@inproceedings{ConradEhrigKaiseretal., author = {Conrad, Holger and Ehrig, Lutz and Kaiser, Bert and Schenk, Hermann and Schuffenhauer, David and Stolz, Michael and Gaudet, Matthieu and Schenk, Harald}, title = {CMOS-kompatibler MEMS-Lautsprecher f{\"u}r Im-Ohr-Anwendungen}, series = {Tagungsband, DAGA 2018, 44. Deutsche Jahrestagung f{\"u}r Akustik, 19.-22. M{\"a}rz 2018, M{\"u}nchen}, booktitle = {Tagungsband, DAGA 2018, 44. Deutsche Jahrestagung f{\"u}r Akustik, 19.-22. M{\"a}rz 2018, M{\"u}nchen}, publisher = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (DEGA)}, address = {Berlin}, isbn = {978-3-939296-13-3}, pages = {892 -- 894}, language = {de} } @misc{StolzMroskKaiseretal., author = {Stolz, Michael and Mrosk, Andreas and Kaiser, Bert and Langa, Sergiu and Ehrig, Lutz and Conrad, Holger and Gaudet, Matthieu and Schenk, Harald}, title = {Optische Charakterisierungsmethoden von siliziumbasierten MEMS mit verdeckten Strukturen}, series = {MikroSystemTechnik-Kongress, Berlin, Germany, 2019}, journal = {MikroSystemTechnik-Kongress, Berlin, Germany, 2019}, publisher = {VDE-Verlag}, pages = {366 -- 369}, abstract = {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. Vollst{\"a}ndig 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 {\"u}ber einen Fre-quenzbereich von 20 Hz bis 20 kHz angeregt. Dabei sind die Strukturen oft verdeckt, was ihre Charakterisierung er-schwert. Es werden zerst{\"o}rungsfreie optische Methoden pr{\"a}sentiert, mit deren Hilfe die Bestimmung der mechanischen Schwingungseigenschaften einzelner Aktoren erm{\"o}glicht wird sowie die Beweglichkeit im verdeckten Zustand nach-gewiesen werden kann.}, language = {de} } @misc{EhrigKaiserConradetal., author = {Ehrig, Lutz and Kaiser, Bert and Conrad, Holger and Schenk, Hermann and Schuffenhauer, David and Stolz, Michael and Gaudet, Matthieu and Schenk, Harald and Kolkovsky, Vladimir}, title = {MEMS-Loudspeaker - A Novel Class of Electroacoustic Transducers for Mobile Audio Applications}, series = {Tonmeistertagung - VDT International Convention, Cologne, Germany, 2018, Proc. TMT 30}, volume = {TMT 30}, journal = {Tonmeistertagung - VDT International Convention, Cologne, Germany, 2018, Proc. TMT 30}, pages = {189 -- 192}, abstract = {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.}, language = {en} } @misc{SpitzWallSchenketal., author = {Spitz, Barbara and Wall, Franziska and Schenk, Hermann and Melnikov, Anton and Ehrig, Lutz and Langa, Sergiu and Stolz, Michael and Kaiser, Bert and Conrad, Holger and Schenk, Harald and Pufe, Wolfram}, title = {Audio-Transducer f{\"u}r In-Ear-Anwendungen auf der Basis CMOS-kompatibler, elektrostatischer Biegeaktoren}, series = {MikroSystemTechnik-Kongress, Berlin, Germany, 2019}, journal = {MikroSystemTechnik-Kongress, Berlin, Germany, 2019}, publisher = {VDE-Verlag}, pages = {54 -- 57}, abstract = {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.}, language = {de} } @misc{KaiserLangaEhrigetal., author = {Kaiser, Bert and Langa, Sergiu and Ehrig, Lutz and Stolz, Michael and Schenk, Hermann and Conrad, Holger and Schenk, Harald and Schimmanz, Klaus and Schuffenhauer, David}, title = {Concept and proof for an all-silicon MEMS micro speaker utilizing air chambers}, series = {Microsystems and Nanoengineering}, journal = {Microsystems and Nanoengineering}, number = {5}, issn = {2055-7434}, doi = {10.1038/s41378-019-0095-9}, pages = {11}, abstract = {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.