@misc{AssafoLautschSuawaetal., author = {Assafo, Maryam and Lautsch, Martin and Suawa, Priscile Fogou and Jongmanns, Marcel and H{\"u}bner, Michael and Reichenbach, Marc and Brockmann, Carsten and Reinhardt, Denis and Langend{\"o}rfer, Peter}, title = {The ForTune Toolbox: Building Solutions for Condition-Based and Predictive Maintenance Focusing on Retrofitting}, publisher = {VDE Verlag}, address = {Berlin}, isbn = {978-3-8007-6204-0}, pages = {S. 541}, language = {en} } @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{MonsalveJongmannsKochetal., author = {Monsalve, Jorge M. and Jongmanns, Marcel and Koch, Sandro G. and Schenk, Harald}, title = {Flow measurement by means of wideband acoustic signals in single-mode waveguides}, series = {Journal of sensors and sensor systems}, volume = {14}, journal = {Journal of sensors and sensor systems}, number = {2}, publisher = {Copernicus Publications}, address = {G{\"o}ttingen, Germany}, issn = {2194-878X}, doi = {10.5194/jsss-14-275-2025}, pages = {275 -- 284}, abstract = {A novel concept of an acoustic flowmeter, based on single-mode waveguides, is proposed, implemented, and analysed in this work. Instead of transmitting a pulse diagonally across the duct's cross-section, this device operates with two ducts that operate simultaneously as pipes and as waveguides. Below the frequency threshold for single-mode propagation, acoustic waves are forced to traverse the waveguides with a plane front, precluding the possibility of beam drifting, inner reflections, and spreading losses. This enables the designer to flexibly increase the sound path and perform a highly sensitive measurement of the flow velocity and speed of sound, even if the excitation frequency is required to be kept below a relatively low value. A device based on this principle was constructed and tested for flow measurements in air. It consists of two waveguides of a circular cross-section (5 mmdiameter) coupled to electroacoustic transducers for the transmission of a wideband chirp (9.8-18.2 kHz). Usage of a wideband signal was possible due to the combined frequency response of a special kind of micromachined ultrasound transducer (MUT) and a commercial micro-electromechanical system (MEMS) microphone. The constructed flowmeter was capable of measuring flow velocities up until the transition to turbulent flow at 16 Lmin-1with a resolution of 0.3 Lmin-1, and it also detected changes of less than 0.2 ms-1in the speed of sound. This topology for flow measurement could prove advantageous for applications where gases of variable composition are conducted in ducts of diameters in the millimetre range.}, language = {en} }