Dependence of Nonlinear Electrophoresis on Particle Size and Electrical Charge

Abstract

This study focuses on the dependence of nonlinear electrophoretic migration of particles on the particle size and particle electrical charge. This is the first report of the experimental assessment of the mobilities of the nonlinear electrophoretic velocity of colloidal polystyrene microparticles under two distinct electric field dependences. A total of nine distinct types of polystyrene microparticles of varying size and varying electrical charge were divided into two groups to study separately the effects of particle size and the effects of particle charge. The mobilities of the nonlinear electrophoretic velocity of each particle type were determined in both the cubic and 3/2 regimes (μ EP,NL(3) and μ EP,NL (3/2) ). The results unveiled that both mobilities had similar relationships with particle size and charge. The magnitude of both μ EP,NL(3) and μ EP,NL (3/2) increased with increasing particle size and decreased with increasing magnitude of particle charge. However, the observed trends were not perfect as discussed in the Results and Discussion section but still provide valuable information. These findings will aid in the design of future size-based and charge-based separations of particles and microorganisms.

Characterization of the Nonlinear Electrophoretic Behavior of Colloidal Particles in a Microfluidic Channel

“…In two recent reports on the characterization of mobility of nonlinear EP, 9,24 the microchannels employed had a negative wall ζ-potential, and all particles had negative particle ζ-potentials that were lower in magnitude than that of the channel wall. These statements also hold true for the work reported by Bentor et al 8 and Ernst et al, 25 where the authors experimentally determined the mobility of the nonlinear EP velocity for latex microparticles of varying sizes and surface charge values, all of which had negative ζ-potentials, with magnitudes lesser than that of the channel wall.…”

Manipulating the insulating post arrangement in DC-biased AC-iEK devices to improve microparticle separations

“…The values of ζ P , μ EP,L and μ (3) EP,NL were experimentally assessed for each particle type using PTV experiments (Table 1) employing a channel with a constant cross section. 25,28–30,38 A three-step EK injection process was used to introduce a defined volume of the microparticle mixture into the iEK device. 39…”

“…Furthermore, the recent reports on the importance of nonlinear electrophoresis (EP NL ) in iEK systems, 25–31 have enabled the design of new separation strategies, employing both DC potentials 14,32 and low-frequency AC potentials. 24 Inclusion of EP NL effects is crucial for designing effective iEK separation strategies, as neglecting these effects results in inaccurate predictions of separation performance.…”

Zeta potential characterization using commercial microfluidic chips

“…17 The electrophoretic component of the velocity has a linear component (proportional to E) and non-linear component (proportional to E 3 or E 3/2 ). [25][26][27] The nonlinear component can be ignored if the Peclet number is smaller or equal to 1 and the Dukhin number is much smaller than 0.1. 28,29 The Peclet number corresponds to the ratio of the convective to the diffusive movement of the ions located close to the surface of the particle, while the Dukhin number refers to the ratio of the surface conductivity to the bulk conductivity of the medium.…”