Introduction: Complex Drops

Elegant and mesmerizing, these 'designer' emulsions can be exploited to pave new ways of understanding complex phenomena in physics, chemistry, biology and material science. For example, arrays of multi-component drops can be designed for probing how collective behavior arises from interactions of simple constituents inside drops across a network of drops in one, two and three dimensions. Such systems could provide understanding of interactions in strongly correlated materials; at present, these interactions lack exact analytical solutions and solutions using numerical analysis are impossible to solve computationally in dimensions greater than two.  Furthermore, two and three dimensional crystalline structures can be encapsulated inside another drop to study crystallinity or non-periodicity of drops under confinement and the evolution of these configurations. Individual drops can be engineered as micro-reactors, smart sensors or as bio-robots. Spherical batteries or encapsulated bubbles for contrast agents with functional shells can be generated. Even stable non-spherical materials for transport of pharmaceuticals in the body and for the study of 'molecular' self assembly are possible. Remarkable and adaptive, these new materials cannot be made by any other means than microfluidics; they are promising sources of fascinating new physical phenomena that are both fundamentally and technologically important.