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Issue 6, 2011
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A ‘microfluidic pinball’ for on-chip generation of Layer-by-Layer polyelectrolyte microcapsules

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Inspired by the game of “pinball” where rolling metal balls are guided by obstacles, here we describe a novel microfluidic technique which utilizes micropillars in a flow channel to continuously generate, encapsulate and guide Layer-by-Layer (LbL) polyelectrolyte microcapsules. Droplet-based microfluidic techniques were exploited to generate oil droplets which were smoothly guided along a row of micropillars to repeatedly travel through three parallel laminar streams consisting of two polymers and a washing solution. Devices were prototyped in PDMS and generated highly monodisperse and stable 45 ± 2 µm sized polyelectrolyte microcapsules. A total of six layers of hydrogen bonded polyelectrolytes (3 bi-layers) were adsorbed on each droplet within <3 minutes and a fluorescent intensity measurement confirmed polymer film deposition. AFM analysis revealed the thickness of each polymer layer to be approx. 2.8 nm. Our design approach not only provides a faster and more efficient alternative to conventional LbL deposition techniques, but also achieves the highest number of polyelectrolyte multilayers (PEMs) reported thus far using microfluidics. Additionally, with our design, a larger number of PEMs can be deposited without adding any extra operational or interfacial complexities (e.g. syringe pumps) which are a necessity in most other designs. Based on the aforementioned advantages of our device, it may be developed into a great tool for drug encapsulation, or to create capsules for biosensing where deposition of thin nanofilms with controlled interfacial properties is highly required.

Graphical abstract: A ‘microfluidic pinball’ for on-chip generation of Layer-by-Layer polyelectrolyte microcapsules

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Publication details

The article was received on 06 Sep 2010, accepted on 25 Nov 2010 and first published on 07 Jan 2011

Article type: Paper
DOI: 10.1039/C0LC00381F
Lab Chip, 2011,11, 1030-1035

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    A ‘microfluidic pinball’ for on-chip generation of Layer-by-Layer polyelectrolyte microcapsules

    C. Kantak, S. Beyer, L. Yobas, T. Bansal and D. Trau, Lab Chip, 2011, 11, 1030
    DOI: 10.1039/C0LC00381F

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