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Technology (Singap World Sci). 2016 Jun;4(2):110-119. Epub 2016 May 13.

Electropermanent magnet actuation for droplet ferromicrofluidics.

Author information

1
Department of Electrical Engineering, School of Engineering, Stanford University, Stanford, CA 94305, USA.
2
Department of Surgery, School of Medicine, Stanford University, Stanford, CA 94305, USA.

Abstract

Droplet actuation is an essential mechanism for droplet-based microfluidic systems. On-demand electromagnetic actuation is used in a ferrofluid-based microfluidic system for water droplet displacement. Electropermanent magnets (EPMs) are used to induce 50 mT magnetic fields in a ferrofluid filled microchannel with gradients up to 6.4 × 104 kA/m2. Short 50 µs current pulses activate the electropermanent magnets and generate negative magnetophoretic forces that range from 10 to 70 nN on 40 to 80 µm water-in-ferrofluid droplets. Maximum droplet displacement velocities of up to 300 µm/s are obtained under flow and no-flow conditions. Electropermanent magnet-activated droplet sorting under continuous flow is demonstrated using a split-junction microfluidic design.

KEYWORDS:

Droplet Microfluidics; Droplet Sorting; Electropermanent Magnets; Ferrofluids; Ferromicrofluidics; Magnetic Actuation

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