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International audience; Due to their unique size-dependent properties, nanoparticles (NPs) have many industrial and biomedical applications. Although NPs are generally characterized based on the size or morphological analysis, the mass of whole particles can be of interest as it represents the total amount of material in the particle regardless of shape, density, or elemental composition. In addition, the shape of nonspherical NPs presents a conceptual challenge, making them difficult to characterize in terms of size or morphological characteristics. Here, we used a novel nano-electro-mechanical sensor mass spectrometry (NEMS-MS) technology to characterize the mass distributions of various NPs. For standard spherical gold NPs, mass distributions covered the range from ∼5 to 250 MDa (8 to ∼415 attograms). Applying the density of gold (19.3 g/cm3) and assuming perfect sphericity, these mass measurements were used to compute the equivalent diameters of the NPs. The sizes determined agreed well with the transmission electron microscopy (TEM) imaging data, with deviations of ∼1.4%. Subsequently, we analyzed the mass distribution of ∼50 nm synthetic silicon dioxide particles, having determined their size by electron microscopy (SEM and TEM). Their estimated density was in line with the literature values derived from differential mobility analyzer and aerosol particle mass analyzer data. Finally, we examined the intact gold nanotetrapods and obtained a mass distribution revealing their controlled polydispersity. The presence of polyethylene glycol coating was also quantified and corroborated nuclear magnetic resonance observations. Our results demonstrate the potential of NEMS-MS-based measurements as an effective means to characterize NPs, whatever their composition, shape or density.

In contrast to the well-known phenomenon of frequency stabilization in a synchronized noisy nonlinear oscillator, little is known about its amplitude stability. In this paper, we investigate experimentally and theoretically the amplitude evolution and stability of a nonlinear nanomechanical self-sustained oscillator that is synchronized with an external harmonic drive. We show that the phase difference between the tones plays a critical role on the amplitude level, and we demonstrate that in the strongly nonlinear regime, its amplitude fluctuations are reduced considerably. These findings bring to light a new facet of the synchronization phenomenon, extending its range of applications beyond the field of clock-references and suggesting a new means to enhance oscillator amplitude stability., 6 pages, 4 figures

Aluminum-based platforms have allowed to reach major milestones for superconducting quantum circuits. For the next generation of devices, materials that are able to maintain low microwave losses while providing new functionalities, such as large kinetic inductance or compatibility with CMOS platform, are needed. Here, we report on a combined direct current and microwave investigation of titanium nitride films of different thicknesses grown using CMOS compatible methods. For microwave resonators made of 3 nm thick TiN, we measured large kinetic inductance [Formula: see text] pH/sq, high mode impedance of [Formula: see text] kΩ while maintaining microwave quality factor [Formula: see text] in the single photon limit. We present an in-depth study of the microwave loss mechanisms in these devices that indicates the importance of quasiparticles and provide insight for further improvement.

Nanoelectromechanical resonators have been successfully used for a variety of sensing applications. Their extreme resolution comes from their small size, which strongly limits their capture area. This leads to a long analysis time and the requirement for large sample quantity. Moreover, the efficiency of the electrical transductions commonly used for silicon resonators degrades with increasing frequency, limiting the achievable mechanical bandwidth and throughput. Multiplexing a large number of high-frequency resonators appears to be a solution, but this is complex with electrical transductions. We propose here a route to solve these issues, with a multiplexing scheme for very high-frequency optomechanical resonators. We demonstrate the simultaneous frequency measurement of three silicon microdisks fabricated with a 200 mm wafer large-scale process. The readout architecture is simple and does not degrade the sensing resolutions. This paves the way toward the realization of sensors for multiparametric analysis with an extremely low limit of detection and response time.

When studying viruses, the most prevalent aspects that come to mind are their structural and functional features, but this leaves in the shadows a quite universal characteristic: their mass. Even if approximations can be derived from size and density measurements, the multi MDa to GDa mass range, featuring a majority of viruses, has so far remained largely unexplored. Recently, nano-electromechanical resonator-based mass spectrometry (NEMS-MS) has demonstrated the ability to measure the mass of intact DNA filled viral capsids in excess of 100 MDa. However, multiple factors have to be taken in consideration when performing NEMS-MS measurements. In this article, phenomena influencing NEMS-MS mass estimates are listed and discussed, including some particle's extraneous physical properties (size, aspect ratio, stiffness), and the influence of frequency noise and device fabrication defects. These factors being accounted for, we could begin to notice subtler effects linked with (e.g.) particle desolvation as a function of operating parameters. Graphical abstract.

