Microfluidic Gradient Formation by Maxwell-Wagner Polarization at an Aqueous Electric Interface

submitted by: zgagnon
This work integrates components from AC electrokinetics, microfluidics, and cell biology to produce tunable spatial chemical gradients in a microfluidic device for studying directed cell migration. I explore a new type of Maxwell Wagner polarization for the injection of aqueous liquid across a liquid-liquid interface. The rate of injection is tunable and used to manipulate fluid much the same way dielectrophoresis is used on bioparticles; fluid can be injected into different streamlines and...

Electrokinetic Concentration and Separation of Particles in Microfluidic Reservoirs

submitted by: xcxuan
This video exhibits the selective concentration and separation of 3 um particles from 1 um particles in the upstream reservoir of a straight microchannel. This size-based particle sorting arises from the negative dielectrophoresis induced at the reservoir-microchannel junction where the size mismatch of the reservoir and microchannel creates strong inherent electric field gradients. Such reservoir-based dielectrophoretic sorting is superior to existing insulator-based dielectrophoresis...

Electrothermal Flow in Insulator-Based Dielectrophoresis

submitted by: xcxuan
In this video 600 nm fluorescent particles were used visualize the electroosmotic fluid flow in insulator-based dielectrophoresis devices. The interaction of Joule heating-induced fluid inhomogeneities and electric field causes electrothermal fluid circulations upstream and downstream the microchannel constriction. By varying the DC and AC field components, we observed different flow patterns in the constriction region due to the competition of electroosmotic flow and electrothermal flow.