1] Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht, D-21502 Geesthacht, Germany [2] State Key Laboratory for Turbulence and Complex Systems, Center for Applied Physics and Technology, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China.
1] Institute of Materials Research, Materials Mechanics, Helmholtz-Zentrum Geesthacht, D-21502 Geesthacht, Germany [2] Institute of Materials Physics and Technology, Hamburg University of Technology, D-21073 Hamburg, Germany.
Nat Commun. 2014 Jul 1;5:4237. doi: 10.1038/ncomms5237.
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 fluid/ionic transport render nanoporous gold a versatile, accurately controllable electrocapillary pump and flow sensor for minute amounts of liquids with exceptionally low operating voltages.
自发浸润能够优雅地推动纳米流动，这是因为在小尺度长度下毛细作用占据主导地位。然而，浸润动力学仅由静态主体几何形状、毛细作用和被浸润液体的流动性决定。这使得主动控制变得特别具有挑战性。在这里，我们展示了在纳米多孔金中电解质的自发浸润，通过控制固-液界面张力的电势可以可逆地打开和关闭流体流动，也就是说，我们可以加速浸润前沿、停止它，并随心所欲地让它继续进行。同时测量质量通量和电流使我们能够记录浸润动力学的简单比例定律，并探索金属纳米孔中的电荷传输。我们的发现表明，高导电性以及流体/离子传输的途径使得纳米多孔金成为一种通用的、可精确控制的电毛细泵和流量传感器，可用于非常少量的液体，其工作电压异常低。
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