TY - GEN A1 - Langa, Sergiu A1 - Conrad, Holger A1 - Kaiser, Bert A1 - Stolz, Michael A1 - Gaudet, Matthieu A1 - Uhlig, Sebastian A1 - Schimmanz, Klaus A1 - Schenk, Harald T1 - Technological aspects of a new micro-electro-mechanical actuation principle: nano e-drive T2 - Microsystem Technologies Y1 - 2017 U6 - https://doi.org/10.1007/s00542-017-3360-6 SN - 1432-1858 VL - 23 IS - 1 SP - 5697 EP - 5708 ER - TY - GEN A1 - Uhlig, Sebastian A1 - Gaudet, Matthieu A1 - Langa, Sergiu A1 - Schimmanz, Klaus A1 - Conrad, Holger A1 - Kaiser, Bert A1 - Schenk, Harald T1 - Electrostatically driven in-plane silicon micropump for modular configuration T2 - Micromachines N2 - In this paper, an in-plane reciprocating displacement micropump for liquids and gases which is actuated by a new class of electrostatic bending actuators is reported. The so-called “Nano Electrostatic Drive” is capable of deflecting beyond the electrode gap distance, enabling large generated forces and deflections. Depending on the requirements of the targeted system, the micropump can be modularly designed to meet the specified differential pressures and flow rates by a serial and parallel arrangement of equally working pumping base units. Two selected, medium specific micropump test structure devices for pumping air and isopropanol were designed and investigated. An analytical approach of the driving unit is presented and two-way Fluid-Structure Interaction (FSI) simulations of the micropump were carried out to determine the dynamic behavior. The simulation showed that the test structure device designed for air expected to overcome a total differential pressure of 130 kPa and deliver a flow rate of 0.11 sccm at a 265 Hz driving frequency. The isopropanol design is expected to generate 210 kPa and pump 0.01 sccm at 21 Hz. The device is monolithically fabricated by CMOS-compatible bulk micromachining processes under the use of standard materials only, such as crystalline silicon, silicon dioxide and alumina. KW - micropump; electrostatic actuation; nano e-drive; in-plane reciprocating displacement micropump; MEMS Y1 - 2018 U6 - https://doi.org/10.3390/mi9040190 SN - 2072-666X VL - 9 IS - 4 ER - TY - CHAP A1 - Conrad, Holger A1 - Gaudet, Matthieu A1 - Kaiser, Bert A1 - Langa, Sergiu A1 - Stolz, Michael A1 - Schenk, Harald T1 - CMOS-kompatible elektrostatische Biegeaktoren (CMOS-compatible electrostatic actuators T2 - MikroSystemTechnik Kongress 2017, München, Germany, 23.-25. Oktober 2017 Y1 - 2017 SN - 978-3-8007-4491-6 SP - 219 EP - 222 PB - VDE-Verlag CY - Berlin [u.a.] ER - TY - CHAP A1 - Uhlig, Sebastian A1 - Gaudet, Matthieu A1 - Langa, Sergiu A1 - Schimmanz, Klaus A1 - Conrad, Holger A1 - Kaiser, Bert A1 - Schenk, Harald T1 - Electrostatically in-plane driven silicon micropump for modular configuration T2 - Conference proceedings, The 3rd Conference on MicroFluidic Handling Systems (MFHS 2017), 4 - 6 October 2017, Enschede, The Netherlands Y1 - 2017 UR - http://publica.fraunhofer.de/dokumente/N-477736.html SP - 57 EP - 60 PB - University of Twente CY - Enschede ER - TY - CHAP A1 - Conrad, Holger A1 - Ehrig, Lutz A1 - Kaiser, Bert A1 - Schenk, Hermann A1 - Schuffenhauer, David A1 - Stolz, Michael A1 - Gaudet, Matthieu A1 - Schenk, Harald T1 - CMOS-kompatibler MEMS-Lautsprecher für Im-Ohr-Anwendungen T2 - Tagungsband, DAGA 2018, 44. Deutsche Jahrestagung für Akustik, 19.