Electrode-assisted trapping and release of droplets on hydrophilic patches in a hydrophobic microchannel

Pit, Arjen; Bonestroo, Sander; Wijnperle, Daniël; Duits, Michael H.G.; Mugele, Friedrich Gunther

doi:10.1007/s10404-016-1789-z

Cited by 12 publications

(7 citation statements)

References 39 publications

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“…The surface properties of the glass microfluidic devices are important factors during the droplet synthesis [ 54 , 55 , 56 ]. In the case of hydrophilic glass, the surface is covered with hydroxyl groups.…”

Section: Hydrophilic Chip Applicationmentioning

confidence: 99%

Micro Droplet Formation towards Continuous Nanoparticles Synthesis

et al. 2018

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In this paper, micro droplets are generated in a microfluidic focusing contactor and then they move sequentially in a free-flowing mode (no wall contact). For this purpose, two different micro-flow glass devices (hydrophobic and hydrophilic) were used. During the study, the influence of the flow rate of the water phase and the oil phase on the droplet size and size distribution was investigated. Moreover, the influence of the oil phase viscosity on the droplet size was analyzed. It was found that the size and size distribution of the droplets can be controlled simply by the aqueous phase flow rate. Additionally, 2D simulations to determine the droplet size were performed and compared with the experiment.

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Section: Hydrophilic Chip Applicationmentioning

confidence: 99%

Micro Droplet Formation towards Continuous Nanoparticles Synthesis

et al. 2018

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“…Trapping is a key process for sample preparation, observation, and detection. Passive droplet trapping using specific microchannel designs [37,38] and active droplet trapping using external energy [39,40] have been widely used for various microfluidic applications. However, trapping of LMs has not yet been studied.…”

Section: Introductionmentioning

confidence: 99%

Dielectrophoretic Trapping of a Floating Liquid Marble

et al. 2019

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A liquid marble, a liquid droplet coated with hydrophobic powder, is an emerging digital microfluidic platform. It can potentially serve as a mixer or reactor for chemical and biological assays in the microscale. Automated manipulation of liquid marbles is essential for the implementation of more microfluidic functions in the technology platform of "lab in a marble". We report the analytical and experimental results of trapping a floating liquid marble using dielectrophoresis in a nonuniform electric field. Liquid marbles with volumes ranging from 5 to 50 μL are effectively trapped by the dielectrophoretic force from a horizontal distance ranging from 10 to 60 mm and under an applied voltage ranging from 1.6 to 5 kV. A one-dimensional analytical model is then proposed for the trapping process and agrees well with experimental data. Finally, based on the relationship between the static friction coefficient and the Bond number of a floating liquid marble, an operation map is derived for successful trapping of the liquid marble, providing a better insight into controlled manipulation of liquid marbles.

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“…F γ is modeled as a sum of two contributions: F γ,s due to the changes of the droplet surface area that pushes the droplet toward configurations with the minimal surface area and F γ,w that results from gradients of surface wettability and pulls an aqueous droplet toward the hydrophilic regions of the ablated track. F γ acts perpendicularly to the edges of the guiding track; it points into the track and its magnitude can be written as Here, γ is the interfacial tension (IFT) between the droplet and host liquids, D L and D R are the interaction lengths of the droplet with the left and right track edge, θ in and θ out are the droplet contact angles (CAs) inside and outside the track, R B is the radius of the contact area between the droplet and the bottom wall of the channel, w is the width of the track, and Δ A = A in – A out (Δ A = A out – A in ) represents the change in the droplet surface area upon moving into (out of) the center of the track. Except for Δ A , all the quantities that enter into eq can be either independently measured beforehand or analytically calculated from the droplet geometry at each time step during the simulation of droplet motion.…”

Section: Methodsmentioning

confidence: 99%

Size-Based Sorting of Emulsion Droplets in Microfluidic Channels Patterned with Laser-Ablated Guiding Tracks

Rehman¹,

Coşkun

Rashid

et al. 2020

Anal. Chem.

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We demonstrate an autonomous, high-throughput mechanism for sorting of emulsion droplets with different sizes concurrently flowing in a microfluidic Hele-Shaw channel. The aqueous droplets of varying radii suspended in olive oil are separated into different streamlines across the channel upon interaction with a shallow (depth ∼ 700 nm) inclined guiding track ablated into the polydimethylsiloxane-coated surface of the channel with focused femtosecond laser pulses. Specifically, the observed differences in the droplet trajectories along the guiding track arise due to the different scaling of the confinement force attracting the droplets into the track, fluid drag, and wall friction, with the droplet radius. In addition, the distance traveled by the droplets along the track also depends on the track width, with wider tracks providing more stable droplet guiding for any given droplet size. We systematically study the influence of the droplet size and velocity on the trajectory of the droplets in the channel and analyze the sensitivity of size-based droplet sorting for varying flow conditions. The droplet guiding and sorting experiments are complemented by modeling of the droplet motion in the channel flow using computational fluid dynamics simulations and a previously developed model of droplet guiding. Finally, we demonstrate a complete separation of droplets produced by fusion of two independent droplet streams at the inlet of the Hele-Shaw channel from unfused daughter droplets. The presented droplet sorting technique can find applications in the development of analytical and preparative microfluidic protocols.

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Electrode-assisted trapping and release of droplets on hydrophilic patches in a hydrophobic microchannel

Cited by 12 publications

References 39 publications

Micro Droplet Formation towards Continuous Nanoparticles Synthesis

Micro Droplet Formation towards Continuous Nanoparticles Synthesis

Dielectrophoretic Trapping of a Floating Liquid Marble

Size-Based Sorting of Emulsion Droplets in Microfluidic Channels Patterned with Laser-Ablated Guiding Tracks

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