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The properties of excitable media are exploited to find minimum-length paths in complex labyrinths. Optimal pathways are experimentally determined by the collection of time-lapse position information on chemical waves propagating through mazes prepared with the Belousov-Zhabotinsky reaction. The corresponding velocity fields provide maps of optimal paths from every point in an image grid to a particular target point. Collisions of waves that were temporarily separated by obstacles mark boundary lines between Significantly different paths with the same absolute distance. The pathfinding algorithm is tested in very complex mazes with a simple reaction-diffusion model.

The interaction of chemical waves propagating through capillary tubes is studied experimentally and numerically. Certain combinations of two or more tubes give rise to logic gates based on input and output signals in the form of chemical waves and wave initiations. The geometrical configuration, the temporal synchronization of the waves, and the ratio of the tube radius to the critical radius of the excitable medium determine the features of the logic gates.

Density fingering of the chlorite–tetrathionate reaction is studied experimentally in a Hele-Shaw cell. It is shown that the dispersion curve describing the linear regime of the evolution of pattern formation is strongly affected by the orientation of the cell. Both the growth rate and the range of wave numbers associated with the unstable modes decrease on increasing the tilt angle from the vertical. From the dispersion curves, the dependence of the most unstable mode on the tilt angle is determined experimentally and compared with that of existing theories. The ratio of the marginal wave number, separating the stable and unstable modes, to the wave number with the maximum growth rate indicates that the high-frequency disturbances are stabilized by the diffusion of the components in the reaction.