Fusion and sorting of two parallel trains of droplets using a railroad-like channel network and guiding tracks

Xu, Linfeng; Lee, Hun; Panchapakesan, Rajagopal; Oh, Kwang W.

doi:10.1039/c2lc40456g

Cited by 36 publications

(31 citation statements)

References 46 publications

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“…The maximum efficiency of 94% was achieved at the optimized flow rate ratio of Q Ratio ¼ 0.85 (case C). As detailed in our previous studies, if the droplet length and the generation frequency are perfectly matched, 100% synchronization efficiency can be attainable, 39,40 after the seamless electrocoalescence at the X-shape junction. In the electrocoalescence, two failure mechanisms were observed as shown in Fig.…”

Section: Resultsmentioning

confidence: 97%

“…In order to perform the parallel synchronization of droplets, the ladder-like channel network was used in which the top and bottom channels were interconnected with narrow fluidic channels. 39,40 The mechanism of synchronization relies on the automatic tuning of velocity of droplets due to the pressure difference between the two channels. As the droplets pass through the ladder-like channel network, the existing pressure difference caused by the droplets squeezed between the channels (top and bottom channel width: 200 lm) allows the oil phase to flow through the narrow fluidic channels until the pressure is matched.…”

Section: Resultsmentioning

confidence: 99%

“…38 (iii) The sample droplets are introduced into a ladder-like channel network to make them synchronized with the washing buffer droplets. 39,40 The droplet synchronization unit enables the two trains of the droplets to be merged laterally. (iv) The two parallel-synchronized droplets are merged at an entrance of the X-shape separation junction by an electric field, which can lead to destabilization of the surface of the droplets to be easily merged.…”

Section: Experimental a Working Principlementioning

confidence: 99%

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Droplet-based microfluidic washing module for magnetic particle-based assays

Lee

2014

Biomicrofluidics

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In this paper, we propose a continuous flow droplet-based microfluidic platform for magnetic particle-based assays by employing in-droplet washing. The dropletbased washing was implemented by traversing functionalized magnetic particles across a laterally merged droplet from one side (containing sample and reagent) to the other (containing buffer) by an external magnetic field. Consequently, the magnetic particles were extracted to a parallel-synchronized train of washing buffer droplets, and unbound reagents were left in an original train of sample droplets. To realize the droplet-based washing function, the following four procedures were sequentially carried in a droplet-based microfluidic device: parallel synchronization of two trains of droplets by using a ladder-like channel network; lateral electrocoalescence by an electric field; magnetic particle manipulation by a magnetic field; and asymmetrical splitting of merged droplets. For the stable droplet synchronization and electrocoalescence, we optimized droplet generation conditions by varying the flow rate ratio (or droplet size). Image analysis was carried out to determine the fluorescent intensity of reagents before and after the washing step. As a result, the unbound reagents in sample droplets were significantly removed by more than a factor of 25 in the single washing step, while the magnetic particles were successfully extracted into washing buffer droplets. As a proof-of-principle, we demonstrate a magnetic particle-based immunoassay with streptavidin-coated magnetic particles and fluorescently labelled biotin in the proposed continuous flow dropletbased microfluidic platform. V C 2014 AIP Publishing LLC.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Experimental a Working Principlementioning

confidence: 99%

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Droplet-based microfluidic washing module for magnetic particle-based assays

Lee

2014

Biomicrofluidics

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“…These allow to steer a droplet in flow along these rails [33], or to fuse two droplets by using two converging rails [34]. Other researchers used similar rails for the fusion and sorting of droplets [35]. As is the case with other passive techniques: it is difficult to release the drop once trapped, or to select which way to steer a drop.…”

Section: Surface Energy Wellsmentioning

confidence: 99%

Droplet Manipulations in Two Phase Flow Microfluidics

2015

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Even though droplet microfluidics has been developed since the early 1980s, the number of applications that have resulted in commercial products is still relatively small. This is partly due to an ongoing maturation and integration of existing methods, but possibly also because of the emergence of new techniques, whose potential has not been fully realized. This review summarizes the currently existing techniques for manipulating droplets in two-phase flow microfluidics. Specifically, very recent developments like the use of acoustic waves, magnetic fields, surface energy wells, and electrostatic traps and rails are discussed. The physical principles are explained, and (potential) advantages and drawbacks of different methods in the sense of versatility, flexibility, tunability and durability are discussed, where possible, per technique and per droplet operation: generation, transport, sorting, coalescence and splitting.

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“…2(a), before the flow reaches the phaseguides, the initial Laplace pressure 46,47 (p i ) within the blood sample is …”

Section: With Phaseguidesmentioning

confidence: 99%

Phaseguide-assisted blood separation microfluidic device for point-of-care applications

Lee

Pinheiro

et al. 2015

Biomicrofluidics

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We propose a blood separation microfluidic device suitable for point-of-care (POC) applications. By utilizing the high gas permeability of polydimethylsiloxane (PDMS) and phaseguide structures, a simple blood separation device is presented. The device consists of two main parts. A separation chamber with the phaseguide structures, where a sample inlet, a tape-sealed outlet, and a dead-end ring channel are connected, and pneumatic chambers, in which manually operating syringes are plugged. The separation chamber and pneumatic chambers are isolated by a thin PDMS wall. By manually pulling out the plunger of the syringe, a negative pressure is instantaneously generated inside the pneumatic chamber. Due to the gas diffusion from the separation chamber to the neighboring pneumatic chamber through the thin permeable PDMS wall, low pressure can be generated, and then the whole blood at the sample inlets starts to be drawn into the separation chamber and separated through the phaseguide structures. Reversely, after removing the tape at the outlet and manually pushing in the plunger of the syringe, a positive pressure will be created which will cause the air to diffuse back into the ring channel, and therefore allow the separated plasma to be recovered at the outlet on demand. In this paper, we focused on the study of the plasma separation and associated design parameters, such as the PDMS wall thickness, the air permeable overlap area between the separation and pneumatic chambers, and the geometry of the phaseguides. The device required only 2 ll of whole blood but yielding approximately 0.38 ll of separated plasma within 12 min. Without any of the requirements of sophisticated equipment or dilution techniques, we can not only separate the plasma from the whole blood for on-chip analysis but also can push out only the separated plasma to the outlet for off-chip analysis. V C 2015 AIP Publishing LLC.

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Fusion and sorting of two parallel trains of droplets using a railroad-like channel network and guiding tracks

Cited by 36 publications

References 46 publications

Droplet-based microfluidic washing module for magnetic particle-based assays

Droplet-based microfluidic washing module for magnetic particle-based assays

Droplet Manipulations in Two Phase Flow Microfluidics

Phaseguide-assisted blood separation microfluidic device for point-of-care applications

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