Showing Spotlights 201 - 208 of 216 in category All (newest first):
Gears, bearings, and liquid lubricants can reduce friction in the macroscopic world, but the origins of friction for small devices such as micro- or nanoelectromechanical systems (NEMS) require other solutions. Despite the unprecedented accuracy by which these devices are nowadays designed and fabricated, their enormous surface-volume ratio leads to severe friction and wear issues, which dramatically reduce their applicability and lifetime. Traditional liquid lubricants become too viscous when confined in layers of molecular thickness. This situation has led to a number of proposals for ways to reduce friction on the nanoscale, such as superlubricity and thermolubricity. Researchers in Switzerland now describe a resonance-induced superlubricity, which also occurs in many natural phenomena from biological systems to the motion of tectonic plates. This new method provides an efficient way to switch friction on and off at the atomic scale and, as a simple way of preventing mechanical damage without chemical contamination, could be of enormous importance for the development of NEMS.
Dec 20th, 2006
There is much discussion of molecules as components for future electronic devices and in recent years it has been possible to position single molecules in electrical junctions. Molecular and nanoscale structures have been shown to be capable of basic electronic functions such as rectification, negative differential resistance and single-electron transistor behavior. These observations show that molecular-electronic functions can be controlled through chemical manipulation. However, the contacts, the local environment and the temperature can all affect molecules' electrical properties. This sensitivity, particularly at the single-molecule level, may limit the use of molecules as active electrical components, and therefore it is important to design and evaluate molecular junctions with a robust and stable electrical response over a wide range of junction configurations and temperatures. A step in this direction, researchers in the UK now report an approach to monitor the electrical properties of single-molecule junctions, which involves precise control of the contact spacing and tilt angle of the molecule.
Dec 12th, 2006
If current research is an indicator, wearable electronics will go far beyond just very small electronic devices. Not only will such devices be embedded on textile substrates, but an electronics device or system could become the fabric itself. Electronics textiles will allow the design and production of a new generation of garments with distributed sensors and electronic functions. Such e-textiles will have the revolutionary ability to sense, act, store, emit, and move (think biomedical monitoring functions or new man-machine interfaces) while leveraging an existing low-cost textile manufacturing infrastructure. Today, only a few steps towards new architectural possibilities of realizing circuit topologies that can be implemented with textile technique have been made: one an example of nonplanar devices and one of textile based devices. Researchers in Italy have now developed an organic field effect transistor (OFET) fully compatible with textile processing techniques.
Nov 21st, 2006
'Carrier mobility' is a major factor in determining the speed of electronic devices. Aggressive scaling of the complementary metal-oxide-semiconductor (CMOS) transistor technology requires a high drive current, which depends on the charge carrier mobility. As the dimensions of nanoelectronic circuits continue to shrink, it is important that the carrier mobility does not deteriorate and, if possible, improves. The search for nanostructures where the carrier mobility values can be preserved or even improved continues owing to the extremely high technological pay-off if successful. Nanowires represent a convenient system to understand the effects of low dimensionality on the carrier drift mobility. One can also look at nanowires as an ultimately scaled transistor channel. New research at the University of California - Riverside demonstrates a method for the significant enhancement of the carrier mobility in silicon nanowires. Such mobility enhancement would allow to make smaller and faster transistors and improve heat removal.
Oct 26th, 2006
Adhesives may be broadly divided in two classes: structural and pressure sensitive. To form a permanent bond, structural adhesives harden via processes such as evaporation of solvent or water (white glue), reaction with radiation (dental adhesives), chemical reaction (two part epoxy), or cooling (hot melt). In contrast, pressure sensitive adhesives (PSAs) form a bond simply by the application of light pressure to attach the adhesive to the adherend. PSAs adhere instantly and firmly to nearly any surface under the application of light pressure, without covalent bonding or activation. Waterborne pressure-sensitive adhesives solve the problem of meeting environmental regulations that forbid the emission of volatile organic compounds in manufacturing. However, often waterborne PSAs have poor adhesive performance. Another problem, particularly relevant to display technologies, is how to make an electrically-conducting material that is also flexible and optically transparent. Indium tin oxide is commonly used as a transparent electrode in displays, but it is brittle and prone to mechanical failure or scratching. Adhesives can be made electrically conductive through the addition of metal particles, but then they lose optical transparency, and their adhesiveness is diminished. New research shows that waterborne PSAs containing single-wall carbon nanotubes (SWNTs) meet the requirements of environmental regulations while improving the adhesive performance. The resulting unprecedented combination of adhesion and conductivity properties holds enormous potential for demanding applications in displays and electronics.
Oct 24th, 2006
Paper manufacturing is one of the mainstays of economic infrastructure and paper products influence many aspects of business and personal life. Pulping, process chemistry, paper coating, and recycling are key areas that can benefit from nanotechnology methods. One such method, layer-by-layer (LbL) assembly, is of great interest of its usage in the field of nanocoating. It allows creating nanometer-sized ultrathin films both on large surfaces and on microfibers and cores with the desired composition. Researchers at Louisiana Tech University have developed a simple and cost effective technique to fabricate an electrically conductive paper by applying layer-by-layer nanoassembly coating directly on wood microfibers during paper making process. Nanocoated wood microfibers and paper may be applied to make electronic devices, such as capacitors, inductors, and transistors fabricated on cost-effective lignocellulose pulp. The use of a conductive nanocoating on wood fibers can open the door for the future development of smart paper technology, applied as sensors, communication devices, electromagnetic shields, and paper-based displays.
Oct 18th, 2006
Spintronics (short for "spin-based electronics") is an emergent technology which exploits the quantum propensity of electrons to spin as well as making use of their charge state. The spin itself is manifested as a detectable weak magnetic energy state characterized as "spin up" and "spin down". Spin flip length is an important parameter to know for designing spintronics devices. Because in spintronics, electron spin carries the information, it is important to know how far electrons can travel in a device before this spin information is lost. In a discovery that could contribute to the emerging field of spintronics, scientists at Oak Ridge National Laboratory (ORNL) and the Institute of Physics, Chinese Academy of Science, have demonstrated a way to measure the distance an electron travels in nanoscale materials before its spin is reversed due to scattering.
Sep 27th, 2006
The ability to generate functional nanoswitches might ultimately allow the integration of nano-components into electronic components. Single molecule switches using scanning tunneling microscope (STM) manipulation have been demonstrated before. Mostly these switches are based on single atoms or small molecules and operate between two distinct states. Researchers now realized the first multi-step switching process by STM manipulation on a single molecule. Instead of small organic molecules they used a large plant molecule which is environmentally friendly and abundant in nature.
Sep 18th, 2006