-22. März 2018, München Y1 - 2018 SN - 978-3-939296-13-3 SP - 892 EP - 894 PB - Deutsche Gesellschaft für Akustik e.V. (DEGA) CY - Berlin ER - 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 - Ehrig, Lutz A1 - Kaiser, Bert A1 - Conrad, Holger A1 - Schenk, Hermann A1 - Schuffenhauer, David A1 - Stolz, Michael A1 - Gaudet, Matthieu A1 - Schenk, Harald A1 - Kolkovsky, Vladimir T1 - MEMS-Loudspeaker - A Novel Class of Electroacoustic Transducers for Mobile Audio Applications T2 - Tonmeistertagung - VDT International Convention, Cologne, Germany, 2018, Proc. TMT 30 N2 - Wireless earphones require a tremendous degree of integration: In addition to the electroacoustic transducer at least the power supply and a radio module have to be accommodated, supplemented by several microphones for hands-free applications or for noise reduction, as well as position and bio sensors, memory and CPU. With increasing integration, the pressure on the individual components increases in terms of size, energy efficiency and costs. In the field of microphones, MEMS technology has enjoyed great popularity for almost 10 years, and due to their benefits (size, cost, integration) MEMS microphones have almost completely supersede other microphone technologies in mobile audio devices and opened up new fields of applications. Y1 - 2018 VL - TMT 30 SP - 189 EP - 192 ER - TY - GEN A1 - Spitz, Barbara A1 - Wall, Franziska A1 - Schenk, Hermann A1 - Melnikov, Anton A1 - Ehrig, Lutz A1 - Langa, Sergiu A1 - Stolz, Michael A1 - Kaiser, Bert A1 - Conrad, Holger A1 - Schenk, Harald A1 - Pufe, Wolfram T1 - Audio-Transducer für In-Ear-Anwendungen auf der Basis CMOS-kompatibler, elektrostatischer Biegeaktoren T2 - MikroSystemTechnik-Kongress, Berlin, Germany, 2019 N2 - Recently an innovative mSpeaker technology, based on a novel kind of CMOS compatible small gap electrostatic actuators for large deflection, has been introduced [1]. In this paper, we devise methods to model such speakers in terms of lumped parameters using the deflection of the beam centre as sole dynamic variable. Optical, acoustical and finite element methods (FEM) are used to validate the non-linear lumped parameter model (LPM). The experimental evaluation and LPM simulations of the total harmonic distortion reveal deeper insights into the mechanisms governing linearity. Y1 - 2019 SP - 54 EP - 57 PB - VDE-Verlag ER - TY - GEN A1 - Kaiser, Bert A1 - Langa, Sergiu A1 - Ehrig, Lutz A1 - Stolz, Michael A1 - Schenk, Hermann A1 - Conrad, Holger A1 - Schenk, Harald A1 - Schimmanz, Klaus A1 - Schuffenhauer, David T1 - Concept and proof for an all-silicon MEMS micro speaker utilizing air chambers T2 - Microsystems and Nanoengineering N2 - MEMS-based micro speakers are attractive candidates as sound transducers for smart devices, particularly wearables and hearables. For such devices, high sound pressure levels, low harmonic distortion and low power consumption are required for industrial, consumer and medical applications. The ability to integrate with microelectronic circuitry, as well as scalable batch production to enable low unit costs, are the key factors benchmarking a technology. The Nanoscopic Electrostatic Drive based, novel micro speaker concept presented in this work essentially comprises in-plane, electrostatic bending actuators, and uses the chip volume rather than the its surface for sound generation. We describe the principle, design, fabrication, and first characterization results. Various design options and governing equations are given and discussed. In a standard acoustical test setup (ear simulator), a MEMS micro speaker generated a sound pressure level of 69 dB at 500 Hz with a total harmonic distortion of 4.4%, thus proving the concept. Further potential on sound pressure as well as linearity improvement is outlined. We expect that the described methods can be used to enhance and design other MEMS devices and foster modeling and simulation approaches. Y1 - 2019 U6 - https://doi.org/10.1038/s41378-019-0095-9 SN - 2055-7434 IS - 5 ER - TY - GEN A1 - Ehrig, Lutz A1 - Kaiser, Bert A1 - Schenk, Hermann A1 - Stolz, Michael A1 - Langa, Sergiu A1 - Conrad, Holger A1 - Schenk, Harald A1 - Männchen, Andreas A1 - Brocks, Tobias T1 - Acoustic validation of electrostatic all-silicon MEMS-speakers T2 - AES International Conference on Headphone Technology, San Francisco, New York, USA, 2019 Y1 - 2019 UR - https://www.aes.org/e-lib/browse.cfm?elib=20522 U6 - https://doi.org/10.17743/aesconf.2019.978-1-942220-29-9 ER - TY - GEN A1 - Ehrig, Lutz A1 - Schenk, Hermann A1 - Wall, Franziska A1 - Melnikov, Anton A1 - Stolz, Michael A1 - Langa, Sergiu A1 - Kaiser, Bert A1 - Conrad, Holger A1 - Schenk, Harald T1 - Electrostatic all silicon MEMS speakers for in-ear audio applications – acoustic measurements and modelling approach T2 - 23rd International Congress on Acoustics, Aachen, Germany, 2019 Y1 - 2019 U6 - https://doi.org/10.18154/RWTH-CONV-239893 ER - TY - GEN A1 - Melnikov, Anton A1 - Schenk, Hermann A1 - Wall, Franziska A1 - Spitz, Barbara A1 - Ehrig, Lutz A1 - Langa, Sergiu A1 - Kaiser, Bert A1 - Conrad, Holger A1 - Schenk, Harald A1 - Stolz, Michael T1 - Minimization of nonlinearities in nano electrostatic drive actuators using validated coupled-field simulation T2 - SPIE Conference: MOEMS and Miniaturized Systems XIX, San Francisco, USA, 2020, Proc. SPIE 11293 Y1 - 2020 U6 - https://doi.org/10.1117/12.2551271 ER - TY - GEN A1 - Schenk, Harald A1 - Stolz, Michael A1 - Langa, Sergiu A1 - Kaiser, Bert T1 - Reliability Aspects of in-plane NED Bending Actuators in Silicon-based MEMS T2 - MikroSystemTechnik Kongress 2021 : Mikroelektronik / Mikrosystemtechnik und ihre Anwendungen Innovative Produkte für zukunftsfähige Märkte 08. – 10. November 2021, Stuttgart-Ludwigsburg N2 - For several years, Fraunhofer IPMS has been developing a new type of an electrostatic MEMS actuator, called nanoscopic electrostatic drive - NED. Since the first publication in 2015, the project group at IPMS has succeeded in providing lateral actuators, which serve as innovative drives in applications such as micro-positioners or micro-speakers. These applications require a high long-term stability of the drive in order to ensure that the system operates as desired. For this purpose, the reliability of such novel lateral electrostatic actuators was evaluated. Long-term studies of NED actuators have shown that different degradation phenomena can occur during operation. The experiments indicate that high electric fields in the range of several MV/m are one of the most important triggers of the degradations observed. On the one hand, they lead to anodic oxidation occurring at the boundary layers between the NED electrodes and neighbored insulators, which results in corrosion of the silicon electrodes. On the other hand, geometry-based field enhancement far from the insulator interfaces lead to permanent field emission, which causes dark discharges in the electrode gap. This in turn leads to cold plasma oxidation and the growth of oxide b ulges on the electrode surfaces. In the course of the experiments, it was shown that corrosion does not take place in a vacuum and can be avoided with the help of passivation layers. Non silicon oxides, e.g. Al2O3, are well suited as passivation layers. Although they bring additional flexural rigidity to the overall structure, which changes the mechanical behavior of the actuators, they increase the effective relative permittivity in the electrode gap, which in turn makes the actuators more effective. Thanks to the passivation coating,the lifespan of the NED actuators was increased and they can become even more effective by choosing a layer with suitable properties. Y1 - 2021 UR - https://www.vde-verlag.de/proceedings-de/455656134.html SN - 978-3-8007-5656-8 SN - 978-3-8007-5657-5 PB - VDE-Verlag 