Micromachined piezoelectric membranes with high nominal quality factors in newtonian liquid media: A Lamb's model validation at the microscale

Although extensively presented as one of the most promising silicon-based micromachined sensor adapted to real-time measurements in liquid media, the cantilevered structure still suffers from its quality factor (Q) dramatic dependence on the liquid viscosity thus lowering the measurement resolution. In this paper, micromachined piezoelectric membranes are introduced as a potential alternative to the cantilevers for biological applications. HighQ-factors (up to 150) of micromachined piezoelectric membranes resonating in various liquid mixtures (water/glycerol and water/ethanol) are thus reported and a theoretical model proposed by Lamb [H. Lamb, On the vibrations of an elastic plate in contact with water, Proc. Roy. Soc. Lond. A 98 (1920) 205?216] is validated for microscale structures proving that the variation of the liquid viscosity (if lower than 10 cP) has no effect on the dynamic behavior of the membranes. To conclude, two types of experiments were performed in water/glycerol mixtures: in-flow (with liquid continuously flowing on the devices) and in-spot (with individual membranes oscillating in a 5 $\mu$L volume of liquid). The results interestingly showed that for the in-spot configuration the Q-factor values are more than two-fold the ones corresponding to in-flow measurements thus providing alternative insights into the way to conceive ideal configurations for real-time biological measurements in liquid media

A combination of capillary and dielectrophoresis-driven assembly methods for wafer scale integration of carbon-nanotube-based nanocarpets

The wafer scale integration of carbon nanotubes (CNT) remains a challenge for electronic and electromechanical applications. We propose a novel CNT integration process relying on the combination of controlled capillary assembly and buried electrode dielectrophoresis (DEP). This process enables us to monitor the precise spatial localization of a high density of CNTs and their alignment in a pre-defined direction. Large arrays of independent and low resistivity (4.4 x 10-5 omega m) interconnections were achieved using this hybrid assembly with double-walled carbon nanotubes (DWNT). Finally, arrays of suspended individual CNT carpets are realized and we demonstrate their potential use as functional devices by monitoring their resonance frequencies (ranging between 1.7 and 10.5 MHz) using a Fabry–Perot interferometer

Piezoelectric amplifiers with integrated actuation and sensing capabilities

We report in this work on unprecedented levels of parametric amplification in microelectromechanical systems (MEMS) resonators with integrated piezoelectric actuation and sensing capabilities operated in air. The method presented here relies on accurate analytical modeling taking into account the geometrical nonlinearities inherent to the bridge-like configuration of the resonators used. The model provides, for the first time, precise analytical formula of the quality factor (Q) enhancement depending on the resonant mode examined. Experimental validations were conducted for resonant modes exhibiting, respectively, hard and soft-spring effects when driven in the nonlinear regime; Q amplification by a factor up to 14 has been obtained in air

Wafer-scale integration of piezoelectric actuation capabilities in nanoelectromechanical systems resonators

In this work, we demonstrate the integration of piezoelectric actuation means on arrays of nanocantilevers at the wafer scale. We use lead titanate zirconate (PZT) as piezoelectric material mainly because of its excellent actuation properties even when geometrically constrained at extreme scal

Wafer-scale integration of piezoelectric actuation capabilities in nanoelectromechanical systems resonators

In this work, we demonstrate the integration of piezoelectric actuation means on arrays of nanocantilevers at the wafer scale. We use lead titanate zirconate (PZT) as piezoelectric material mainly because of its excellent actuation properties even when geometrically constrained at extreme scal

A 0.3mW/Ch 1.25V Piezo-Resistance Digital ROIC for Liquid Dispensing MEMS

Peer reviewe

Complete Set of Elastic Moduli of a Spin-Crossover Solid: Spin-State Dependence and Mechanical Actuation

Molecular spin crossover complexes are promising candidates for mechanical actuation purposes. The relationships between their crystal structure and mechanical properties remain, however, not well understood. In this study, combining high pressure synchrotron Xray diffraction and nuclear inelastic scattering measurements, we assessed the effective macroscopic bulk modulus (11.5 ± 2.0 GPa), Young’s modulus (10.9 ± 1.0 GPa) and Poisson’s ratio (0.34 ± 0.04) of the spin crossover complex [FeII(HB(tz)3)2] (tz = 1,2,4-triazol-1-yl) in its low spin state. Crystal structure analysis revealed a pronounced anisotropy of the lattice compressibility, which was correlated with the difference in spacing between the molecules in different crystallographic directions. Switching the molecules from the low spin to the high spin state leads to a remarkable drop of the Young’s modulus to 7.1 ± 0.5 GPa, which was also assessed in thin film samples by means of micromechanical measurements. These results are in agreement with the high cooperativity of the spin crossover in this compound and highlight its application potential in terms of recoverable stress (21 ± 1 MPa) and work density (15 ± 6 mJ/cm3)

Biomechanical sensors from the macro to the nanoscale - the way forward

Détecter un ensemble de marqueurs biologiques dans un sérum de patient ou bien des molécules spécifiques d'un herbicide dans un échantillon prélevé dans l'eau d'une rivière ? Etre capable de transformer une interaction biologique en un signal électrique ou encore déposer des volumes infiniment faibles de molécules biologiques sur une surface solide à des fins de diagnostique ? Passer de la fabrication de microcapteurs inertiels pour la navigation à la conception et au développement de biocapteurs micromécaniques ? Nous démontrons que le fil conducteur permettant de faire le lien entre ces domaines en apparence disjoints est matérialisé par des micro- et nanosystèmes électromécaniques développés au sein du LAAS à partir de la feuille blanche jusqu'à l'intégration du système avec son électronique associée. Quel lendemain pour les bio- microsystèmes électromécaniques ? Faut-il encore miniaturiser ? Est-il pertinent d'entreprendre le contraire ? Comment poursuivre l'aventure transdisciplinaire en étant sûr du fait que la réussite est au bout de la route ? Nous tentons de répondre à l'ensemble de ces questions tout au long de ce manuscrit retraçant l'ensemble de nos travaux de recherche effectués au LAAS et ailleurs depuis l'an 2000

Actionnements électriques de fluides dédiés aux microsystèmes

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF