitivity but also to determine their concentration. 

Each year, bacterial infections claim several million lives worldwide. That is why detecting harmful microorganisms is crucial – not only in the diagnosis of diseases but also, for example, in food production. However, the methods available so far are often time-consuming, require expensive equipment or can only be used by specialists. Moreover, they are often unable to distinguish between active bacteria and their decay products. 

By contrast, the newly developed method detects only intact bacteria. It makes use of the fact that microorganisms only ever attack certain body cells, which they recognize from the latter's specific sugar molecule structure. This matrix, known as the glycocalyx, differs depending on the type of cell. It serves, so to speak, as an identifier for the body cells. This means that to capture a specific bacterium, we need only to know the recognizable structure in the glycocalyx of its preferred host cell and then use this as “bait".

SwRI Develops More Effective Particle Conversion Surfaces for Space Instruments

SwRI space scientists are collaborating with materials specialists to create more effective particle detection surfaces for spacecraft instruments. Pictured is a conversion surface substrate developed specifically for the IMAP-Lo instrument.
Photo Credit: Courtesy of SwRI

Southwest Research Institute is investing internal funding to develop more effective conversion surfaces to allow future spacecraft instruments to collect and analyze low-energy particles. Conversion surfaces are ultra-smooth, ultra-thin surfaces covering a silicon wafer that converts neutral atoms into ions to more effectively detect particles from outer space.

Changing the charge of particles simplifies and enhances detection and analysis capabilities. Dr. Jianliang Lin of the Institute’s Mechanical Engineering Division and Dr. Justyna Sokół of SwRI’s Space Science Division lead the multidisciplinary project. The project builds on the successful creation of conversion surfaces for the IMAP-Lo instrument for the Interstellar Mapping and Acceleration Probe (IMAP) spacecraft. IMAP, which is set to launch in 2025, will help researchers better understand the boundary of our heliosphere, the region of space encompassing the solar system, where the solar wind has a significant influence.

“When low-energy atoms enter the instrument from outer space, they bounce off the conversion surface and either gain or lose an electron, making their electrical charge unbalanced. This makes it easier to increase their speed and analyze their mass and other properties,” Sokół said.

A self-cleaning wall paint

Qaisar Maqbool and Günther Rupprechter
Photo Credit: Courtesy of Technische Universität Wien

A breakthrough in catalysis research leads to a new wall paint that cleans itself when exposed to sunlight and chemically breaks down air pollutants.

Typically, beautiful white wall paint does not stay beautiful and white forever. Often, various substances from the air accumulate on its surface. This can be a desired effect because it makes the air cleaner for a while – but over time, the color changes and needs to be renewed.

A research team from TU Wien and the Università Politecnica delle Marche (Italy) has now succeeded in developing special titanium oxide nanoparticles that can be added to ordinary, commercially available wall paint to establish self-cleaning power: The nanoparticles are photocatalytically active, they can use sunlight not only to bind substances from the air, but also to decompose them afterwards. The wall makes the air cleaner – and cleans itself at the same time. Waste was used as the raw material for the new wall paint: metal scrap, which would otherwise have to be discarded, and dried fallen leaves.

World's first high-resolution brain developed by 3D printer

Franziska Chalupa-Gantner and Aleksandr Ovsianikov at work.
Photo Credit: Courtesy of Technische Universität Wien

In a joint project between TU Wien and MedUni Vienna, the world's first 3D-printed "brain phantom" has been developed, which is modelled on the structure of brain fibres and can be imaged using a special variant of magnetic resonance imaging (dMRI). As a scientific team led by TU Wien and MedUni Vienna has now shown in a study, these brain models can be used to advance research into neurodegenerative diseases such as Alzheimer's, Parkinson's and multiple sclerosis. The research work was published in the journal Advanced Materials Technologies.

Magnetic resonance imaging (MRI) is a widely used diagnostic imaging technique that is primarily used to examine the brain. MRI can be used to examine the structure and function of the brain without the use of ionizing radiation. In a special variant of MRI, diffusion-weighted MRI (dMRI), the direction of the nerve fibers in the brain can also be determined. However, it is very difficult to correctly determine the direction of nerve fibers at the crossing points of nerve fiber bundles, as nerve fibers with different directions overlap there. In order to further improve the process and test analysis and evaluation methods, an international team in collaboration with the TU Wien and the Medical University of Vienna developed a so-called "brain phantom", which was produced using a high-resolution 3D printing process.

