#A billion holes can make a battery Researchers at the University of Maryland have invented a single tiny structure that includes all the components of a battery that they say could bring about the ultimate miniaturization of energy storage components.
The structure is called a nanopore: a tiny hole in a ceramic sheet that holds electrolyte to carry the electrical charge between nanotube electrodes at either end.
The existing device is a test but the bitsy battery performs well. First author Chanyuan Liu a graduate student in materials science & engineering says that it can be charged fully in 12 minutes
and it can be recharged thousands of time. A team of UMD chemists and materials scientists collaborated on the project:
Gary Rubloff director of the Maryland Nanocenter and a professor in the Department of Materials science and engineering and in the Institute for Systems Research;
Sang Bok Lee a professor in the Department of chemistry and Biochemisty and the Department of Materials science and engineering;
and seven of their Ph d. students (two now graduated. Many millions of these nanopores can be crammed into one larger battery the size of a postage stamp.
One of the reasons the researchers think this unit is so successful is because each nanopore is shaped just like the others
which allows them to pack the tiny thin batteries together efficiently. Coauthor Eleanor Gillette's modeling shows that the unique design of the nanopore battery is responsible for its success. The space inside the holes is so small that the space they take up all added together would be no more than a grain of sand.
Now that the scientists have the battery working and have demonstrated the concept they have identified also improvements that could make the next version 10 times more powerful.
The next step to commercialization: the inventors have conceived strategies for manufacturing the battery in large batches s
#Team grows uniform nanowires A researcher from Missouri University of Science and Technology has developed a new way to grow nanowire arrays with a determined diameter length and uniform consistency.
This approach to growing nanomaterials will improve the efficiency of various devices including solar cells and fuel cells.
These semiconducting nanowires could also replace thin films that cover today's solar panels. Current panels can process only 20 percent of the solar energy they take in.
By applying the nanowires the surface area of the panels would increase and allow more efficient solar energy capture and conversion.
The wires could also be applied in the biomedical field to maximize heat production in hyperthermia treatment of cancer.
In fuel cells these nanowire arrays can be used to lower production expenses by relying on more cost-efficient catalysts.
My team and I hope to replace or outperform the current use of platinum and show that these nanowire arrays are better catalysts for the oxygen reduction reactions in the cells says Dr. Manashi Nath assistant professor of chemistry at Missouri S&t.
The nanowires which are grown on patterned nanoelectrodes are visible only through an electron microscope. Nath creates the nanowire arrays through a process that she calls confined electrodeposition on lithographically patterned nanoelectrodes.
To grow the nanowires Nath writes an image file that creates a pattern for the shape
and size she wants to produce. Using electron beam lithography she then stamps the pattern onto a polymer matrix
and the nanowires are grown by applying electric current through electrodeposition. Nath grows the nanowires in a parallel pattern
which resembles a series of nails protruding from a piece of lumber. One end is held secure to a metal conductor like copper
or gold while the other end spikes outward. The entire structure is surrounded by a polymer matrix.
Nath and her research team can produce wires of any shape or size. To increase the nanowires'surface area Nath can make them hollow in the middle much like carbon nanotubes found in optics and electronics.
The nanowires allow current to travel through them. The polymer which is nonconductive can be removed to allow the wires to stand freely
and yet not lose shape or consistency. Currently the wires are made from the metal chalcogenides
which includes cadmium telluride cobalt selenide or iron selenide. Explore further: Controlling photoluminescence with silicon nanophotonics for better device e
#Micro-and nano-swimmers can be propelled through media similar to bodily fluids Micro -or even nanorobots could someday perform medical tasks in the human body.
Researchers from the Max Planck Institute for Intelligent Systems in Stuttgart have taken now a first step towards this goal.
They have succeeded in constructing swimming bodies that simultaneously meet two requirements: they are small enough to be used in bodily fluids
or even individual cells and they are able to navigate through complex biological fluids. In the 1966 movie Fantastic Voyage a submarine complete with crew is shrunk in size
so that it can navigate through the human body enabling the crew to perform surgery in the brain.
This scenario remains in the realm of science fiction and transporting a surgical team to a disease site will certainly remain fiction.
Nevertheless tiny submarines that could navigate through the body could be of great benefit: they could deliver drugs precisely to a target location a point on the retina for instance.
