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Liquid marbles are formed by encapsulating microscale volume of liquid in a particulate sheath. The marble thus formed is robust and resists rupture if the particulate layer covers the entire volume of liquid and prevents contact between the liquid and the substrate. Liquid marbles have been objects of study over the past decade. Research has been focused on understanding their formation and properties -both static and dynamic. A range of particulate materials as well as liquids have been employed to make these objects. This paper summarizes the state of the art in this regard and discusses new developments that are being discussed. Finally, some directions are proposed based on lacunae observed in the community's understanding -both in terms of the science as well as on the application front.

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Drops that impact and stick to a surface (splattered drops) commonly show noncircular triple lines. Physical or chemical defects on the surface are known to pin the triple line in this static metastable state. We report an experimental study to relate the defect distribution on a surface to the triple-line microstructure of such drops. Triple lines of an ensemble of splattered drops have been imaged on a range of surfaces varying in wetting properties. Local contact angles have been calculated, and the microscale pinning force distribution has been estimated. We propose a novel method of estimating defect strength distribution from the pinning forces, using extreme value analysis. From this analysis, we show that pinning force distributions have finite upper and lower bounds. We show that most common surfaces show both hydrophobic and hydrophilic defects, but their strength distributions are asymmetric in relation to the surface's advancing and receding angles. In addition, we show that the range of microscopic pinning forces varies linearly with macroscopic contact angle hysteresis but, surprisingly, with a nonzero intercept. We explain the intercept by drawing an analogy to static and dynamic friction.

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