(516e) AC Electrohydrodynamics of Polarized Laminar Flows | AIChE

(516e) AC Electrohydrodynamics of Polarized Laminar Flows

Authors 

Mavrogiannis, N. - Presenter, Johns Hopkins University
Gagnon, Z. R., Johns Hopkins University
In this work, we explore the fluidic dielectrophoresis (fDEP) behavior of laminar flows subjected to an external alternating current (AC) electric field. In fDEP, an AC field is applied across a liquid electrical interface created between two co-flowing streams. We show that the field drives an interfacial displacement that is dependent on the field frequency and that relative differences in electrical conductivity and dielectric constant between the two liquid flows. At low frequency, this deflection is independent of dielectric constant, while at high frequency it is independent of electrical conductivity. At intermediate frequencies, we observe a cross-over frequency that is sensitive to both fluid electrical properties, and where no fluid displacement is observed. We present an electrohydrodynamic polarization model that accurately predicts this electrical dependence. Furthermore, we experimentally validate this model using high-speed imaging and capture the interfacial fluid velocity of the displacing interface. We show that the interface velocity can be well-predicted by a simple uni-directional transport model. Finally, we demonstrate the ability to rapidly measure fluid properties, including liquid dielectric constant and viscosity at low-cost using a simple microfluidic device.