Molecular devices

Kybernetes

ISSN: 0368-492X

Article publication date: 1 December 1999

284

Keywords

Citation

Rudall, B.H. (1999), "Molecular devices", Kybernetes, Vol. 28 No. 9. https://doi.org/10.1108/k.1999.06728iaa.005

Publisher

:

Emerald Group Publishing Limited

Copyright © 1999, MCB UP Limited


Molecular devices

Keywords Automation, Cybernetics, Research, Technological developments

Abstacts Reports and surveys are given of selected current research and development in systems and cybernetics. They include: RSI and the brain, Innovations, Biocybernetics, Mathematics and cybernetics, Molecular devices, Devices controlled by thought, Automation and cybernetics, VDU radiation.

Molecular devices

An article in Chemistry in Britain (March 1999) describes how UK chemists have designed the first molecular units that can carry out complex logical functions of the kind used in silicon chips. This research integrates work carried out earlier with the successes of performing the basic logical functions such as AND and NOT. This led to the functions being able to complete more complex tasks and gave hope that they could be the basis for molecular computers which would be many times more powerful and faster for their size than silicon-based devices. Dr Prasanna "AP" de Silva of the Queen’s University, Belfast, Northern Ireland UK, is a leading researcher in the field who has spent more than a decade designing such systems where the molecules form the basis for computational devices. The report says that the:

new molecules use chemical inputs and light as output, visibly demonstrating their so-called NOR and INHIBIT logic behaviour. NOR represents the integration of NOT and OR, while INHIBIT is equivalent to a special combination of AND and NOT. If there are three inputs then a signal will only be produced if they are "000" for the NOR logic gate and "110" for the INHIBIT gate. The designed combination of many logic gates of this kind allows circuits to execute calculations. A bipyridyl group acts as a reception within a "fluorophore-spacer receptor" system in which an anthracene fluorophore is the output device that gives a glow when stimulated. This system can complex either hydrogen or zinc ions (or H or Hg). This is its input. According to de Silva, either one of these ions will quench the output glow, which gives the molecule its logical NOR behaviour. An output signal is only produced when neither hydrogen nor zinc is present.

For the INHIBIT function the researchers built what is described as a deceptively simple molecule with four inputs. INHIBIT, de Silva explains in the report:

is a normal AND gate with an extra disabling input. When this input is live the entire AND operation is disabled so the input goes through a NOT gate before the AND.

Details of this operation and the INHIBIT truth table are published in Chemistry in Britain and the behaviour described fits the INHIBIT "truth table" which is to be published in J. Am. Chem. Soc.

It is certain that since the devices described are not hard-wired as conventional circuits are, they will have many unusual applications.

Related articles