Friday, April 30, 2010

This week in nanotechnology - April 30, 2010

Researchers have found a way to make carbon nanotube membranes that could find wide application as extra-fine air filters and as scaffolds for catalysts that speed chemical reactions. These filters can remove up to 99 percent of particulates with diameters of less than a micrometer.

Though scientists argue that the emerging technology of spintronics may trump conventional electronics for building the next generation of faster, smaller, more efficient computers and high-tech devices, no one has actually seen the spin – a quantum mechanical property of electrons—in individual atoms until now. Now, physicists have presented the first images of spin in action.

nanoscale world map

The different shape and appearance of these individual cobalt atoms is caused by the different spin directions.

Tiny, melanin-covered nanoparticles may protect bone marrow from the harmful effects of radiation therapy. Radiation therapy is used to kill cancer cells and shrink tumors. But because radiation also damages normal cells, doctors must limit the dose. Melanin, the naturally occurring pigment that gives skin and hair its color, helps shield the skin from the damaging effects of sunlight and has been shown to protect against radiation.

Three new studies illustrate why graphene should be the nanomaterial of choice to strengthen composite materials used in everything from wind turbines to aircraft wings. Composites infused with graphene are stronger, stiffer, and less prone to failure than composites infused with carbon nanotubes or other nanoparticles, according to the studies. This means graphene, an atom-thick sheet of carbon atoms arranged like a nanoscale chain-link fence, could be a key enabler in the development of next-generation nanocomposite materials.

Scientists have established a revolutionary nanocrystal-making robot called WANDA (Workstation for Automated Nanomaterial Discovery and Analysis), capable of producing nanocrystals with staggering precision. This one-of-a-kind robot provides colloidal nanocrystals with custom-made properties for electronics, biological labeling and luminescent devices.

Watching a living brain in the act of seeing - with single-synapse resolution: Pioneering a novel microscopy method, neuroscientists have shown that individual neurons carry out significant aspects of sensory processing: specifically, in this case, determining which direction an object in the field of view is moving. Their method makes it possible for the first time to observe individual synapses, nerve contact sites that are just one micrometer in size, on a single neuron in a living mammalian brain.

Friday, April 23, 2010

This week in nanotechnology - April 23, 2010

A new biosensor can measure whether neurons are performing correctly when communicating with each other, giving researchers a tool to test the effectiveness of new epilepsy or seizure treatments. The novel sensor exploits conductive carbon nanotubes and is only 2 micrometers in diameter, or about 50 times smaller than the diameter of a human hair.

Researchers have developed nano-sized cantilevers for atomic force microscopes whose gentle touch could help discern the workings of living cells and other soft materials in their natural, liquid environment. Used in combination with a revolutionary detection mechanism, this new imaging tool is sensitive enough to investigate soft materials without the limitations present in other cantilevers.

IBM scientists have created a 3D map of the earth so small that 1,000 of them could fit on one grain of salt. The scientists accomplished this by means of a new, breakthrough technique that uses a tiny, silicon tip with a sharp apex — 100,000 times smaller than a sharpened pencil — to create patterns and structures as small as 15 nanometers at greatly reduced cost and complexity. This patterning technique opens new prospects for developing nanosized objects in fields such as electronics, future chip technology, medicine, life sciences, and opto-electronics.

nanoscale world map

The world just got a little smaller. IBM scientists have created a complete 3D map of the world measuring only 22 by 11 micrometers. The nano-world was “written” – on a polymer - at this size 1000 world maps could fit on a grain of salt. In the relief, one thousand meters of altitude correspond to roughly eight nanometers. It is composed of 500,000 pixels, each measuring 20 nm2 and was created in only 2 minutes and 23 seconds.

New research demonstrates that a vaccine delivered by a Nanopatch induces a similarly protective immune response as a vaccine delivered by needle and syringe, but uses 100 times less vaccine. This discovery has implications for many vaccination programs in both industrialised and developing nations, which must overcome issues with vaccine shortages and distribution. Being both painless and needle-free, the nanopatch offers hope for those with needle phobia, as well as improving the vaccination experience for young children.

