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.
Super-tough materials with exceptional mechanical properties are in critical need for applications under extreme conditions such as jet engines, power turbines, catalytic heat exchangers, military armors, aircrafts, and spacecrafts. Researchers involved in improving man-made composite materials are trying to understand how some of the amazing high-performance materials found in Nature can be copied or even improved upon. Nature has evolved complex bottom-up methods for fabricating ordered nanostructured materials that often have extraordinary mechanical strength and toughness. One of the best examples is nacre, the pearly internal layer of many mollusc shells. It has evolved through millions of years to a level of optimization currently achieved in very few engineered composites. In a novel approach, scientists have prepared a high-performing nanocomposite material that takes advantage of two different exceptional natural materials - layered nacre and the marine adhesive of mussels. The resulting nanostructured composite film exhibits high strength exceeding that of even nacre.
Proteins are very specific about which other proteins or biochemicals they will interact with and therefore are of great use for biosensing applications. For instance, if a malignant cancer develops in the human body, the cancer cells produce certain types of proteins. Identifying such proteins enables early detection of cancer. One of the goals of nanobiotechnology is to develop protein chips that are sensitively responsive to a very tiny amount of specific proteins in order to enable such early stage diagnosis. For example, a protein that is known to bind to a protein produced by a cancer cell could be attached to a biochip. If this particular cancer cell protein were present in a sample passed over the chip, it would bind to the protein on the chip, causing a detectable change in the electrical signal passing through the chip. This change in the electrical signal would be registered by the device, confirming the presence of the protein in the sample. While this sounds very promising for the future of diagnostic systems, with the promise of protein chips capable of single-molecule resolution, the controlled assembly of proteins into bioactive nanostructures still is a key challenge in nanobiotechnology. Researchers in Germany took a further step towards this goal by developing a native protein nanolithography technique that allows for the nanostructured assembly of even fragile proteins.
Experts and the public generally differ in their perceptions of risk. While this might be due to social and demographic factors, it is generally assumed by scientists who conduct risk research that experts' risk assessments are based more strongly on actual or perceived knowledge about a technology than lay people's risk assessments. In the case of nanotechnology, surveys show that most people are not familiar with it. The public perception of an emerging technology will have a major influence on the acceptance of this technology and its commercial success. If the public perception turns negative, potentially beneficial technologies will be severely constrained as is the case for instance with gene technology. It seems plausible that the evaluation of new technologies, such as nanotechnologies, is guided by people's theories and values. For instance, people for whom the technological revolution is associated with positive outcomes - and who are not afraid of possible negative side effects of technological progress - may assess nanotechnology applications more positively than people for whom negative effects outweigh positive effects. Researchers in Switzerland conducted two studies which examined how lay people and experts perceived various nanotechnology applications and how companies address the public's concerns.
Tremendous progress has been made over the past few years to control the aspects of fabricating simple nanostructures such as wires, tubes, spheres, cubes etc. However, in order to build functional nanodevices, for instance for nanoelectronics or nanobiotechnology, much more complex nanoarchitectures are needed. Initially, the most common, mostly top-down, fabrication methods used for this purpose have been based on nanolithographic techniques. Unfortunately, these methods are burdened with throughput restrictions and high cost and will be of limited use for commercial mass production of nanostructures. To overcome the limitations of nanolithography, a lot of attention has been focused on self-organized bottom-up approaches, which bear good prospects for large-scale fabrication of nanostructures with controlled morphology and dimensionality, and controlled synthesis of arrays. However, the fabrication of complex nanoarchitectures requires sophisticated transfer techniques, which are far from routine, time consuming, and with low reproducibility. To add to the arsenal of scaleable bottom-up fabrication processes, researchers in Germany have developed a method for the batch fabrication of 3D-nanostructures with tunable surface properties. Resembling suspended nanowire webs, these structures have a high potential for catalytic, sensing, or fluidic applications where a high surface to volume ratio is required.