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 - 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 - 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 - Ruffert, Christine A1 - Monsalve Guaracao, Jorge Mario A1 - Völz, Uwe A1 - Jongmanns, Marcel A1 - Betz, Björn A1 - Langa, Sergiu A1 - Amelung, Jörg A1 - Wiersig, Marcus T1 - Rapid characterisation of mixtures of hydrogen and natural gas by means of ultrasonic time-delay estimation T2 - Journal of Sensors and Sensor Systems N2 - The implementation of the “power-to-gas” concept, where hydrogen and natural gas are blended and transported in the existing network, requires a quick, on-site method to monitor the content of hydrogen in the mixture. We evaluate a rapid characterisation of this mixture based on the measurement of the speed of sound, using micromachined ultrasonic transducers (MUTs). Two MUT-based prototypes were implemented to analyse a mixture of natural gas and hydrogen under controlled conditions. Changes in the hydrogen content below 2 mol % (in a mixture that was adjusted between 6 mol % and 16 mol %) were discriminated by both devices, including the uncertainty due to the temperature compensation and the time-delay estimation. The obtained values of the speed of sound were consistent with those calculated from independent, non-acoustic measurements performed with a gas chromatograph and a density sensor. An MUT-based flow meter is thus capable of reporting both gas intake and the molar fraction of hydrogen, provided that the source of natural gas is kept constant. Y1 - 2024 U6 - https://doi.org/10.5194/jsss-13-179-2024 SN - 2194-878X VL - 13 IS - 2 SP - 185 ER - TY - GEN A1 - Uhlig, Sebastian A1 - Gaudet, Matthieu A1 - Langa, Sergiu A1 - Ruffert, Christine A1 - Jongmanns, Marcel A1 - Schenk, Harald T1 - Highly integrable silicon micropumps using lateral electrostatic bending actuators T2 - Microsystem Technologies N2 - We present the design, fabrication, and characterization of an innovative silicon-based micropump with high potential for portable lab-on-chip (LoC) as well as point-of-care (PoC) applications. The actuators of the pump are electrostatic driven in-plane bending devices, which were presented earlier (Borcia et al. in Phys Rev Fluids 3(8): 084202, 2018. 10.1103/PhysRevFluids.3.084202; Uhlig et al. in Micromachines, 9(4), 2018. 10.3390/mi9040190). This paper presents the characterization results achieved with the micropump. The dielectric non-polar liquid Novec7100™ was used as a test liquid due to its adequate physical properties. When applying a periodic voltage of 130 V, a flow rate of up to 80 µL/min was detected. The counter pressure amounts up to 30 kPa and the correspondent fluidic power (volumetric flow rate times the counter pressure) was calculated to 10 µW. The pump contains passive flap valves at the inlet and outlet, which are based on a bending cantilever design. Depending on the application requirements, the micropump can be designed modularly to adjust the specific parameters by an adequate arrangement of pump base units. In this paper, the proof of principle is shown using a single base unit with different number of stacked NED-actuator beams, as well as the serial arrangement of base units. Both modular concepts target the increase of backpressure of the NED-micropump in an inherently different way compared to conventional membrane micropumps. Y1 - 2024 U6 - https://doi.org/10.1007/s00542-024-05635-w SN - 0946-7076 VL - 30 IS - 8 SP - 949 EP - 960 PB - Springer Science and Business Media LLC 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 - PAT A1 - Schenk, Harald A1 - Langa, Sergiu T1 - MEMS-Bauelement und Verfahren zum Herstellen eines MEMS-Bauelements N2 - Ein Verfahren zum Herstellen eines MEMS-Bauelements umfasst ein Bereitstellen eines Halbleitersubstrats, ein Ausführen eines anisotropen nasschemischen Ätzprozesses in dem Halbleitersubstrat, um zumindest ein bewegliches Element aus dem Halbleitersubstrat herauszubilden, und ein Erzeugen eines Schichtstapels, so dass das bewegliche Element in einer Kavität und in einer ersten MEMS-Schicht zwischen einer zweiten MEMS-Schicht und einer dritten MEMS-Schicht angeordnet ist, um mit einem in der Kavität angeordneten Fluid zu interagieren. Y1 - 2023 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 -