Fluid rheological effects on streaming dielectrophoresis in a post‐array microchannel

Abstract

Recent studies have demonstrated the strong influences of fluid rheological properties on insulator‐based dielectrophoresis (iDEP) in single‐constriction microchannels. However, it is yet to be understood how iDEP in non‐Newtonian fluids depends on the geometry of insulating structures. We report in this work an experimental study of fluid rheological effects on streaming DEP in a post‐array microchannel that presents multiple contractions and expansions. The iDEP focusing and trapping of particles in a viscoelastic polyethylene oxide solution are comparable to those in a Newtonian buffer, which is consistent with the observations in a single‐constriction microchannel. Similarly, the insignificant iDEP effects in a shear‐thinning xanthan gum solution also agree with those in the single‐constriction channel except that gel‐like structures are observed to only form in the post‐array microchannel under large DC electric fields. In contrast, the iDEP effects in both viscoelastic and shear‐thinning polyacrylamide solution are significantly weaker than in the single‐constriction channel. Moreover, instabilities occur in the electroosmotic flow and appear to be only dependent on the DC electric field. These phenomena may be associated with the dynamics of polymers as they are electrokinetically advected around and through the posts.

Particle Size-Dependent Electrophoresis in Polymer Solutions

“…The studies reviewed above are all concerned with particle electrophoresis in Newtonian fluids. Recent investigations have highlighted the significant impacts of fluid rheological properties on various electrokinetic phenomena. − In particular, a couple of theoretical papers predict the onset of particle size-dependent electrophoresis in non-Newtonian fluids even under the thin-Debye-layer limit. Khair et al developed a general framework to calculate the electrophoretic velocity of a uniformly charged colloidal particle immersed in a complex fluid with a shear-rate-dependent viscosity.…”

The electrodynamics of rod‐like microparticles based on optically induced dielectrophoresis

“…Microfluidic chip, also known as lab-on-a-chip or micro total analysis system, has the advantages of small size, low cost, low consumption of samples and reagents, and so on, so it is especially suitable for biological applications. Compared with other manipulation techniques, such as atomic force microscope [10,11], microneedle [12,13], acoustic trap [14,15], optical tweezers [16,17], and magnetic tweezers [18][19][20], the dielectrophoresis (DEP) microfluidic chip [21,22], as a micro-nano manipulation technology that is easy to integrate and control, can realize the manipulation of single or large quantities of particles [23][24][25][26][27][28] due to the characteristics of noncontact, non-damage, and high flux. However, traditional electrophoretic technology requires the design and processing of complex physical electrodes, which causes the problems of high cost and long design cycle inevitably.…”