@misc{VarlamovaReifStolzetal., author = {Varlamova, Olga and Reif, J{\"u}rgen and Stolz, Michael and Borcia, Rodica and Borcia, Ion-Dan and Bestehorn, Michael}, title = {Wetting properties of LIPSS structured silicon surfaces}, series = {The European Physical Journal B}, volume = {92}, journal = {The European Physical Journal B}, number = {5}, issn = {1434-6036}, doi = {10.1140/epjb/e2019-90672-2}, pages = {8}, abstract = {The controlled dynamics of liquid drops via generation of specific wetting states on a solid surface is of great interests both in the fundamental and applied sciences. Considering that the wettability is strongly dependent on the surface topography and surface roughness, we investigate - through experiments and theory - the effect of laser-induced periodic surface structures (LIPSS) generated on silicon (100) targets as a control parameter of wetting properties. To obtain structured silicon surfaces with different morphological features, we patterned the surface by irradiation with femtosecond pulses from an amplified Ti:Sapphire laser system (790 nm/100 fs/1 kHz) at a fluence in the range of 0.4-1.2 J/cm2 on a spot with a diameter about of 100 μm. Variation of the applied irradiation dose results in surface modifications with the roughness about of a few tens of nanometers are ranging from regular LIPSS patterns with the lateral period of about 500-700 nm to complex agglomerations of 3-D microstructures with several-μm feature size. The theoretical study on the correlation of wetting properties with the surface topography has been performed within a phase field model. We found an excellent agreement of numerical results with experiments.}, 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}, title = {Electrostatic all-silicon MEMS audio transducer 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{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{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} } @inproceedings{GaudetUhligStolzetal., author = {Gaudet, Matthieu and Uhlig, Sebastian and Stolz, Michael and Arscott, S. and Conrad, Holger and Langa, Sergiu and Kaiser, Bert and Schenk, Harald}, title = {Electrostatic bending actuators with liquid filled nanometer scale gap}, series = {MEMS 2017, the 30th IEEE International Conference on Micro Electro Mechanical Systems, Las Vegas, Nevada, USA, January 22-26 2017}, booktitle = {MEMS 2017, the 30th IEEE International Conference on Micro Electro Mechanical Systems, Las Vegas, Nevada, USA, January 22-26 2017}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-5090-5078-9}, pages = {175 -- 178}, language = {en} } @misc{LangaConradKaiseretal., author = {Langa, Sergiu and Conrad, Holger and Kaiser, Bert and Stolz, Michael and Gaudet, Matthieu and Uhlig, Sebastian and Schimmanz, Klaus and Schenk, Harald}, title = {Technological aspects of a new micro-electro-mechanical actuation principle: nano e-drive}, series = {Microsystem Technologies}, volume = {23}, journal = {Microsystem Technologies}, number = {1}, issn = {1432-1858}, doi = {10.1007/s00542-017-3360-6}, pages = {5697 -- 5708}, language = {en} } @misc{ConradSchenkKaiseretal., author = {Conrad, Holger and Schenk, Harald and Kaiser, Bert and Langa, Sergiu and Gaudet, Matthieu and Schimmanz, Klaus and Stolz, Michael and Lenz, Miriam}, title = {A small-gap electrostatic micro-actuator for large deflections}, series = {Nature Communications}, journal = {Nature Communications}, number = {6}, issn = {2041-1723}, doi = {10.1038/ncomms10078}, pages = {10078}, language = {en} } @inproceedings{SchenkConradGaudetetal., author = {Schenk, Harald and Conrad, Holger and Gaudet, Matthieu and Uhlig, Sebastian and Kaiser, Bert and Langa, Sergiu and Stolz, Michael and Schimmanz, Klaus}, title = {A novel electrostatic micro-actuator class and its application potential for optical MEMS}, series = {2016 International Conference on Optical MEMS and Nanophotonics,31 July-04 August 2016, Singapore, proceedings}, booktitle = {2016 International Conference on Optical MEMS and Nanophotonics,31 July-04 August 2016, Singapore, proceedings}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-5090-1036-3}, doi = {10.1109/OMN.2016.7565867}, pages = {Tu 3.11-1 -- Tu 3.11-2}, language = {en} } @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{MelnikovSchenkMonsalveetal., author = {Melnikov, Anton and Schenk, Hermann A. G. and Monsalve, 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} }