And they could make it possible to carry out gene therapy in a specific cell. If things go according to Peer Fischer leader of the Micro Nano
and Molecular Systems Research Group at the Max Planck Institute for Intelligent Systems in Stuttgart then doctors will in the foreseeable future call upon micro
-or even nanorobots to carry out such tasks. The little helpers would accurately home in on targets in the body eliminating the need for more major surgery
or by making some procedures minimally invasive. A microscopic scallop could not swim in waterhowever there are two fundamental challenges to realize these goals.
Obviously such vehicles must be small enough to be injected into the eyeball for example with a syringe.
Secondly once introduced into the body they must be able to move through bodily fluids and tissue.
On both fronts the research group led by Peer Fischer has made now significant progress. Together with researchers at the Technion in Israel and the Technical University in Dortmund the Stuttgart-based group describes in a recent paper a kind of artificial scallop just a few hundred micrometers in diameter.
They designed it so that the device travels in liquids by simply opening and closing its shells.
This is not as obvious as it sounds. The shell is only a few times larger than the thickness of a human hair says Fischer.
A liquid like water is about as viscous for these devices as honey or even tar is for us.
However because the researchers have in the long term set their sights on using the device in biological media they tested their swimmer directly in appropriate model fluids.
This temporally asymmetric pattern of movement causes the fluid to be less viscous during opening than during the subsequent closing stroke says doctoral student Tian Qiu a member of the team in Stuttgart.
and close and ultimately how the device moves by applying an external magnetic field. However the researchers'discovery that micro-devices can swim through some liquids with symmetrical movements does not just apply to magnetically-driven micro-robots.
Indeed a scallop-shaped miniature submarine could also be driven by an actuator that responds for example to temperature changes.
The actual micro-scallop was made of a relatively hard plastic. The challenge was to make the shells extremely thin
The scientists who have published their work in Nature Communications want to put their micro-swimmers to the test in specific biological fluids.
Now for the first time the researchers in Stuttgart have succeeded in devising a suitable propeller with a diameter of around 100 nanometres or one-tenth of a micrometre.
The miniature swimmer measures just 400 nanometres in length. To make their nano-propeller the scientists used a technique they developed themselves.
When they then applied a rotating magnetic field the nickel-containing nano-screw also started to rotate causing the propeller to move forward through a liquid.
As in the case of their plastic micro-scallop the researchers also envision medical applications for their nanosubmarine.
and therefore highly viscous structures explains co-author Debora Schamel a doctoral student at the Max Planck Institute in Stuttgart.
For the first time we have a nanorobot that's small enough to swim through this tight mesh.
The tiny submarine could also be used in media other than synovial fluid. Other liquids in which such nanovehicles could deliver drugs for example include the vitreous humor of the eye mucous membranes and even blood.
Theoretically given the size of our device it could conceivably also be used within cells Fischer says cautiously.
Of course to achieve this a way would have to be found to inject the nanosubmarines into cells.
#Researchers create unique graphene nanopores with optical antennas for DNA sequencing High-speed reading of the genetic code should get a boost with the creation of the world's first graphene nanopores pores measuring approximately 2 nanometers in diameter that feature a"built-in
"optical antenna. Researchers with Berkeley Lab and the University of California (UC) Berkeley have invented a simple,
one-step process for producing these nanopores in a graphene membrane using the photothermal properties of gold nanorods."
"With our integrated graphene nanopore with plasmonic optical antenna, we can obtain direct optical DNA sequence detection,
"says Luke Lee, the Arnold and Barbara Silverman Distinguished Professor at UC Berkeley. Lee and Alex Zettl, a physicist who holds joint appointments with Berkeley Lab's Materials sciences Division
and UC Berkeley's Physics department, were the leaders of a study in which a hot spot on a graphene membrane formed a nanopore with a self-integrated optical antenna.
The hot spot was created by photon-to-heat conversion of a gold nanorod.""We believe our approach opens new avenues for simultaneous electrical and optical nanopore DNA sequencing
and for regulating DNA translocation,"says Zettl, who is also a member of the Kavli Energy Nanoscience Institute (Kavli ENSI).
Nanopore sequencing of DNA, in which DNA strands are threaded through nanoscale pores and read one letter at a time,
has been touted for its ability to make DNA sequencing a faster and more routine procedure. Under today's technology, the DNA letters are"read"by an electrical current passing through nanopores fabricated on a silicon chip.
