When two or more micrometric droplets condensing on a superhydrophobic substrate merge, the coalesced droplet jump out of plane. 10 years after its discovery, we now know that such jumping droplet-condensation is thermally more efficient than regular dropwise condensation. As such out-of-plane jumping departures of the droplets is independent of the gravity, the effect of surface orientation has never been formally studied. Here we have shown through extensive experiments and theoretical analysis that even the jumping-droplet condensation is not immune to gravitational orientation for longer periods of condensation (more than 3 h). The result is degradation of heat transfer efficiency with time, for non-vertical surfaces. You can read the story here.

Liquid-Infused Surfaces (LIS) or Slippery Liquid-Infused Surfaces (SLIPS) are super-repellent substrates which are more slippery (Contact Angle Hysteresis less than 1°) and much more durable than regular superhydrophobic surfaces. These surfaces are made by infusing chemically compatible lubricating liquids within the pores of a textured surface. The current methods of making slippery surfaces out of any material is coating the surface with an absorbent/textured polymer. While this method is successful, it suffers from several problems- a) the polymer coatings are often expensive and b) the assembly process is also complex. Here we have used common hydrocarbon-based polymers used in food packaging (e.g., polyethylene, polypropylene) and infused them with compatible oils to create an inexpensive, easily obtainable super-repellant coating. Link for paper

If you wring a glass rod with a piece of cotton and bring it near a thin stream of water, the stream is deflected away from the rod. Something similar happened when we brought water near a subsrate covered with frost in our laboratory: few pieces of frost dendrites broke off and flew towards the water. We even went into a walk-in freezer to do the same experiment. After setting up the the high-speed camera, Peltier stage, lights, the environmental controller for an hour or so in the freezing cold, we observed no frost jumping. This spectacular "failure" and numerical analysis suggested that temperature gradient between the surface and the ambient air, the top of the frost develops negative charges on the warmer ends which in turn polarizes and induces positive charges on the opposing water film (or droplet). You can read the story here.

Granular rafts are a special type of particle-covered interfaces, similar to liquid marbles or the coated liquid droplets in Pickering emulsions. The complexity in these rafts come from the large size (more than 100 micron in diameter) and density of the particles (in our case, density is 2.5 times more than water). Through our simple table-top experiments and first-principles models, here we explain why rafts behave like a composite material, showing granular as well as elastic solid properties. Here is our story so far.