Backyard insect inspires invisibility devices, next gen tech

Brochosomes are hollow, nanoscopic, soccer ball-shaped spheroids with through-holes that are produced by the common backyard insect, the leafhopper. Researchers found that the through-holes of these hollow buckyballs help reduce the reflection of light. This is the first biological example showing short wavelength, low-pass antireflection functionality enabled by through-holes and hollow structures.
Image Credit: Lin Wang and Tak-Sing Wong / Pennsylvania State University
(CC BY-NC-ND 4.0 DEED)

Leafhoppers, a common backyard insect, secrete and coat themselves in tiny mysterious particles that could provide both the inspiration and the instructions for next-generation technology, according to a new study led by Penn State researchers. In a first, the team precisely replicated the complex geometry of these particles, called brochosomes, and elucidated a better understanding of how they absorb both visible and ultraviolet light.

This could allow the development of bioinspired optical materials with possible applications ranging from invisible cloaking devices to coatings to more efficiently harvest solar energy, said Tak-Sing Wong, professor of mechanical engineering and biomedical engineering. Wong led the study, which was published in the Proceedings of the National Academy of Sciences (PNAS).

The unique, tiny particles have an unusual soccer ball-like geometry with cavities, and their exact purpose for the insects has been something of a mystery to scientists since the 1950s. In 2017, Wong led the Penn State research team that was the first to create a basic, synthetic version of brochosomes in an effort to better understand their function.

Rice researchers develop 3D-printed wood from its own natural components

Researchers at Rice University have unlocked the potential to use 3D printing.
Photo Credit: Gustavo Raskosky/Rice University.

Researchers at Rice University have unlocked the potential to use 3D printing to make sustainable wood structures, offering a greener alternative to traditional manufacturing methods.

Wood has historically been marred by wasteful practices generated during shaping processes, driving up costs and environmental impact. Now researchers in materials science and nanoengineering at Rice have developed an additive-free, water-based ink made of lignin and cellulose, the fundamental building blocks of wood. The ink can be used to produce architecturally intricate wood structures via a 3D printing technique known as direct ink writing.

The work was recently published in the journal Science Advances.

“The ability to create a wood structure directly from its own natural components sets the stage for a more eco-friendly and innovative future,” said Muhammad Rahman, an assistant research professor of materials science and nanoengineering at Rice. “It heralds a new era of sustainable 3D-printed wood construction.”

The implications are far-reaching, potentially revolutionizing industries such as furniture and construction.

Rice research could advance soft robotics manufacturing, design

Te Faye Yap (left) and Daniel Preston
Photo Credit: Jeff Fitlow/Rice University

Soft robots use pliant materials such as elastomers to interact safely with the human body and other challenging, delicate objects and environments. A team of Rice University researchers has developed an analytical model that can predict the curing time of platinum-catalyzed silicone elastomers as a function of temperature. The model could help reduce energy waste and improve throughput for elastomer-based components manufacturing.

“In our study, we looked at elastomers as a class of materials that enables soft robotics, a field that has seen a huge surge in growth over the past decade,” said Daniel Preston, a Rice assistant professor of mechanical engineering and corresponding author on a study published in Cell Reports Physical Science. “While there is some related research on materials like epoxies and even on several specific silicone elastomers, until now there was no detailed quantitative account of the curing reaction for many of the commercially available silicone elastomers that people are actually using to make soft robots. Our work fills that gap.”

The platinum-catalyzed silicone elastomers that Preston and his team studied typically start out as two viscoelastic liquids that, when mixed together, transform over time into a rubbery solid. As a liquid mixture, they can be poured into intricate molds and thus used for casting complex components. The curing process can occur at room temperature, but it can also be sped up using heat.

Manufacturing processes involving elastomers have typically relied on empirical estimates for temperature and duration to control the curing process. However, this ballpark approach makes it difficult to predict how elastomers will behave under varying curing conditions. Having a quantitative framework to determine exactly how temperature impacts curing speed will enable manufacturers to maximize efficiency and reduce waste.

New research on tungsten unlocks potential for improving fusion materials

Through a combination of modeling and state-of-the-art experimental techniques, researchers shed light on the complex behavior of phonons in tungsten. This advancement could lead to the development of more efficient and resilient fusion reactor materials.
Image Credit: Courtesy of SLAC National Accelerator Laboratory

In the pursuit of clean and endless energy, nuclear fusion is a promising frontier. But in fusion reactors, where scientists attempt to make energy by fusing atoms together, mimicking the sun's power generation process, things can get extremely hot. To overcome this, researchers have been diving deep into the science of heat management, focusing on a special metal called tungsten.