Trying to read electrical signals from DNA passing through thousands of nanopores at once, however, can result in major bottlenecks.
Adding an optical component to this readout would help eliminate such bottlenecks.""Direct and enhanced optical signals are obtained at the junction of a nanopore
and its optical antenna,"says Lee.""Simultaneously correlating this optical signal with the electrical signal from conventional nanopore sequencing provides an added dimension that would be an enormous advantage for high-throughput DNA readout."
"A key to the success of this effort is the single-step photothermal mechanism that enables the creation of graphene nanopores with self-aligned plasmonic optical antennas.
The dimensions of the nanopores and the optical characteristics of the plasmonic antenna are tunable, with the antenna functioning as both optical signal transducer and enhancer.
The atomically thin nature of the graphene membrane makes it ideal for high resolution, high throughput,
single-molecule DNA sequencing. DNA molecules can be labeled with fluorescent dyes so that each base-pair fluoresces at a signature intensity as it passes through the junction of the nanopore and its optical antenna."
"In addition, either the gold nanoplasmonic optical antenna or the graphene can be functionalized to be responsive to different base-pair combinations,
"Lee says.""The gold plasmonic optical antenna can also be functionalized to enable the direct optical detection of RNA, proteins, protein-protein interactions, DNA-protein interactions,
and other biological systems.""The results of this study were reported in Nano Letters in a paper titled"Graphene nanopore with a Self-Integrated Optical Antenna. e
#Measuring nano-vibrations In a recent paper published in Nature Nanotechnology, Joel Moser and ICFO colleagues of the Nanooptomechanics research group led by Prof.
Adrian Bachtold, together with Marc Dykman (Michigan University), report on an experiment in which a carbon nanotube mechanical resonator exhibits quality factors of up to 5 million,
30 times better than the best quality factors measured in nanotubes to date. Imagine that the host of a dinner party tries to get his guests'attention by giving a single tap of his oyster spoon on his crystal glass.
Now, imagine, to the amazement of all that the crystal glass vibrates for several long minutes,
producing a clear ringing sound. Surely the guests would marvel at this almost never ending crystal tone.
Some might even want to investigate the origin of this phenomenon rather than listen to the host's speech.
The secret of such an imaginary non-stop vibrating system relies on the fact that it dissipates very little energy.
The energy dissipation of a vibrating system is quantified by the quality factor. In laboratories, by knowing the quality factor,
scientists can quantify how long the system can vibrate and how much energy is lost in the process.
This allows them to determine how precise the resonator can be at measuring or sensing objects.
Scientists use mechanical resonators to study all sorts of physical phenomena. Nowadays, carbon nanotube mechanical resonators are in demand because of their extremely small size and their outstanding capability of sensing objects at the nanoscale.
Though they are very good mass and force sensors, their quality factors have been somewhat modest.
However, the discovery made by the ICFO researchers is a major advancement in the field of nano mechanics and an exciting starting point for future innovative technologies.
What is a Mechanical Resonator? A mechanical resonator is a system that vibrates at very precise frequencies.
Like a guitar string or a tightrope, a carbon nanotube resonator consists of a tiny, vibrating bridge-like (string) structure with typical dimensions of 1#m in length and 1nm in diameter.
If the quality factor of the resonator is high, the string will vibrate at a very precise frequency,
thus enabling these systems to become appealing mass and force sensors, and exciting quantum systems. Why is This Discovery so Important?
For many years, researchers observed that quality factors decreased with the volume of the resonator, that is the smaller the resonator the lower the quality factor,
and because of this trend it was unthinkable that nanotubes could exhibit giant quality factors. The giant quality factors that ICFO researchers have measured have not been observed before in nanotube resonators mainly
because their vibrational states are extremely fragile and easily perturbed when measured. The values detected by the team of scientists was achieved through the use of an ultra-clean nanotube at cryostat temperatures of 30mk(-273.12 Celsius-colder than the temperature of outerspace!
and by employing an ultra-low noise method to detect minuscule vibrations quickly while reducing as much as possible the electrostatic noise.
Joel Moser claims that finding these quality factors has been challenging since"nanotube resonators are enormously sensitive to surrounding electrical charges that fluctuate constantly.
This stormy environment strongly affects our ability to capture the intrinsic behavior of nanotube resonators.
For this reason, we had to take a very large number of snapshots of the nanotube's mechanical behavior.
