Controlled electrocoalescence in microfluidics: Targeting a single lamella

Priest, Craig; Herminghaus, Stephan; Seemann, Ralf

doi:10.1063/1.2357039

Cited by 229 publications

(239 citation statements)

References 9 publications

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“…The most widely applied method relies on submitting the drops to an electric field (electrofusion). 90,91,96,[98][99][100] In this case, the drops were observed to reproducibly merge under a very broad set of conditions, with forcing voltages ranging from 1 V to several kV and field frequencies from DC to several kHz. Moreover, fusion was performed using electrodes that were either embedded in the micro-channel or as far away as several mm, with the mean electric fields applied parallel or perpendicular to the touching drop surfaces.…”

Section: B Active Fusion Approachesmentioning

confidence: 79%

Dynamics of microfluidic droplets

2010

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This critical review discusses the current understanding of the formation, transport, and merging of drops in microfluidics. We focus on the physical ingredients which determine the flow of drops in microchannels and recall classical results of fluid dynamics which help explain the observed behaviour. We begin by introducing the main physical ingredients that differentiate droplet microfluidics from single-phase microfluidics, namely the modifications to the flow and pressure fields that are introduced by the presence of interfacial tension. Then three practical aspects are studied in detail: (i) The formation of drops and the dominant interactions depending on the geometry in which they are formed.(ii) The transport of drops, namely the evaluation of drop velocity, the pressure-velocity relationships, and the flow field induced by the presence of the drop. (iii) The fusion of two drops, including different methods of bridging the liquid film between them which enables their merging.

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Section: B Active Fusion Approachesmentioning

confidence: 79%

Dynamics of microfluidic droplets

2010

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“…9,13,14 Magnetic fields have also been used with success. 15 Although these methods offer significant control compared with previous efforts to implement flow-induced coalescence, electromagnetic fields place strict requirements on the composition of the fluid within the droplet, and they can damage fragile contents such as DNA and proteins.…”

Section: Introductionmentioning

confidence: 99%

Coalescence and splitting of confined droplets at microfluidic junctions

et al. 2009

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The ability to merge two droplets is an important component of droplet-based lab-on-a-chip devices, yet flow-induced coalescence is difficult to achieve due to long film drainage times compared with relatively short residence times. We examine droplet collisions at a simple microfluidic T-junction and characterize the response for a wide range of droplet sizes and speeds. We find that three primary responses occur, where coalescence occurs easily at low collision speeds, smaller droplets traveling faster slip past one another without coalescing, and larger and faster droplets can break one another into multiple segments. The critical capillary number for coalescence agrees well with previously reported scaling for isolated droplet pairs when local curvature and speed are taken into account. The critical capillary number for splitting of droplets agrees well with a previously reported stability condition for individual droplets stretching in an extensional flow. Quantifying the necessary conditions for coalescence and non-coalescence behavior should enable the informed design of lab on chip devices based on discrete liquid segments.

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“…The threshold voltage for an electrically induced thin-film instability is proportional to the thickness of this layer 9,10 . Therefore, as the droplets approach the picoinjector, the moment of coalescence depends on the magnitude of the electric field.…”

Section: Representative Resultsmentioning

confidence: 99%

Picoinjection of Microfluidic Drops Without Metal Electrodes

O’Donovan

Tran

Sciambi

et al. 2014

JoVE

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Existing methods for picoinjecting reagents into microfluidic drops require metal electrodes integrated into the microfluidic chip. The integration of these electrodes adds cumbersome and error-prone steps to the device fabrication process. We have developed a technique that obviates the needs for metal electrodes during picoinjection. Instead, it uses the injection fluid itself as an electrode, since most biological reagents contain dissolved electrolytes and are conductive. By eliminating the electrodes, we reduce device fabrication time and complexity, and make the devices more robust. In addition, with our approach, the injection volume depends on the voltage applied to the picoinjection solution; this allows us to rapidly adjust the volume injected by modulating the applied voltage. We demonstrate that our technique is compatible with reagents incorporating common biological compounds, including buffers, enzymes, and nucleic acids. Video LinkThe video component of this article can be found at

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Controlled electrocoalescence in microfluidics: Targeting a single lamella

Cited by 229 publications

References 9 publications

Dynamics of microfluidic droplets

Dynamics of microfluidic droplets

Coalescence and splitting of confined droplets at microfluidic junctions

Picoinjection of Microfluidic Drops Without Metal Electrodes

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