| The forced vibration of a thin flexible plate or membrane in a sealed cavity with a small opening can cause fluid to be pumped into and out-of the cavity. At particular frequencies and amplitudes of vibration, a streaming of vortex rings can occur near the orifice. These vortex rings move under their own self-induced momentum. Downstream of the opening the rings ultimately break up and can form a fully developed jet. This work is dedicated to the analysis, design, and fabrication of electrostatic micro fluidic actuators, which use the pulsing mechanism described above to generate a fluid flow. Particle Image Velocimetry (PIV) is used to visualize the jet at various drive frequencies. The complex coupling between the electric field driving the membrane, the deformation of the membrane, and the compressible squeeze film in the cavity are studied in depth. Theoretical modeling, computer simulation (CFD-Computational Fluid Dynamics) and experiments are used to characterize the performance of the actuator. A low dimensional theoretical model, which takes into account the coupled physics of the problem, is derived from the Newton equation. The model is used to predict the membrane motion for varying voltage and frequency inputs. The system response predicted with the model is compared to numerical simulations, and it was found that the model can accurately capture the system response for a given input. Finally, a protocol for fabricating the actuator using Micro Electrical Mechanical Systems (MEMS) processes is presented. |
