Liquid marbles: topical context within soft matter and recent progress.

The study of particle stabilized interfaces has a long history in terms of emulsions, foams and related dry powders. The same underlying interfacial energy principles also allow hydrophobic particles to encapsulate individual droplets into a stable form as individual macroscopic objects, which have recently been called "Liquid Marbles". Here we discuss conceptual similarities to superhydrophobic surfaces, capillary origami, slippery liquids-infused porous surfaces (SLIPS) and Leidenfrost droplets. We provide a review of recent progress on liquid marbles, since our earlier Emerging Area article (Soft Matter, 2011, 7, 5473-5481), and speculate on possible future directions from new liquid-infused liquid marbles to microarray applications. We highlight a range of properties of liquid marbles and describe applications including detecting changes in physical properties (e.g. pH, UV, NIR, temperature), use for gas sensing, synthesis of compounds/composites, blood typing and cell culture.