Light-Sensitive Diffusion Diodes for Reaction-Diffusion Waves

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.