References of "Rochus, Véronique"
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See detailPoly-SiGe-based MEMS Xylophone Bar Magnetometer
Rochus, Véronique; Jansen, R.; Tilmans, H. A. C. et al

in IEEE SENSORS 2012 (2012, October)

This paper presents the design, fabrication and preliminary characterization of highly sensitive MEMS-based Xylophone Bar Magnetometers (XBMs) realized in imec’s poly-SiGe MEMS technology. Key for our ... [more ▼]

This paper presents the design, fabrication and preliminary characterization of highly sensitive MEMS-based Xylophone Bar Magnetometers (XBMs) realized in imec’s poly-SiGe MEMS technology. Key for our Lorentz force driven capacitively sensed resonant sensor are the combination of reasonably high Q-factor and conductivity of imec’s poly-SiGe, our optimized multiphysics sensor design targeting the maximization of the Q-factor in a wide temperature range as well as our proprietary monolithic above-CMOS integration and packaging schemes. Prototypes 3-axis devices were fabricated and characterized. We present optical vibrometer and electrical S-parameter measurements of XBMs performed in vacuum with a reference magnet at increasing sensor separation. The optical oscillation amplitude is well correlated with the magnetic field amplitude. The electrical 2-port measurements, 1st port as Lorentz force actuator and 2nd port as capacitive sensor, also reproduces the designed magnetic field dependence. This opens the way towards the on-chip integration of small footprint extremely sensitive magnetometers. [less ▲]

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See detailMechanical and tribological characterization of a thermally actuated MEMS cantilever
Pustan, Marius; Rochus, Véronique; Golinval, Jean-Claude ULg

in Microsystem Technologies (2012)

The temperature effect on the mechanical and tribological behaviors of a microelectromechanical systems cantilever is experimentally investigated using an atomic force microscope. A nonlinear variation of ... [more ▼]

The temperature effect on the mechanical and tribological behaviors of a microelectromechanical systems cantilever is experimentally investigated using an atomic force microscope. A nonlinear variation of the bending stiffness of microcantilevers as a function of temperature is determined. The variation of the adhesion force between the tip of atomic force microscope (AFM) probe (Si3N4) and the microcantilever fabricated in gold is monitored at different temperatures. Using the lateral mode operation of atomic force microscope, the influence of temperature on friction coefficient between the tip of AFM probe and microcantilever is presented. Finite element analysis is used to estimate the thermal field distribution in microcantilever and the axial expansion. [less ▲]

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See detailTopology optimization of electrostatic micro-actuators including electromechanical stability constraint
Lemaire, Etienne ULg; Van Miegroet, Laurent ULg; Rochus, Véronique et al

Conference (2011, November 16)

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See detailA Micro-Macroapproach to Predict Stiction due to Surface Contact in Microelectromechanical Systems
Wu, Ling ULg; Noels, Ludovic ULg; Rochus, Véronique et al

in IEEE/ASME Journal of Microelectromechanical Systems (2011), 20(4), 976-990

Stiction, which results from contact between surfaces, is a major failure mode in micro electro-mechanical systems (MEMS). Indeed microscopic structures tend to adhere to each other when their surfaces ... [more ▼]

Stiction, which results from contact between surfaces, is a major failure mode in micro electro-mechanical systems (MEMS). Indeed microscopic structures tend to adhere to each other when their surfaces enter into contact and when the restoring forces are unable to overcome the interfacial forces. Since incidental contacts cannot be completely excluded and since contacts between moving parts can be part of the normal operation of some types of MEMS, stiction prediction is an important consideration when designing micro and nano-devices. In this paper a micro-macro multi-scale approach is developed in order to predict possible stiction. At the lower scale, the unloading adhesive contact-distance curves of two interacting rough surfaces are established based on a previously presented model [L. Wu et al., J. Appl. Phys. 106, 113502, 2009]. In this model, dry conditions are assumed and only the van der Waals forces as adhesion source are accounted for. The resulting unloading adhesive contact-distance curves are dependant on the material and on surface properties, such as, elastic modulus, surface energy and on the rough surfaces topography parameters; the standard deviation of asperity heights and the asperities density. At the higher scale, a finite element analysis is considered to determine the residual cantilever beam configuration due to the adhesive forces once contact happened. Toward this end, the adhesive contact-distance curve computed previously is integrated on the surface of the finite elements as a contact law. Effects of design parameters can then be studied for given material and surface properties. [less ▲]

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See detailModeling and finite element analysis of mechanical behavior of flexible MEMS components
Pustan, Marius ULg; Paquay, Stéphane; Rochus, Véronique et al

in Microsystem Technologies (2011), 17(4), 553-562

This paper describes the studies of the mechanical characteristics of flexible MEMS components including theoretical approaches, finite element analysis and experimental investigations. Modeling and ... [more ▼]

