Introduction to Nanoscience and Nanotechnology

Chapter 7

Radical Nanotechnology

The most far-reaching version of nanotechnology, described as radical nanotechnology, is the construction of machines whose mechanical components are the size of molecules. Although under a single umbrella, this encompasses technological goals that are often not distinguished but are actually quite different. One aspect of radical nanotechnology is molecular manufacturing, which postulates the possibility of mechanically placing atoms at controlled positions to assemble a macroscopic object. There are plenty of examples of the deliberate positioning of atoms and nanoparticles using scanning tunneling microscopes (STMs; see Chapter 4, Section 4.4.2) or atomic force microscopes (AFMs), but these were carried out slowly by a human operator. In addition, one must carefully choose the combination of atoms and surfaces to make this possible. Molecular manufacturing would require a manipulator/assembler, which is itself microscopic, able to recognize the different atoms around it and assemble them. There would also need to be a huge number of copies of the assembler. For example, a mobile phone contains more than 1024 atoms; so even if an assembler could position a million atoms per second (which is not unreasonable—things work fast at the nanoscale), it would still take more than 1018 seconds or 30 billion years (about the age of the universe) to assemble the phone. Vast numbers of copies are not necessarily a problem, especially if the assembler can ...