Brand, Oliver

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Now showing 1 - 10 of 18
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    NanoFANS Fall 2017 Forum: Introduction
    (Georgia Institute of Technology, 2017-10-19) Brand, Oliver
    Introduction for the Fall 2017 NanoFANS Forum.
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    NanoFANS Spring 2017 Forum: Introduction
    (Georgia Institute of Technology, 2017-05-03) Brand, Oliver
    Introduction for the Spring 2017 NanoFANS Forum.
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    Introduction to Low Flow Measurement and Control
    (Georgia Institute of Technology, 2016-09-14) Brand, Oliver ; Reid, Matthew
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    NanoFANS Spring 2016 Forum: Welcome
    (Georgia Institute of Technology, 2016-05-25) Brand, Oliver
    Welcome address for the 14th 2016 NanoFANS Forum.
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    Resonant MEMS
    (Georgia Institute of Technology, 2015-12-08) Brand, Oliver
    The presentation discusses resonant MEMS and, in particular, resonant microsensors, in which the measurand affects a characteristic of the resonance behavior of a microstructure, such as its resonance frequency or quality factor. The seminar will cover the theoretical background of resonant MEMS and discuss different ways of how the measurand can interact with the resonance characteristics of a MEMS structure. The resonant MEMS concepts will be explained using a number of examples, including chemical sensors and magnetic field sensors.
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    Characteristics of laterally vibrating resonant microcantilevers in viscous liquid media
    (Georgia Institute of Technology, 2012-01) Cox, Russell ; Josse, Fabien ; Heinrich, Stephen M. ; Brand, Oliver ; Dufour, Isabelle
    The characteristics of microcantilevers vibrating laterally in viscous liquid media are investigated and compared to those of similar microcantilevers vibrating in the out-of-plane direction. The hydrodynamic loading on the vibrating beam is first determined using a numerical model. A semi-analytical expression for the hydrodynamic forces in terms of the Reynolds number and the aspect ratio (beam thickness over beam width) is obtained by introducing a correction factor to Stokes’ solution for a vibrating plate of infinite area to account for the effects of the thickness. The results enable the effects of fluid damping and effective fluid mass on the resonant frequency and the quality factor (Q) to be investigated as a function of both the beam’s geometry and liquid medium’s properties and compared to experimentally determined values given in the literature. The resonant frequency and Q are found to be higher for laterally vibrating microcantilevers compared to those of similar geometry experiencing transverse (out-of-plane) vibration. Compared to transversely vibrating beams, the resonant frequency of laterally vibrating beams is shown to decrease at a slower rate (with respect to changes in viscosity) in media having higher viscosities than water. The theoretical results are compared to experimental data obtained for cantilevers completely immersed in solutions of varying aqueous percent glycerol. The increases in resonant frequency and Q are expected to yield much lower limits of detection in liquid-phase chemical sensing applications.
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    Workshop micro-and nanosystems (MNS) horizon 2040
    (Georgia Institute of Technology, 2010-09-30) Brand, Oliver
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    SGER: resonant microsensor based on decoupled sensing scheme for liquid-phase biochemical sensing
    (Georgia Institute of Technology, 2010-08-01) Brand, Oliver ; Beardslee, L. A.
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    Cancellation of environmental effects in resonant mass sensors based on resonance mode and effective mass
    (Georgia Institute of Technology, 2009-06) Naeli, Kianoush ; Brand, Oliver
    novel technique is developed to cancel the effect of environmental parameters, e.g., temperature and humidity, in resonant mass sensing. Utilizing a single resonator, the environmental cancellation is achieved by monitoring a pair of resonant overtones and the effective sensed mass in those overtones. As an eminent advantage, especially compared to dual-mode temperature compensation techniques, the presented technique eliminates any need for previously measured look-up tables or fitting the measurement data. We show that a resonant cantilever beam is an appropriate platform for applying this technique, and derive an analytical expression to relate the actual and effective sensed masses on a cantilever beam. Thereby, it is shown that in applying the presented technique successfully, the effective sensed masses must not be the same in the investigated pair of resonance overtones. To prove the feasibility of the proposed technique, flexural resonance frequencies of a silicon cantilever are measured before and after loading with a strip of photoresist. Applying the presented technique shows significant reductions in influence of environmental parameters, with the temperature and humidity coefficients of frequency being improved from −19.5 to 0.2 ppm °C⁻¹ and from 0.7 to −0.03 ppm %RH⁻¹, respectively.
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    Effect of Stress Due to Plastic Package Moisture Absorption in Hall Sensors
    (Georgia Institute of Technology, 2009-06) Cesaretti, Juan Manuel ; Taylor, W. P. ; Monreal, G. ; Brand, Oliver
    Commercial magnetic sensors based on the Hall effect are usually encapsulated in non-hermetic plastic packages. These plastic packages are known to swell in high humidity conditions due to moisture absorption. This swelling will modify the stress seen by the Hall sensor, causing the Hall sensitivity to be altered due to the piezo-Hall effect. The sensitivity drift, which is random in nature, may become the long-term stability limiting factor in high-end sensors. The objective of this work is to characterize in depth the sensitivity change due to moisture absorption and to review and implement two Hall sensitivity compensation methods.