Development of Analytical Models of T- and U-shaped Cantilever-based MEMS Devices for Sensing and Energy Harvesting Applications

Dynamic-mode cantilever-based structures supporting end masses are frequently used as MEMS/NEMS devices in application areas as diverse as chemical/biosensing, atomic force microscopy, and energy harvesting. This paper presents a new analytical solution for the free vibration of a cantilever with a rigid end mass of finite size. The effects of both translational and rotational inertia as well as horizontal eccentricity of the end mass are incorporated into the model. This model is general regarding the end-mass distribution/geometry and is validated here for the commonly encountered geometries of T- and U-shaped cantilevers. Comparisons with 3D FEA simulations and experiments on silicon and organic MEMS are quite encouraging. The new solution gives insight into device behavior, provides an efficient tool for preliminary design, and may be extended in a straightforward manner to account for inherent energy dissipation in the case of organic-based cantilevers

Fabrication and characterisation of carbon-based devices

Thin film material properties and measurement characterisation techniques are crucial for the development of micro-electromechanical systems (MEMS) devices. Furthermore, as the technology scales down from microtechnology towards nanotechnology, nanoscale materials such as carbon nanotubes (CNTs) are required in electronic devices to overcome the limitations encountered by conventional materials at the nanoscale. The integration of CNTs into micro-electronics and material applications is expected to provide a wide range of new applications. The work presented in this thesis has contributed to the development of thin film material characterisation through research on the thermal conductivity measurement and the control of the residual stress of thin film materials used commonly in MEMS devices. In addition, the use of CNTs in micro-electronics and as filler reinforcement in composite materials applications have been investigated, leading to low resistivity CNTs interconnects and CNTs-Polyimide (PI) composites based resistive humidity sensors. In the first part of this thesis, the thermal conductivity of conductive thin films as well as the control of the residual stress arising from fabrication process in PI micro-cantilevers have been studied. A MEMS device has been developed for the thermal conductivity characterisation of conductive thin films showing good agreement with thermal conductivity of bulk material. Low energy Ar+ ion bombardment in a plasma has been used to control the residual stress present in PI cantilevers. Appropriate ion energy and exposure time have led to stress relaxation of the beams resulting in a straight PI cantilever beam. In the second part of this thesis, low resistivity CNTs interconnects have been developed using both dielectrophoresis (DEP) and Focused Ion Beam (FIB) techniques. An investigation of the effects of CNT concentration, applied voltage and frequency on the CNTs alignment between Al and Ti electrodes has resulted in the lowering of the CNTs’ resistance. The deposition of Pt contact using FIB at the CNTs-metal electrodes interface has been found to decrease the high contact resistances of the devices by four and two orders of magnitude for Al and Ti electrodes respectively. The last part of this thesis focuses on the preparation of CNTs-PI composite materials, its characterisation and its application as resistive humidity sensor. The integration of CNTs inside the PI matrix has resulted in enhancing significantly the electrical and mechanical properties of the composites. In particular, a DEP technique employed to induce CNTs alignment inside the PI matrix during curing has been attributed to play an important role in improving the composite properties and lowering the percolation threshold. In addition, the fabrication and testing of CNTs-PI resistive humidity sensors have been carried out. The sensing performance of the devices have shown to be dependent highly on the CNT concentration. Finally, the alignment of CNTs by DEP has improved the sensing properties of CNTs-PI humidity sensors and confirmed that the change of resistance in response to humidity is governed by the change of the CNTs’ resistances due to charge transfer from the water molecules to the CNTs

Benign Fibrous Histiocytoma of the Buccal Mucosa: Case Report and Literature Review

Benign fibrous histiocytoma is an interesting and challenging entity even in its most usual, cutaneous presentation. Noncutaneous presentation is extremely limited, even more so for the mucosa of the head and neck area. We herein report such a case, describing the clinical characteristics of the lesion, complete diagnostic evaluation, management, and follow-up. Diagnostic histopathological challenges are specifically illustrated. A complete review of the relevant literature is also included

Long-range and rapid transport of individual nano-objects by a hybrid electrothermoplasmonic nanotweezer

Plasmon-enhanced optical trapping is being actively studied to provide efficient manipulation of nanometre-sized objects. However, a long-standing issue with previously proposed solutions is how to controllably load the trap on-demand without relying on Brownian diffusion. Here, we show that the photo-induced heating of a nanoantenna in conjunction with an applied a.c. electric field can initiate rapid microscale fluid motion and particle transport with a velocity exceeding 10 μm s -1 , which is over two orders of magnitude faster than previously predicted. Our electrothermoplasmonic device enables on-demand long-range and rapid delivery of single nano-objects to specific plasmonic nanoantennas, where they can be trapped and even locked in place. We also present a physical model that elucidates the role of both heat-induced fluidic motion and plasmonic field enhancement in the plasmon-assisted optical trapping process. Finally, by applying a d.c. field or low-frequency a.c. field (below 10 Hz) while the particle is held in the trap by the gradient force, the trapped nano-objects can be immobilized into plasmonic hotspots, thereby providing the potential for effective low-power nanomanufacturing on-chip

