We study here the curious particle dynamics resulting from electro-osmotic flow around a microchannel junction corner whose dielectric walls are weakly polarizable. The hydrodynamic velocity field is obtained via superposition of a linear irrotational term associated with the equilibrium zeta potentials of both the microchannel and particle surfaces and the nonlinear induced-charge electro-osmotic flow which originates from the interaction of the externally applied electric field on the charge cloud it induces at the solid-liquid interface. The particle dynamics are analyzed by considering dielectrophoretic forces via the addition of a mobility term to the flow field in the limit of Stokes drag law. The former, non-divergence free term is responsible for migration of particles towards the sharp microchannel junction corner, where they can potentially accumulate. Experimental observations of particle trapping for various applied electric fields and microparticle size are rationalized in terms of the growing relative importance of the dielectrophoretic force and induced-charge contributions to the global velocity field with increasing intensity of the externally applied electric field.
REFERENCES
1.
P.
Takhistov
, K.
Duginova
, and H.-C.
Chang
, “Electrokinetic mixing vortices due to electrolyte depletion at microchannel junctions
,” J. Colloid Interface Sci.
263
(1
), 133
–143
(2003
).2.
S. K.
Thamida
and H.-C.
Chang
, “Nonlinear electrokinetic ejection and entrainment due to polarization at nearly insulated wedges
,” Phys. Fluids
14
(12
), 4315
–4328
(2002
).3.
G.
Yossifon
, I.
Frankel
, and T.
Miloh
, “On electro-osmotic flows through microchannel junctions
,” Phys. Fluids
18
(11
), 117108
(2006
).4.
Y.
Eckstein
, G.
Yossifon
, A.
Seifert
, and T.
Miloh
, “Nonlinear electrokinetic phenomena around nearly insulated sharp tips in microflows
,” J. Colloid Interface Sci.
338
(1
), 243
–249
(2009
).5.
Z.
Wu
and D.
Li
, “Micromixing using induced-charge electrokinetic flow
,” Electrochim. Acta
53
(19
), 5827
–5835
(2008
).6.
J.-K.
Chen
and R.-J.
Yang
, “Vortex generation in electroosmotic flow passing through sharp corners
,” Microfluid. Nanofluid.
5
(6
), 719
–725
(2008
).7.
H.
Zhao
and H. H.
Bau
, “Microfluidic chaotic stirrer utilizing induced-charge electro-osmosis
,” Phys. Rev. E
75
(6
), 066217
(2007
).8.
T. M.
Squires
and M. Z.
Bazant
, “Induced-charge electro-osmosis
,” J. Fluid Mech.
509
, 217
–252
(2004
).9.
S. J. R.
Staton
, K. P.
Chen
, T. J.
Taylor
, J. R.
Pacheco
, and M. A.
Hayes
, “Characterization of particle capture in a sawtooth patterned insulating electrokinetic microfluidic device
,” Electrophoresis
31
(22
), 3634
–3641
(2010
).10.
S. K.
Srivastava
, A.
Gencoglu
, and A. R.
Minerick
, “DC insulator dielectrophoretic applications in microdevice technology: A review
,” Anal. Bioanal. Chem.
399
(1
), 301
–321
(2011
).11.
K.-T.
Liao
and C.-F.
Chou
, “Nanoscale molecular traps and dams for ultrafast protein enrichment in high-conductivity buffers
,” J. Am. Chem. Soc.
134
(21
), 8742
–8745
(2012
).12.
A.
Ramos
, H.
Morgan
, N. G.
Green
, and A.
Castellanos
, “Ac electrokinetics: A review of forces in microelectrode structures
,” J. Phys. D: Appl. Phys.
31
(18
), 2338
(1998
).13.
A.
Ramos
, H.
Morgan
, N. G.
Green
, and A.
Castellanos
, “AC electric-field-induced fluid flow in microelectrodes
,” J. Colloid Interface Sci.
217
(2
), 420
–422
(1999
).14.
