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 - 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 - 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 - Monsalve, Jorge M. 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 - 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 - 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 - 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 - Schenk, Harald A1 - Conrad, Holger A1 - Gaudet, Matthieu A1 - Uhlig, Sebastian A1 - Kaiser, Bert A1 - Langa, Sergiu A1 - Stolz, Michael A1 - Schimmanz, Klaus T1 - A contribution to the expansion of the applicability of electrostatic forces in micro transducers T2 - MOEMS and Miniaturized Systems XVI, 30 January-1 February 2017, San Francisco, California, United States Y1 - 2017 SN - 978-1-5106-0674-6 SN - 978-1-5106-0673-9 U6 - https://doi.org/10.1117/12.2249575 PB - SPIE CY - Bellingham, Washington, USA ER -