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Issue 14, 2018
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Magnetophoretic induced convective capture of highly diffusive superparamagnetic nanoparticles

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Abstract

Micro-magnets producing magnetic field gradients as high as 106 T m−1 have been used to efficiently trap nanoparticles with a magnetic core of just 12 nm in diameter. Particle capture efficiency increases with increasing particle concentration. Comparison of measured capture kinetics with numerical modelling reveals that a threshold concentration exists below which capture is diffusion-driven and above which it is convectively-driven. This comparison also shows that two-way fluid–particle coupling is responsible for the formation of convective cells, the size of which is governed by the height of the droplet. Our results indicate that for a suspension with a nanoparticle concentration suitable for bioassays (around 0.25 mg ml−1), all particles can be captured in less than 10 minutes. Since nanoparticles have a significantly higher surface-to-volume ratio than the more widely used microparticles, their efficient capture should contribute to the development of next generation digital microfluidic lab-on-chip immunoassays.

Graphical abstract: Magnetophoretic induced convective capture of highly diffusive superparamagnetic nanoparticles

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Publication details

The article was received on 25 Nov 2017, accepted on 12 Mar 2018 and first published on 13 Mar 2018


Article type: Paper
DOI: 10.1039/C7SM02324C
Citation: Soft Matter, 2018,14, 2671-2681
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    Magnetophoretic induced convective capture of highly diffusive superparamagnetic nanoparticles

    M. Fratzl, S. Delshadi, T. Devillers, F. Bruckert, O. Cugat, N. M. Dempsey and G. Blaire, Soft Matter, 2018, 14, 2671
    DOI: 10.1039/C7SM02324C

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