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261 results on '"Wallrabe U"'

6. Design rule and orientation layout for MEMS curved beams on silicon

Author

Tzung-Ming Chen, Zhenyu Liu, Korvink, J.G., and Wallrabe, U.

Subjects
Elasticity -- Analysis, Friction -- Control, Microelectromechanical systems -- Design and construction, Microstructure -- Mechanical properties, Microstructure -- Design and construction, Silicon -- Mechanical properties, Silicon -- Electric properties, Engineering and manufacturing industries, Science and technology
Published
2010

11. Torque evaluation of a LIGA fabricated electrostatic micromotor

Author

Samper, V.D., Sangster, A.J., Reuben, R.L., and Wallrabe, U.

Subjects
Electrostatics -- Research, Microstructure -- Research, Torque -- Measurement, Engineering and manufacturing industries, Science and technology
Abstract

The dynamic analysis of a twin stator electrostatic wobble motor is presented incorporating finite element electric field predictions and rolling and sliding friction models. The problem of torque measurement in actual devices is then examined and a solution is described which allows the evaluation of torques smaller than [10.sup.-7] Nm without affecting the wobble motion of the device. Theoretical and practical results for actual devices are compared. [308] Index Terms - Electrostatic, LIGA, micromotor, torque, wobble.

Published
1999

12. Advanced LIGA technology for the integration of an electrostatically controlled bearing in a wobble micromotor

Author

Samper, V.D., Sangster, A.J., Wallrabe, U., Reuben, R.L., and Grund, J.K.

Subjects
Advanced materials -- Research, Bearings (Machinery) -- Design and construction, Electric motors -- Design and construction, Electrostatic apparatus and appliances -- Research, Engineering and manufacturing industries, Science and technology
Abstract

This work concerns the alleviation of friction in a novel design of multistator electrostatic wobble motor. The output torque and the kinematic accuracy of this device are limited by the sliding friction between the rotor and the top surface of the bearing. A solution for an axial bearing has been developed using an advanced LIGA technique to integrate polymethylmethacrylate (PMMA) cylinders into nickel micro structures. A new version of the micromotor has been fabricated, utilizing an axial electrostatic field to hold the rotor against an engineered sliding surface. The integrated bearing stabilizes the rotor and potentially permits operation in liquid environments by sealing the stator electrodes. [334] Index Terms - Electrostatic bearing, electrostatic motor, LIGA process, micromotor, wobble motor.

Published
1998

14. Multistator LIGA-fabricated electrostatic wobble motors with integrated synchronous control

Author

Samper, V.D., Sangster, A.J., Reuben, R.L., and Wallrabe, U.

Subjects
Electrostatics -- Analysis, Rotors -- Design and construction, Actuators -- Design and construction, Nanotechnology -- Research, Engineering and manufacturing industries, Science and technology
Abstract

A novel design of an electrostatic wobble motor is presented, which incorporates multiple concentric rotor-stator surface pairs to increase the space-usage efficiency and a segmented bearing for the implementation of synchronous control. The device has been successfully fabricated using the Lithographie, Galvanoformung, Abformung (LIGA) technique. The finite-element method is used to predict the available output torque, and the potential for extracting the useful output from the device is assessed. Index Terms - Electrostatic, LIGA process, synchronous control, wobble motor.

Published
1998

16. Energy-aware 3D micro-machined inductive suspensions with polymer magnetic composite core

Author

Poletkin, K.V., Lu, Z., Moazenzadeh, A., Mariappan, S.G., Korvink, J.G., Wallrabe, U., and Badilita, V.

Subjects
ddc:620, Engineering & allied operations
Abstract

This paper addresses the issue of Joule heating in micromachined inductive suspensions (MIS) and reports a significant decrease of the operating temperature by using a polymer magnetic composite (PMC) core. The PMC material has a high resistivity, thus inhibiting the formation of eddy currents, and a high permeability, thus guiding the magnetic field more efficiently within the MIS structure. We experimentally study the distribution of the PMC material inside the MIS structure and evaluate the effect of the core from the dependence of the levitation height on the excitation current. The experiments carried on in ambient room temperature demonstrate that the temperature inside the micromachined inductive suspension is reduced to 58°C, which is a record-low temperature compared to other MIS structures reported before.

Published
2018

18. Magnetic Lenz lenses improve the limit-of-detection in nuclear magnetic resonance

Author

Spengler, N., While, P. T., Meissner, M. V., Wallrabe, U., and Korvink, J. G.

Subjects
ddc:620, Engineering & allied operations
Abstract

A high NMR detection sensitivity is indispensable when dealing with mass and volume-limited samples, or whenever a high spatial resolution is required. The use of miniaturised RF coils is a proven way to increase sensitivity, but situations may arise where space restrictions could prevent the use of a small resonant coil, e.g., in the interior of the smallest practicable micro-coils. We present the use of magnetic lenses, denoted as Lenz lenses due to their working principle, to focus the magnetic flux of an RF coil into a smaller volume and thereby locally enhance the sensitivity of the NMR experimentÐat the expense of the total sensitive volume. Besides focusing, such lenses facilitate re-guiding or re-shaping of magnetic fields much like optical lenses do with light beams. For the first time we experimentally demonstrate the use of Lenz lenses in magnetic resonance and provide a compact mathematical description of the working principle. Through simulations we show that optimal arrangements can be found.

Published
2017

31. Undisturbed interferometric sensing through a fluid interface by electrically-tunable lenses and micro mirrors

Author

Czarske, Jürgen, Leithold, C., Radner, Hannes, Büttner, Lars, Stürmer, Moritz, Wallrabe, U., Czarske, Jürgen, Leithold, C., Radner, Hannes, Büttner, Lars, Stürmer, Moritz, and Wallrabe, U.

Abstract

We have harnessed the power of various programmable photonics devices for an interferometric measurement technique. Distortion-free laser-based velocity measurements through a dynamic gas-liquid interface are enabled by a closed-loop optoelectronic system. We are employing electrically tunable lenses and micro mirrors to correct low-order wavefront distortions effectively. Our work represents a paradigm shift in interferometric velocity measurement techniques from using static to dynamic optical elements.

Published
2015

40. Scannable optofluidic slit

Author

Schuhladen, S., primary, Banerjee, K., additional, Stuermer, M., additional, Mueller, P., additional, Wallrabe, U., additional, and Zappe, H., additional

Published
2014
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