A flat screen that can be rolled up and put into a jacket pocket - organic transistors with low energy consumption could make this possible. Scientists at the Max Planck Institute for Solid State Research in Stuttgart and at the Universities of Stuttgart and Erlangen have constructed complementary circuits from organic transistors characterised by low supply voltages and low consumption values. These energy-saving electronic components consist of two different transistor types. The new organic electronic components can be operated with significantly lower voltages than previous organic circuits - voltages, such as those supplied by normal household batteries from 1.5 to 3 volts (Nature, February 2007).
Transistors made from organic materials have an advantage over normal silicon transistors. They can be constructed on flexible surfaces, such as plastic film, making organic circuits ideal for portable and mobile devices. However, until now, organic transistors have also had a big disadvantage: they consumed too much energy. Scientists have now constructed energy-saving organic circuits.
To this purpose, they make use of two principles: on the one hand, they use self-organising organic monolayers as the insulator for the transistor. Certain organic compounds deposit themselves under specific conditions on a substrate with an active surface. The coating consists of a layer of organic molecules less than 3 nm thick. This monolayer lowers the operating voltage of the transistor as this is directly dependent on the thickness of the insulator. On the other hand, the scientists linked p channel transistors and n channel transistors in complementary circuits. Up to now, organic circuits have mostly been realised in the form of unipolar circuits, which consist of transistors of just one type only (either p channel or n channel). In this kind of unipolar circuit, there is a constant undesirable cross-current, whereas with the complementary construction, one of the two transistors blocks the flow of the current - an opportunity to save energy. According to Dr. Hagen Klauk of the Max Planck Institute for Solid State Research, "Complementary circuits have been standard in silicon technology for 25 years. We believe that organic electronics can also benefit from the advantages of complementary circuit technology. And by combining it with self-organising monolayers, we could lower the supply voltage to that of small batteries."
The scientists thus created organic field effect transistors on a glass substrate. A field effect transistor has three circuit points - gate, source and drain. Irrespective of the voltage at the gate, a current flows from the source to the drain electrode through the charge carrier formed in the semiconductor. The scientists use the air-stable organic compounds: pentacene; and hexadecafluoro copper phthalocyanine. Between the gate and the semi-conductor layer there is an insulator, in this case a very thin self-organising monolayer. Aluminium is used for the gate electrode. Applying aluminium in a defined pattern to the glass substrate makes possible the construction of complementary circuits.
The researchers made different electronic circuits, including complementary inverters, NAND gates and ring oscillators. Of particular importance: the materials used allowed them to make the transistors and circuits at temperatures up to 90 degrees Celsius. A relatively low temperature is necessary for electronic components to allow a change to flexible and transparent plastic substrates. The scientists demonstrated that their method was also suitable for this purpose: they built these transistors on PEN, polyethylene naphthalate. Hagen Klauk explains why that was an advantage: "Silicon transistors need a substrate that is resistant to the high temperatures created in the manufacture of the transistors. In contrast, organic transistors can be created at temperatures less than 100 degrees Celsius - plastics can therefore be used as the substrate. These are flexible and nevertheless robust." Organic complementary circuits can consequently be used everywhere where products need to be simultaneously robust and mobile, for example in a portable, battery-powered flat screen.
Image: Max Planck Institute for Solid State Research
A new technology puts an end to the tedious business of buying shoes: Customers can now try on a variety of models in front of a virtual mirror without changing their shoes. They can navigate through the collection by simply pointing at products on a computer screen.
A Paris shop has put an end to the tiresome procedure of putting on and taking off shoes: Instead of trying on dozens of pairs, the customer simply stands in front of a virtual mirror. On his foot, he can see his favorite model with the red stripes, he then selects the gold leather alternative for comparison. This entertaining form of shopping can be found on the Avenue des Champs Elysées, where adidas has opened its most modern shop anywhere in the world. The virtual mirror was developed by researchers at the Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut HHI, in Berlin. Unlike a conventional mirror, it does not display a true reflection. Instead, a camera captures the customer’s feet and legs and displays them as a video scene on the monitor. The various shoe models are inserted into this picture. “Thanks to the 3-D image processing techniques developed at the HHI, the software is so fast that it can follow the customer’s movements in real time,” says Jürgen Rurainsky, one of the virtual mirror’s developers.
Time and frequency information can be transferred between laboratories or to other users in several ways, often using the Global Positioning System (GPS). But today's best atomic clocks are so accurate—neither gaining nor losing one second in as long as 400 million years—that more stable methods are needed. The best solution may be to use lasers to transfer data over fiber-optic cables, according to scientists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.
Now that Microsoft, Sony, and Nintendo all have their videogame consoles in the market, the transitional phase of the console cycle is in full effect as each vendor has entered the game. What is interesting about this particular generation of gaming manufacturers is that each vendor has clearly differentiated hardware and strategies. Who will win? IDC says none of the three new consoles will dominate the market in the next five years like the PS2 dominated last cycle; however, Nintendo's Wii will outship and outsell the 360 and PS3 in 2007 and 2008.
An underwater robot, shaped like a flattened orange, maneuvered untethered and autonomously within a 115-meter-deep sinkhole during tests this month in Mexico, a prelude to its mission to probe the mysterious nether reaches of the world's deepest sinkhole.
Bill Stone, leader of the NASA-funded Deep Phreatic Thermal Explorer (DEPTHX) mission, said the 2.5-meter-diameter vehicle performed "phenomenally well" during early February tests in the geothermal sinkhole, or cenote, known as La Pilita. Carnegie Mellon University researchers developed the software that guided the DEPTHX craft.
Lenovo has voluntarily recalled certain 9-cell lithium-ion batteries. These batteries were manufactured for use with ThinkPad notebook computers that shipped worldwide between November 2005 and February 2007.
The batteries were sold with new notebook computers or as optional or replacement batteries on the models listed below.