This paper describes the studies of the mechanical characteristics of flexible MEMS components including theoretical approaches, finite element analysis and experimental investigations. Modeling and finite element analyses together with theoretical and experimental investigations are performed to estimate the elastic behavior of MEMS components as microcantilevers, microbridges and micromembranes. Finite element analysis of microcomponents deflections under different loading and the stress distribution in beams are determined and compared with the experimental measurements performed using an atomic force microscope. The modeling of a micromembrane supported by four hinges that enable out-of-plane motion is presented. Finite element analysis and experimental investigations are performed to visualize the deflection of the mobile part of the micromembrane under an applied force and the stress distribution in hinges. In additional, this paper provides analytical relations to compute the stiffness and the stress of the investigated flexible MEMS components. [less ▲]

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See detailEffects of the electrode positions on the dynamical behaviour of electrostatically actuated MEMS resonators
Pustan, Marius ULg; Paquay, Stéphane; Rochus, Véronique et al

(2011, April 18)

The influence of the lower electrode positions on the dynamic response of polysilicon MEMS resonators is studied and presented in this paper. The change in the frequency response of investigated MEMS ... [more ▼]

The influence of the lower electrode positions on the dynamic response of polysilicon MEMS resonators is studied and presented in this paper. The change in the frequency response of investigated MEMS resonators as function of the lower electrode positions is measured using a vibrometer analyzer. The decrease in the amplitude and velocity of oscillations if the lower electrode is moved from the beam free-end toward to the beam anchor is experimental monitored. The measurements are performed in ambient conditions in order to characterize the forced-response Q-factor of samples. A decrease of the Q- factor if the lower electrode is moved toward to the beam anchor is experimental determined. Different responses of MEMS resonators may be obtained if the position of the lower electrode is modified. Indeed the resonator stiffness, velocity and amplitude of oscillations are changed. [less ▲]

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See detailDesign of Microswitch Systems Avoiding Stiction due to Surface Contact
Wu, Ling ULg; Noels, Ludovic ULg; Rochus, Véronique et al

in Proulx, Tom (Ed.) MEMS and Nanotechnology, Volume 2 (2011)

Stiction which results from contact between surfaces is a major failure mode in micro electro-mechanical systems (MEMS). Increasing restoring forces using high spring constant allows avoiding stiction but ... [more ▼]

Stiction which results from contact between surfaces is a major failure mode in micro electro-mechanical systems (MEMS). Increasing restoring forces using high spring constant allows avoiding stiction but leads to an increase of the actuation voltage so that the switch’s efficiency is threatened. A statistical rough surfaces interaction model, based on Maugis’ and Kim’s formulations is applied to estimate the adhesive forces in MEMS switches. Based on the knowledge of these forces, the proper design range of the equivalent spring constant, which is the main factor of restoring force in MEMS switches, can be determined. The upper limit of equivalent spring constant depends mainly on the expected actuator voltage and on the geometric parameters, such as initial gap size and thickness of dielectric layer. The lower limit is assessed on the value of adhesive forces between the two contacting rough surfaces. It mainly depends on the adhesive work of contact surfaces and on the surfaces’ roughness. In order to study more complicated structures, this framework will be used in a multiscale model: resulting unloading micro adhesive contact-distance curves of two rough surfaces will be used as contact forces in a finite-element model. In this paper the extraction of these curves for the particular case of gold to gold micro-switches is pursued. [less ▲]

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See detailNANOTRIBOLOGICAL AND NANOMECHANICAL CHARACTERIZATIONS OF MEMS MATERIALS
Pustan, Marius ULg; Rochus, Veronique; Golinval, Jean-Claude ULg

Poster (2010, December)

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See detailMultiphysic topology optimization of electromechanical micro-actuators considering pull-in effect
Lemaire, Etienne ULg; Van Miegroet, Laurent ULg; Schoonjans, Thibaut et al

in Proceedings of the IVth European Conference on Computational Mechanics (ECCM 2010) (2010)

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See detailTopology optimization of microbeams including layer deposition manufacturing constraints
Lemaire, Etienne ULg; Rochus, Véronique; Fleury, Claude et al

Conference (2007, May)

As many manufacturing techniques, microfabrication methods possess limitations. Consequently, manufacturing constraints have to be considered during microsystems design process. Therefore, the direct use ... [more ▼]

As many manufacturing techniques, microfabrication methods possess limitations. Consequently, manufacturing constraints have to be considered during microsystems design process. Therefore, the direct use of automatic design tools like topology optimization is not possible. For instance, optimal topologies generally contain closed cavities that cannot be produced using the usual microfabrication techniques like layer deposition. The present paper intends to add a layer deposition constraint to the optimization problem using recent developments of CONLIN software. However, with this new optimization procedure we could observe that classical sensitivities filtering makes optimization problem rather unstable while filtering the density field itself keeps good convergence properties. [less ▲]

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