Information Technology Reference
In-Depth Information
Chapter 5
Reaction-Diffusion Processor: Possibilities
and Limitations
The future of analog calculations is boundless. Being a
daydreamer, I see how they eventually take the place of
digital ones, especially first for solving the differential
equations in partial derivatives and for simulation in
neuroscience. Several decades are need for this to occur. In
the meantime, I believe that
this is a very fruitful and
challenging
field
of
research
although
(but maybe
therefore) it is not popular today.
Lee A. Rubel,
From a letter to a friend
5.1 Reaction-Diffusion Processor: Basic Principles
At the heart of information processing by reaction-diffusion systems is the concept
of reaction-diffusion processor. A schematic diagram of this device, which is based
on a chemical or a biochemical system, is shown in Fig.
5.1
. Chemical reaction-
diffusion media of the Belousov-Zhabotinsky type represent a convenient starting
material for the creation of information processing devices. They are stable and not
toxic.
The temperature range and the temporal scales of processes in them are suitable
for recording the characteristics of these media by available physical methods.
Chemical components required for the formation of these media are readily avail-
able, and their cost is low. At the same time, those dynamic regimes that are most
important for information processing appear when the environment is operating in a
steady state (far from equilibrium). Therefore, the initial components of the reaction
must be continuously fed to the environment, maintaining their initial concentra-
tions constant, and the products of the reactions occurring in the medium must be
carried off. Dynamical regimes of the Belousov-Zhabotinsky media are sensitive to
temperature changes. Therefore, the medium processing the information must be
thermostatted.
Information processing by a processor involves several levels characteristic of
this system.
