Enhanced particle trapping performance of induced charge electroosmosis

Abstract

By increasing the number of floating electrodes or enlarging the width of single floating electrode, this work provides effective ways to strongly improve the particle trapping performance of induced charge electroosmosis (ICEO). Particle trapping with double or triple separate narrow floating electrodes increases the effective actuating range of ICEO flow and therefore enhance the optimum trapping ability to be 1.63 or 2.34 times of that with single narrow electrode (width of L=200μm), and the ideal trapping frequency is independent of the electrode number due to the mutual independence of electrochemical ion relaxation over each electrode. Furthermore, using a single wide floating electrode with the effective width equal to three separate narrow floating electrodes (L=600μm) instead of a single narrow one slightly lowers the ideal trapping frequency due to an increase in the characteristic polarization length, but the trapping performance is only up to 1.59 times of that with original single narrow electrode, implying that vertical channel confinement effect may severely suppresses the effective actuating range of ICEO flow and renders the trapping performance not as expected. Trapping experiments over wide floating electrode with different channel height were carried out, showing that the trapping performance increases by correctly increasing the channel height.

Recent advances in direct current electrokinetic manipulation of particles for microfluidic applications

“…This flow has a nonlinear quadratic dependence on the electric field and often consists of two counter‐rotating rolls . It has been extensively studied around conducting surfaces (e.g., metal electrodes and particles) that can be either electrically activated or left floating . Induced charge electroosmotic fluid flow also takes place around inert objects with sharp edges (e.g., acute corners) because of the electric field leakage , which has been demonstrated to disturb the local fluid flow and particle motion .…”

Simulation analysis of rectifying microfluidic mixing with field‐effect‐tunable electrothermal induced flow

“…In particular, the recent advancement of microfabrication technology facilitates the easy integration of closed packed microelectrode arrays into miniaturization systems, providing an opportunity for exerting ponderomotive electrostatic forces on the fluid medium itself by using AC electric field . In contrast with DC electroosmosis over charged insulating surfaces , electroconvective flow appears in the form of micro‐vortex above a microelectrode array with signal amplitude often less than ten volts , so AC electrokinetics can realize more flexible control on local fluid movement, and find various interesting applications, such as pumping, mixing, and causing concentration gradient of analyte in microfluidic devices, in virtue of its controllability through adjusting the amplitudes, phases, and field frequencies of the electric signal , for example alternating‐current electrothermal (ACET) and alternating‐current electroosmosis (ACEO) , as shown in Fig. .…”

Flexible particle flow‐focusing in microchannel driven by droplet‐directed induced‐charge electroosmosis

“…Nevertheless, how to use ICEO fluid motion to achieve particle manipulation with intended functions has rarely been exploited. Recently, we first reported continuous‐flow focusing of micro‐particles with ICEO above a central gate electrodes (GE) . It is noteworthy that, since particle flow‐focusing by transverse ICEO is due to fluidic drag force, it has a longer function range than dielectrophoresis (DEP) or traveling‐wave DEP effect which exists merely in a field gradient or the presence of a spatial phase variation.…”