High performance accelerometers are required in many different domains as sophisticated navigation control systems, research or consumer electronics.A variety of transduction mechanisms has been used to sense the acceleration: capacitive, piezoresistive, thermal... Optomechanical transduction is a promising avenue to realize accelerometers with extremely sensitive readout of mechanical motion with high bandwidth. This also has the advantage of being immune to electromagnetic interferences contrary to the traditional transduction methods.In this work, an optomechanical accelerometer is presented which employs Whispering Gallery Modes disk or ring resonator as displacement sensor. The motion of an inertial mass detunes the resonant cavity and thus modulates the optical power at the output of the sensor.The designs and technological developments of three optomechanical accelerometers are described. We present also the optical and mechanical sensor characterisations. The aim of the thesis is to evaluate the potential of an optomechanical approach for high performance accelerometers., De nombreux domaines requièrent des accéléromètres à très hautes performances, que ce soit pour des systèmes de navigation ou le marché de l'électronique ou encore dans le domaine de la recherche.Beaucoup de méthodes différentes ont été utilisées pour mesurer une accélération comme les accéléromètres capacitifs, piezorésitifs ou encore thermiques. Cependant la transduction optomécanique semble pouvoir apporter de nouveaux avantages en comparaison des méthodes traditionnelles. En effet, l'optomécanique permet de détecter des déplacements mécaniques extrêmement petits et donc d'obtenir des résolutions très importantes tout en gardant une bande passante intéressante. Les capteurs optomécaniques contrairement aux capteurs basés sur d'autres méthodes, peuvent être utilisés dans des environnements non protégés des ondes électromagnétiques.Dans le cadre de ce travail, nous présentons un accéléromètre optomécanique avec une cavité optique résonante à Whispering Gallery Modes pour détecter le mouvement d'une masse inertielle. Le mouvement de cette dernière modifie les conditions de résonance de la cavité ce qui conduit à une modulation de la puissance optique en sortie du capteur. Trois différents modèles d'accéléromètres optomécaniques seront détaillés ainsi que leur développement technologique. Nous présenterons également leurs caractérisations optiques et mécaniques.Finalement ces travaux de recherche permettent d'évaluer le potentiel d'une approche optomécanique pour la conception d'accéléromètres à hautes performances.

