A Discrete Model for an Electrostatically Driven Micro-Hydraulic Actuator
High-force, large-deflection actuators are critical for devices such as valves and pumps used in micro-fluidic systems. The major technical impediment in improving the performance of the micro-actuators lies in the lack of understanding the physical phenomena and their interactions of electric, mechanical, and fluidic fields for performing their intended functions. Because of the complexity of the actuator, the fully coupled numerical analysis such as finite element analysis is extremely expensive. Here, we introduce a discrete model of an Electrostatic Micro-Hydraulic (EMH) actuator. The model considers all dynamic forces which are involved in a time operation of the hydraulic actuator cell and covers three major physics: electrostatic, mechanical and fluidic. The physics have been coupled together to investigate the dynamic of the device. The discrete dynamic model developed in this work may be used for simple yet accurate predictions of dynamic performance of such actuators, and is preferable to more complicated and very expensive coupled numerical models. The analysis relies on physics-based equations and can be modified to accommodate different chamber geometries, different material properties and different working fluids. Results from the analytical model compare favorably with experimental measurements.