A Scanning Tunneling Microscope as a Switch in a Nanocomputer

There are several “molecular machines” that have been devised on a nanometer scale, made from proteins, DNA, and other molecules. A molecular machine is a system that generates physical forces at the atomic level, controlled by an external stimulus. Since all of the proposed circuits connect components linearly, they only communicate with one machine at a time. Now, Anirban Bandyopadhyay and Somobrata Acharya have devised an ingenious device that has the potential to communicate different instructions to many molecular machines simultaneously. They demonstrated that 2,3,5,6-tetramethyl-1–4-benzoquinone (duroquinone; DRQ) can be assembled as 17 identical molecules, one central molecule surrounded radially by 16 others. The central molecule can control the conformation of all the others when switched to one of four logic states by suitable pulses from an atomic sharp needle of a scanning tunneling microscope (STM).