Nanotechnology involves engineering systems at the molecular scale of 1-100 nanometers. One nanometer is one billionth of a meter, around the size of 3-6 atoms lined up or the thickness of DNA. K. Eric Drexler popularized the term "nanotechnology" in the 1980s to describe building machines only a few nanometers wide using molecules. Biologists, chemists, physicists and engineers study substances at the nanoscale. Engineers are trying to use nano-sized wires in microprocessors while doctors search for medical applications using nanoparticles. Nanowires and carbon nanotubes around 1 nanometer in diameter interest scientists for building transistors and electronic devices. Molecular manufacturing could one day build devices atom by atom to create