Showing Spotlights 1761 - 1768 of 2426 in category All (newest first):
A major issue for using self-contained nanodevices, for instance as implantable nanosensors or environmental monitoring devices, is the question of how to power these tiny machines with an independent power source. Options include nanobatteries and nanogenerators that harvest energy from their environment. By converting mechanical energy from body movement, engine vibrations, or water or air flow into electricity, these nanoscale power plants could make possible a new class of self-powered medical devices, sensors and portable electronics. Probably the leading team that is driving forward the work on nanogenerators for converting mechanical energy into electricity is Zhong Lin Wang's group at Georgia Tech. Wang's team has now designed and demonstrated an innovative approach to fabricating a nanogenerator by integrating nanowires and pyramid-shaped nanobrushes into a multilayer power generator. By demonstrating an effective way for raising the output current, voltage and power, this work provides the technological platform for scaling up the performance of nanogenerators to a level that some day might be able to independently power devices like pacemakers or iPods.
Oct 27th, 2008
The method that has been traditionally used in binary information storage is by making a distinction between storage (designated as 1) and non-storage (designated as 0). In reality, each imprint (or non-imprint) can store either 1 or 0. Thus the sequence and the numbers of 1 and 0 define everything with respect to the amount of information that can be stored and retrieved at the hardware level, no matter how sophisticated the overlaying software routines are. Ever since computers were developed, information storage has adhered to the eight-bit system. No matter how sophisticated information storage technologies have become - exploiting magnetoresistance, developing optical storage media such as CDs, DVDs and blue-ray discs, or the development of holographic storage media - a bit is always represented by manipulating a single feature, i.e., a transition or non-transition. Now, in contrast, consider the following: There are four colors, each of which could at least represent two or more bits; whereas in conventional methods only a single bit is available. In terms of color, this is somewhat similar to a black and white system that can support at most two kinds of transitions - 0 to 1 and 1 to 0. On the other hand, in four-color coded systems there can be 16 such unique transitions.
Oct 23rd, 2008
There is a general perception that nanotechnologies will have a significant impact on developing 'green' and 'clean' technologies with considerable environmental benefits - be it in areas ranging from water treatment to energy breakthroughs and hydrogen applications. As a matter of fact, renewable energy applications probably are the areas where nanotechnology will make its first large-scale commercial breakthroughs. Conflicting with this positive message is the growing body of research that raises questions about the potentially negative effects of engineered nanoparticles on human health and the environment. However, there is one area of nanotechnology that so far hasn't received the necessary attention: the actual processes of manufacturing nanomaterials and the environmental footprint they create, in absolute terms and in comparison with existing industrial manufacturing processes. Analogous to other industrial manufacturing processes, nanoproducts must proceed through various manufacturing stages to produce a material or device with nanoscale dimensions.
Oct 22nd, 2008
Nanoscale membranes are of great interest to researchers not only for nanofiltration applications but also in areas such as flexible electronics, extremely sensitive sensors, nanomedical applications and biomolecular research. Many of these applications would require the nanomembranes to be arranged in three-dimensional structures such as tubes, helices, rings, or wrinkles. So far, the roll-up of ultra-thin layers was heavily limited in materials choice, in most cases involving epitaxial semiconductor layers. The fabrication often requires a selective underetching procedure to release the nanomembranes from their substrate, a process which not only removes the underlying sacrificial layer but also in many cases dissolves the nanomembrane material itself. A new approach developed by scientists in Germany and Hong Kong now allows controlled fabrication of pure metal and oxide tubes as well as many other material combinations. They describe a general method to produce well-defined micro- and nanotubes from thin solid films deposited by mass production tools.
Oct 21st, 2008
The European Commission's current assessment of nanotechnology applications to the food chain range from the almost certain (e.g., membranes, antibacterials, flavors, filters, food supplements, stabilizers) through to the probable (e.g., pathogen and contaminant sensors, environmental monitors, coupled sensing and warning devices, and remote sensing and tracking devices) to the improbable (e.g., 'creating unlimited amounts of food by synthesis at the atomic level'). The European Commission has now decided that it would like to address the possible safety issues arising from nanoscience and nanotechnologies in a stepwise fashion, thereby facilitating the establishment of a roadmap for future actions in the area of food and feed safety and the environment. As a first step in this exercise, the Commission has asked the European Food Safety Authority (EFSA) to prepare a scientific opinion in order to identify the needs for risk assessment, to assess the appropriateness of methods for risk assessment, and to perform an assessment of the potential risks posed by nanoscience and nanotechnologies in the food and feed area, and assess the appropriateness of current risk assessment methods.
Oct 20th, 2008
Poll after poll shows that most people today, assuming they have even heard the term, don't understand what nanotechnology is. Those who have heard about it are often misinformed by science fiction books and movies or tend to either focus on hype or fear surrounding available information about nanotechnologies. A team of scientists have described the key issues quite nicely: There is a general recognition that few people understand the implications of the technology, the technology itself or even the definition of the word. This lack of understanding stems from a lack of knowledge about science in general but more specifically difficulty in grasping the size scale and symbolism of nanotechnology. A potential key to informing the general public is establishing the ability to comprehend the scale of nanotechnology. Transitioning from the macro to the nanoscale seems to require an ability to comprehend scales of one-billion. Scaling is a skill not common in most individuals and tests of their ability to extrapolate size based upon scaling a common object demonstrates that most individuals cannot scale to the extent needed to make the transition to nanoscale.
Oct 17th, 2008
While individual carbon nanotubes could find applications in nanoelectronics, in order to exploit their intriguing properties on the macroscale, for instance in thin films and membranes, many trillions of these tubes must be assembled. These macroscopic aggregates are commonly called buckypapers - thin sheets made from intertwined carbon nanotubes. Buckypapers could find numerous applications: As one of the most thermally conductive materials known, buckypaper could lead to the development of more efficient heat sinks for chips; a more energy-efficient and lighter background illumination material for displays; a protective material for electronic circuits from electromagnetic interference due to its unusually high current-carrying capacity; or switchable surfaces. Borrowing a technology from the textile industry, researchers have developed a novel nanotechnology fabrication technique that results in high-quality CNT membranes with controllable thickness and topology at high-speed and low-cost for many practical applications.
Oct 15th, 2008
Ink-jet printing of metal nanoparticles for conductive metal patterns has attracted great interest as an alternative to expensive fabrication techniques like vapor deposition. The bulk of the research in this area focuses on printing metal nanoparticle suspensions for metallization. For example, silver and gold nanoparticle suspensions have been inkjet printed to build active microelectromechanical systems (MEMS), flexible conductors and radio frequency identification (RFID) tags. Nobel metals like silver and gold are preferred nanoparticles for ink-jet formulations because they are good electrical conductors and they do not cause oxidation problems. However, gold and silver still are too expensive for most high volume, ultra low-cost applications such as RFID tags with required unit costs below one cent. A new technique developed in Switzerland uses flame spray synthesis in combination with a simple in-situ functionalization step to synthesize graphene coated copper nanoparticles which are air-stable and can be easily handled at ambient conditions. This work illustrates graphene's potential as a protective shell material for nanoparticles, enabling control and design of the chemical reactivity of non-noble metals.
Oct 14th, 2008