Abstract
Waves of chemical concentration, created by the interaction between reaction and diffusion, occur in a number of chemical systems far from equilibrium. In appropriately chosen polymer gels, these waves generate mechanical forces, which can result in locomotion. When a component of the system is photosensitive, light can be used to modulate and control these waves. In this Concept article, we examine various forms of photo‐control of such systems, focusing particularly on the Belousov–Zhabotinsky oscillating chemical reaction. The phenomena we consider include image storage and image processing, feedback‐control and feedback‐induced clustering of waves, and phototropic and photophobic locomotion. Several of these phenomena have analogues in or potential applications to biological systems.
Making waves: This article addresses how light can be used to control reaction–diffusion waves and wave‐driven active locomotion. Inhomogeneous illumination of a gel containing the constituents of an oscillating chemical reaction can be used to generate unidirectional and reciprocating locomotion of the gel, phenomena analogous to biological crawling motion and round‐trip migration.