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Issue 17, 2014
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Microfluidic on-demand droplet merging using surface acoustic waves

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Individual droplets can be isolated within microfluidic systems by use of an immiscible carrier layer. This type of two phase systems, often termed “digital microfluidics”, find wide ranging applications in chemical synthesis and analysis. To conduct on-chip biochemical analysis, a key step is to be able to merge droplets selectively in order to initiate the required reactions. In this paper, a novel microfluidic chip integrating interdigital transducers is designed to merge multiple droplets on-demand. The approach uses surface acoustic wave induced acoustic radiation forces to immobilize droplets as they pass from a channel into a small expansion chamber, there they can be held until successive droplets arrive. Hence, no requirement is placed on the initial spacing between droplets. When the merged volume reaches a critical size, drag forces exerted by the flowing oil phase act to overcome the retaining acoustic radiation forces, causing the merged volume to exit the chamber. This will occur after a predetermined number of droplets have merged depending on the initial droplet size and selected actuation power.

Graphical abstract: Microfluidic on-demand droplet merging using surface acoustic waves

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Publication details

The article was received on 17 Apr 2014, accepted on 20 Jun 2014 and first published on 23 Jun 2014

Article type: Paper
DOI: 10.1039/C4LC00456F
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Lab Chip, 2014,14, 3325-3333

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    Microfluidic on-demand droplet merging using surface acoustic waves

    M. Sesen, T. Alan and A. Neild, Lab Chip, 2014, 14, 3325
    DOI: 10.1039/C4LC00456F

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