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 Guaracao, 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 - TY - GEN A1 - Monsalve Guaracao, Jorge Mario A1 - Melnikov, Anton A1 - Kaiser, Bert A1 - Schuffenhauer, David A1 - Stolz, Michael A1 - Ehrig, Lutz A1 - Schenk, Hermann A1 - Conrad, Holger A1 - Schenk, Harald T1 - Large-Signal Equivalent-Circuit Model of Asymmetric Electrostatic Transducers T2 - IEEE/ASME Transactions on Mechatronics N2 - This article presents a circuit model that is able to capture the full nonlinear behavior of an asymmetric electrostatic transducer whose dynamics are governed by a single degree of freedom. Effects such as stress-stiffening and pull-in are accounted for. The simulation of a displacement-dependent capacitor and a nonlinear spring is accomplished with arbitrary behavioral sources, which are a standard component of circuit simulators. As an application example, the parameters of the model were fitted to emulate the behavior of an electrostatic MEMS loudspeaker whose finite-element (FEM) simulations and acoustic characterisation where already reported in the literature. The obtained waveforms show good agreement with the amplitude and distortion that was reported both in the transient FEM simulations and in the experimental measurements. This model is also used to predict the performance of this device as a microphone, coupling it to a two-stage charge amplifier. Additional complex behaviors can be introduced to this network model if it is required. KW - Acoustic transducers KW - Duffing oscillator KW - Acoustic electrostatic actuators KW - equivalent-circuit model KW - microactuators KW - Electrostatics KW - Transducers KW - Mathematical models KW - Integrated circuit modeling KW - Capacitors KW - Microphones KW - Force Y1 - 2021 U6 - https://doi.org/10.1109/TMECH.2021.3112267 SN - 1083-4435 SN - 1941-014X VL - 7 IS - 5 SP - 2612 EP - 2622 ER - TY - GEN A1 - Kaiser, Bert A1 - Schenk, Hermann A. G. A1 - Ehrig, Lutz A1 - Wall, Franziska A1 - Monsalve Guaracao, Jorge Mario A1 - Langa, Sergiu A1 - Stolz, Michael A1 - Melnikov, Anton A1 - Conrad, Holger A1 - Schuffenhauer, David A1 - Schenk, Harald T1 - The push-pull principle: an electrostatic actuator concept for low distortion acoustic transducers T2 - Microsystems & Nanoengineering N2 - Electrostatic actuators are of particular interest for microsystems (MEMS), and in particular for MEMS audio transducers for use in advanced true wireless applications. They are attractive because of their typically low electrical capacitance and because they can be fabricated from materials that are compatible with standard complementary metal-oxide semiconductor (CMOS) technology. For high audio performance and in particular low harmonic distortion (THD) the implementation of the push-pull principle provides strong benefits. With an arrangement of three electrodes in a conjunct moving configuration on a beam, we demonstrate here for the first time a balanced bending actuator incarnating the push-pull principle operating at low voltages. Our first design already exhibits a harmonic distortion as low as 1.2% at 79 dB using a signal voltage of only 6 Vp and a constant voltage of only ±10 Vdc in a standard acoustic measurement setup. Thus, exceeding our previously reported approach in all three key performance indications at the same time. We expect that our novel electrode configurations will stimulate innovative electrostatic actuator developments for a broad range of applications. In this paper we report the basic theory, the fabrication and the performance of our novel actuator design acting as an audio transducer. Y1 - 2022 U6 - https://doi.org/10.1038/s41378-022-00458-z SN - 2055-7434 VL - Vol. 8 ER - TY - GEN