@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{MeiselMelnikovAlexanderetal., author = {Meisel, Tenia and Melnikov, Anton and Alexander, Adrian and Br{\"a}ndel, Tim and Monsalve, Jorge M. and Kaiser, Bert and Schenk, Haral}, title = {Directivity optimization of MEMS ultrasonic transducers by implementing acoustic horns}, series = {Proceedings of the 24th International Congress on Acoustics, Gyeongju, Republic of Korea, 24-28 October 2022}, journal = {Proceedings of the 24th International Congress on Acoustics, Gyeongju, Republic of Korea, 24-28 October 2022}, pages = {9}, abstract = {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.}, language = {en} } @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} }