Mimicking the human nervous system for bionic applications could become a reality with the help of a method developed to process carbon nanotubes. While these nanostructures have electrical and other properties that make them attractive to use as artificial neural bundles in prosthetic devices, the challenge has been to make bundles with enough fibers to match that of a real neuron bundle. With current technology, the weight alone of wires required to match the density of receptors at even the fingertips would make it impossible to accommodate. Now, by adapting conventional glass fiber drawing technology to process carbon nanotubes into multichannel assemblies, researchers believe they are on a path that could lead to a breakthrough.

Scientists take first step toward controlling the growth of nanomaterials without catalysts. The question of how one-dimensional crystals grow sometimes without catalysts has been troublesome for scientists and engineers who need to produce large amounts of nanomaterials for specific applications. Working with zinc oxide, a common semiconductor widely used as a nanomaterial, researchers now demonstrated a new understanding of the subject by showing that nanotubes can be formed solely due to the strain energy and screw dislocations that drive their growth.

If you think that building an artificial human brain is science fiction, you are probably right – for now. But don't think for a moment that researchers are not working hard on laying the foundations for what is called neuromorphic engineering – a new interdisciplinary discipline that includes nanotechnologies and whose goal is to design artificial neural systems with physical architectures similar to biological nervous systems. One of the key components of any neuromorphic effort is the design of artificial synapses. The human brain contains vastly more synapses than neurons – by a factor of about 10,000 – and therefore it is necessary to develop a nanoscale, low power, synapse-like device if scientists want to scale neuromorphic circuits towards the human brain level. New research now suggests that memristor devices are capable of emulating the biological synapses with properly designed CMOS neuron components.

Friday, April 16, 2010

This week in nanotechnology, April 16, 2010

A team of MIT researchers has found a novel way to mimic the process by which plants use the power of sunlight to split water and make chemical fuel to power their growth. In this case, the team used a modified virus as a kind of biological scaffold that can assemble the nanoscale components needed to split a water molecule into hydrogen and oxygen atoms.

A study released this week suggests that anti-cancer chemotherapies which use nanoparticles to deliver drugs deep inside tumor tissue will be more effective if the particles are positively electrically charged because they are taken up to a greater extent by proliferating cells.

atomic-scale black holes
Researchers invented 2-nanometer core gold particles, designated “payload” in the cartoon above, which can be coated with different surface materials such as green fluorescent dye (pictured) or anti-cancer drugs, giving them “tunable” properties and functionalities. The scientists found that positively charged gold nanoparticles crossed the cell membrane more readily than negatively charged particles, indicating a promising new approach for improving drug delivery to the majority of cells within tumors.

In an electrifying first, Stanford scientists have plugged in to algae cells with an ultrasharp nano-electrode and harnessed a tiny electric current. They found it at the very source of energy production - photosynthesis, a plant's method of converting sunlight to chemical energy. It may be a first step toward generating "high efficiency" bioelectricity that doesn't give off carbon dioxide as a byproduct, the researchers say.

Scientists create 'molecular paper' just two molecules thick. Two-dimensional, “sheet-like” nanostructures are commonly employed in biological systems such as cell membranes, and their unique properties have inspired interest in materials such as graphene. Now, Berkeley Lab scientists have made the largest two-dimensional polymer crystal self-assembled in water to date. This entirely new material mirrors the structural complexity of biological systems with the durable architecture needed for membranes or integration into functional devices.

Researchers have found a new method for generating tunable wavelengths, as well as more easily switching back and forth between two wavelengths, employing quantum-dot lasers. Prospective application fields are biomedicine and nanosurgery. Under the EU’s “FAST-DOT” project, the researchers have recently discovered that, under some circumstances, quantum-dot lasers do emit first short-wavelength photons and then long-wavelength photons.

A new fabrication technique, combined with well-developed carbon chemistry, enables the synthesis of solution-processable black graphene quantum dots with uniform size through solution chemistry. These graphene quantum dots can be used as sensitizers for solar cells and brinf all-carbon solar cells a step closer.

Friday, April 9, 2010

This week in nanotechnology - April 9, 2010

HP Labs researchers have discovered that the “memristor“ – a resistor with memory that represents the fourth basic circuit element in electrical engineering – has more capabilities than was previously thought. In addition to being useful in storage devices, the memristor can perform logic, enabling computation to one day be performed in chips where data is stored, rather than on a specialized central processing unit.

Nanobio chip checks for oral cancer: The gentle touch of a lesion on the tongue or cheek with a brush can help detect oral cancer with success rates comparable to more invasive techniques, according to preliminary studies by researchers at Rice University, the University of Texas Health Science Centers at Houston and San Antonio and the University of Texas M.D. Anderson Cancer Center.