Only a few of these snapshots captured the intrinsic nature of the nanotube's dynamics, when the storm momentarily relented.
During these short quiet moments, the nanotube revealed its ultra-high quality factor to us"."With the discovery of such high quality factors from this study, ICFO scientists have opened a whole new realm of possibilities for sensing applications,
and quantum experiments. For instance, nanotube resonators might be used to detect individual nuclear spins, which would be an important step towards magnetic resonance imaging (MRI) with a spatial resolution at the atomic level.
For the moment, Adrian Bachtold comments that"achieving MRI at the atomic level would be fantastic. But, for this, we would first have to solve various technological problems that are extremely challenging. n
#Method for symmetry-breaking in feedback-driven self-assembly of optical metamaterials (Phys. org) If you can uniformly break the symmetry of nanorod pairs in a colloidal solution you're a step ahead of the game toward achieving new and exciting metamaterial properties.
But traditional thermodynamic-driven colloidal assembly of these metamaterials which are defined materials by their non-naturally-occurring properties often result in structures with high degree of symmetries in the bulk material.
In this case the energy requirement does not allow the structure to break its symmetry. In a study led by Xiang Zhang director of Berkeley Lab's Materials sciences Division he
and his research group at the University of California (UC) Berkeley achieved symmetry-breaking in a bulk metamaterial solution for the first time.
Zhang and his group demonstrated self-assembled optical metamaterials with tailored broken-symmetries and hence unique electromagnetic responses that can be achieved via their new method.
The results have been published in Nature Nanotechnology. The paper is titled Feedback-driven self-assembly of symmetry-breaking optical metamaterials in solution.
We developed an innovative self-assembly route which could surpass the conventional thermodynamic limit in chemical synthetic systems explains Sui Yang lead author of the Nature Nanotechnology paper and member of Zhang's research group.
Specifically we use the material's own property as a self-correction feedback mechanism to self-determine the final structure.
This led the group to produce nanostructures that have historically been considered impossible to assemble. The widely used method of metamaterial synthesis is top-down fabrication such as electron beam
or focus ion beam lithography that often results in strongly anisotropic and small-scale metamaterials. People build metamaterials using top-down methods that include light exposure
and electron beam exposure which are inefficient and costly says Xingjie Ni another lead author on the paper.
If we want to use metamaterials we need to develop a way to build them cheaply and efficiently.
The bottom-up route fills these requirements. Starting with a solution of colloidal nanorods Yang and Ni built on the common self-assembly technique used to build nanoparticles.
The twist that they added was to introduce a feedback mechanism by which to obtain the desired product.
The desired product when synthesizing colloidal gold nanorods which are stabilized during growth to obtain preferential bonding along longitudinal facets is pairs of rods
or dimers that are shifted by a certain amount: their symmetry is broken uniformly. When you have this reaction you get all kinds of products.
You have a pair of nanorods with no shift at all relative to one another; or a pair that are shifted too much;
or not enough. This is a typical process and is governed by thermodynamics explains Yang. The team used a laser to excite the plasmonic resonance of specific particles produced in the reaction.
This allowed them to separate out the undesired resonances indicating nanorod pairs that are shifted not the desired amount
and dissociate those pairs using heat from the excitation. Only the desired resonance survives in this process Ni says.
we use the material's own properties to drive nanostructure formation in solution. This has the intrinsic value of making many structures in one batch.
The method developed in Zhang's research group can be applied to many other nanoparticles; indeed almost any structure that can self-assemble could be produced in this way.
The unique feedback mechanism leads to precisely controlled nanostructures with beyond conventional symmetries and functionalities.
Chemists gain edge in next-gen energy Rice university scientists who want to gain an edge in energy production and storage report they have found it in molybdenum disulfide.
The versatile chemical compound classified as a dichalcogenide is inert along its flat sides but previous studies determined the material's edges are highly efficient catalysts for hydrogen evolution reaction (HER) a process used in fuel cells to pull hydrogen from water.
Tour and his colleagues have found a cost-effective way to create flexible films of the material that maximize the amount of exposed edge
and have potential for a variety of energy-oriented applications. The Rice research appears in the journal Advanced Materials.
Molybdenum disulfide isn't quite as flat as graphene the atom-thick form of pure carbon
This crystal structure creates a more robust edge and the more edge the better for catalytic reactions
What we see in the images are short 5-to 6-nanometer planes and a lot of edge as though the material had drilled bore holes all the way through.
