Cation-induced electrohydrodynamic flow in aqueous solutions

Abstract

Recently, single-molecule manipulation techniques in micro- and nanofluidic channels have attracted significant attention. To precisely control the transport velocity, the dynamics of the surrounding liquid must be understood in addition to the behavior of the target particles. Some unknowns about interactions between electrolyte ions and solvents remain to be clarified from a microscopic viewpoint. Herein, we propose a technique to generate a liquid flow driven by ion transport phenomena, the so-called electrohydrodynamic (EHD) flow, where electrolyte ions are dialyzed using a cation-exchange membrane. With this method, it is possible to apply an electric body force in liquids, which is different from electroosmotic flows that are limited to ion transport in electric double layers, and is expected to be a good candidate for detailed control of liquid flows in micro- and nanofluidic channels. To collect basic design data based on the knowledge of microscopic fluid dynamics of the present technique, a mathematical model of an EHD flow dragged by electrical carriers in an ionic current is developed and results are compared with experimental data. In our experiments, EHD flows are efficiently driven by applied electric fields in a cation dominant current. To induce such an EHD flow, the externally applied electric potential can be drastically reduced to 2.0 V in comparison with previous methods because we do not need an excessively high voltage to inject electrical charges into liquids. This method enables us to induce EHD flows in aqueous solutions and is expected to open the door to low-voltage driven liquid flow control.

Electrical Sensing of Au Nanoparticles Manipulated by an Optical Vortex

“…They theoretically and experimentally investigated induced-charge electroosmosis and induced-charge electrophoresis of asymmetric metallic particles exposed to DC and AC electric fields. In previous studies, we also discussed charge induction effects that drove electrohydrodynamic flows of liquids. , The present study provides experimental results that suggested some possibilities of ionic current and flow characteristics induced by Au NPs at the nanoscale, and further details will be clarified in the future.…”

“…In previous studies, we also discussed charge induction effects that drove electrohydrodynamic flows of liquids. 57,58 The present study provides experimental results that suggested some possibilities of ionic current and flow characteristics induced by Au NPs at the nanoscale, and further details will be clarified in the future.…”

Manipulating nanoliter fluid circuits on an all-glass chip by the magnetic field

“…For example, many nanoflow studies have focused on using carbon nanotubes to transport water flows 1. 16 Scientists use evaporation, 17 , 18 electroosmotic flow, 19 high voltage, 20 ions, 21 nanowires, 22 surface charge, 23 and even large HPLC pumps 24 to control the nanometer flow. Nanofluidic technology also needs microfluidic technology, such as temperature-controlled peristaltic pumps, 25 air-controlled valves, 26 microfluidics combined with membranes, 27 170 V silicon dioxide thin film deformable pumps, 28 and 4W ultrasonic drives.…”

Local Electric Field and Electrical Conductivity Analysis Using a Glass Microelectrode

“…In micro- and nanofluidic channels that are filled with electrolyte solutions, electric double layers are formed by highly concentrated counterion near the channel surface and induce an electroosmotic flow (EOF) under external electric fields. − EOFs are also known to be generated in ion-exchange materials in which electrically charged functional groups are fixed, as well as in artificially manufactured fluidic channels. , In highly polarized conditions, liquid flows are driven by ion transport in strong electric fields. We also reported that this kind of phenomena could be observed in the macroscopic liquid phase, which is known as electrohydrodynamic flows. , On the other hand, we do not have conventional methods to evaluate electrolyte concentrations and electric fields in such small spaces.…”

“…We also reported that this kind of phenomena could be observed in the macroscopic liquid phase, which is known as electrohydrodynamic flows. 15 , 17 On the other hand, we do not have conventional methods to evaluate electrolyte concentrations and electric fields in such small spaces.…”