Continuous separation of microparticles by size with Direct current‐dielectrophoresis

Abstract

Direct current-dielectrophoresis (DC-DEP), the induced motion of the dielectric particles in a spatially nonuniform DC electric field, is demonstrated to be a highly efficient method to separate the microparticles by size. The locally nonuniform electric field is generated by an insulating block fabricated inside a polydimethylsiloxane microchannel. The particle experiences a negative DEP (accordingly a repulsive force) at the corners of the block, where the local electric-field strength is the strongest. Thus, the particle deviates from the streamline and the degree of deviation is dependent on the DEP force (i.e., the particle size). Combined with the electrokinetic flow, mixed polystyrene particles of a few micrometers difference in diameter can be continuously separated into distinct reservoirs. For separating target particles of a specific size, it is required to simply adjust the voltage outputs of the electrodes. A numerical model based on the Lagrangian tracking method is developed to simulate the particle motion and the results showed a reasonable agreement with the experimental data.

Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

“…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].…”

Continuous particle separation based on electrical properties using alternating current dielectrophoresis

“…Therefore, the effect of the finite particle size on the local fields is a difficult problem to solve numerically. A simplified model based on Lagrangian tracking method [9,26] is used to predict the particle motion in this study. In this model, the effect of the particle size on the flow and electrical fields are neglected, and only the effects of the resultant forces due to the electrical and flow fields on particle are considered.…”

“…Either direct current or alternating current field can be used. However, in the case of direct current field, the non-conducting particles and cells experience only n-DEP [9]. DEP has been successfully implemented for cell sorting [10,11], sample preparation [12,13], cell detection [14,15,16], cell trapping [17], particle focusing [18,19], cell characterization [20] and cell patterning [21,22].…”

“…The dependence of the DEP force on the size and the electrical properties makes it possible for cell/ particle separation based on the size and electrical properties differences. Utilizing these, DEP has also been implemented for cell/particle separation [9,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. These separation applications include the separation of the cancer cells from the blood stream [23,24], the separation of the platelets from diluted whole blood [31], the separation of red blood cells and the white blood cells [34], the separation of viable and non-viable yeast cells [33], the separation of human leukocytes [25] and the separation of healthy and unhealthy oocyte cells [36].…”