New research, led by scientists at the Department of Energy’s SLAC National Accelerator Laboratory, highlights tungsten's potential to significantly improve fusion reactor technology based on new findings about its ability to conduct heat. This advancement could accelerate the development of more efficient and resilient fusion reactor materials. Their results were published today in Science Advances.

"What excites us is the potential of our findings to influence the design of artificial materials for fusion and other energy applications," said collaborator Siegfried Glenzer, director of the High Energy Density Division at SLAC. “Our work demonstrates the capability to probe materials at the atomic scale, providing valuable data for further research and development."

Scientists reveal the first unconventional superconductor that can be found in mineral form in nature

A miassite crystal grown by Paul Canfield.
Photo Credit: Paul Canfield

Scientists from Ames National Laboratory have identified the first unconventional superconductor with a chemical composition also found in nature. Miassite is one of only four minerals found in nature that act as a superconductor when grown in the lab. The team’s investigation of miassite revealed that it is an unconventional superconductor with properties similar to high-temperature superconductors. Their findings further scientists’ understanding of this type of superconductivity, which could lead to more sustainable and economical superconductor-based technology in the future.

Superconductivity is when a material can conduct electricity without energy loss. Superconductors have applications including medical MRI machines, power cables, and quantum computers. Conventional superconductors are well understood but have low critical temperatures. The critical temperature is the highest temperature at which a material acts as a superconductor.

In the 1980s, scientists discovered unconventional superconductors, many of which have much higher critical temperatures. According to Ruslan Prozorov, a scientist at Ames Lab, all these materials are grown in the lab. This fact has led to the general belief that unconventional superconductivity is not a natural phenomenon.

Prozorov explained that it is difficult to find superconductors in nature because most superconducting elements and compounds are metals and tend to react with other elements, like oxygen. He said that miassite (Rh17S15) is an interesting mineral for several reasons, one of which is its complex chemical formula. “Intuitively, you think that this is something which is produced deliberately during a focused search, and it cannot possibly exist in nature,” said Prozorov, “But it turns out it does.”

More than flying cars: eVTOL battery analysis reveals unique operating demands

The operating phases of an eVTOL need varying amounts of power; some require the battery to discharge high amounts of current rapidly, reducing the distance the vehicle can travel before its battery must be recharged.
Illustration Credit: Andy Sproles/ORNL, U.S. Dept. of Energy

Researchers at the Department of Energy’s Oak Ridge National Laboratory are taking cleaner transportation to the skies by creating and evaluating new batteries for airborne electric vehicles that take off and land vertically. 

These aircraft, commonly called eVTOLs, range from delivery drones to urban air taxis. They are designed to rise into the air like a helicopter and fly using wing-borne lift like an airplane. Compared with helicopters, eVTOLs generally use more rotors spinning at a lower speed, making them both safer and quieter.

The airborne EV’s aren’t just flying cars, and ORNL researchers conclude that eVTOL batteries can’t just be adapted from electric car batteries. So far that has been the dominant approach to the technology, which is mostly in the modeling stage. ORNL researchers took a different tack by evaluating how lithium-ion batteries fare under extremely high-power draw. 

“The eVTOL program presents a unique opportunity for creating a brand-new type of battery with very different requirements and capabilities than what we have seen before," said Ilias Belharouak, an ORNL Corporate Fellow who guides the research. 

Tiny Tunable Nanotubes

By wrapping a carbon nanotube with a ribbon-like polymer, Duke researchers were able to create nanotubes that conduct electricity when struck with low-energy light that our eyes cannot see. In the future, the approach could make it possible to optimize semiconductors for applications ranging from night vision to new forms of computing.
Illustration Credit: Francesco Mastrocinque

It might look like a roll of chicken wire, but this tiny cylinder of carbon atoms -- too small to see with the naked eye -- could one day be used for making electronic devices ranging from night vision goggles and motion detectors to more efficient solar cells, thanks to techniques developed by researchers at Duke University.

First discovered in the early 1990s, carbon nanotubes are made from single sheets of carbon atoms rolled up like a straw.

Carbon isn’t exactly a newfangled material. All life on Earth is based on carbon. It’s the same stuff found in diamonds, charcoal, and pencil lead.

What makes carbon nanotubes special are their remarkable properties. These tiny cylinders are stronger than steel, and yet so thin that 50,000 of them would equal the thickness of a human hair.

They’re also amazingly good at conducting electricity and heat, which is why, in the push for faster, smaller, more efficient electronics, carbon nanotubes have long been touted as potential replacements for silicon.