| The process of moving or altering items at an atomic or molecular scale is known as nanomanipulation. Nanomanipulation is employed in order to produce extremely produce precise structures and can be broken into two subcategories: nanofabrication and self-assembly. Nanofabrication Nanofabrication is the use of tools to sculpt or build a range of products, materials or structures at atomic level precision. Nanofabrication is normally done either by removing miniscule particles (even individual atoms and molecules) from a piece of material until the required structure is achieved or by building the material up, atom by atom or molecule by molecule. The first method is similar to carving from a block of wood or stone and the second method similar to brick laying. In order to do this a piece of equipment called a nanomanipulator is required. Nanomanipulators Although initially developed for other purposes, modified Atomic Force Microscopes and Scanning Tunnelling Microscopes are now used extensively as nanomanipulators. By altering charge (polarity) along with the magnitude and duration of voltage pulse between the microscope tip and sample surface, single atoms can be lifted, moved, replaced and otherwise manipulated. Self Assembly Self-assembly is a nanotechnology field that deals with the construction of nanoscale materials, products, devices and systems without the use of external tools. In effect, they build themselves. Self assembly is known as a bottom up process in that components arrange themselves into a structured units or patterns from a base rather than being shaped by removal of material like in nanolithography (a top down process) Applications For Nanomanipulation Nanomanipulation applications that are currently used include: • Preparing and carbon nanotubes • Semiconductor preparation and etching for microchip production • Microbiological system preparation • MEMS development, assembly and testing • Transmission electron microscopy probe preparation • Construction of components for molecular and quantum computers Accuracy Limitations At the time of writing nanomanipulators have a precision or accuracy as small as a couple of nanometers. Although impressive, in order to provide for true placement of individual atoms an accuracy around one tenth of a nanometer is required. The problem with this is that the manipulator ‘fingers’ are themselves made from many atoms, limiting the accuracy. To get a feeling for the limits of accuracy this imposes, imagine trying to push a golf ball into the hole with a bulldozer. Future of Nanomanipulation – Molecular Manufacturing Nanomanipulation is tipped to lead to a new form of manufacturing – molecular manufacturing. The end goal of molecular manufacturing is the production of precision components and whole products starting with molecule by molecule assembly. Tiny robots would bring molecules together at the nano level and then, layer by layer, build a full size product. If each stage in the development of these products doubles the size of the previous stage, a metre sized component will be achieved in 30 steps from the nano level. |