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Dileep Mampallil

Publications and source records attributed to Dileep Mampallil.

3 recordsLinked to original sources

One-Step Self-Organized Multifunctional Micromotors via Evaporative Liquid-Liquid Phase Separation

Active microcarriers capable of transporting multiple functional components and navigating complex environments are highly desirable for biomedical applications, yet their fabrication typically requires complex multistep processes. Here we show that evaporation-induced liquid-liquid phase separation in all aqueous polymer and protein mixtures provides a simple one-step route to multifunctional micromotors. During droplet evaporation, micron-sized condensates spontaneously form and encapsulate enzymes, nanoparticles, and drugs. Evaporation-induced Marangoni flows and interfacial adsorption generate asymmetric internal self-organization of nanoparticles, producing Janus-like architectures and spontaneously emergent shape anisotropy without the need for patterned fabrication. Dual functionality with internal magnetic anisotropy allowed catalytic propulsion steered by magnetic torque, enabling directional motion even in homogeneous environments. Thus, we present a versatile platform for the one-step construction of biocompatible, multifunctional micromotors with internally asymmetric architectures.

cond-mat.soft

Water Drop on Thin Viscous Oil Layers: From Stick-Slip Spreading to Dewetting

The impact of water droplets on thin layers of immiscible viscous liquids, such as oil films, is commonly encountered across contexts ranging from kitchen activities to industrial processes. In this study, we experimentally investigate the short-term and long-term behavior of water drops spreading on silicone oil-coated surfaces. During the initial spreading, especially towards zero impact energies, the drop edge exhibits stick-slip dynamics, characterized by intermittent stops. The stick-slip behaviour diminishes with increasing spreading energy from impacts, where the drop spreads without noticeably displacing the oil layer. In the long-term dynamics, regardless of whether the spreading is gradual or impact-driven, the drop eventually spreads onto the surface under the oil layer, governed by the dewetting dynamics of the oil. The delay for the second spreading is independent of the Weber number, indicating that the impact initially does not significantly deform the oil layer. Our findings provide new insights into the dynamics of water-oil interactions, with implications for both practical applications and fundamental research.

physics.flu-dyn

Evaporating microfluidic droplets: A tool to study pathogen viability in bioaerosols

Pathogens in droplets on fomites and aerosols go through extreme physiochemical conditions, such as confinement and osmotic stress, due to evaporation. Still, these droplets are the predominant transmission routes of many contagious diseases. The biggest challenge for studying the survival mechanisms of pathogens in extreme conditions is closely observing them, especially in aerosols, due to the small droplet sizes, movements, and fast evaporative dynamics. To mimic evaporating aerosols and microdroplets, we employ microfluidic emulsion droplets. The presence of oil forms a microdroplet cluster with spatially gradient evaporation rates, which helps studying the impact of evaporation and its rate. With Escherichia coli, we show that the viability is adversely affected by the evaporation and its rate. Our method can mimic bioaerosol evaporation with controlled number of cells inside. In general, the droplets can act as microreactors with varying kinetics induced by different evaporation rates.

cond-mat.soft