Intelligence, reason of state and the art of governing risk and opportunity in early modern Europe

Drawing upon primary and secondary historical material, this paper explores the role of intelligence in early modern government. It focuses upon developments in seventeenth- and early-eighteenth-century England, a site-specific genealogical moment in the broader history of state power/knowledges. Addressing a tendency in Foucauldian work to neglect pre-eighteenth-century governance, the analysis reveals a set of interrelated processes which gave rise to an innovative technique for anticipating hazard and opportunity for the state. At the intersection of raison d’État, the evolving art of government, widespread routines of secrecy and a post-Westphalia field of European competition and exchange, intelligence was imagined as a fundamental solution to the concurrent problems of ensuring peace and stability while improving state forces. In the administrative offices of the English Secretary of State, an assemblage of complex and interrelated procedures sought to produce and manipulate information in ways which exposed both possible risks to the state and potential opportunities for expansion and gain. As this suggests, the art of intelligence played an important if largely unacknowledged role in the formation and growth of the early modern state. Ensuring strategic advantage over rivals, intelligence also limited the ability of England's neighbours to dominate trade, control the seas and master the colonies, functioning as a constitutive feature of European balance and equilibrium. As the analysis concludes, understanding intelligence as a form of governmental technique – a way of doing something – reveals an entirely novel way of thinking about and investigating its myriad (historical and contemporary) formations

El pensamiento político de la Contrarreforma y la razón de estado

This article reconstructs the history of political thought from the sixteenth to the first decades of seventeenth century: a period of strong conflicts between the religious sphere and the political changes of the states in their trajectory towards absolutism. The analysis of the polemic against Machiavelli, Bodin and the <em>politiques</em> shows how it was questioned at the conceptual and practical levels the autonomy of politics from religious morality and the tendency of the states to evade ecclesiastical control respectively. The schools of thought discussed here –from anti-Machiavellism to the encomiastic literature of the existent governments, from Tacitism to the reason State, to the critical writings of the society, mainly utopia- outline on the one hand, the effort to preserve an image of politics as just government, with a virtuous prince, but on the other, the inevitable commitment to the praxis of political realism, well represented by the developments of the concept of reason of State in Botero and other writers from the seventeenth century. It was only with the arrival of Modern natural law which brought to the fore the questions of the origin and purpose of civil society, that political thought partly detached from the eternal conflict between morals and political praxis opening the era of rational and scientific research and individual rights.<br><br>Este artículo reconstruye la historia del pensamiento político de la segunda mitad del siglo XVI a las primeras décadas del siglo XVII: un período de fuertes conflictos entre la esfera religiosa y los cambios políticos de los estados más avanzados hacia el absolutismo. El análisis de la polémica contra Maquiavelo, Bodin, y los <em>politiques</em> muestra como fueron cuestionados en el plano conceptual la autonomía de la política de la moral religiosa y en el plano práctico la tendencia de los estados a sustraerse del control eclesiástico. Las corrientes de pensamiento que se analizan aquí –del antimaquiavelismo a la literatura encomiástica de los gobiernos existentes, del tacitismo a la razón de Estado, hasta las escrituras críticas de la sociedad como la utopía- perfilan por un lado el esfuerzo de conservar una imagen de la política como gobierno justo, con un príncipe virtuoso, pero por el otro el inevitable compromiso con las praxis del realismo político, bien representado por la evolución del concepto de razón de Estado en Botero y en otros escritores del siglo XVII. Fue sólo con la llegada del derecho natural moderno, que puso en primer plano la cuestión del origen y los fines de la sociedad civil, que el pensamiento político se sustrajo en parte de la discusión sobre el eterno conflicto entre moral y praxis política para abrir la era de la investigación racional y científica y de los derechos individuales

Conception logique et topologique en technologie MOS

La méthode de conception logique de cellules MOS tient compte des problèmes d'implantation (diffusion, dépôt métallique (AL) et masquage) en technologies NMOS et CMOS dans l'ordonnancement optimise des variables. La forme arborescente série-parallèle est simplifiée par compactage des transistors. Étapes de minimisation. Application aux portes complexes NMOS et CMOS et aux macro-cellules les utilisant pour des fonctions logiques. Fonctions réalisées en logique de transfert se prêtant à l'implantation automatisée. Application à la conception de circuits complexes : circuit d'extraction de racine carrée et multiplicateur. Problèmes de synchronisation et temporisation

Des résultats éloignés des fractures diaphysaires de la cuisse chez l'enfant.

Paris, 1920-1921, t. 43, n ° 303.Th.--Méd.--Paris, 1920-1921