TechBlog

Researchers at Northwestern University and Princeton University have created a new kind of polymer that, because of its extraordinary thermal and mechanical properties, could be used in everything from airplanes to solar cells.

The polymer, a nanocomposite that incorporates functionalized, exfoliated graphene sheets, even conducts electricity, and researchers hope to use that property to eventually create thermally stable, optically transparent conducting polymers.

Continue reading ‘By Adding Graphene, Researchers Create Superior Polymer’ »

White organic light-emitting diodes offer a power efficiency, lifetime, and brightness that together constitute a significant advance toward viable devices for lighting.

Light-emitting diodes (LEDs) are used in both displays and illumination applications because they are small, robust, and potentially very efficient. Organic light-emitting diodes (OLEDs) continue to gain attention from the scientific and industrial community. In contrast to their inorganic counterpart, OLEDs are flat and diffuse area light sources with the device thickness being in the range of 1–2mm. Thus far, OLED development has been triggered mainly by applications in the display segment, starting with applications for MP3 music players, mobile phones, and other portable devices. Recently, Sony brought to market the first OLED TV, which indicates that a more general penetration of the display market is close at hand.

OLEDs have not yet entered the lighting market, but that will probably change soon. Already most of the big players in the field are preparing for OLEDs to become ‘the next big thing.’ However, several critical problems need to be solved before widespread use for lighting becomes feasible. Specifically, the lifetimes, power efficiencies, reliability, and cost-effectiveness of white OLEDs must be able to compete with existing lighting technologies.

Continue reading ‘Making highly efficient white light-emitting diodes’ »

Researchers at Northwestern University and Princeton University have created a new kind of polymer that, because of its extraordinary thermal and mechanical properties, could be used in everything from airplanes to solar cells.

The polymer, a nanocomposite that incorporates functionalized, exfoliated graphene sheets, even conducts electricity, and researchers hope to use that property to eventually create thermally stable, optically transparent conducting polymers.

The results of their research were published May 11 in the online version of Nature Nanotechnology.

Continue reading ‘By Adding Graphene, Researchers Create Superior Polymer’ »

Microcantilever actuators made from carbon nanotube (CNT)-polymer composites could dramatically improve the performance of microelectromechanical systems, according to scientists in Taiwan. The researchers from National Tsing Hua University have developed an easy to actuate material that rapidly suppresses unwanted oscillations thanks to a low quality factor.

“Lightweight and highly flexible CNT-composites provide fast electrothermo-actuation at low power,” Weileun Fang told nanotechweb.org. “Moving the actuator from its original position to its pull-in position can be employed to define two different states such as 0/1 or on/off, which suits many applications in communications and displays.”

The group’s nanocomposite device has a pull-in voltage of just 50?V for a full deflection of 560?µm. As Fang explains, this value is very low compared with existing microcantilevers, which can demand at least 500?V to achieve a similar displacement. The researchers believe that CNT-based field amplification is responsible for the low pull-in voltage.

Continue reading ‘Nanocomposite offers MEMS upgrade’ »

In response to the electronics industry’s rallying cry of “smaller and faster,” the next breakthroughs in the electronics size barrier are likely to come from microchips and data storage devices created out of novel materials such as organic molecules and polymers. With innovative measurement techniques and new ways to position the molecules, NIST researchers reported at the March Meeting of the American Physical Society how they have improved manipulation of so-called block copolymers—polymers made of a mixture of two or more different molecule building blocks that are tethered at a junction point—which can form arrays of tiny dots that could be used as the basis for electronic components that pack terabytes (1000 gigabytes) of memory in something as small as a pack of gum.

One of the challenges in polymer nanotechnology is how to control their self-assembly—a hard-to-control process for materials which require precision. An important recent NIST accomplishment has been in developing accurate measurements of thin film polymeric nanostructure in 3-D. (Ironically, while determining atomic structure is well-established, measuring the slightly larger internal structure of the polymers—on the order of 10 to 20 nanometers—is much harder.) Ron Jones, together with colleagues from NIST, the University of Maryland and IBM, has used NIST’s neutron scattering and reflectivity facility to deflect neutrons off block copolymer films from many different angles. By combining the many 2-D neutron scattering pictures into a single composite scattering pattern, this technique provides the first quantitative method for imaging the 3-D internal structure of thin film polymeric nanostructures using neutron scattering—a crucial tool to see if the nanoscale polymer structures are in their required positions.

NIST researchers also have developed new insights on how best to nudge these self-assembling material into those positions. August Bosse will report on computer simulations that model how the polymers assemble when they are placed on templates lined with troughs separated by crests. When a heated zone is swept across the template, the polymer molecules assemble into almost defect free, well-aligned lines faster over the entire template, an important feature for nanotech manufacturing applications. Sangcheol Kim (working with a team that included researchers from the University of Maryland and IBM) has found that changing the surface chemistry of the template by making some parts hydrophillic and some parts hydrophobic also can elegantly control the dimension of the block-copolymer pattern relative to the chemical template.

Continue reading ‘Copolymers Block Out New Approaches To Microelectronics’ »

Dutch-sponsored researcher Christos Tsekrekos has investigated how a small network for at home or in a company can function optimally. His research analyses the MGDM technique (Mode Group Diversity Multiplexing) of the Eindhoven University of Technology. This technique transmits each TV, telephone and Internet signal via a separate group of light rays through the optical fiber cable.

 Such a technology has not yet been marketed. Yet in the ideal situation it could be applied in a glass or polymer fiber, has the potential of being cheap, and transmits all information without disruption.

Existing systems for small networks at home or in a company make use of multimode glass fibers or multimode polymer optical fibers (POF). The latter are relatively thick cables (about 1 mm thick, thus thicker than the glass fiber m thick). Multimode fiber cables can conduct many light rays and?which is 0.125 can operate free of disruption and with a greater bandwidth than a wireless connection. However, due to a slight variation in the speed of the light rays through the multimode fiber, a signal transmitted by all of these rays becomes spread out. Consequently, the signals become broader and therefore fewer signals fit in the fiber, limiting the transmission capacity.

Continue reading ‘Separate Signals Through Optical Fibers For Ultrafast Home Network’ »