A1 - Monsalve Guaracao, 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 - Wall, Franziska A1 - Schenk, Hermann A. G. A1 - Melnikov, Anton A1 - Kaiser, Bert A1 - Schenk, Harald T1 - A non-destructive electro-acoustic method to characterize the pull-in voltage of electrostatic actuators T2 - Nonlinear Dynamics N2 - For electrostatic actuators, the pull-in marks an upper limit for the operation range. Once reached, the electrodes come into contact and are shorted without further protection. A non-destructive measurement technique to predict this failure mode is of high interest to allow, e.g. fabrication monitoring or reliability studies. To this end, we develop a surprisingly simple nonlinear lumped parameter model (LPM) for a rather complex electrostatic actuator, designed for an in-ear loudspeaker application. It turns out that a single degree-of-freedom model with only one parameter is sufficient. Our key approach is to experimentally determine this free model parameter by analysing harmonic distortions at low frequencies. Harmonic distortions are a very sensitive tool for nonlinearities. Our method is suggested by simulations with a 2D stationary finite element method (FEM), demonstrating how the analysis of harmonic distortions for voltages far below the pull-in can predict not only the DC pull-in but also the quasi-static AC pull-in voltages at different working points. The distortion analysis of electrostatic actuator ensembles therefore seems a viable route for their non-destructive characterization in the nonlinear domain. KW - Pull-in KW - Electrostatic actuator KW - Microspeaker KW - Harmonic distortions Y1 - 2023 UR - https://link.springer.com/article/10.1007/s11071-023-08811-1 U6 - https://doi.org/10.1007/s11071-023-08811-1 SN - 1573-269X SN - 0924-090X VL - 111 IS - 19 SP - 17809 EP - 17818 ER - TY - GEN A1 - Monsalve Guaracao, Jorge Mario A1 - Kaiser, Bert A1 - Schenk, Harald T1 - Design of Micromachined Ultrasonic Transducers for Variability with the Sample-Average Approximation Method T2 - Tagungsband MikroSystemTechnik Kongress 2023, Dresden, 23. - 25. Oktober 2023 Y1 - 2023 SN - 978-3-8007-6204-0 SN - 978-3-8007-6203-3 SP - S. 639 PB - VDE Verlag CY - Berlin ER - TY - GEN A1 - Ruffert, Christine A1 - Schenk, Hermann A. G. A1 - Kaiser, Bert A1 - Ehrig, Lutz A1 - Monsalve Guaracao, Jorge Mario A1 - Langa, Sergiu A1 - Wall, Franziska A1 - Melnikov, Anton A1 - Stolz, Michael A1 - Morsk, Andreas A1 - Schuffenhauer, David A1 - Conrad, Holger A1 - Schenk, Harald T1 - Elektrostatischer Gegentakt NED-Aktor für Im-Ohr-µLautsprecher Y1 - 2023 UR - https://publica.fraunhofer.de/entities/publication/af8b72ee-2b53-4478-a964-a9dfb17ac3ad/details U6 - https://doi.org/10.24406/publica-2553 N1 - Im Rahmen der Mittelstandskonferenz 2023 in Berlin präsentiert. ER - TY - GEN A1 - Ruffert, Christine A1 - Jongmanns, Marcel A1 - Kaiser, Bert A1 - Langa, Sergiu T1 - Design and characterization of a silicon MEMS microvalve for proportional flow control based on electrostatic bending actuators T2 - Microsystem Technologies N2 - We designed a MEMS microvalve based on the nanoscopic electrostatic drive (NED) technology (Nat Commun 6:10078, 2015). NED actuators, electrostatically controlled bending beams, are implemented in a clamped-clamped configuration. A normally open plunger valve was designed and characterized. The device is manufactured from silicon. Gas flow rates of up to 37 SCCM can be proportionally controlled between 10% and 100%. A 10% leakage is always present at low backpressures (< 10 kPa) and increases to roughly 20% at 75 kPa backpressure. The structure has been tested up to backpressures of 300 kPa without damage to the structures, but the leakage increases to over 95%. Our