Self assembled structures from colloidal particles have many applications in biology, as chemical sensors and as photonic crystals. The control of shape and valency of the colloidal particle is very important since it will determine the 3D lattices of the assembled structure. There have been several prior effort to fabricating particles with complex shapes. Most particles with anisotropic shape are from the simple assembly of spheres or the modification of spherical particles. Interference lithography is one of the few techniques which can provide direct and systematic control over symmetry and volume fraction of the 3D structure. It involves the simple creation of interference patterns in a photoresist systems and subsequent pinch off of the parent structure through a drying process. Researchers at MIT have now presented a new facile and high-yield route for the fabrication of highly nonspherical complex multivalent nanoparticles. This technique exploits the ability of holographic interference lithography to control network topology. These research results could lay the groundwork for establishing and demonstrating control over particle shape in colloidal nanoparticles.
Nano-this and nano-that. These days it seems you need the prefix "nano" for products or applications if you want to be either very trendy or incredibly scary. This "nanotrend" has assumed "mega" proportions: Patent offices around the world are swamped with nanotechnology-related applications; investment advisors compile nanotechnology stock indices and predict a coming boom in nanotechnology stocks with misleading estimates floating around of a trillion-dollar industry within 10 years; pundits promise a new world with radically different medical procedures, manufacturing technologies and solutions to environmental problems; nano conferences and trade shows are thriving all over the world; scientific journals are awash in articles dealing with nanoscience discoveries and nano- technology breakthroughs. Nanotechnology has been plagued by a lot of hype, but cynicism and criticism have not been far behind. Science fiction writers exploit fears of nanorobots turning into killers; the media can run amok when news about potential health problems with nanoproducts surface (as happened last year with a product recall for a bathroom cleaner in Germany). Some see doomsday scenarios of molecular self-assembly turning the world into "grey goo." The emerging polarization of opinions on nanotechnology is reminiscent of controversies about genetically modified plants or nuclear energy. Vague promises of a better life are met by equally vague, generalized fears about a worse future. These debates have some aspects in common: the subject is complex and not easy to explain; there is no consensus on risks and benefits; scientists and corporations seem able to proceed unchecked, and it is unclear who is in control.
Research into the subject of radiation damage in graphite began in the early 1940s as a part of the development of nuclear weapons and nuclear power. Some designs of nuclear power reactors, such as the Chernobyl reactors, use graphite as moderator (the material which slows down the neutrons released from fission so that they cause more fission). The damage to the graphite moderators caused by radiation has been one of the major concerns of the nuclear power industry and radiation defects, i.e. structural irregularities, in graphite produced upon irradiation, their structure, properties and formation mechanisms, have been subject of intense research. Several years ago, defects in carbon materials became a hot topic again but now in the context of carbon layered nanostructures, such as multiwalled and bundled carbon nanotubes, which closely resemble graphite in their structure. The formation of irradiation-induced defects in graphite like layered carbon nanostructures, multiwalled and bundled carbon nanotubes, nanoonions, etc. changes their mechanical and electronic properties and may even trigger dramatic structural changes. While the terms "radiation damage" and "defect" are perceived negatively by people, the nanoengineering research community is trying to make use of defect structures for the deliberate modification of carbon nanomaterials, which can eventually be used in the manufacturing of nanoelectromechanical systems (NEMS). This process is sometimes called "defect-assisted engineering."
For computer chips, 'smaller and faster' just isn't good enough anymore. Power and heat have become the biggest issues for chip manufacturers and companies integrating these chips in everyday devices such as cell phones and laptops. The computing power of today's computer chips is provided mostly by operations switching at ever higher frequency. This physically induced power dissipation represents the limiting factor to a further increase of the capability of integrated circuits. Heat dissipation of the latest Intel processors has become a widely discussed issue. By the end of the decade, you might as well be feeling a rocket nozzle than touching a chip. And soon after 2010, computer chips could feel like the bubbly hot surface of the sun itself. As the electronics industry continues to churn out smaller and slimmer portable devices, manufacturers have been challenged to find new ways to combat the persistent problem of thermal management. New research suggests that the integration of carbon nanotubes (CNTs) as heat sinks into electronic devices might provide a solution to this problem.
