Dielectrophoretic focusing of particles in a microchannel constriction using DC‐biased AC flectric fields

Abstract

This paper presents a fundamental study of particle electrokinetic focusing in a single microchannel constriction. Through both experiments and simulations, we demonstrate that such dielectrophoresis-induced particle focusing can be implemented in a much smaller magnitude of DC-biased AC electric fields (10 kV/m in total) as compared to pure DC electric fields (up to 100 kV/m). This is attributed to the increase in the ratio of cross-stream particle dielectrophoretic velocity to streamwise electrokinetic velocity as only the DC field component contributes to the latter. The effects of the 1 kHz frequency AC to DC electric field ratio on particle trajectories and velocity variations through the microchannel constriction are also examined, which are found to agree with the simulation results.

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

“…3B. This is believed to be a consequence of the constriction-induced dielectrophoretic focusing effect on 590 nm particles as we have demonstrated previously [25].…”

“…Using our previously developed model [20,25], we estimated the potential influence of DEP on the trajectories of the 590 nm tracing particles in the above experiment. It was found that the induced dielectrophoretic velocity was on the order of 50 mm/s in the fluid circulation regions, and could reach 150 mm/s if the particle was within 2 mm distance from the corners of the constriction.…”

“…In insulator-based dielectrophoresis (iDEP), both DC and AC voltages (of any frequency) can be applied to the remote electrodes positioned in end-channel reservoirs for transporting and manipulating particles. The electric field gradients are caused by the blockage of electric current due to in-channel hurdles, posts, and ridges [18][19][20][21][22][23][24][25][26][27].…”

dc electrokinetic transport of cylindrical cells in straight microchannels

“…[2][3][4][5][6] The success of these electrically controlled microfluidic devices for particle transport relies on a comprehensive understanding of fluid and particle behavior in these devices. However, most existing theoretical [7][8][9][10][11] and experimental [12][13][14][15][16][17][18][19] studies on the electrokinetic transport in microfluidic devices have been performed exclusively on spherical particles. In fact, a large amount of particles used in microfluidic applications, such as biological entities 1 and synthetic nanowires, 20,21 is nonspherical.…”

“…11,15 Dielectrophoresis refers to a nonlinear electrokinetic phenomenon 30 in which a force is exerted on a dielectric particle when it is subjected to a spatially nonuniform electric field. This kind of electrokinetic phenomenon has been widely used to manipulate spherical particles in microfluidics such as particle trapping, [31][32][33][34][35] separation, 16,[35][36][37][38][39][40][41] focusing, 14,18,35 and cell discrimination. 42,43 Previous numerical and experimental studies demonstrate that the DEP effect should be taken into account to study the electrokinetic transport of spherical particles where nonuniform electric fields are present.…”