A Microfabricated Planar Digital Microrobot for Precise Positioning Based on Bistable Modules

International audienceSize reduction is a constant objective in new technologies, for which very accurate devices are needed when manipulating sub-millimetric objects. A new kind of microfabricated microrobot based on the use of bistable modules is designed to perform open-loop controlled micropositioning tasks. The DiMiBot (Digital MicroroBot) opens a new paradigm in the design of microrobots by using mechanical stability instead of complex control strategies. We propose a new architecture of digital microrobot for which forward and inverse kinematics models are easy to use. These kinematic models are validated with FEA simulations before the fabrication of a real DiMiBot prototype. Tests and characterization of the prototype are made and compared to the desired behavior. Thanks to its submicrometric resolution and to its small dimensions ( 400 μm thickness), it is able to manipulate micro-objects in confined environments, where no other robot can be used

Wet chemical deposition of transparent conducting coatings in glass tubes

A modified dip coating process was developed to deposit transparent conducting sol-gel SnO2:Sb (ATO, antimony doped tin oxide) coatings inside tubes and cavities in optical quality. The necessity for this improvement arises from the fact that the conventional dip coating process applied to tubes results in coatings with poor and non-reproducible properties, showing large variations in the thickness, an increased roughness and an island-like morphology. The main reason for this is found in a delayed and restricted solvent evaporation, due to an impediment of a laminar flow and a progressive saturation of the atmosphere inside the tube. By means of an additional exhausting pipe, a forced laminar flow was, therefore, generated inside the tube, which guarantees a fast evaporation and hydrolysis of the sol-gel films by a continuous renewal of the atmosphere. In this way, ATO coatings with an excellent thickness uniformity and a low roughness of Ra ≈ nm could be deposited on borosilicate glass tubes of 300 mm length and inner diameters down to 11 mm. After a heat treatment at temperatures up to 550 °C, single layer coatings exhibit a high optical transmission (T>85%) and a resistance down to 10 kΩ over a length of 22 cm

Presentation and characterization of novel thick-film PZT microactuators.

International audienceWe propose in this paper the characterization of a new generation of piezoelectric cantilevers called thick-films piezoelectric actuators. Based on the bonding and thinning process of a bulk PZT layer onto a silicon layer, these cantilevers can provide better static and dynamic performances compared to traditional piezocantilevers, additionally to the small dimensions

L'invention de la forêt méditerranéenne de la fin du XVIIIe siècle aux années 1960

Les campagnes médiatiques de protection des bois ont réussi à imposer comme une certitude l'idée de l'existence immuable de la forêt méditerranéenne. Milieu spécifique particulièrement fragile et dégradé par l'homme, cette dernière nous est présentée comme une évidence naturelle qui se passe d'histoire. Toutefois, à une époque où les forêts naturelles n'existent plus, une définition complète ne saurait écarter l'impact des hommes sur les boisements. Centrée sur l'analyse des représenta..

L'invention de la forêt méditerranéenne de la fin du XVIIIe siècle aux années 1960. Thèse de doctorat d'histoire

Les campagnes médiatiques de protection des bois ont réussi à imposer comme une certitude l'idée de l'existence immuable de la forêt méditerranéenne. Milieu spécifique particulièrement fragile et dégradé par l'homme, cette dernière nous est présentée comme une évidence naturelle qui se passe d'histoire. Toutefois, à une époque où les forêts naturelles n'existent plus, une définition complète ne saurait écarter l'impact des hommes sur les boisements. Centrée sur l'analyse des représenta..

Paysages et conflits en Provence

Avec la Révolution, la mise en place d’une politique centralisatrice, les débuts de l’industrialisation et de l’urbanisation, sans oublier les théories libérales, physiocrates et productivistes, l’aménagement des bois provençaux est totalement remis en cause. Dans cette période charnière, entre le xviiie et le xixe siècle, les changements radicaux dans la vision des paysages forestiers et dans l’utilisation des espaces ruraux favorisent l’essor de conflits multiples. L’administration, les élus, les notables locaux, les étrangers à la Provence et les paysans des communes rurales opposent leurs regards sur les paysages. De leur côté, les éleveurs, les sylviculteurs, les agriculteurs mais aussi les ingénieurs des Eaux et Forêts ou les dirigeants de petites industries veulent forger des espaces différents et même antinomiques pour satisfaire leurs besoins productifs. Oubliant pour un temps leurs rivalités, les différentes composantes de la société provençale s’unissent pour refuser le modèle forestier et les aménagements en taillis sous futaies imposés par des Eaux et Forets. Pour des raisons économiques, sociales mais surtout identitaires et culturelles, elles refusent l’intervention de l’État central qui cherche à imposer un paysage forestier uniforme. Cet article vise donc à démêler l’écheveau complexe de ces antagonismes pour comprendre les dernières résistances aux évolutions du monde moderne qui se traduisent clairement dans les paysages.In the aftermath of the French Revolution, with a new centralized political system, and the emergence of industrialization and urbanization, not to mention an atmosphere of liberal, physiocratic and productivist ideas, the development of woodlands in Provence was radically called into question.  In this pivotal period, at the turn of the 19th century, radical changes in the vision of forest landscapes and in the use of country land gave rise to countless conflicts. Civil servants, local councillors and notables, foreign residents and rural people were totally at variance with each other about the landscape. For their part, breeders, foresters, farmers, but also engineers of the Forestry Commission or small industry directors had new but conflicting ideas about the landscape they wanted, depending on their production requirements. Putting their rivalries aside for a time, the various elements of the Provençal society came together to refuse the management style proposed by the Forestry Commission. For economic and social reasons, and especially to assert their identity and culture, they refused to see the centralized State come in and impose a uniform forest landscape. In this paper we try to unravel a complex tangle of such antagonisms in order to understand the last resistance to modern evolutions that are unmistakable in the landscapes

