Search

Your search keyword '"Mampallil, Dileep"' showing total 37 results
Start Over Author "Mampallil, Dileep"
37 results on '"Mampallil, Dileep"'

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

Author

Kumar, Shubham, Sahu, Piyush, Bharatsingh, Surjit, Salwan, Gaurav, and Mampallil, Dileep

Subjects
Physics - Fluid Dynamics, Condensed Matter - Soft Condensed Matter
Abstract

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.

Published
2024

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

Author

Gopu, Maheshwar, Agrawal, Akanksha, Mukherjee, Raju, and Mampallil, Dileep

Subjects
Condensed Matter - Soft Condensed Matter, Physics - Biological Physics
Abstract

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., Comment: * Equal contribution

Published
2021

11. Spheroids formation in large drops suspended in superhydrophobic paper cones.

Author

Mohapatra, Omkar, Gopu, Maheshwar, Ashraf, Rahail, Easo George, Jijo, Patil, Saniya, Mukherjee, Raju, Kumar, Sanjay, and Mampallil, Dileep

Subjects
SUPERHYDROPHOBIC surfaces, CELL culture, MEDICAL screening, DRUG development, OVARIAN cancer, CANCER cells
Abstract

The utilization of 3D cell culture for spheroid formation holds significant implications in cancer research, contributing to a fundamental understanding of the disease and aiding drug development. Conventional methods such as the hanging drop technique and other alternatives encounter limitations due to smaller drop volumes, leading to nutrient starvation and restricted culture duration. In this study, we present a straightforward approach to creating superhydrophobic paper cones capable of accommodating large volumes of culture media drops. These paper cones have sterility, autoclavability, and bacterial repellent properties. Leveraging these attributes, we successfully generate large spheroids of ovarian cancer cells and, as a proof of concept, conduct drug screening to assess the impact of carboplatin. Thus, our method enables the preparation of flexible superhydrophobic surfaces for laboratory applications in an expeditious manner, exemplified here through spheroid formation and drug screening demonstrations. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

21. A review on suppression and utilization of the coffee-ring effect

Author

Mampallil, Dileep (author), Eral, H.B. (author), Mampallil, Dileep (author), and Eral, H.B. (author)

Abstract

Evaporation of sessile droplets containing non-volatile solutes dispersed in a volatile solvent leaves behind ring-like solid stains. As the volatile species evaporates, pinning of the contact line gives rise to capillary flows that transport non-volatile solutes to the contact line. This phenomenon, called the coffee-ring effect, compromises the overall performance of industrially relevant manufacturing processes involving evaporation such as printing, biochemical analysis, manufacturing of nano-structured materials through colloidal and macromolecular patterning. Various approaches have been developed to suppress this phenomenon, which is otherwise difficult to avoid. The coffee-ring effect has also been leveraged to prepare new materials through convection induced assembly. This review underlines not only the strategies developed to suppress the coffee-ring effect but also sheds light on approaches to arrive at novel processes and materials. Working principles and applicability of these strategies are discussed together with a critical comparison., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Intensified Reaction and Separation Systems

Published
2018
Full Text
View/download PDF

24. Acoustic control of evaporative colloidal self-assembly: suppression of the coffee-ring effect

Author

Mampallil, Dileep, Reboud, Julien, Wilson, Rab, Wylie, Douglas, Klug, David R., and Cooper, Jonathan M.

Subjects
Physics::Fluid Dynamics
Abstract

We study the influence of acoustic fields on the evaporative self-assembly of solute particles suspended inside sessile droplets of complex fluids. The self-assembly process often results in an undesirable ring-like heterogeneous residue, a phenomenon known as the coffee-ring effect. Here we show that this ring-like self-assembly can be controlled acoustically to form homogeneous disc-like or concentrated spot-like residues. The principle of our method lies in the formation of dynamic patterns of particles in acoustically excited droplets, which inhibits the evaporation-driven convective transport of particles towards the contact line. We elucidate the mechanisms of this pattern formation and also obtain conditions for the suppression of the coffee-ring effect. Our results provide a more general solution to suppress the coffee-ring effect without any physiochemical modification of the fluids, the particles or the surface, thus potentially useful in a broad range of industrial and analytical applications that require homogenous solute depositions.

Published
2015

27. Electro osmotic shear flow in microchannels

Author

Mampallil, Dileep, van den Ende, Dirk, Mugele, Frieder, Verpoorte, Sabeth, Andersson-Svahn, Helen, Emnéus, Jenny, Pamme, Nicole, and Physics of Complex Fluids

Subjects
Shear flow, Electro osmotic flow, Gate electrodes
Abstract

We study electro osmotic shear flow in micro channels by chemically and electrically modifying the surface charge of the channel walls. For chemical modification one of the channel walls was treated with cationic polymer. For electric modification, we patterned gate electrodes on one of the channel walls. The applied shear stress is controlled either by the electro osmotic flow (EOF) driving field or by the gate voltage. Such a system can work as an in situ microrheometer for lab on a chip devices.

Published
2010

Catalog

Books, media, physical & digital resources
See catalog results