Manipulation and control of droplets on surfaces in a homogeneous electric field

Hartmann, Johannes; Schür, Maximilian T.; Hardt, Steffen

doi:10.1038/s41467-021-27879-0

Cited by 43 publications

(25 citation statements)

References 65 publications

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“…Electric fields are widely used to steer particles and droplets for applications in directed assembly (van Blaaderen et al 2013;Harraq, Choudhury & Bharti 2022), microfluidics (Link et al 2006;Hartmann, Schuer & Hardt 2022), ink-jet printing (Basaran, Gao & Bhat 2013), modulation of emulsion microstucture and rheology (Eow & Ghadiri 2002;Tao et al 2016) and electrosprays (Ganan-Calvo et al 2018). An important issue in practical applications is the droplet interactions due to electric polarization and electrohydrodynamic flows.…”

Section: Introductionmentioning

confidence: 99%

Tandem droplet locomotion in a uniform electric field

Sorgentone

Vlahovska

2022

J. Fluid Mech.

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An isolated charge-neutral droplet in a uniform electric field experiences no net force. However, a droplet pair can move in response to field-induced dipolar and hydrodynamic interactions. If the droplets are identical, the centre of mass of the pair remains fixed. Here, we show that if the droplets have different properties, the pair experiences a net motion due to non-reciprocal electrohydrodynamic interactions. We analyse the three-dimensional droplet trajectories using asymptotic theory, assuming spherical droplets and large separations, and numerical simulations based on a boundary integral method. The dynamics can be quite intricate depending on the initial orientation of the droplets line-of-centres relative to the applied field direction. Drops tend to migrate towards a configuration with line-of-centres either parallel or perpendicular to the applied field direction, while either coming into contact or indefinitely separating. We elucidate the conditions under which these different interaction scenarios take place. Intriguingly, we find that in some cases droplets can form a pair (tandem) that translates either parallel or perpendicular to the applied field direction.

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Section: Introductionmentioning

confidence: 99%

Tandem droplet locomotion in a uniform electric field

Sorgentone

Vlahovska

2022

J. Fluid Mech.

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“…Liquid manipulation is a ubiquitous process in nature and modern industry where physics, chemistry, and engineering intersect. − It has drawn a lot of attention because of the great potential in microfluidic devices, water harvesting, chemical reactions, lubrication systems, condensation, heat transfer, and so forth. Mechanically, liquid manipulation on solid surfaces is induced by the interfacial energy gradient at the solid/liquid interface; based on this principle, various strategies have been developed to create this gradient and convert it into liquid motion, such as decorating surfaces with wettability or structure gradients, − applying external stimuli of thermal, light, electric, or magnetic, of which functional surface structures are a hot research topic with positive progress.…”

Section: Introductionmentioning

confidence: 99%

Bioinspired Functional Structures for Lubricant Control at Surfaces and Interfaces: Wedged-Groove with Oriented Capillary Patterns

Chen

Dai

Yang

et al. 2022

ACS Appl. Mater. Interfaces

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In this work, a design concept of bioinspired functional surfaces is proposed for lubricant control at surfaces and interfaces subjected to external thermal gradients. Inspired by the conical structures of cactus and the motion configuration of Centipedes, a bioinspired surface of wedged-groove with an oriented capillary pattern is constructed. The effect of geometrical parameters on the directional lubricant manipulation capacity and sliding anisotropy is discussed. It is found that by regulating the orientation of the capillary pattern, a controllable lubricant self-transport capacity can be achieved for varying conditions from surfaces to interfaces, with or without thermal gradients. The lubricant self-transport process is captured, and the mechanism is revealed. The design philosophy of the proposed bioinspired functional surface is believed to have potential applications for lubricant control in modern machinery and complex liquid control in lab-on-a-chip and microfluidics devices.

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“…Active droplet interplay can even serve as minimalistic models by which to gain perspective on the circumstances required for life to begin 16 – 18 . The ability to control the attraction and coupling of droplets on surfaces is also important for a variety of applications, ranging from thermal management technologies to microfluidic liquid handling 19 – 22 . Droplet microfluidics on planar substrates in fact has experienced a meteoric development 23 , 24 .…”

Section: Introductionmentioning

confidence: 99%

“…Droplet microfluidics on planar substrates in fact has experienced a meteoric development 23 , 24 . Existing strategies for the management of droplets on surfaces beyond those triggered by external stimuli (electric, magnetic, luminic) 21 , 22 , 25 – 28 are based either in prepared surfaces having a physico-chemical anisotropy 19 , 29 – 34 or vapour emanated by nearby droplets of carefully balanced binary composition 20 . Active droplets that interact and act by themselves via messages through a surface are eagerly awaited.…”

Section: Introductionmentioning

confidence: 99%

Droplets in underlying chemical communication recreate cell interaction behaviors

2022

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The sensory-motor interaction is a hallmark of living systems. However, developing inanimate systems with “recognize and attack” abilities remains challenging. On the other hand, controlling the inter-droplet dynamics on surfaces is key in microengineering and biomedical applications. We show here that a pair of droplets can become intelligently interactive (chemospecific stimulus-response inter-droplet autonomous operation) when placed on a nanoporous thin film surface. We find an attacker-victim-like non-reciprocal interaction between spatially separated droplets leading to an only-in-one shape instability that triggers a drop projection to selectively couple, resembling cellular phenomenologies such as pseudopod emission and phagocytic-like functions. The nanopore-driven underlying communication and associated chemical activity are the main physical ingredients behind the observed behavior. Our results reveal that basic features found in many living cell types can emerge from a simple two-droplet framework. This work is a promising step towards the design of microfluidic smart robotics and for origin-of-life protocell models.

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Manipulation and control of droplets on surfaces in a homogeneous electric field

Cited by 43 publications

References 65 publications

Tandem droplet locomotion in a uniform electric field

Tandem droplet locomotion in a uniform electric field

Bioinspired Functional Structures for Lubricant Control at Surfaces and Interfaces: Wedged-Groove with Oriented Capillary Patterns

Droplets in underlying chemical communication recreate cell interaction behaviors

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