@misc{RuffertSchenkKaiseretal., author = {Ruffert, Christine and Schenk, Hermann A. G. and Kaiser, Bert and Ehrig, Lutz and Monsalve Guaracao, Jorge Mario and Langa, Sergiu and Wall, Franziska and Melnikov, Anton and Stolz, Michael and Morsk, Andreas and Schuffenhauer, David and Conrad, Holger and Schenk, Harald}, title = {Elektrostatischer Gegentakt NED-Aktor f{\"u}r Im-Ohr-µLautsprecher}, doi = {10.24406/publica-2553}, language = {de} } @misc{RuffertJongmannsKaiseretal., author = {Ruffert, Christine and Jongmanns, Marcel and Kaiser, Bert and Langa, Sergiu}, title = {Design and characterization of a silicon MEMS microvalve for proportional flow control based on electrostatic bending actuators}, series = {Microsystem Technologies}, volume = {2024}, journal = {Microsystem Technologies}, issn = {1432-1858}, doi = {10.1007/s00542-024-05684-1}, pages = {8}, abstract = {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.}, language = {en} } @misc{RuffertMonsalveGuaracaoVoelzetal., author = {Ruffert, Christine and Monsalve Guaracao, Jorge Mario and V{\"o}lz, Uwe and Jongmanns, Marcel and Betz, Bj{\"o}rn and Langa, Sergiu and Amelung, J{\"o}rg and Wiersig, Marcus}, title = {Rapid characterisation of mixtures of hydrogen and natural gas by means of ultrasonic time-delay estimation}, series = {Journal of Sensors and Sensor Systems}, volume = {13}, journal = {Journal of Sensors and Sensor Systems}, number = {2}, issn = {2194-878X}, doi = {10.5194/jsss-13-179-2024}, pages = {185}, abstract = {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.}, language = {en} } @misc{UhligGaudetLangaetal., author = {Uhlig, Sebastian and Gaudet, Matthieu and Langa, Sergiu and Ruffert, Christine and Jongmanns, Marcel and Schenk, Harald}, title = {Highly integrable silicon micropumps using lateral electrostatic bending actuators}, series = {Microsystem Technologies}, volume = {30}, journal = {Microsystem Technologies}, number = {8}, publisher = {Springer Science and Business Media LLC}, issn = {0946-7076}, doi = {10.1007/s00542-024-05635-w}, pages = {949 -- 960}, abstract = {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.}, language = {en} } @misc{GuaracoLangaStolzetal., author = {Guaraco, Jorge Mario Monsalve and Langa, Sergiu and Stolz, Michael and Mrosk, Andreas and Kaiser, Bert and Schenk, Harald}, title = {Design of micromachines under uncertainty with the sample-average approximation method}, series = {Journal of Advanced Mechanical Design, Systems, and Manufacturing}, volume = {18 (2024)}, journal = {Journal of Advanced Mechanical Design, Systems, and Manufacturing}, number = {2}, publisher = {Japan Society of Mechanical Engineers}, issn = {1881-3054}, doi = {10.1299/jamdsm.2024jamdsm0018}, language = {en} } @misc{MelnikovSchenkMonsalveGuaracaoetal., author = {Melnikov, Anton and Schenk, Hermann A. G. and Monsalve Guaracao, Jorge Mario and Wall, Franziska and Stolz, Michael and Mrosk, Andreas and Langa, Sergiu and Kaiser, Bert}, title = {Coulomb-actuated microbeams revisited: experimental and numerical modal decomposition of the saddle-node bifurcation}, series = {Microsystems \& Nanoengineering}, volume = {7}, journal = {Microsystems \& Nanoengineering}, number = {1}, issn = {2055-7434}, doi = {10.1038/s41378-021-00265-y}, abstract = {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.}, language = {en} } @misc{SchenkLanga, author = {Schenk, Harald and Langa, Sergiu}, title = {MEMS-Bauelement und Verfahren zum Herstellen eines MEMS-Bauelements}, abstract = {Ein Verfahren zum Herstellen eines MEMS-Bauelements umfasst ein Bereitstellen eines Halbleitersubstrats, ein Ausf{\"u}hren eines anisotropen nasschemischen {\"A}tzprozesses in dem Halbleitersubstrat, um zumindest ein bewegliches Element aus dem Halbleitersubstrat herauszubilden, und ein Erzeugen eines Schichtstapels, so dass das bewegliche Element in einer Kavit{\"a}t und in einer ersten MEMS-Schicht zwischen einer zweiten MEMS-Schicht und einer dritten MEMS-Schicht angeordnet ist, um mit einem in der Kavit{\"a}t angeordneten Fluid zu interagieren.}, language = {de} } @misc{SchenkConradGaudetetal., author = {Schenk, Harald and Conrad, Holger and Gaudet, Matthieu and Schimmanz, Klaus and Langa, Sergiu and Kaiser, Bert}, title = {MEMS transducer for interacting with a volume flow of a fluid and method for manufacturing the same}, abstract = {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.}, language = {en} }