Free Vibration Analysis of a Circular Diaphragm in the Partially Confined Fluid Chamber of an Electrostatically Actuated Micro Pump

Micro pumps play a significant role in various electromechanical structures especially biomechanical devices where fluid delivery in micro scale is theessential requirement. These pumps are basically composed of three parts: moving part excited by an actuation mechanism, fluid chamber, and flow channel(valves). This paper investigates the free vibration of a circular diaphragm in an electrostatically actuated micro pump. Fluid chamber is cylindrical with rigidcircumferential wall and covered by the deformable diaphragm. Bottom surface has a central outlet and an annular rigid section. Complete liquid-structureinteraction between the elastic diaphragm and working fluid is adopted considering the time-variant fluidinducedpressure (linear Bernoulli equation) and kinematic compatibility in the boundaries. The governing equation for the lateral deflection of thediaphragm is derived using assumed-modes method. It is seen that higher modes frequencies are less affected by the coupling effect. Effect of material properties onthe natural frequencies of the coupled system is also investigated. Moreover, the change in the natural frequency of the system by the application of a bias DC voltage is depicted

Keywords:

Micro pump , Coupled vibration , Electrostatic force ,