Swarms of nanobots are all very well, but how do you control the blighters?  Scientists in Japan have now developed a machine made from 17 molecules of the chemical duroquinone, which was able to control eight microscopic machines simultaneously in a test.

If [in the future] you want to remotely operate on a tumour you might want to send some molecular machines there,” explained Dr Anirban Bandyopadhyay of the International Center for Young Scientists, Tsukuba, Japan.  “But you cannot just put them into the blood and [expect them] to go to the right place.”  Dr Bandyopadhyay believes his device may offer a solution. One day they may be able to guide the nanobots through the body and control their functions, he said.  “That kind of device simply did not exist; this is the first time we have created a nano-brain,”

BBC News has more details:

The machines resemble a ring with four protruding spokes that can be independently rotated to represent four different states…One duroquinone molecule sits at the centre of a ring formed by the remaining 16. All are connected by chemical bonds, known as hydrogen bonds.  The state of the control molecule at the centre is switched by a scanning tunnelling microscope (STM).  Researchers showed they could change the central molecule’s state and simultaneously switch the states of the surrounding 16.  To test the control unit, the researchers simulated docking eight existing nano-machines to the structure, creating a “nano-factory”.

MSNBC has a brief explanatory animation