Diversity of non-equilibrium patterns and emergence of activity in confined electrohydrodynamically driven liquids

Abstract

Spontaneous emergence of organized states in materials driven by non-equilibrium conditions is of notable fundamental and technological interest. In many cases, the states are complex, and their emergence is challenging to predict. Here, we show that an unexpectedly diverse collection of dissipative organized states emerges in a simple system of two liquids under planar confinement when driven by electrohydrodynamic shearing. At low shearing, a symmetry breaking at the liquid-liquid interface leads to a one-dimensional corrugation pattern. At slightly stronger shearing, topological changes give raise to the emergence of Quincke rolling filaments, filament networks, and two-dimensional bicontinuous fluidic lattices. At strong shearing, the system transitions into dissipating polygonal, toroidal, and active droplets that form dilute gas-like states at low densities and complex active emulsions at higher densities. The diversity of the observed dissipative organized states is exceptional, pointing toward non-equilibrium optical devices and new avenues in several fields of research.