Figure 2.

Schematic of different mechanisms for imposing asymmetry to the electric field in alternating current electrothermal effects (ACET) devices. (a) Direct current (DC) biased configuration. The left electrode is always at a positive potential and subject to faradaic charging, while the right electrode is always at a negative potential and subject to capacitive charging. (b) Travelling wave configuration. The induced temperature gradient generates a charge density which is moved with the travelling electric field. Note that the direction of propagation of travelling wave is opposite to the direction of fluid flow. (c) Two-phase asymmetric configuration. The narrow electrodes in two adjacent pairs have different polarities. The superposition of the two configurations enhances the electric field in region B. Reproduced with permission from [6,68,69].