Continuous dielectrophoretic separation of particles in a spiral microchannel

Abstract

Particle separation is a fundamental operation in the areas of biology and physical chemistry. A variety of force fields have been used to separate particles in microfluidic devices, among which electric field may be the most popular one due to its general applicability and adaptability. So far, however, electrophoresis-based separations have been limited primarily to batchwise processes. Dielectrophoresis (DEP)-based separations require in-channel micro-electrodes or micro-insulators to produce electric field gradients. This article introduces a novel particle separation technique in DC electrokinetic flow through a planar double-spiral microchannel. The continuous separation arises from the cross-stream dielectrophoretic motion of particles induced by the non-uniform electric field inherent to curved channels. Specifically, particles are focused by DEP to one sidewall of the first spiral, and then dielectrophoretically deflected toward the other sidewall of the second spiral at a particle-dependent rate, leading to focused particle streams along different flow paths. This DEP-based particle separation technique is demonstrated in an asymmetric double-spiral microchannel by continuously separating a mixture of 5/10 microm particles and 3/5 microm particles.

Dielectrophoretic monitoring of microorganisms in environmental applications

“…Many different approaches have been employed to apply DEP forces on particles, the most traditional manner is to use arrays of microelectrodes of a variety of geometries [34] and locations within a microchannel, from lateral electrodes [35] to threedimensional (3-D) cages [36,37] and 3-D electrodes [38]. Other novel approaches include: insulator-based DEP (iDEP) with 3-D columns or posts [39][40][41][42], oil menisci [43], glass spheres [44], microchannel with a geometry gradient [45,46], insulating hurdles [1,47], nanopipettes [19,48], spiral microchannels [49,50], and conical-pore membranes [51].…”

Dielectrophoresis in microfluidics technology

“…DEP is applicable even for non-conducting particles and can be generated either by using direct current (DC) or alternating current (AC) field. DC-DEP [4][5][6][7][8][9][10][11][12][13][14][15][16], AC-DEP and DC-biased AC-DEP [91][92][93][94][95][96][97][98][99] have been successfully implemented for the manipulation of micro/nanoparticles.…”

Inertial focusing dynamics in spiral microchannels

“…13 Inertial focusing represents one passive technique used to manipulate and separate cells on the microscale without an externally applied force or field, in addition to hydrophoresis, 14 deterministic lateral displacement, 15 and gravitational methods. 16 There are also a plethora of active techniques including dielectrophoresis, [17][18][19] magnetophoresis, 20 and acoustophoresis. 21 Several reviews comparing these different techniques are also available in the literature.…”