Light-Sensitive Diffusion Diodes for Reaction-Diffusion Waves
Chase A. Fuller, Daniel Cohen-Cobos, John F. Lindner and Niklas Manz
We use the Tyson-Fife model of the Belousov-Zhabotinsky reaction to numerically investigate the propagation of chemical reaction-diffusion waves through narrow, quasi-one-dimensional channels. We create soft obstacles in the form of activator and inhibitor diffusion coefficient inhomogeneities. Using a Fast Inhibitor Diffusion Region, in which the inhibitor’s diffusion is larger than the activator’s diffusion, the system can exhibit unidirectional propagation behavior – the diffusion diode. In a light-sensitive BZ-system, we discover a nonlinear compensation relationship between a higher activator diffusion (causing increased wave speed) and illumination (causing decreased wave speed) to achieve normal wave behavior. This enables the creation of a very energy efficient on/off-switch for chemical computation circuits in which a low intensity light pulse can be applied to a diffusion diode to disable wave propagation.
Keywords: Barkley model, Belousov-Zhabotinsky reaction, diffusion coefficient, Diode effect, fast inhibitor diffusion region, fast propagation region, light-sensitivity, nonlinear wave, numerical simulation, reaction-diffusion wave, Tyson-Fife model