Issue 36, 2015

Acoustic suppression of the coffee-ring effect


We study the influence of acoustic fields on the evaporative self-assembly of solute particles suspended inside sessile droplets of complex fluids. The self-assembly process often results in an undesirable ring-like heterogeneous residue, a phenomenon known as the coffee-ring effect. Here we show that this ring-like self-assembly can be controlled acoustically to form homogeneous disc-like or concentrated spot-like residues. The principle of our method lies in the formation of dynamic patterns of particles in acoustically excited droplets, which inhibits the evaporation-driven convective transport of particles towards the contact line. We elucidate the mechanisms of this pattern formation and also obtain conditions for the suppression of the coffee-ring effect. Our results provide a more general solution to suppress the coffee-ring effect without any physiochemical modification of the fluids, the particles or the surface, thus potentially useful in a broad range of industrial and analytical applications that require homogenous solute depositions.

Graphical abstract: Acoustic suppression of the coffee-ring effect

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Article information

Article type
18 May 2015
17 Jul 2015
First published
20 Jul 2015
This article is Open Access
Creative Commons BY license

Soft Matter, 2015,11, 7207-7213

Author version available

Acoustic suppression of the coffee-ring effect

D. Mampallil, J. Reboud, R. Wilson, D. Wylie, D. R. Klug and J. M. Cooper, Soft Matter, 2015, 11, 7207 DOI: 10.1039/C5SM01196E

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