Digital Microrobotics based on bistable modules : Design of a non-redundant digital micropositioning robot.

International audienceHigh precision manipulation becomes a recurrent need in micro or nanoscale. Microrobots based on active material were designed to perform micromanipulation tasks in various environments such as microrobotic stations or electronic microscopes (SEM, TEM). These active materials are used to generate proportional actuation, but show some drawbacks we want to avoid (non linearity, integration of sensors, . . . ). In this paper we propose a new type of microrobot, called digital microrobot. It is based on the use of bistable modules (Fig. 1), and generates a discrete workspace. This microrobot can be used in open-loop mode and gets rid of bulky and expensive instruments and sensor integration. Moreover, no external energy is required to maintain the microrobot in a given position. The study presented in this paper is dedicated to the design of the robotic structure in order to generate a desired workspace

In situ H(2)S passivation of In(0.53)Ga(0.47)As/InP metal-oxide-semiconductor capacitors with atomic-layer deposited HfO(2) gate dielectric

We have studied an in situ passivation of In(0.53)Ga(0.47)As, based on H(2)S exposure (50-350 degrees C) following metal organic vapor phase epitaxy growth, prior to atomic layer deposition of HfO(2) using Hf[N(CH(3))(2)](4) and H(2)O precursors. X-ray photoelectron spectroscopy revealed the suppression of As oxide formation in air exposed InGaAs surfaces for all H(2)S exposure temperatures. Transmission electron microscopy analysis demonstrates a reduction of the interface oxide between the In(0.53)Ga(0.47)As epitaxial layer and the amorphous HfO(2) resulting from the in situ H(2)S passivation. The capacitance-voltage and current-voltage behavior of Pd/HfO(2)/In(0.53)Ga(0.47)As/InP structures demonstrates that the electrical characteristics of samples exposed to 50 degrees C H(2)S at the end of the metal-organic vapor-phase epitaxy In(0.53)Ga(0.47)As growth are comparable to those obtained using an ex situ aqueous (NH(4))(2)S passivation. (c) 2008 American Institute of Physics. (DOI: 10.1063/1.2829586

Structural analysis, elemental profiling, and electrical characterization of HfO2 thin films deposited on In0.53Ga0.47As surfaces by atomic layer deposition

In this work results are presented on the structural analysis, chemical composition, and interface state densities of HfO2 thin films deposited by atomic layer deposition (ALD) from Hf[N(CH3)(2)](4) and H2O on In0.53Ga0.47As/InP substrates. The structural and chemical properties are investigated using high resolution cross-sectional transmission electron microscopy and electron energy loss spectroscopy. HfO2 films (3-15 nm) deposited on In0.53Ga0.47As are studied following a range of surface treatments including in situ treatment of the In0.53Ga0.47As surface by H2S exposure at 50-350 degrees C immediately following the metal organic vapor phase epitaxy growth of the In0.53Ga0.47As layer, ex situ treatment with (NH4)(2)S, and deposition on the native oxides of In0.53Ga0.47As with no surface treatment. The structural analysis indicates that the In0.53Ga0.47As surface preparation prior to HfO2 film deposition influences the thickness of the HfO2 film and the interlayer oxide. The complete interfacial self-cleaning of the In(0.53)Gas(0.47)As native oxides is not observed using an ALD process based on the Hf[N(CH3)(2)](4) precursor and H2O. Elemental profiling of the HfO2/In0.53Ga0.47As interface region by electron energy loss spectroscopy reveals an interface oxide layer of 1-2 nm in thickness, which consists primarily of Ga oxides. Using a conductance method approximation, peak interface state densities in the range from 6 x 10(12) to 2 x 10(13) cm(-2) eV(-1) are estimated depending on the surface preparation. (C) 2009 American Institute of Physics. [doi:10.1063/1.3243234