TY - GEN A1 - Stolz, Michael A1 - Mrosk, Andreas A1 - Kaiser, Bert A1 - Langa, Sergiu A1 - Ehrig, Lutz A1 - Conrad, Holger A1 - Gaudet, Matthieu A1 - Schenk, Harald T1 - Optische Charakterisierungsmethoden von siliziumbasierten MEMS mit verdeckten Strukturen T2 - MikroSystemTechnik-Kongress, Berlin, Germany, 2019 N2 - In der Arbeitsgruppe integrierte Siliziumsysteme des Fraunhofer IPMS werden am Standort Cottbus innovative Anwen-dungen eines neuartigen nanoskopischen elektrostatischen Antriebs (nanoskopic electrostatic drive – NED) untersucht. Eine der vielversprechendsten Anwendungen sind Lautsprecher. Vollständig aus Silizium gefertigte MEMS-Lautsprecher auf Basis von NED-Biegeaktoren werden vor den akustischen Messungen mechanisch und elektrisch cha-rakterisiert. Beidseitig eingespannte elektrostatisch betriebene in-plane NED-Aktoren werden dabei über einen Fre-quenzbereich von 20 Hz bis 20 kHz angeregt. Dabei sind die Strukturen oft verdeckt, was ihre Charakterisierung er-schwert. Es werden zerstörungsfreie optische Methoden präsentiert, mit deren Hilfe die Bestimmung der mechanischen Schwingungseigenschaften einzelner Aktoren ermöglicht wird sowie die Beweglichkeit im verdeckten Zustand nach-gewiesen werden kann. Y1 - 2019 UR - https://www.ipms.fraunhofer.de/de/events/2019/mst-kongress.html SP - 366 EP - 369 PB - VDE-Verlag ER - TY - GEN A1 - Melnikov, Anton A1 - Schenk, Hermann A. G. A1 - Monsalve, Jorge Mario A1 - Wall, Franziska A1 - Stolz, Michael A1 - Mrosk, Andreas A1 - Langa, Sergiu A1 - Kaiser, Bert T1 - Coulomb-actuated microbeams revisited: experimental and numerical modal decomposition of the saddle-node bifurcation T2 - Microsystems & Nanoengineering N2 - Electrostatic micromechanical actuators have numerous applications in science and technology. In many applications, they are operated in a narrow frequency range close to resonance and at a drive voltage of low variation. Recently, new applications, such as microelectromechanical systems (MEMS) microspeakers (µSpeakers), have emerged that require operation over a wide frequency and dynamic range. Simulating the dynamic performance under such circumstances is still highly cumbersome. State-of-the-art finite element analysis struggles with pull-in instability and does not deliver the necessary information about unstable equilibrium states accordingly. Convincing lumped-parameter models amenable to direct physical interpretation are missing. This inhibits the indispensable in-depth analysis of the dynamic stability of such systems. In this paper, we take a major step towards mending the situation. By combining the finite element method (FEM) with an arc-length solver, we obtain the full bifurcation diagram for electrostatic actuators based on prismatic Euler-Bernoulli beams. A subsequent modal analysis then shows that within very narrow error margins, it is exclusively the lowest Euler-Bernoulli eigenmode that dominates the beam physics over the entire relevant drive voltage range. An experiment directly recording the deflection profile of a MEMS microbeam is performed and confirms the numerical findings with astonishing precision. This enables modeling the system using a single spatial degree of freedom. KW - Engineering KW - NEMS KW - Sensors Y1 - 2021 U6 - https://doi.org/10.1038/s41378-021-00265-y SN - 2055-7434 VL - 7 IS - 1 ER - TY - GEN A1 - Monsalve, Jorge Mario A1 - Melnikov, Anton A1 - Stolz, Michael A1 - Mrosk, Andreas A1 - Jongmanns, Marcel A1 - Wall, Franziska A1 - Langa, Sergiu A1 - Marica-Bercu, Ioana A1 - Brändel, Tim A1 - Kircher, Marco A1 - Schenk, Hermann A. G. A1 - Kaiser, Bert A1 - Schenk, Harald T1 - Proof of concept of an air-coupled electrostatic ultrasonic transducer based on lateral motion T2 - Sensors and Actuators A: Physical N2 - An alternative implementation of an electrostatic MUT (Micromachined Ultrasonic Transducer), relying on multiple beams that displace along the chip’s surface instead of a single membrane displacing perpendicular to it, is presented in this work. With this approach, a design requiring a low bias voltage (24 V) and occupying a small area (3.3×3.3 mm², 2D/λ≈0.77) was shown to generate a sound pressure level of 82 dB (re. 20 µPa-rms) at 40 kHz and a distance of 8.9 cm. The high level of damping allows this transducer to operate in a wide frequency range (35-63 kHz). The operation of this device as an ultrasonic receiver was also proven. An implementation of this transducer as a rangefinder requires a strong reduction in the noise level, particularly coming from radio-frequency interference, in order to increase its detection range. Y1 - 2022 U6 - https://doi.org/10.1016/j.sna.2022.113813 SN - 1873-3069 SN - 0924-4247 VL - Vol. 345 ER - TY - GEN A1 - Schenk, Harald A1 - Melnikov, Anton A1 - Stolz, Michael A1 - Wall, Franziska A1 - Kaiser, Bert A1 - Mrosk, Andreas A1 - Schuffenhauer, David A1 - Monsalve, Jorge Mario A1 - Langa, Sergiu A1 - Schenk, Hermann A1 - Ehrig, Lutz A1 - Conrad, Holger A1 - Ahnert, Maik T1 - Nonlinearity of balanced MEMS loudspeakers: optical experiments and numerical modeling using time-harmonic signals T2 - 27th International Congress on Sound and Vibration, Annual Congress of International Institute of Acoustics and Vibration (IIAV) N2 - A recently introduced novel actuator class, called the nano electrostatic drive (NED), uses the elec-trostatic actuation to generate large deflections of elastic structures. The NED principle was recently successfully applied to create an all silicon loudspeaker based on micro-electro-mechanical systems (MEMS) technology. Such MEMS audio transducers cover the full frequency range required for high fidelity audio applications. High fidelity audio reproduction also demands minimizing harmonic distortions substantially below 1 %. A major advance in this direction is combining the NED principle with a push-pull driving scheme in a balanced design (BNED), eliminating even harmonics. The practical implementation of a BNED design is however demanding. The nature of the Coulomb force, the impact of stress stiffening and the large deformations required for generating high sound pressures, to name a few aspects, potentially contribute to the harmonic distortion and therefore need advanced experimental methods and simulation models to allow for an apt design. In this paper, we report first results of an experimental technique, combining an optical microscope with a high-speed camera, capable of analyzing the local details of the actuator movement at frame rates of 50,000 frames per second. Dynamic features, such as the excitation of harmonics and intermodulations become clearly visible. These experimental results are then used to scrutinize and refine our multi physics FEM simulations. Y1 - 2021 UR - https://www.researchgate.net/publication/354465569_Nonlinearity_of_balanced_MEMS_loudspeakers_optical_experiments_and_numerical_modeling_using_time-harmonic_signals ER -