Roman Beigelbeck
Danube University Krems
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Publication
Featured researches published by Roman Beigelbeck.
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control | 2010
Bernhard Jakoby; Roman Beigelbeck; Franz Keplinger; Frieder Lucklum; A.O. Niedermayer; Erwin K. Reichel; Christian Riesch; Thomas Voglhuber-Brunnmaier; Bernhard Weiss
This paper reviews our recent work on vibrating sensors for the physical properties of fluids, particularly viscosity and density. Several device designs and the associated properties, specifically with respect to the sensed rheological domain and the onset of non-Newtonian behavior, are discussed.
Journal of Applied Physics | 2004
Roman Beigelbeck; Bernhard Jakoby
In this article we investigate the spurious excitation of compressional waves by thickness-shear-mode resonators, which are commonly used for chemical sensing and viscosity sensing. In particular, we consider the excitation mechanism due to the nonuniform shear displacement present at the sensitive surface of the resonator. To illustrate the basic mechanism we analytically develop a general solution for a two-dimensional model describing the displacement and the pressure distribution in the liquid obtained in terms of Fourier integrals. We discuss these solutions and derive a useful approximation for the far field representing said compressional modes. We finally illustrate the results considering a practical example and associated numerical results.
Measurement Science and Technology | 2013
Roman Beigelbeck; Hannes Antlinger; Samir Cerimovic; Stefan Clara; Franz Keplinger; Bernhard Jakoby
Increasing demands for online monitoring of liquids have not only resuted in many new devices relying on well-established sensing parameters like shear viscosity but also initiated research on alternative parameters. Recently, the longitudinal viscosity has been evaluated as a promising candidate because the devices arising enable the bulk of the liquid to be probed rather than a thin surface layer. We report on a multi-purpose sensor which allows simultaneous measurement of the sound velocity and longitudinal viscosity of liquids. The device embodiment features a cube-shaped chamber containing the sample liquid, where one boundary surface carries a flush-mounted PZT transducer. In operation, the transducer induces standing, resonant pressure waves in the liquid under test. We studied the influences of sound velocity and longitudinal viscosity on the generated pressure waves by means of the Navier–Stokes equation for adiabatic compressible liquids and exploited both parameters as the basic sensing mechanism. Furthermore, a three-port network model describing the interaction of the transducer and sample liquid was developed in order to be applied for extracting the parameters of interest from the raw measurement data. Finally, we demonstrate the device and method by carrying out and discussing test measurements on glycerol–water solutions.
ieee sensors | 2008
Roman Beigelbeck; F. Kohl; Samir Cerimovic; A. Talić; Franz Keplinger; Bernhard Jakoby
We demonstrate that the thermal conductivity and diffusivity of fluids can be measured independently of their motion state utilizing a micromachined calorimetric sensor. The sensor membrane bears a heating resistor and two symmetrically arranged thermistors. By immersing the sensor into the laminar-flowing sample fluid and applying an AC heating current, the frequency response of the thermistor temperatures can be exploited to evaluate the thermal properties of the fluid. We developed a novel analytical model to describe the conductive transfer in the micromachined sensor as well as the fully conjugated heat transfer in the fluid. The validity of this model was confirmed experimentally by a practical example using nitrogen as fluid flowing through a rectangular flow channel. Based on these results, a thermal parameter extraction procedure can be deduced. Moreover, with known thermal parameters, the arrangement can also be used for flow measurements.
Measurement Science and Technology | 2011
Roman Beigelbeck; Herbert Nachtnebel; F. Kohl; Bernhard Jakoby
In recent decades, the demands for online monitoring of liquids in various applications have increased significantly. In this context, the sensing of the thermal transport parameters of liquids (i.e. thermal conductivity and diffusivity) may be an interesting alternative to well-established monitoring parameters like permittivity, mass density or shear viscosity. We developed a micromachined thermal property sensor, applicable to non-flowing liquids, featuring three in parallel microbridges, which carry either a heater or one of in total two thermistors. Its active sensing region was designed to achieve almost negligible spurious thermal shunts between heater and thermistors. This enables the adoption of a simple two-dimensional model to describe the heat transfer from the heater to the thermistors, which is mainly governed by the thermal properties of the sample liquid. Founded on this theoretical model, a novel measurement method for the thermal parameters was devised that relies solely on the frequency response of the measured peak temperature and allows simultaneous extraction of the thermal conductivity and diffusivity of liquids. In this contribution, we describe the device prototype, the model, the deduced measurement method and the experimental verification by means of test measurements carried out on five sample liquids.
