Fully-microfabricated electromagnetically-actuated membrane for microspeaker

This paper presents an electromagnetically actuated membrane that can be microfabricated on silicon wafers in a batch process. The wax-bonded micromagnet suspended by a parylene diaphragm (7×7 mm²) is actuated by the Lorentz force when a current is applied to the dual-layer electroplated coils. Experimental results show that the electromagnetic actuation produces a flat frequency response of 0.3 μm_peak-to-peak up to 400 Hz (with 1.5 μm_peak-to-peak displacement at the resonant frequency of 420 Hz) for an applied current of 40.8 mA_rms into the 52 Ω coil.