Parallel Plate Electrostatic Actuators in Liquids: Displacement-Voltage Optimisation for Microfluidic Applications

We study Parallel Plate Electrostatic Actuators (PPEAs) in liquids of various permittivities. We demonstrate and provide experimental validation that the pull-in effect can be shifted beyond one third of the initial gap and even be eliminated when PPEAs are operated in liquids, Displacement-voltage characteristics depend strongly on the insulating layers of the plate electrodes. Applications in microfluidics requiring either binary state actuation (e.g. pumps, valves) or continuous displacements over the whole gap (e.g. microtweezers) will benefit from this work. Electrode potential screening and undesirable electrochemistry in lossy dielectric liquids are counteracted using AC-voltages,