Friday, September 3, 2010

This week in nanotechnology - September 3, 2010

Sugar, salt, alcohol and a little serendipity led a Northwestern University research team to discover a new class of nanostructures that could be used for gas storage and food and medical technologies. And the compounds are edible. The porous crystals are the first known all-natural metal-organic frameworks (MOFs) that are simple to make. Most other MOFs are made from petroleum-based ingredients, but the Northwestern MOFs you can pop into your mouth and eat, and the researchers have.

Silicon oxide nanoelectronics circuits break barrier. Scientists at Rice University have created the first two-terminal memory chips that use only silicon, one of the most common substances on the planet, in a way that should be easily adaptable to nanoelectronic manufacturing techniques and promises to extend the limits of miniaturization subject to Moore's Law.

Playing snooker with atoms. Scientists speak of sputtering when energy-rich ions hit a solid object and cause atoms to be released from its surface. The phenomenon can be exploited to apply microscopically thin coatings to glass surfaces. A research team has developed a special sputtering technique that greatly increases the efficiency of the coating process.

One of the most difficult aspects of working at the nanoscale is actually seeing the object being worked on. Biological structures like viruses, which are smaller than the wavelength of light, are invisible to standard optical microscopes and difficult to capture in their native form with other imaging techniques. A multidisciplinary research group at UCLA has now teamed up to not only visualize a virus but to use the results to adapt the virus so that it can deliver medication instead of disease.

To watch a magician transform a vase of flowers into a rabbit, it's best to have a front-row seat. Likewise, for chemical transformations in solution, the best view belongs to the molecular spectators closest to the action. Those special molecules comprise the "first solvation shell," and although it has been known for decades that they can sense and dictate the fate of nearly every chemical reaction, it has been virtually impossible to watch them respond. University of Michigan researchers Kevin Kubarych and Carlos Baiz, however, recently achieved the feat.
An optical microscopy image of seven color filters illuminated by white microscope light

The molecules shown here in yellow are first-hand observers to an ultrafast chemical reaction. As the reaction proceeds, the vibrational frequencies of the yellow molecules change. By "listening" to changes in these vibrational frequencies, researchers could observe the chemical reaction underway. The rainbow colors indicate how the "notes" of the yellow molecules change in response to the reaction.

Physicists at the National Institute of Standards and Technology have used a small crystal of ions (electrically charged atoms) to detect forces at the scale of yoctonewtons - that's 0.000000000000000000000001 Newtons. The ion sensor works by examining how an applied force affects ion motion, based on changes in laser light reflected off the ions.

Researchers at Georgia Tech have developed a new class of electronic logic device in which current is switched by an electric field generated by the application of mechanical strain to zinc oxide nanowires. The devices, which include transistors and diodes, could be used in nanometer-scale robotics, nano-electromechanical systems (NEMS), micro-electromechanical systems (MEMS) and microfluidic devices. The mechanical action used to initiate the strain could be as simple as pushing a button, or be created by the flow of a liquid, stretching of muscles or the movement of a robotic component.

Researchers at Caltech have devised a new technique - using a sheet of carbon just one atom thick - to visualize the structure of molecules. The technique, which was used to obtain the first direct images of how water coats surfaces at room temperature, can also be used to image a potentially unlimited number of other molecules, including antibodies and other biomolecules.