Tools and Methods Used in Nanotechnology

The number of tools and methods used in nanotechnology is not too large, but those available today are of great importance. The first, big step towards the nanotechnology development was the invention of scanning probe microscopes – the scanning tunneling microscope (STM) and the atomic force microscope (AFM) in the mid 1980’s. These microscopes are capable of imaging an object’s surface topography in three dimensions with extremely high magnification, up to 1,000,000 times (Schellenbach, 2002). Such a high magnification allows researches to “see” substances at the scale of individual atoms. Beside that, these microscopes can be used to move individual atoms from place to place (Stix, 2001). The most famous example of using the STM microscope to position single atoms was writing the IBM corporate logo with xenon atoms (Wejnert, 1996). The STM works by moving a sharp, conductive probe over a scanning surface. The probe’s tip is the size of a single atom. It can be maneuvered very precisely in all three dimensions. The distance between the tip and the sample surface is controlled by the change in the voltage applied to the vertical element. The AFM on the other hand, works by recording the interatomic forces between its tip and the surface atoms as the tip is scanned over the surface of the sample. The AFM differs from the STM in that it can image both conducting and nonconducting surfaces (Wejnert, 1996; Whitesides & Love, 2001).

One of the key ideas of nanotechnology involves the concept of an assembler. Assembler is defined as a molecular machine that can be programmed to build virtually any molecular structure or device (including itself) from simpler chemical building blocks (Drexler, 1986; Regis 2001). These nanomachines would operate in a similar way to their large-scale counterparts. Their moving parts, however, would be created from a small number of atoms and held together by the power of their atomic bonds. They would be incredibly fast and precise, but to construct a desired object many of them would be needed. Each product obtained from a molecular machine could be completely precise, down to the tiniest degree of detail that exists in the world (Berry, 1991).

Most technologies available today are based on so-called top-down manufacturing approach. This method involves the construction of precisely formed products from blocks or chunks of raw material through processes of cutting, molding and carving. Using these methods, we have been able to fabricate a remarkable variety of machinery and electronics devices. However, the sizes at which we can make these devices are severely limited by the precision of our tools (Lenhert, 2002). Bottom-up manufacturing is inspired by molecular biology, where cells can be regarded as self-replicating collections of molecular nanomachines (Whitesides, 2001). Bottom-up method, using the assembler, would allow us to construct products made of single molecules by putting atoms in selected places. Such molecular machine systems would be able to assemble products cheaply, in vast quantities and of astonishing complexity and size (Drexler, 2001). Nanotechnology promises nothing less than complete control over the physical structure of matter. Using nanotechnology, production would be carried out by a large number of tiny devices, operating in parallel, in a fashion similar to the molecular machinery found in living organisms (Reynolds, 2001).