J.
Wu
, Y.
Ben
, D.
Battigelli
, and H.-C.
Chang
, “Long-range AC electroosmotic trapping and detection of bioparticles
,” Ind. Eng. Chem. Res.
44
(8
), 2815
–2822
(2005
).15.
K. F.
Hoettges
, M. B.
McDonnell
, and M. P.
Hughes
, “Use of combined dielectrophoretic/electrohydrodynamic forces for biosensor enhancement
,” J. Phys. D: Appl. Phys.
36
(20
), L101
(2003
).16.
Y.
Green
and G.
Yossifon
, “Dynamical trapping of colloids at the stagnation points of electro-osmotic vortices of the second kind
,” Phys. Rev. E
87
(3
), 033005
(2013
).17.
J. R.
Anderson
, D. T.
Chiu
, R. J.
Jackman
, O.
Cherniavskaya
, J. C.
McDonald
, H.
Wu
, S. H.
Whitesides
, and G. M.
Whitesides
, “Fabrication of topologically complex three-dimensional microfluidic systems in PDMS by rapid prototyping
,” Anal. Chem.
72
(14
), 3158
–3164
(2000
).18.
K.
Haubert
, T.
Drier
, and D.
Beebe
, “PDMS bonding by means of a portable, low-cost corona system
,” Lab Chip
6
(12
), 1548
–1549
(2006
).19.
G. Y.
Tang
, D. G.
Yan
, C.
Yang
, H. Q.
Gong
, C. J.
Chai
, and Y. C.
Lam
, “Joule heating and its effects on electroosmotic flow in microfluidic channels
,” J. Phys.: Conf. Ser.
34
(1
), 925
(2006
).20.
L. D.
Landau
, L. P.
Pitaevskii
, and E. M.
Lifshitz
, Electrodynamics of Continuous Media
, 2nd ed. (Butterworth-Heinemann
, Oxford, England
, 1979
), Vol. 8
.21.
L. M.
Milne-Thomson
, Theoretical Hydrodynamics
, 5th ed., Dover Books on Physics
Vol. 4
(Dover Publications
, New York
, 2011
).22.
J.
Lyklema
, Fundamentals of Interface and Colloid Science: Solid-Liquid Interfaces
, 1st ed. (Academic Press
, London
, 1995
).23.
A.
Babiano
, J. H. E.
Cartwright
, O.
Piro
, and A.
Provenzale
, “Dynamics of a small neutrally buoyant sphere in a fluid and targeting in hamiltonian systems
,” Phys. Rev. Lett.
84
(25
), 5764
–5767
(2000
).24.
S.-J.
Liu
, H.-H.
Wei
, S.-H.
Hwang
, and H.-C.
Chang
, “Dynamic particle trapping, release, and sorting by microvortices on a substrate
,” Phys. Rev. E
82
(2
), 026308
(2010
).25.
L.
Rozitsky
, A.
Fine
, D.
Dado
, S.
Nussbaum-Ben-Shaul
, S.
Levenberg
, and G.
Yossifon
, “Quantifying continuous-flow dielectrophoretic trapping of cells and micro-particles on micro-electrode array
,” Biomed. Microdevices
15
(5
), 859
–865
(2013
).26.
T. B.
Jones
, Electromechanics of Particles
(Cambridge University Press
, Cambridge
, 1995
).27.
See supplementary material at http://dx.doi.org/10.1063/1.4891674 for movies and global numerical solution of the particle pathline patterns at relative low applied electric field.
28.
B. J.
Kirby
and E. F.
Hasselbrink
, Jr., “Zeta potential of microfluidic substrates: 2. Data for polymers
,” Electrophoresis
25
(2
), 203
–213
(2004
).29.
J. D.
Posner
, “Properties and electrokinetic behavior of non-dilute colloidal suspensions
,” Mech. Res. Commun.
36
(1
), 22
–32
(2009
).© 2014 AIP Publishing LLC.
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