Current fabrication technologies for nanoscale devices include deep-UV or electron-beam (e-beam) lithography. Both of these techniques involve successive deposition of metal or insulating layer and a resist layer, which is patterned using a UV source or a scanning electron beam. The process needs to be repeated for each layer of the architecture while the sample is taken out of the high vacuum chamber. Thus, multilayer lithography processes seriously compromise throughput and cost. In addition, the resolution is limited in the sub-10 nm regime. Researchers at the Institute of Bioengineering and Nanotechnology (IBN) in Singapore have now successfully demonstrated, for the first time, a lithography-free, direct-write technique for fabricating discrete field-effect transistors, as well as digital logic gates on a single nanowire.
Nanoparticle chirality has attracted much attention among nanoscientists, and the application of chiral nanoparticles in chemistry, biology and medicine is of great importance for the development of new molecular nanosystems. In chemistry, chirality usually refers to molecules. Discovering efficient methods to produce, control and identify enantiomerically pure chiral compounds is critical for the further development of pharmaceuticals, agrochemicals, fragrances and food additives. An important example in the area of nanomaterials is the synthesis of metallic nanoparticles with controlled size, shape, composition, and morphology for catalytic applications.
For nanotechnology researchers, movement at the nanoscale is a challenging problem and there is much to be learned from nature's motor systems. There are various approaches to creating self-propelled micro- and nanosized motors and one promising approach rests on catalytic conversion of chemical to mechanical energy - a process that is ubiquitous in biology, powering such important and diverse processes as cell division, skeletal muscle movement, protein synthesis, and transport of cargo within cells. Self-propelled motion of synthetic materials can be useful in applications such as bottom-up assembly of structures, pattern formation, drug delivery at specific locations, etc. Researchers have now presented a novel and versatile light-driven catalytic micromotor system, which is the cleanest and simplest of its kind.
Developing chemicals, molecular precursors, and industrial products from petroleum resources is a conventional practice. Plastics, detergents, even pharmaceuticals are derived from petrochemicals. With an increasing focus on the economic and environmental issues associated with the processing of petroleum-based chemicals, scientists are seeking for alternative routes to develop molecules from naturally available plant or crop-based raw materials. Particularly interesting for the fields of nanotechnology is the design and development of soft nanomaterials from renewable sources. Generating these materials from renewable resources could have a significant impact on production technologies and economies.
The ability to extract, dispense and manipulate very small amounts of liquids on the micro- and nanoscale is important in biotechnology, chemistry and also for patterning inorganic, organic and biological inks. Several methods for dispensing liquids exist, but many require complicated electrodes and high-voltage circuits. Researchers in Italy have now demonstrated a pyroelectrohydrodynamic droplet dispenser based on pyroelectric forces.Researchers in Italy have developed and demonstrated a completely new method for extracting and dispensing very small amounts of liquid - as small as few attoliters - from liquid droplet reservoirs or thin liquid films by a method called pyroelectrohydrodynamic (Pyro-EHD).
Steel is one of the most widely used engineering materials in the world. Its pre-eminent position amongst the engineering materials arises due to the abundance and low cost of its main constituent, i.e. iron, and its amenability to produce a wide variety of engineered microstructures with superior properties, and recyclability. Currently, there is a growing awareness about the potential benefits of nanotechnology in the modern engineering industry, and a number of leading research institutes and companies are pursuing research in the area of nanostructured steels. The focus of the ongoing efforts has been largely manipulation of microstructures at the nano-scale through innovative processing techniques and adoption of novel alloying strategies.
Material scientists have been fascinated by spider silks for a long time - ultra-strong and extensible self-assembling biopolymers that outperform the mechanical characteristics of many synthetic materials, including steel. While the source of these unique material properties are thought to lie in the distinct protein structures found in spider silk, the physical mechanisms behind them have remained poorly understood for decades. This is partly due to the fact that structural models of spider silk with atomic-level resolution have not been available, preventing a molecular-level analysis. So far, only small models of isolated crystalline domains of silk have been reported. Yet, the integrated structure of the semi-amorphous regions combined with crystalline domains in silk is critical for properties such as toughness and fracture mechanisms. To unravel silk's secrets and ultimately be able to create synthetic materials that duplicate, or even exceed, the extraordinary properties of natural silk, researchers need to fully understand the links between genetic makeup, chemical interactions, and structure, as well as its macroscale mechanical properties.
Controllable fabrication of complex, three-dimensional (3D) nanoscale structures remains a difficult challenge. Researchers are experimenting with a wide range of nanofabrication techniques, from top-down approaches such as mechanical machining to biomimetic replication of complex biotemplates to bottom-up fabrication using anisotropic self-assembly systems - to just name a few examples. New work at Johns Hopkins University utilizes the extrinsic stresses that develop during thin-film deposition - but can also be induced by external forces post-deposition - for the self-assembly of 3D curved and simultaneously patterned structures. This technique is fairly simple and low-cost since it requires only thermal evaporation and low temperature processing; the stress for self-assembly can be controlled to occur only when required. Furthermore, the layers that are selected for 3D structuring can also easily be patterned with conventional electron-beam lithographic processing.