IEEE Sensors Journal | 2012
Simone Dalola; Samir Cerimovic; F. Kohl; Roman Beigelbeck; J. Schalko; Vittorio Ferrari; Daniele Marioli; Franz Keplinger; Thilo Sauter
A smart system for flow measurement is presented, consisting of a micromachined thermal flow sensor combined with a smart front-end electronic interface. The flow sensor is based on a novel thermal transduction method, which combines the hot-film and calorimetric sensing principles. The sensor consists of four germanium thermistors embedded in a thin membrane and connected to form a Wheatstone bridge supplied with a constant DC current. In this configuration, both the bridge unbalance voltage and the voltage at the bridge supply terminals are functions of the flow offering high initial sensitivity, i.e., near zero flow and wide measurement range, respectively. The front-end interface is based on a CMOS relaxation oscillator circuit where the frequency and the duty cycle of a rectangular-wave output signal are related to the bridge unbalance voltage and the voltage at the bridge supply terminals, respectively. Furthermore, the amplitude of the output signal is a linear function of the operating temperature. In this way, a single output signal advantageously carries two pieces of information related to the flow velocity and provides an additional measurement of the sensor operating temperature, which enables the correction of the temperature dependence of the sensor readouts. The system has been experimentally characterized for the measurement of nitrogen gas flow velocity at different sensor temperatures. The initial sensitivities at room temperature result 13.7 kHz/(m/s) and 23.5%/(m/s), in agreement with FEM simulations, for frequency and duty cycle readouts, respectively, with an equivalent velocity resolution of about 0.5 and 1.3 cm/s.
international conference on solid state sensors actuators and microsystems | 2005
Franz Keplinger; Roman Beigelbeck; F. Kohl; Samuel Kvasnica; A. Jachimowicz; Bemhard Jakoby
Utilizing the symmetrical and the antisymmetrical vibration modes of a micromachined U-shaped cantilever, a magnetic field sensor, allowing the simultaneous measurement of two orthogonal field components, can be produced. This device enables the measurement of magnetic flux densities over seven decades (starting from about 10/sup -6/ T). We discuss analytical models describing various cantilever vibration modes and their verification by a device prototype.
ieee sensors | 2007
Roman Beigelbeck; F. Kohl; Franz Keplinger; J. Kuntner; Bernhard Jakoby
Design, simulation, and optimization of micromachined sensor devices often require accurate knowledge of thermal thin-film properties, e. g., for PECVD-Si3N4. These thermal parameters can differ considerably from those stated for bulk material and they are typically process-dependent. We developed a novel method to determine the thermal conductivity as well as the heat capacity of such thin-films based on a micromachined cantilever device. In this contribution, we describe a newly devised test device together with the associated extraction procedure and report on an experimental verification for a dielectric PECVD silicon nitride thin-film.
emerging technologies and factory automation | 2005
F. Kohl; Roman Beigelbeck; J. Sckalko; A. Jackimowicz
Miniaturized thermal flow sensors based on thin film technology and Si-micromachining offer air-flow sensitivities in the cm/s range and respond within milliseconds. The descending slope of the sensor characteristic gives sufficient dynamic compression to extend the flow measurement range over five orders of magnitude. With a novel design approach advanced transduction principles become feasible, which enable added system functionality like autonomous self-check, adaptive sensitivity and transduction fault analysis. Closed loop transduction and the redundancy of all key elements of the sensor are generic foundations of the approach. All temperature sensors and the thermal actuators are designed for pulsed-mode operation and match directly with the I/O characteristics of highly integrated microelectronic circuitry
Measurement Science and Technology | 2014
Thomas Voglhuber-Brunnmaier; A.O. Niedermayer; Roman Beigelbeck; Bernhard Jakoby
A recently introduced method for robust determination of the parameters of strongly damped resonances is evaluated in terms of achievable accuracy. The method extracts and analyzes the locus of the resonant subsystem of noisy recorded complex spectra, such that the interfering influences of many environmental factors are eliminated. Estimator performance is compared to the absolute lower limit determining the Cramer–Rao lower bound (CRLB) for the variance of the estimated parameters. A generic model that is suitable for representation of a large class of sensors is used and analyzed. It is shown that the proposed robust method converges to the CRLB for low measurement noise.