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January 18, 2012
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January 18, 2012
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This paper discusses the design and realization of a micromachined micro Coriolis flow sensor with integrated electrodes for both electrostatic actuation and capacitive readout. The sensor was realized using semicircular channels just beneath the surface of the silicon wafer. The channels have thin silicon nitride walls to minimize the channel mass with respect to the mass of the moving fluid. A comb-shaped electrode design is used to prevent squeezed film damping so that the sensor can operate at atmospheric pressure, thus eliminating the need for vacuum packaging. The new sensor chip no longer requires large external magnets and the size of the chip itself has been reduced to 7.5×7.5 mm 2 . Zusammenfassung Der Beitrag berichtet über Design und Herstellung eines mikromechanischen Coriolis-Durchflusssensors mit integrierten Elektroden sowohl für die Anregung wie für das Auslesen. Der Sensor wurde realisiert mittels halbkreisförmiger Kanäle unterhalb der Siliziumoberfläche. Zur Minimierung der Masse bestehen die Kanalwände aus Siliziumnitrid. Ein kammförmiges Design der Elektroden wurde gewählt, um Dämpfung zu verhindern und damit das Arbeiten bei Atmosphärendruck zu ermöglichen. Das neue Sensorchip benötigt keine externe Magneten mehr und hat Abmessungen von nur noch 7,5×7,5 mm 2 .
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January 18, 2012
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A new coupling scheme for cavity enhanced absorption spectroscopy makes use of an intracavity acousto-optical modulator to actively switch light into (and out of) a resonator. This allows cavity ringdown spectroscopy (CRDS) to be implemented with broadband temporally incoherent light sources with low spectral power densities. The method is demonstrated for the first time using a broadband supercontinuum source.
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January 18, 2012
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A modular sensor concept for various gas measurement applications requiring high sensitivity and fast response time is presented. The proposed differential photoacoustic detection combines the selectivity of the traditional absorption method and the high sensitivity of the novel cantilever enhanced photoacoustic detector. High precision is achieved using short optical path length resulting in fast response time and wide dynamic measurement range. An example realization for greenhouse gas flux measurement is presented. Zusammenfassung Für verschiedenartige Gasmessungen, die hohe Empfindlichkeiten und schnelle Reaktionszeiten erfordern, wird ein modulares Sensorkonzept vorgestellt. Das dabei verwendete differentielle photoakustische Messprinzip kombiniert die Selektivität konventioneller Absorptionsmethoden mit der hohen Empfindlichkeit neuartiger photoakustischer Detektion mittels Schwingbalken. Hohe Messgenauigkeit wird durch eine kurze optische Weglänge erzielt und resultiert in schneller Reaktionszeit und hoher Dynamik. Als Beispielanwendung wir die Flussmessung von Treibhausgasen beschrieben.
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January 18, 2012
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With conventional methods sound velocity is determined by means of the back wall echo or a reflector at a known position. This paper presents a novel approach for combined measurement of both the sound velocity and the distance in fluids with scattering particles. The basic idea is that the echo becomes strongest when the scattering particle is located within the maximum of the sound field, and thus the position of that maximum along the measuring depth is related to the respective time of flight. The paper gives a proof of concept by measurements in fluids covering the wide range of sound velocities between 1116 m / s and 2740 m / s with an ultrasonic transducer equipped with a lens. In a detailed measurement using water at different temperatures, an uncertainty of the velocity determination of less than 0.1% was achieved. Further experiments and simulations with an annular array demonstrate that the focus position can be varied without moving the transducer, and thus sound velocity profiles can be measured.
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January 18, 2012
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The design of modern sensors, which are often realized by Micro-Electro-Mechanical Systems (MEMS) technologies, strongly depends on the availability of appropriate computer aided engineering (CAE) tools, since the fabrication of each prototype is quite costly. We present the finite network as well as the Finite Element (FE) approach used for the design of a silicon microphone, and show how both methods in combination are indispensable tools for an efficient development process.
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January 18, 2012
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Lab-on-a-chip systems are essential the current research and are expanding towards clinical applications. The system integration of sensors for the analysis of the specimens is a new challenge in the design process of all system components for lab on a chip devices. In this article the requirements for a system and sensor integration are defined and the developed analysis system are presented.
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January 18, 2012
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A novel principle for an optical absolute position encoder is presented which is based on the diffraction of light. Optimized for the integration into miniature linear motors, the encoder is designed to enable highly dynamic, micrometer precise positioning in clean room environments. For the first time it is shown how q -ary pseudo-random-sequences can be coded by optical diffraction, enabling improvements in e. g. code-efficiency, ability of integration, and robustness.
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January 18, 2012
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With spreading of the fibre-Bragg-grating (FBG) based sensor technology the demand for highly accurate sensors is growing. This study shows the limitation of the accuracy of standard FBG-sensors (FBGS) and an approach is presented to the development of highly accurate FBGS. FBGs inscribed into highly birefringent (HiBi) optical fibres show promising properties to reach an accuracy higher than Standard-FBG. In this study FBGs were inscribed into several HiBi-fibres and the effective refractive indices as well as the birefringence were determined. These investigations are important to establish a reproducible fabrication process for HiBi-FBGs that can be used for highly accurate fibre based measurements.
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January 18, 2012
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A wide range of processes in the fields of medicine, biotechnology, process engineering, as well as chemical analyses require a specific detection and quantification of certain substances like heavy metals, antibiotics, or metabolic intermediates. Numerous recent studies have clearly demonstrated the ability of biological transducers to cope with such measurement tasks. This paper presents the development of an integrated Whole-Cell sensor, which is based on the detection of a dependent fluorescence. Thereby we investigate the potential of a compact and robust optical biosensor.
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January 18, 2012
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The detection of gases is a rather new application of infrared thermal imaging. The industrial importance of several gases led to the development of sensitive cameras using narrowband filters. Such cameras are commercially available for the detection of volatile organic compounds, SF 6 , and CO. Results are presented for IR imaging of CO 2 and potential applications are discussed.
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January 18, 2012
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Infrared-based oil condition sensors provide valuable information about the condition of gears and thus permit long-term planning of maintenance work. Currently available systems are mainly based on non-dispersive methods providing information about one single oil condition parameter only. In many cases they are even adapted to only one type of oil. Miniaturized infrared spectrometers offer the possibility to simultaneously acquire a wealth of relevant oil condition parameters and are also applicable to a broad range of oil types. In this paper we present a method for selecting an appropriate spectral apparatus based on a multivariate calibration. We also show and discuss limitations of the respective spectral apparatus in terms of spectral bandwidth, resolution, and SNR on the quality of spectral data analysis. In addition, the realization and measurement results of a miniaturized infrared spectrometer are shown based on a linear variable filter (LVF) for gear oil monitoring of offshore wind turbine gearboxes.
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January 18, 2012