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In this paper a novel type of piezoelectric MEMS loudspeaker is presented. The device concept is based on concentrically cascaded PZT actuators making it the first two-way MEMS speaker reported. As a further novelty, the device is designed to operate without a closed membrane offering significant improvements with respect to acoustic performance, energy efficiency and manufacturability. Extensive FEA studies have revealed a very high SPL of more than 85 dB at 500 Hz for a device 10 × 10 mm2 in size. At higher frequencies even larger SPL values are achieved enabling a flat frequency response with 95 dB for frequencies above 800 Hz. Based on the concept speaker prototypes have been fabricated using MEMS technology and are currently being characterized

This paper presents design, fabrication and measurements for single-axis piezoelectric MEMS micromirrors with 1 mm2 apertures. These micromirrors, which feature thin-film PZT actuators and mechanical leverage amplification, are dedicated for laser projection and meet the requirements of high resonant frequency and large deflection angles. To identify the optimal micromirror geometries a parametric study by means of FEM simulations and analytic modeling has been performed. Characterization, related to the material qualities of PZT and the mechanical performance of the micromirrors, have verified the reliability of the process, the robustness and the performance of the fabricated prototypes. According to the measurements the fabricated micromirrors feature high Q-factor about 1570. The micromirror reaches the theta(ind opt)·D product of 42.5 °·mm at 32 kHz driven by a low voltage of 7 V. Furthermore, new designs with larger apertures and deflections are currently being developed

In this work, we present a method for growing highly c-axis oriented aluminum scandium nitride (AlScN) thin films on (100) silicon (Si), silicon dioxide (SiO2) and epitaxial polysilicon (poly-Si) substrates using a substrate independent approach. The presented method offers great advantages in applications such as piezoelectric thin-film-based surface acoustic wave devices where a metallic seed layer cannot be used. The approach relies on a thin AlN layer to establish a wurtzite nucleation layer for the growth of w-AlScN films. Both AlScN thin film and seed layer AlN are prepared by DC reactive magnetron sputtering process where a Sc concentration of 27% is used throughout this study. The crystal quality of (0002) orientation of Al0.73Sc0.27N films on all three substrates is significantly improved by introducing a 20 nm AlN seed layer. Although AlN has a smaller capacitance than AlScN, limiting the charge stored on the electrode plates, the combined piezoelectric coefficient d33,f with 500 nm AlScN is only slightly reduced by about 4.5% in the presence of the seed layer.

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This paper presents modeling, fabrication and characterization of two designs of two-axis gimbal-less, thin-film PZT driven micromirrors with 1mm 2 apertures. These micromirrors reach high frequencies for piston (21 kHz) and torsional modes (28.9 kHz) and the opt·D product achieves up to 20.7°·mm driven by a unipolar rectangular pulse of 10 V. The combination of high frequency operation and the high driving force of the piezoelectric actuators leads to a very short reaction time. Furthermore, by combining the two adjacent torsion modes of the micromirrors circle laser beam trajectories can be realized

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Ohmic MEMS switches can be operated reliable under DC load if important factors determining its reliability are considered as a whole. First of all, these are bi-directional actuation with high forces, a very low contact resistance and good heat dissipation. The present work describes the reliability of a surface-micromachined ohmic switch with gold contacts, combining all this features. Hot switching of 50mA at 10Vdc is possible in ambient air for more than 50 million cycles. With a load of 10mA more than 100 million cycles have been demonstrated repeatedly