A micro membrane vibrator with thermally driven bimorph cantilever beams

A micro membrane vibrator consisting of bimorph cantilever beams and a membrane is designed, fabricated, and tested here. Due to the discrepancy of thermal expansion coefficients between different layers, the membrane moves with temperature change. The four-layer structure including SiO2-polysilicon- insulated SiO2-aluminum is fabricated with four masks. The numerical finite element program ANSYS 51 is used to investigate the behavior of different designs to have larger displacement and force. According to the testing results, we observe that our designs can induce the maximum Z-axis displacement up to 117μm when input power is 6.98 W. The working frequency is about 40 Hz when the amplitude is kept between 2 and 5μm approximately.