Issue 7, 2017

Microfluidic pumping by micromolar salt concentrations


An ion-exchange-resin-based microfluidic pump is introduced that utilizes trace amounts of ions to generate fluid flows. We show experimentally that our pump operates in almost deionized water for periods exceeding 24 h and induces fluid flows of μm s−1 over hundreds of μm. This flow displays a far-field, power-law decay which is characteristic of two-dimensional (2D) flow when the system is strongly confined and of three-dimensional (3D) flow when it is not. Using theory and numerical calculations we demonstrate that our observations are consistent with electroosmotic pumping driven by μmol L−1 ion concentrations in the sample cell that serve as ‘fuel’ to the pump. Our study thus reveals that trace amounts of charge carriers can produce surprisingly strong fluid flows; an insight that should benefit the design of a new class of microfluidic pumps that operate at very low fuel concentrations.

Graphical abstract: Microfluidic pumping by micromolar salt concentrations

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Article information

Article type
02 Oct 2016
11 Jan 2017
First published
12 Jan 2017
This article is Open Access
Creative Commons BY license

Soft Matter, 2017,13, 1505-1518

Microfluidic pumping by micromolar salt concentrations

R. Niu, P. Kreissl, A. T. Brown, G. Rempfer, D. Botin, C. Holm, T. Palberg and J. de Graaf, Soft Matter, 2017, 13, 1505 DOI: 10.1039/C6SM02240E

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