A new type of actuation device has been conceptualized that meets the needs of both large displacement, force and bandwidth within a package more compact than currently available magnetostrictive and stack-type piezo actuators of similar rating. This concept relies on micro-scale electrohydrodynamic (EHD) pumping of a dielectric liquid with a small concentration of free charges. Configured as an actuator, the EHD pump(s) would be used to move fluid between two reservoirs — each having a compliant membrane that interfaces to the world to provide the means to achieve vibration cancellation or micro actuation.
Ordinarily limited to generating flow in macroscale applications, the EHD pump is shown to exhibit an exciting scaling law as its size is reduced. As the pump volume to surface area decreases, the energy going toward increasing pressure in the pump has an increasingly larger effect. Since volume/surface area is proportional to 1/a2, where a is the characteristic width or diameter of the pump, the pressure head generated scales similarly. Analytical and numerical studies have shown the EHD-pumped actuator to be capable of delivering equal force and bandwidth to magnetostrictive and stack-type piezo actuators, but with consdierably greater displacement and roughly 1/10th of the size. Further, this type of actuator offers the possibility for deployment in active vibration control or micro actuation applications at significantly greater temperatures.