Encoding information into precipitation structures

Abstract

Material design at submicron scales would be profoundly affected if the formation ofprecipitation patterns could be easily controlled. It would allow the direct building ofbulk structures, in contrast to traditional techniques which consist of removingmaterial in order to create patterns. Here, we discuss an extension of our recentproposal of using electrical currents to control precipitation bands which emerge inthe wake of reaction fronts in A+ + B– → C reaction–diffusion processes. Our main result, based on simulating thereaction–diffusion–precipitation equations, is that the dynamics of the charged agents canbe guided by an appropriately designed time-dependent electric current so that, in additionto the control of the band spacing, the width of the precipitation bands can also be tuned.This makes straightforward the encoding of information into precipitation patterns and, asan amusing example, we demonstrate the feasibility by showing how to encode a musicalrhythm.