Experiments on opto-electrically generated microfluidic vortices
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Strong microfluidic vortices are generated when a near-infrared (1,064 nm) laser beam is focused within a microchannel and an alternating current (AC) electric field is simultaneously applied. The electric field is generated from a parallel-plate, indium tin oxide (ITO) electrodes separated by 50 μm. We present the first μ-PIV analysis of the flow structure of such vortices. The vortices exhibit a sink-type behavior in the plane normal to the electric field and the flow speeds are characterized as a function of the electric field strength and biasing AC signal frequency. At a constant AC frequency of 100 kHz, the fluid velocity increases as the square of the electric field strength. At constant electric field strength fluid velocity does not change appreciably in the 30–50 kHz range and it decreases at larger frequencies (>1 MHz) until at approximately 5 MHz when Brownian motion dominates the movement of the 300 nm μ-PIV tracer particles. Presence of strongly focused laser beams in an interdigitated-electrode configuration can also lead to strong microfluidic vortices. When the center of the illumination is focused in the middle of an electrode strip, particles experiencing negative dielectrophoresis are carried towards the illumination and aggregate in this area.
KeywordsMicroTAS Opto-electrostatic micro vortex Micropump Electrohydrodynamics Dielectrophoresis
We would like to acknowledge support from NSF Grant CMMI-0654031. Aloke Kumar acknowledges partial support from the Adelberg Fellowship, Purdue University. S.J.W. acknowledges support under a National Science Foundation Graduate Research Fellowship.
- Chakraborty S (2008) Electrothermal effects. Encyclopedia of Microfluidics and Nanofluidics. L. Dongqing, Springer, BerlinGoogle Scholar
- Inouâe S, Spring KR (1997) Video microscopy: the fundamentals. Plenum Press, New YorkGoogle Scholar
- Jones TB (1995) Electromechanics of particles. Cambridge University Press, CambridgeGoogle Scholar
- Koch M, Evans A, Brunnschweiler A (2000) Microfluidic technology and applications. Research Studies Press, BaldockGoogle Scholar
- Kumar A, Ewing AH, Wereley ST (2008) Optical tweezers for manipulating cells and particles. Encyclopedia of Microfluidics and Nanofluidics. L. Dongqing, Springer, BerlinGoogle Scholar
- Morgan H, Green NG (2003) AC electrokinetics: colloids and nanoparticles. Research Studies Press, PhiladelphiaGoogle Scholar
- Papagiakoumou E, Pietreanu D, Makropoulou MI, Kovacs E, Serafetinides AA (2006) Evaluation of trapping efficiency of optical tweezers by dielectrophoresis. J Biomed Opt 11:014035-014031–014035-014037.Google Scholar
- Pickard JE, Pries AR, Ley K (2006) Micro-PIV measurement of flow fields around adherent leukocytes. FASEB J 20:A1322–A1322Google Scholar
- Pohl HA (1978) Dielectrophoresis: the behavior of neutral matter in nonuniform electric fields. Cambridge University Press, CambridgeGoogle Scholar
- Rowe AD, Leake MC, Morgan H, Berry RM (2003) Rapid rotation of micron and submicron dielectric particles measured using optical tweezers. J Modern Optics 50:1539–1554Google Scholar