Organic materials offer new electronic functionality not available in inorganic devices. Promising examples of novel characteristics in organic devices range from the memory effects observed in monolayers and polymer films to negative differential resistance devices. However, the integration of organic compounds within nanoscale electronic circuitry poses considerable challenges for materials physics and chemistry, and a detailed understanding of the conduction mechanisms, switching and memory is still lacking. With increasing research into very different material systems such as oxides, solid-state electrolytes, phase-change memory materials, it is becoming clear that electronic switching on the smallest length scale cannot be purely electronic phenomena. Rather, a motion of heavier constituents has to be involved that will in turn change the electronic properties. New work conducted at Bell Labs demonstrates the success of such a line of thought in molecular systems. The Bell scientists demonstrated a novel approach to creating and chemically modifying conducting electronic states in nanoscale molecular devices.
Polystyrene (PS), also known under its trademark name styrofoam, is found in your home, office, local grocery, fast food outlet and in the cafeteria. It comes in many shapes and forms, from foam egg cartons and meat trays, plates and salad boxes, from coffee cups and utensils to CD jewel boxes, and from produce trays to those foam peanuts used in packing and the lightweight foam pieces that cushion new appliances and electronics. According to the U.S. Environmental Protection Agency's Municipal Solid Waste statistics (the things we read at Nanowerk to bring you interesting stories...), solid waste in the U.S. in 2005 contained almost 2.6 million tons of PS - a material that takes hundreds of years to break down and which is not recovered in recycling. PS is also a principle component of marine debris. Motivated by this problem of 'white pollution', a group of researchers in China developed a nanocomposite material that not only has superabsorbent capabilities but also utilizes waste PS foam. If commercially successful, this and similar methods of recycling waste PS into new products could go along way in reducing the worldwide harmful effects of white pollution.
Science fiction style robots like Star Wars' R2-D2 or the NS-5 model in I, Robot firmly belong into the realm of Hollywood - and so do "nanobots" a la Michael Crichton's Prey. Staying with both feet firmly on scientific ground, robotics can be defined as the theory and application of robots, a completely self-contained electronic, electric, or mechanical device, to such activities as manufacturing. Scale that robot down to a few billionth of a meter and you are talking nanotechnology robotics; nanorobotics in short. The field of nanorobotics brings together several disciplines, including nanofabrication processes used for producing nanoscale robots, nanoactuators, nanosensors, and physical modeling at nanoscales. Nanorobotic manipulation technologies, including the assembly of nanometer-sized parts, the manipulation of biological cells or molecules, and the types of robots used to perform these tasks also form a component of nanorobotics. Nanorobotics might one day even lead to the holy grail of nanotechnology where automated and self-contained molecular assemblers not only are capable of building complex molecules but build copies of themselves - "self-replication" - or even complete everyday products (this vision is nicely illustrated in the clip "Productive Nanosystems: From Molecules to Superproducts"). Whether this will ever happen is hotly debated - to understand where both sides stand, read the famous 2003 debate where Drexler and Smalley make the case for and against molecular assemblers. Today's nanorobotics research deals with more mundane issues such as how to build nanoscale motors and simple nanomanipulators.
In the future, 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. Reporting a novel approach through the construction of all-organic wire electrochemical transistor devices (WECT) , researchers in Sweden show that textile monofilaments can be coated with continuous thin films of a conducting polymer and used to create microscale WECTs on single fibers. They also demonstrate inverters and multiplexers for digital logic. This opens an avenue for three-dimensional polymer micro-electronics, where large-scale circuits can be designed and integrated directly into the three-dimensional structure of woven fibers.