Metrology at the nano scale

Progress in nanotechnology relies on ever more accurate measurements of quantities such as distance, force and current industry has long depended on accurate measurement. In the 19th century, for example, the performance of steam engines was seriously limited by inaccurately made components, a situation that was transformed by Henry Maudsley's screw micrometer calliper. And early in the 20th century, the development of telegraphy relied on improved standards of electrical resistance. Before this, each country had its own standards and crossborder communication was difficult. The same is true today of nanotechnology if it is to be fully exploited by industry. Principles of measurement that work well at the macroscopic level often become completely unworkable at the nanometre scale - about 100 nm and below. Imaging, for example, is not possible on this scale using optical microscopes, and it is virtually impossible to weigh a nanometre-scale object with any accuracy. In addition to needing more accurate measurements, nanotechnology also often requires a greater variety of measurements than conventional technology. For example, standard techniques used to make microchips generally need accurate length measurements, but the manufacture of electronics at the molecular scale requires magnetic, electrical, mechanical and chemical measurements as well. (U.K.)