unprecedented microvalve concept shows that it is possible to manufacture all-silicon MEMS microvalves with proportional control of the flow rate. The presented work is a proof of concept to test the capabilities of the NED technology for the use in microvalves. There are plans to decrease the leakage in future designs by introducing an additional sealing layer as well as manufacturing a shutter instead of a plunger design. Y1 - 2024 U6 - https://doi.org/10.1007/s00542-024-05684-1 SN - 1432-1858 SN - 0946-7076 VL - 2024 ER - TY - GEN A1 - Guaraco, Jorge Mario Monsalve A1 - Langa, Sergiu A1 - Stolz, Michael A1 - Mrosk, Andreas A1 - Kaiser, Bert A1 - Schenk, Harald T1 - Design of micromachines under uncertainty with the sample-average approximation method T2 - Journal of Advanced Mechanical Design, Systems, and Manufacturing Y1 - 2024 U6 - https://doi.org/10.1299/jamdsm.2024jamdsm0018 SN - 1881-3054 VL - 18 (2024) IS - 2 PB - Japan Society of Mechanical Engineers ER - TY - GEN A1 - Melnikov, Anton A1 - Schenk, Hermann A. G. A1 - Monsalve Guaracao, 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 - Meisel, Tenia A1 - Melnikov, Anton A1 - Alexander, Adrian A1 - Brändel, Tim A1 - Monsalve, Jorge M. A1 - Kaiser, Bert A1 - Schenk, Haral T1 - Directivity optimization of MEMS ultrasonic transducers by implementing acoustic horns T2 - Proceedings of the 24th International Congress on Acoustics, Gyeongju, Republic of Korea, 24–28 October 2022 N2 - The applications of microscopic ultrasonic transducers are often limited due to their non-optimal directivity pattern. The aim of this work is to design passive structures to adapt the directivity pattern to an intended application, e.g. range finder. The horns were designed and optimized using a Finite-Element-Method (FEM) model and manufactured by a conventional 3d-printing technique. The experimental validation was done using a novel MEMS-based ultrasonic transducer based on lateral actuation developed by Fraunhofer IPMS. This transducer type generates sound waves by displacing air inside a 3x3 mm² silicon chip using microscopic sized beams instead of using a diaphragm. This article presents several horn structures that exhibit a pronounced main lobe, inter alia an exponential horn and a folded horn with reduced overall dimensions, both optimized for an operatin g frequency of 40 kHz. We have shown numerically and experimentally that directivity properties of the transducer were significantly improved considering peak pressure, reduction of the side lobes and main lobe width by simple horn geometries. The implementation of the designed horns will enable additional applications where a specific directivity pattern is required. Furthermore, the given results imply th at the presented design strategies can be used to create various directivity patterns. KW - Acoustics KW - Acoustic horn KW - Directivity optimization KW - Ultrasonic transducer KW - Ultrasound Y1 - 2022 UR - https://www.researchgate.net/publication/365285295_Directivity_optimization_of_MEMS_ultrasonic_transducers_by_implementing_acoustic_horns ER - TY - PAT A1 - Schenk, Harald A1 - Conrad, Holger A1 - Gaudet, Matthieu A1 - Schimmanz, Klaus A1 - Langa, Sergiu A1 - Kaiser, Bert T1 - MEMS transducer for interacting with a volume flow of a fluid and method for manufacturing the same N2 - A MEMS transducer for interacting with a volume flow of a fluid includes a substrate including a cavity, and an electromechanical transducer connected to the substrate in the cavity and including an element deformable along a lateral movement direction, wherein a deformation of the deformable element along the lateral movement direction and the volume flow of the fluid are causally related. Y1 - 2025 ER -