A review on Electrohydrodynamic (EHD) pumps

With growth of tiny electronic chips and microfluidic applications, the demand for fluid propellant in micro and meso scale has risen. However, in such sizes it is hard to manufacture a pump with high performance and reliability. Generally, pumps in micro/meso scale based on their mechanism fall into two distinct categories: mechanical and non-mechanical pumps. More often, mechanical pumps are not suitable for cryogenic applications due to destructive effect of thermal fatigue on the pump s components such as valve membrane and flaps. On the other hand, non-mechanical pumps have no moving part, therefore, can operate with higher resistance to thermal stresses. The Electrohydrodynamic (EHD) pumps is a type of non-mechanical pumps which induce dielectric fluid under a high voltage electric field by injection or generation of ions in the vicinity of electrodes. Under the intensity of high electric field, free charges begin to move toward the electrode with opposite polarity. The interaction of charged particles with fluid s molecules exerts a small drag force that results in a net flow along the channel. Three different methods of EHD pumping; Ion-drag, induction, and conduction have been developed so far which is briefly outlined in this review paper with a special focus on heat transfer enhancement applications.