Development of Simple-Structure Magnetic Membrane Actuator for Synthetic Jet Application

In this work, a magnetic membrane actuator that involves simple fabrication process and low cost is developed based on electroplating technique, and its dynamic performance is examined. The magnetic actuator consists of an element of soft ferromagnetic material embedded in PDMS circular membrane. It is driven by attracting the soft ferromagnetic element using external magnet that is attached on a shaft of electrical motor. When the shaft is rotated, the magnet will move back and forth towards the membrane. In this study, the nickel element as a soft ferromagnetic material is designed as a simple circular disk with four straight arms, and it is fabricated into three different thicknesses, i.e. 49±3, 70±7 and 100±6 μm, while PDMS thickness is fixed at 280±33 µm. The dynamic performances of 2-cm membrane actuators are examined using a capacitive sensor in the actuating frequency range of 40-240 Hz. The experimental results show that there are two motion patterns, i.e. small and strong oscillations, where the transition frequency is approximately at 100 Hz. In addition, with the increment of nickel element’s thickness, gain and peak frequency, where gain peaks occur, increase while peak-to-peak amplitude decreases.