Huilong Fei a graduate student; and their colleagues. It catalyzes the separation of hydrogen from water when exposed to a current.
but traditionally employed to thicken natural oxide layers on metals. The film was exposed then to sulfur vapor at 300 degrees Celsius (572 degrees Fahrenheit) for one hour.
The films can also serve as supercapacitors which store energy quickly as static charge and release it in a burst.
Though they don't store as much energy as an electrochemical battery they have long lifespans and are in wide use
because they can deliver far more power than a battery. The Rice lab built supercapacitors with the films;
in tests they retained 90 percent of their capacity after 10000 charge-discharge cycles and 83 percent after 20000 cycles.
We see anodization as a route to materials for multiple platforms in the next generation of alternative energy devices Tour said.
These could be fuel cells supercapacitors and batteries. And we've demonstrated two of those three are possible with this new material l
#Better bomb-sniffing technology with new detector material University of Utah engineers have developed a new type of carbon nanotube material for handheld sensors that will be quicker
and better at sniffing out explosives, deadly gases and illegal drugs. A carbon nanotube is a cylindrical material that is a hexagonal
or six-sided array of carbon atoms rolled up into a tube. Carbon nanotubes are known for their strength
and high electrical conductivity and are used in products from baseball bats and other sports equipment to lithium-ion batteries and touchscreen computer displays.
Vaporsens, a university spin-off company plans to build a prototype handheld sensor by year's end
and produce the first commercial scanners early next year, says cofounder Ling Zang, a professor of materials science and engineering and senior author of a study of the technology published online Nov 4 in the journal
Advanced Materials. The new kind of nanotubes also could lead to flexible solar panels that can be rolled up
and stored or even"painted"on clothing such as a jacket, he adds. Zang and his team found a way to break up bundles of the carbon nanotubes with a polymer
and then deposit a microscopic amount on electrodes in a prototype handheld scanner that can detect toxic gases such as sarin or chlorine,
or explosives such as TNT. When the sensor detects molecules from an explosive, deadly gas or drugs such as methamphetamine,
they alter the electrical current through the nanotube materials, signaling the presence of any of those substances,
Zang says.""You can apply voltage between the electrodes and monitor the current through the nanotube,"says Zang, a professor with USTAR, the Utah Science Technology and Research economic development initiative."
"If you have explosives or toxic chemicals caught by the nanotube, you will see an increase or decrease in the current."
"By modifying the surface of the nanotubes with a polymer, the material can be tuned to detect any of more than a dozen explosives,
including homemade bombs, and about two-dozen different toxic gases, says Zang. The technology also can be applied to existing detectors
or airport scanners used to sense explosives or chemical threats. Zang says scanners with the new technology"could be used by the military police,
first responders and private industry focused on public safety.""Unlike the today's detectors, which analyze the spectra of ionized molecules of explosives and chemicals,
the Utah carbon nanotube technology has four advantages s
#A quantum leap in nanoparticle efficiency (Phys. org) New research has unlocked the secrets of efficiency in nanomaterials that is materials with very tiny particles
which will improve the future development of chemical sensors used in chemical and engineering industries.
In an international study University of Melbourne and the National Institute of Standards and Technology in the US found that pairs of closely spaced nano particles made of gold can act as optical antennas.
These antennae concentrate the light shining on them into tiny regions located in the gap between the nano particles.
Researcher developed new technology to detect these levels of light. Researchers found the precise geometry of nanoparticle pairs that maximises light concentration resolving a hotly debated area of quantum physics.
This geometry now determines the efficiency nanoparticle use as a chemical sensor in sensing minute quantities of chemicals in air and water.
Chief Investigator Ken Crozier a professor of Physics and Electronic engineering at the University of Melbourne said Up until now there were two competing theories surrounding
what gap was required between particles to best concentrate the light but we now have the technology to test it.
The study was published in Nature Communications and provides scientists with a deeper understanding of the physics of nano material.
Lead author Dr Wenqi Zhu from the National Institute of Standards and Technology (NIST) in the United states performed the work under Crozier's supervision as a Phd student at Harvard university said We found the ultimate limit for light
concentration for fabricated nanoparticles. Professor Crozier said This work is important for engineers and scientists working in the nanomaterial industry y
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