Magnetically controllable generation of ferrofluid droplets

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This paper reports the manipulation of ferrofluid droplets by using a microfluidic flow-focusing device equipped with a magnetic tweezer. Besides the traditional flow rate controlling method, the magnetic field also can be applied to control the size of the droplets. Two major effects in magnetic manipulation process: magnetoviscous effect and magnetic drag effect, were studied. Under a fixed flow rate (CP = 1 mL/h, DP = 0.2 mL/h), the average sizes of ferrofluid droplets were tunable from 135 to 95 μm by varying the magnetic field from 0 to 60 mT. Moreover, square wave magnetic field can be used to periodically generate droplets with different sizes. These results are helpful to understand the generation mechanism of the ferrofluid droplet and supply a novel method for manipulating droplets with a predetermined size and distribution.

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This work was supported by Collaborative Innovation Center of Suzhou Nano Science and Technology. Financial support from the National Natural Science Foundation of China (Grant No. 11125210), the National Basic Research Program of China (973 Program, Grant No.2012CB937500) and the Anhui Provincial Natural Science Foundation of China (1408085QA17) is gratefully acknowledged.

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Correspondence to Xinglong Gong.

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Supplementary material 1 (WMV 4153 kb)

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Supplementary material 4 (WMV 2816 kb)

Supplementary material 5 (WMV 5499 kb)

Supplementary material 6 (WMV 8227 kb)

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Yan, Q., Xuan, S., Ruan, X. et al. Magnetically controllable generation of ferrofluid droplets. Microfluid Nanofluid 19, 1377–1384 (2015).

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  • Microfluidic
  • Magnetic
  • Ferrofluid
  • Flow-focusing
  • Droplets