Friday, January 28, 2011

This week in nanotechnology - January 28, 2011

Van der Waals forces are fundamental for chemistry, biology and physics. However, they are among the weakest known chemical interactions, so they are notoriously hard to study. This force is so weak that it is hard to notice in everyday life. But delve into the world of micro-machines and nano-robots, and you will feel the force – everywhere. To study the van-der-Waals force, researchers have designed a sophisticated experimental setup that can measure the interactions between single atoms and a surface.

Researchers developed a molecular machine constructed in a similar way to a record player. The team has succeeded for the first time in directly controlling the magnetic state of a single molecule at room temperature. The switchable molecule could be used both in the construction of tiny electromagnetic storage units and in the medical imaging.

Curved carbon for electronics of the future. A new scientific discovery could have profound implications for nanoelectronic components. Researchers from the Nano-Science Center at the Niels Bohr Institute, University of Copenhagen, in collaboration with Japanese researchers, have shown how electrons on thin tubes of graphite exhibit a unique interaction between their motion and their attached magnetic field – the so-called spin. The discovery paves the way for unprecedented control over the spin of electrons and may have a big impact on applications for spin-based nanoelectronics.

Despite the sophistication and range of contemporary microscopy techniques, many important biological phenomena still elude the precision of even the most sensitive tools. The need for refined imaging methods for fundamental research and biomedical applications related to the study of disease remains acute. Researchers at the Biodesign Institute at Arizona State University have pioneered a new technique capable of peering into single cells and even intracellular processes with unprecedented clarity. The method, known as electrochemical impedance microscopy (EIM) may be used to explore subtle features of profound importance for basic and applied research, including cell adhesion, cell death (or apoptosis) and electroporation—a process that can be used to introduce DNA or drugs into cells.

Researchers from Boston College, MIT, Clemson University and the University of Virginia have used nanotechnology to achieve a 60-90 percent increase in the thermoelectric figure of merit of p-type half-Heusler, a common bulk semiconductor compound. The dramatic increase in the figure of merit, used to measure a material's relative thermoelectric performance, could pave the way for a new generation of products – from car exhaust systems and power plants to solar power technology – that runs cleaner.

Northwestern University researchers have developed a new technique for rapidly prototyping nanoscale devices and structures that is so inexpensive the "print head" can be thrown away when done.
Hard-tip, soft-spring lithography (HSL) rolls into one method the best of scanning-probe lithography -- high resolution -- and the best of polymer pen lithography -- low cost and easy implementation.

And finally, some Friday fun. Take a look at some of the winning images from a recent nano-image competition, like this 'stem of nanoflowers'.
nanoflowers

Friday, January 21, 2011

This week in nanotechnology - January 21, 2011

To rebuild damaged parts of a human body from scratch is a dream that has long fired human imagination, from Mary Shelley's Doctor Frankenstein to modern day surgeons. Now, a team of European scientists, working in the frame of the EUREKA project ModPolEUV, has made a promising contribution to reconstructive surgery thanks to an original multidisciplinary approach matching cutting-edge medicine to the latest developments in nanotechnology. They managed to develop a new and simple way to create nanostructured materials that would allow a better development of human cells.

Measuring the attractive forces between atoms and surfaces with unprecedented precision, University of Arizona physicists have produced data that could refine our understanding of the structure of atoms and improve nanotechnology. To study the van-der-Waals force,the team designed a sophisticated experimental setup that can measure the interactions between single atoms and a surface.

Scientists have coaxed polymers to braid themselves into wispy nanoscale ropes that approach the structural complexity of biological materials. Their work is the latest development in the push to develop self-assembling nanoscale materials that mimic the intricacy and functionality of nature's handiwork, but which are rugged enough to withstand harsh conditions such as heat and dryness.
porphyrins

A nanoscale rope that braids itself, as seen in this atomic force microscopy image of the structure at a resolution of one-millionth of a meter.

Researchers at Northwestern University have placed nanocrystals of rock salt into lead telluride, creating a material that can harness electricity from heat-generating items such as vehicle exhaust systems, industrial processes and equipment and sun light more efficiently than scientists have seen in the past. The material exhibits a high thermoelectric figure of merit that is expected to enable 14 percent of heat waste to electricity, a scientific first.

Butterfly wings behind anti-counterfeiting nanotechnology: Researchers are using nanoholes to create unique anti-counterfeiting security features. How this works is microscopic gratings composed of nanostructures interact with light to produce the shimmering iridescence seen on the Costa Rican morpho butterfly. The nanostructures act to reflect and refract light waves to produce the morpho's signature blue wings and absorb other unwanted light.

In solar cells and photodetectors, an optical radiation excites electrons to higher energy states, thereby a photocurrent begins to flow. Scientists have now found a way to directly measure the time during which photo-excited electrons flow in nanoscale photodetectors.

University of Illinois materials scientists have developed a simple, generalizable technique to fabricate complex structures that assemble themselves. Their advance utilizes a new class of self-assembling materials that they developed. The team demonstrated that they can produce a large, complex structure – an intricate lattice – from tiny colloidal particles called triblock Janus spheres.

