Organization of microbeads in Leidenfrost drops

Abstract

We investigated the organization of micrometric hydrophilic beads (glass or basalt) immersed in Leidenfrost drops. Starting from a large volume of water compared to the volume of the beads, while the liquid evaporates, we observed that the grains are eventually trapped at the interface of the droplet and accumulate. At a moment, the grains entirely cover the droplet. We measured the surface area at this moment as a function of the total mass of particles inserted in the droplet. We concluded that the grains form a monolayer around the droplet assuming (i) that the packing of the beads at the surface is a random close packing and (ii) that the initial surface of the drop is larger than the maximum surface that the beads can cover. Regarding the evaporation dynamics, the beads are found to reduce the evaporation rate of the drop. The slowdown of the evaporation is interpreted as being the consequence of the dewetting of the particles located at the droplet interface which make of the effective surface of evaporation smaller. As a matter of fact, contact angles of the beads with the water deduced from the evaporation rates are consistent with contact angles of beads directly measured at the air -water interface in a container.

Lattice Boltzmann modeling of self-propelled Leidenfrost droplets on ratchet surfaces

“…Using a low pressure environment, Celestini et al [21] found that the Leidenfrost droplets of water can be generated at room temperature. In addition, Celestini and Kirstetter [22] have investigated the influence of an electric field on Leidenfrost droplets and Maquet et al [23] have studied the organization of microbeads in Leidenfrost droplets. Most recently, Wells et al…”

Complex Fluids Droplets in Leidenfrost State

“…To obtain such liquid marbles, one can use hydrophobic grains (Aussilous and Quéré, 2001). In the present case, however, we considered glass beads and basalt beads which are both hydrophilic materials (Maquet et al, 2014). The grains fully covered the droplet thermally insulating the droplet from the plate.…”

Multifunctional Liquid Marble Compound Lenses

“…As a result, the assembly process demonstrates a facile fabrication strategy to create a monolayer of microlenses encapsulating a liquid marble without an extra process, such as a cleaning 38 or evaporation. 39 We then rely on the mobility of liquid marbles under shear to create arrays of compound lenses. Finally, we polymerize the lenses to arrest the assembled structure and form a mechanically robust hierarchical material.…”

“…The formation of a monolayer of microlenses with the same refractive index as the droplet leads to first demonstration of liquid marbles that function as compound lenses. As a result, the assembly process demonstrates a facile fabrication strategy to create a monolayer of microlenses encapsulating a liquid marble without an extra process, such as a cleaning or evaporation . We then rely on the mobility of liquid marbles under shear to create arrays of compound lenses.…”