Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 46: P11: Wetting, Micro and Nano Fluidics
CPP 46.13: Poster
Mittwoch, 18. März 2015, 10:00–13:00, Poster A
Switchable imbibition in nanoporous gold — •Yahui Xue1, 2, Juergen Markmann1, Huiling Duan2, Joerg Weissmueller1,3, and Patrick Huber3 — 1Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht, D-21502 Geesthacht, Germany — 2State Key Laboratory for Turbulence and Complex Systems, Center for Applied Physics and Technology, Peking University, Beijing 100871, China — 3Institute of Materials Physics and Technology, Hamburg University of Technology, D-21073 Hamburg, Germany
Spontaneous imbibition enables the elegant propelling of nano-flows because of the dominance of capillarity at small length scales. The imbibition kinetics are, however, solely determined by the static host geometry, the capillarity, and the fluidity of the imbibed liquid. This makes active control particularly challenging. Here we show for aqueous electrolyte imbibition in nanoporous gold that the fluid flow can be reversibly switched on and off through electric potential control of the solid-liquid interfacial tension, that is, we can accelerate the imbibition front, stop it, and have it proceed at will. Simultaneous measurements of the mass flux and the electrical current allow us to document simple scaling laws for the imbibition kinetics, and to explore the charge transport in the metallic nanopores. Our findings demonstrate that the high electric conductivity along with the pathways for fluidic/ionic transport render nanoporous gold a versatile, accurately controllable electrocapillary pump and flow sensor for minute amounts of liquids with exceptionally low operating voltages - see also Y. Xue et al., Nature Comm. 5, 4237 (2014).