A simple cotton T-shirt may one day be converted into tougher, more comfortable body armor for soldiers or police officers. Researchers drastically increased the toughness of a T-shirt by combining the carbon in the shirt’s cotton with boron – the third hardest material on earth. The result is a lightweight shirt reinforced with boron carbide, the same material used to protect tanks.

Carbon nanotubes, long touted for applications in materials and electronics, may also be the stuff of atomic-scale black holes. Physicists at Harvard University have found that a high-voltage nanotube can cause cold atoms to spiral inward under dramatic acceleration before disintegrating violently. Their experiments are the first to demonstrate something akin to a black hole at atomic scale.

atomic-scale black holes

Launched laser-cooled atoms are captured by a single, suspended, single-wall carbon nanotube charged to hundreds of volts. A captured atom spirals towards the nanotube (white path) and reaches the environs of the tube surface, where its valence electron (yellow) tunnels into the tube. The resulting ion (purple) is ejected and detected, and the dynamics at the nanoscale are sensitively probed.

Silicon has dominated solid-state electronics for more than four decades but now a variety of other materials are being explored in photonic devices to expand the wavelength range of operation and to improve performance. Graphene is such a material – although most research on graphene so far has focused mainly on electronics. IBM researchers have now shown that graphene-based devices can be used in optical communications. Introducing this new material system into photonics could have a significant impact on mainstream optical applications.

Friday, April 2, 2010

This week in nanotechnology - April 2, 2010

By combining a new generation of piezoelectric nanogenerators with two types of nanowire sensors, researchers have created what are believed to be the first self-powered nanometer-scale sensing devices that draw power from the conversion of mechanical energy. The new devices can measure the pH of liquids or detect the presence of ultraviolet light using electrical current produced from mechanical energy in the environment.

Scientists have discovered the world's smallest superconductor, a sheet of four pairs of molecules less than one nanometer wide. This study provides the first evidence that nanoscale molecular superconducting wires can be fabricated, which could be used for nanoscale electronic devices and energy applications.

This image shows the smallest superconductor, which is only .87 nanometer wide

This image shows the smallest superconductor, which is only .87 nanometer wide.

A nanometer-scale probe designed to slip into a cell wall and fuse with it could offer researchers a portal for extended eavesdropping on the inner electrical activity of individual cells. Everything from signals generated as cells communicate with each other to "digestive rumblings" as cells react to medication could be monitored for up to a week. Current methods of probing a cell are so destructive they usually only allow a few hours of observation before the cell dies. The researchers are the first to implant an inorganic device into a cell wall without damaging it.

A tiny defect in graphene may create smaller, faster electronics. When most of us hear the word 'defect', we think of a problem that has to be solved. But a team of researchers have created a new defect that just might be a solution to a growing challenge in the development of future electronic devices. They found a way to create a well-defined, extended defect several atoms across, containing octagonal and pentagonal carbon rings embedded in a perfect graphene sheet. This defect acts as a quasi-one-dimensional metallic wire that easily conducts electric current. Such defects could be used as metallic interconnects or elements of device structures of all-carbon, atomic-scale electronics.

An artist's conception of a row of intentional molecular defects in a sheet of graphene

An artist's conception of a row of intentional molecular defects in a sheet of graphene. The defects effectively create a metal wire in the sheet. This discovery may lead to smaller yet faster computers in the future.

Nanotechnology-enabled pill signals it has been swallowed. Seeking a way to confirm that patients have taken their medication, engineering researchers have added a tiny microchip and digestible antenna to a standard pill capsule. The prototype is intended to pave the way for mass-produced pills that, when ingested, automatically alert doctors, loved ones or scientists working with patients in clinical drug trials.

And finally, again some amazing images. During the 2009 MRS Fall Meeting in Boston, MA last year, the MRS conducted the eigth installment of the popular "Science as Art" competition. The six first-place and second-place winners are shown here.

single crystalline diamond grain that is anisotropically etched by hot spheres of molten nickel

Easter eggs? The imaged object is a single crystalline diamond grain that is anisotropically etched by hot spheres of molten nickel (red). Self-organized nickel particles are obtained by sintering a thin Ni film (100 nm) that is evaporated on a polished diamond substrate.