}, language = {en} } @misc{EhrigKaiserSchenketal., author = {Ehrig, Lutz and Kaiser, Bert and Schenk, Hermann and Stolz, Michael and Langa, Sergiu and Conrad, Holger and Schenk, Harald and M{\"a}nnchen, Andreas and Brocks, Tobias}, title = {Acoustic validation of electrostatic all-silicon MEMS-speakers}, series = {AES International Conference on Headphone Technology, San Francisco, New York, USA, 2019}, journal = {AES International Conference on Headphone Technology, San Francisco, New York, USA, 2019}, doi = {10.17743/aesconf.2019.978-1-942220-29-9}, language = {en} } @misc{EhrigSchenkWalletal., author = {Ehrig, Lutz and Schenk, Hermann and Wall, Franziska and Melnikov, Anton and Stolz, Michael and Langa, Sergiu and Kaiser, Bert and Conrad, Holger and Schenk, Harald}, title = {Electrostatic all silicon MEMS speakers for in-ear audio applications - acoustic measurements and modelling approach}, series = {23rd International Congress on Acoustics, Aachen, Germany, 2019}, journal = {23rd International Congress on Acoustics, Aachen, Germany, 2019}, doi = {10.18154/RWTH-CONV-239893}, pages = {6}, language = {en} } @misc{MelnikovSchenkWalletal., author = {Melnikov, Anton and Schenk, Hermann and Wall, Franziska and Spitz, Barbara and Ehrig, Lutz and Langa, Sergiu and Kaiser, Bert and Conrad, Holger and Schenk, Harald and Stolz, Michael}, title = {Minimization of nonlinearities in nano electrostatic drive actuators using validated coupled-field simulation}, series = {SPIE Conference: MOEMS and Miniaturized Systems XIX, San Francisco, USA, 2020, Proc. SPIE 11293}, journal = {SPIE Conference: MOEMS and Miniaturized Systems XIX, San Francisco, USA, 2020, Proc. SPIE 11293}, doi = {10.1117/12.2551271}, language = {en} } @misc{SchenkMelnikovStolzetal., author = {Schenk, Harald and Melnikov, Anton and Stolz, Michael and Wall, Franziska and Kaiser, Bert and Mrosk, Andreas and Schuffenhauer, David and Monsalve Guaracao, Jorge Mario and Langa, Sergiu and Schenk, Hermann and Ehrig, Lutz and Conrad, Holger and Ahnert, Maik}, title = {Nonlinearity of balanced MEMS loudspeakers: optical experiments and numerical modeling using time-harmonic signals}, series = {27th International Congress on Sound and Vibration, Annual Congress of International Institute of Acoustics and Vibration (IIAV)}, journal = {27th International Congress on Sound and Vibration, Annual Congress of International Institute of Acoustics and Vibration (IIAV)}, pages = {7}, abstract = {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.}, language = {en} } @misc{MonsalveGuaracaoMelnikovKaiseretal., author = {Monsalve Guaracao, Jorge Mario and Melnikov, Anton and Kaiser, Bert and Schuffenhauer, David and Stolz, Michael and Ehrig, Lutz and Schenk, Hermann and Conrad, Holger and Schenk, Harald}, title = {Large-Signal Equivalent-Circuit Model of Asymmetric Electrostatic Transducers}, series = {IEEE/ASME Transactions on Mechatronics}, volume = {7}, journal = {IEEE/ASME Transactions on Mechatronics}, number = {5}, issn = {1083-4435}, doi = {10.1109/TMECH.2021.3112267}, pages = {2612 -- 2622}, abstract = {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.}, language = {en} }