Friday, January 14, 2011

This week in nanotechnology - January 14, 2011

A team of scientists has created very soft hydrogel particles that closely mirror some of the key properties of red blood cells, potentially helping pave the way for the development of synthetic blood. Tests of the particles' ability to perform functions such as transporting oxygen or carrying therapeutic drugs have not been conducted, and they do not remain in the cardiovascular system as long as real red blood cells.

New research shows how light can be used to control the electrical properties of graphene, paving the way for graphene-based optoelectronic devices and highly sensitive sensors.

A few unassuming drops of liquid locked in a very precise game of "follow the leader" could one day be found in mobile phone cameras, medical imaging equipment, implantable drug delivery devices, and even implantable eye lenses. Engineering researchers have developed liquid pistons, in which oscillating droplets of ferrofluid precisely displace a surrounding liquid. The pulsating motion of the ferrofluid droplets, which are saturated with metal nanoparticles, can be used to pump small volumes of liquid. The study also demonstrated how droplets can function as liquid lenses that constantly move, bringing objects into and out of focus.

European researchers report direct observation of carbon monoxide binding. Carbon monoxide is highly toxic since it blocks the binding site for oxygen in hemoglobin. This very principle – a porphyrin ring with a central iron or cobalt atom that the poisonous gas attaches to – can be used to implement sensors to warn against carbon monoxide. Physicists have now deciphered the mechanism for binding of gas molecules to iron and cobalt porphyrins.
porphyrins

A scanning tunneling microscopy image (left) shows four porphyrins. The models (right) illustrate the two systems shown in the picture. The protrusions correspond to the central atom (yellow sphere) and the two elevated portions to the saddle (orange). The characteristic cross shape results from the attached carbon monoxide molecules (red and blue).

Many futurists envision a world in which polymer membranes with molecular-sized channels are used to capture carbon, produce solar-based fuels, or desalinate sea water, among many other functions. This will require methods by which such membranes can be readily fabricated in bulk quantities. A technique representing a significant first step down that road has now been successfully demonstrated.

Researchers have created the first coils of silicon nanowire on a substrate that can be stretched to more than double their original length, moving us closer to incorporating stretchable electronic devices into clothing, implantable health-monitoring devices, and a host of other applications.

Fastest movie in the world recorded - a method to film nanostructures. Processes at a molecular level are not only miniscule, they are often extremely fast, and therefore difficult to capture in action. Scientists now present a method that takes us a good step towards producing a "molecular movie". They can record two pictures at such a short time interval that it will soon be possible to observe molecules and nanostructures in real time.

Researchers have demonstrated bio-inspired structures that self-assemble from simple building blocks: spheres. The helical "supermolecules" are made of tiny colloid balls instead of atoms or molecules. Similar methods could be used to make new materials with the functionality of complex colloidal molecules.

Friday, January 7, 2011

This week in nanotechnology - January 7, 2011

An entirely new type of nanomaterial developed at Rensselaer Polytechnic Institute could enable the next generation of high-power rechargeable lithium (Li)-ion batteries for electric automobiles, as well as batteries for laptop computers, mobile phones, and other portable devices. The new material, dubbed a "nanoscoop" because its shape resembles a cone with a scoop of ice cream on top, can withstand extremely high rates of charge and discharge that would cause conventional electrodes used in today's Li-ion batteries to rapidly deteriorate and fail. The nanoscoop's success lies in its unique material composition, structure, and size.

A quick look at new Cornell research hints at colorful patchwork quilts, but they are actually pictures of graphene -- one atom-thick sheets of carbon stitched together at tilted interfaces. Researchers have unveiled striking, atomic-resolution details of what graphene "quilts" look like at the boundaries between patches, and have uncovered key insights into graphene's electrical and mechanical properties.
A false-color microscopy image overlay depicting the shapes and lattice orientations of several grains in graphene

A false-color microscopy image overlay depicting the shapes and lattice orientations of several grains in graphene.

Researchers are creating a new type of solar cell designed to self-repair like natural photosynthetic systems in plants by using carbon nanotubes and DNA, an approach aimed at increasing service life and reducing cost. The design exploits the unusual electrical properties of single-wall carbon nanotubes, using them as molecular wires in light harvesting cells.

A promising approach for making solar cells that are inexpensive, lightweight and flexible is to use organic (that is, carbon-containing) compounds instead of expensive, highly purified silicon. But one stubborn problem has slowed the development of such cells: Researchers have had a hard time coming up with appropriate materials for the electrodes to carry the current to and from the cells. Now, a team of MIT researchers has come up with a practical way of using a possible substitute made from graphene.

Nanotechnologists at the University of Texas at Dallas have invented a broadly deployable technology for producing weavable, knittable, sewable, and knottable yarns containing up to 95 weight percent of otherwise unspinnable guest powders and nanofibers. The researchers describe the use of biscrolling to solve these problems, and demonstrate the feasibility of using their biscrolled yarns for applications ranging from superconducting cables and electronic textiles to batteries and fuel cells containing flexible woven electrodes.