Reference Work Entry

Handbook of Natural Computing

pp 1897-1920

Reaction–Diffusion Computing

  • Andrew AdamatzkyAffiliated withDepartment of Computer Science, University of the West of England
  • , Benjamin De Lacy CostelloAffiliated withCentre for Research in Analytical, Material and Sensor Sciences, Faculty of Applied Sciences, University of the West of England


A reaction–diffusion computer is a spatially extended chemical system, which processes information by transforming an input concentration profile to an output concentration profile in a deterministic and controlled manner. In reaction–diffusion computers, the data are represented by concentration profiles of reagents, information is transferred by propagating diffusive and phase waves, computation is implemented via the interaction of these traveling patterns (diffusive and excitation waves), and the results of the computation are recorded as a final concentration profile. Chemical reaction–diffusion computing is among the leaders in providing experimental prototypes in the fields of unconventional and nature-inspired computing. This chapter provides a case-study introduction to the field of reaction–diffusion computing, and shows how selected problems and tasks of computational geometry, robotics, and logics can be solved by encoding data within transient states of a chemical medium and by programming the dynamics and interactions of chemical waves.