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Issue 14, 2015
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Microfluidic plug steering using surface acoustic waves

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Digital microfluidic systems, in which isolated droplets are dispersed in a carrier medium, offer a method to study biological assays and chemical reactions highly efficiently. However, it's challenging to manipulate these droplets in closed microchannel devices. Here, we present a method to selectively steer plugs (droplets with diameters larger than the channel's width) at a specially designed Y-junction within a microfluidic chip. The method makes use of surface acoustic waves (SAWs) impinging on a multiphase interface in which an acoustic contrast is present. As a result, the liquid–liquid interface is subjected to acoustic radiation forces. These forces are exploited to steer plugs into selected branches of the Y-junction. Furthermore, the input power can be finely tuned to split a plug into two uneven plugs. The steering of plugs as a whole, based on plug volume and velocity is thoroughly characterized. The results indicate that there is a threshold plug volume after which the steering requires elevated electrical energy input. This plug steering method can easily be integrated to existing lab-on-a-chip devices and it offers a robust and active plug manipulation technique in closed microchannels.

Graphical abstract: Microfluidic plug steering using surface acoustic waves

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Article information

24 Apr 2015
05 Jun 2015
First published
16 Jun 2015

Lab Chip, 2015,15, 3030-3038
Article type

Microfluidic plug steering using surface acoustic waves

M. Sesen, T. Alan and A. Neild, Lab Chip, 2015, 15, 3030
DOI: 10.1039/C5LC00468C

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