Gas-Flow Sensor Based on Self-Oscillating and Self-Sensing Cantilever

Zöllner, Jens-Peter; Durstewitz, Steve; Stauffenberg, Jaqueline; Ivanov, Tzvetan; Holz, Mathias; Ehrhardt, Waleed; Riegel, W.-Ulrich; Rangelow, Ivo W.

doi:10.3390/proceedings2130846

Cited by 5 publications

(6 citation statements)

References 7 publications

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“…The transducer is realized as a silicon beam with integrated piezo-resistive deflection sensing and integrated thermo-mechanical actuation (Methods). Such transducers have already been successfully applied in atomic force microscopy and scanning probe lithography 44 , as well as other sensing tasks like gas flow sensing and gas mixture analysis 45,46 . The integration of actuation and sensing into the beam has the advantage of being able to implement real-time feedback loops.…”

Section: Sensing Propertiesmentioning

confidence: 99%

“…Here l Si is the length of the sensor, d Si is the thickness of the sensor, E Si is the elasticity module, ρ Si is the density of Si and δ n is a pre-factor for the nth mode. Quality factor Q 0 of an oscillating beam in air was derived elsewhere 45 and is mainly determined by damping due to the surrounding fluid. It can be calculated according to…”

Section: Theoretical Descriptionmentioning

confidence: 99%

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Neuromorphic acoustic sensing using an adaptive microelectromechanical cochlea with integrated feedback

et al. 2023

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Many speech processing systems struggle in conditions with low signal-to-noise ratios and in changing acoustic environments. Adaptation at the transduction level with integrated signal processing could help to address this; in human hearing, transduction and signal processing are integrated and can be adaptively tuned for noisy conditions. Here we report a microelectromechanical cochlea as a bio-inspired acoustic sensor with integrated signal processing functionality. Real-time feedback is used to tune the sensing and processing properties, and dynamic switching between linear and nonlinear characteristics improves the detection of signals in noisy conditions, increases the sensor dynamic range and enables adaptation to changing acoustic environments. The transition to nonlinear behaviour is attributed to a Hopf bifurcation and we experimentally validate its dependence on sensor and feedback parameters. We also show that output-signal coupling between two coupled sensors can increase the frequency coverage.

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Section: Sensing Propertiesmentioning

confidence: 99%

Section: Theoretical Descriptionmentioning

confidence: 99%

Neuromorphic acoustic sensing using an adaptive microelectromechanical cochlea with integrated feedback

et al. 2023

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“…A second effect relates to the drag force (

) resulting from the influence of the surrounding flowing gas over the resonator. The fluid course interacts with the solid structure, inducing a resonator deflection along the gas flow direction that depends on the fluid velocity (

), gas density (

), section of solid exposed to the fluid flow (

) and body geometry through drag coefficient (

), that can be quantified by the Reynolds number (Re) [ 21 ]:

As a consequence, the resonator is shifted from its zero-displacement equilibrium point to a new one where the anchors stiffness equals the drag force. This causes the well-known mechanical spring-hardening effect to take place: the resonator becomes stiffer for large deflections with the consequent increase in resonance frequency.…”

Section: Theoretical Analysismentioning

confidence: 99%

“…Another project developed a gas flowmeter based on a sail-shaped resonator working as an oscillator with a CMOS amplifier on a PCB connected to a flow chamber, obtaining a resolution as low as 0.2 mm/s [ 20 ]. Finally, a self-oscillating cantilever also proved flow sensing capabilities both in dynamic and static modes [ 21 ]. In any case, a detailed analysis of the impact of gas flow on a microelectromechanical resonator response remains an open topic.…”

Section: Introductionmentioning

confidence: 99%

Impact of Fluid Flow on CMOS-MEMS Resonators Oriented to Gas Sensing

Perelló-Roig

Verd

Bota

et al. 2020

Sensors

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Based on experimental data, this paper thoroughly investigates the impact of a gas fluid flow on the behavior of a MEMS resonator specifically oriented to gas sensing. It is demonstrated that the gas stream action itself modifies the device resonance frequency in a way that depends on the resonator clamp shape with a corresponding non-negligible impact on the gravimetric sensor resolution. Results indicate that such an effect must be accounted when designing MEMS resonators with potential applications in the detection of volatile organic compounds (VOCs). In addition, the impact of thermal perturbations was also investigated. Two types of four-anchored CMOS-MEMS plate resonators were designed and fabricated: one with straight anchors, while the other was sustained through folded flexure clamps. The mechanical structures were monolithically integrated together with an embedded readout amplifier to operate as a self-sustained fully integrated oscillator on a commercial CMOS technology, featuring low-cost batch production and easy integration. The folded flexure anchor resonator provided a flow impact reduction of 5× compared to the straight anchor resonator, while the temperature sensitivity was enhanced to −115 ppm/°C, an outstanding result compared to the −2403 ppm/°C measured for the straight anchored structure.

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“…[8] untersuchten unter Nutzung dieser Beziehungen die Bestimmung von Dichte und Viskosität von Gasen mittels Mikrocantilever. In [9]…”

Section: Einleitung In Die Thematikunclassified