In the vast majority of commercial MEMS inertial sensors, both seismic mass and sensing elements are patterned in the same silicon layer. This sets stringent design trade-offs, in particular for a capacitive sensor: a large silicon thickness increases seismic mass and decreases the Brownian noise floor. A low silicon thickness on the other hand, allows smaller gaps between electrodes, higher capacitance variation and lower electrical noise floor. For this reason, several examples of multi-layer MEMS devices were presented in the past. Yet, increasing capacitance density while reducing mechanical noise floor has not been achieved so far. Breaking the single-layer trade-off could enable new emerging applications that require high-performance sensors within a consumer size.In this work, multi-layer, in-plane and out-of-plane accelerometer are presented. Thanks to the multi-layer process the devices can feature a thick layer for large inertial mass, as well as a thin layer for high capacitive density. These aspects, together with surface-variation detection, allow to obtain µg/√Hz resolution and large full-scale while keeping compact size.The sensors are designed through analytical modeling and finite elements method simulations in order to reach the highest dynamic range with the lowest noise at given footprint.Few critical aspects were encountered during the fabrication of the sensors, especially for out-of-plane accelerometers. The notching of the thick-layer etching coupled to the strong lag effect caused most of the z-axis sensors to fail. This forced a reduction of the process thickness and relative loss of performance for this type of sensors.The characterization of the sensors is performed both at wafer-level (static capacitance, resonance frequency) and at die level (scale factor, noise-floor, full-scale). The die-level measurements are carried out with a dedicated electronic circuit implemented with discrete components, developed during this work.In-plane accelerometers showed static capacitance and resonance frequency in line with theory. They achieved resolution smaller than 8 µg/rtHz and full scale in the order of 160g. These aspects together lead to a dynamic range of more than 145dB (BW=1Hz) for a device with a footprint of only 0.24 mm². This it more than 100 times larger than the DR of consumer device of similar size. These results are achieved while keeping a large bandwidth and working with an open-loop readout.Out-of-plane sensors showed resonance frequency higher than expected due to fabrication tolerances. The devices had both smaller mass and thicker springs explaining the observed mechanical behavior. Despite the loss of scale factor due to the larger resonance frequency, these sensors achieved resolution ranging from 50-80 µg/rtHz. Again, such performance was obtained while keeping large resonance frequency (>8 kHz), small footprint (down to 0.22 mm²) and a potential full-scale of more than 200g. In the future, design corrections and process improvement could lead to device with thicker inertial layer, aligning the performance of out-of-plane sensors to those of in-plane ones and leading to a high-performance 3-axis accelerometer.This type of sensor could address the demand of emerging applications for high-stability, low-noise and large DR accelerometers within consumer footprint.Finally, the proposed technology offers a fabrication platform for inertial MEMS sensors and actuators. New design possibilities and great potentialities have been demonstrated with the first fabricated accelerometers. In the future this new concept could be applied to several other types of MEMS, like gyroscope or micro-mirrors., La plupart des capteurs inertiels MEMS commerciaux comportent une masse d’épreuve et des moyens de transductions issus d’une même couche de silicium. Il en découle des compromis forts, notamment pour la détection capacitive : une couche épaisse permet d’augmenter la masse et donc de réduire le bruit brownien; inversement, une couche fine permet de réduire la taille des entrefers entre les électrodes, d’obtenir une variation de capacité plus importante, et donc de réduire la contribution du bruit électronique. Plusieurs composants MEMS multicouches ont déjà été réalisés et rapportés dans la littérature, mais aucun n’a cherché à augmenter la densité capacitive tout en réduisant le bruit thermomécanique. Pourtant, la disparition du compromis lié au procédé monocouche permet d’atteindre les hautes performances nécessaires aux applications émergeantes, en conservant la surface d’un capteur grand public.Cette thèse présente des accéléromètres multicouches à détection dans le plan et hors plan. Le procédé de fabrication combine une couche épaisse, dédiée à la réalisation de grandes masses d’épreuve, et une couche fine, permettant d’obtenir de fortes densités capacitives. Ces deux avantages, combinés à une détection par variation de surface, permettent d’obtenir une résolution de l’ordre du µg/rtHz, une grande gamme dynamique, tout en conservant une taille réduite. Le dimensionnement des capteurs a cherché à maximiser la gamme dynamique et minimiser le bruit en partant d’une taille fixée. D’abord analytique, il a été validé par des simulations par éléments finis.Le procédé de fabrication VLSI a été appliqué à des plaques 200mm. Plusieurs points critiques ont été rencontrés, notamment la surgravure des fonds de tranchée (notching). Combinée à la disparité de vitesse de gravure, elle a entrainé la destruction de beaucoup de capteurs hors plan. Ce problème a été résolu en amincissant la couche épaisse, entrainant une légère perte de performances.Les capteurs ont été caractérisés sur plaque (capacité statique, fréquence de résonance), puis au niveau puce (sensibilité, niveau de bruit, gamme dynamique). Ces dernières mesures ont nécessité le développement d’une électronique dédiée, à partir de composants discrets.Les accéléromètres dans le plan présentent une capacité statique et une fréquence de résonance très proches de la théorie. Ils atteignent une résolution de 8µg/rtHz pour une gamme dynamique de l’ordre de 160g. Cette dynamique de 145dB est fournie par un composant de seulement 0.24mm² ; elle est 100 fois plus élevée que la dynamique d’un composant grand public de même taille. De plus, la bande passante est importante et le capteur est lu en boucle ouverte.Les accéléromètres hors-plan présentent une forte fréquence de résonance, au-delà de 8kHz. La masse sismique plus fine, combinée à des ressorts plus larges, explique ce décalage par rapport au dimensionnement initial. Malgré la réduction de sensibilité induite, les capteurs présentent une résolution de 50 à 80µg/rtHz. L’encombrement est faible (jusqu’à 0.22mm²) et la gamme dynamique a été évaluée à plus de 200g. Dans le futur, des corrections de design et des améliorations dans le procédé de fabrication permettront d’utiliser l’épaisseur initialement prévue, afin d’harmoniser les performances avec celles de l’accéléromètre dans le plan et d’obtenir un accéléromètre 3-axes hautes performances.Ce type de capteurs pourrait jouer un grand rôle dans les applications émergentes en fournissant une bonne stabilité, un faible bruit et une grande gamme dynamique, tout en conservant l’empreinte d’un capteur grand-public.Ce nouveau procédé de fabrication montre donc déjà un gros potentiel à travers les premiers composants réalisés, mais ouvre également de nouvelles possibilités en termes de design. Dans le futur, il pourrait servir de plateforme technologique pour les capteurs inertiels, notamment les gyromètres, mais aussi pour les actionneurs, comme les micro-miroirs.