Disseny i construcció d'una sonda atmosfèrica

The project consists of the construction of a functional meteorological probe, controlled by an Arduino microcontroller. This probe was design to measure pressure and temperature as functions of the altitude. This device is the first of its kind built at the EETAC, thus a considerable effort of requirement definition has been done. In the present report we describe how all the probesystems were designed, and all the necessary components as well as the reason why they were chosen are described. The resulting design is modular in order to facilitate future improvements/expansions.The steps necessary for the assembly of all the components in a common structure are detailed, as well as the choice of tools and materials. All the systems developed were tested simulating conditions similar to those expected in the real mission.Finally, after the construction and validation processes, all the materials and the tasks needed to launch the probe up to at an altitude of 35 km are detailed.The present report is intended to serve as a guide for futuresimilar projects in EETAC. The resulting device from this work is named FourCast after our surnames

3D Structuration Techniques of LTCC for Microsystems Applications

This thesis aimed at developing new 3D structuration techniques for a relatively recent new ceramic technology called LTCC, which stands for Low Temperature, Co-fired Ceramic. It is a material originally developed for the microelectronic packaging industry; its chemical and thermal stabilities make it suitable to military-grade and automotive applications, such as car ignition systems and Wi-Fi antennae (GHz frequencies). In recent years however, the research in ceramic microsystems has seen a growing interest for microfluidics, packaging, MEMS and sensors. Positioned at the crossing of classical thick-film technology on alumina substrate and of high temperature ceramics, this new kind of easily structurable ceramic is filling the technological and dimensional gap between microsystems in Silicon and classical "macro microsystems", in the sense that we can now structure microdevices in the range from 150 mm to 150 mm. In effect, LTCC technology allows printing conductors and other inks from 30 mm to many mm, structuration from 150 mm to 150 mm, and suspended structures with gaps down to 30 mm thanks to sacrificial materials. Sensors and their packaging are now merged in what we can call "functional packaging". The contributions of this thesis lie both in the technological aspects we brought, and in the innovative microfluidic sensors and devices created using our developed methods. These realizations would not have been possible with the standard lamination and firing techniques used so far. Hence, we allow circumventing the problems related to microfluidics circuitry: for instance, the difficulty to control final fired dimensions, the burden to produce cavities or open structures and the associated delaminations of tapes, and the absence of "recipe" for the industrialization of fluidic devices. The achievements of the presented research can be summarized as follows: The control of final dimensions is mastered after having studied the influence of lamination parameters, proving they have a considerable impact. It is now possible to have a set of design rules for a given material, deviating from suppliers' recommendations for the manufacture of slender structures requiring reduced lamination. A new lamination method was set up, permitting the assembly of complex microfluidic circuits that would normally not sustain standard lamination. The method is based on partial pseudo-isostatic sub-laminations, with the help of a constrained rubber, subsequently consolidated together with a final standard uniaxial lamination. The conflict between well bonded tapes and acceptable output geometry is greatly attenuated. We achieved the formulation of a new class of Sacrificial Volume Materials (SVM) to allow the fabrication of open structures on LTCC and on standard alumina substrates; these are indeed screen-printable inks made by mixing together mineral compounds, a glassy phase and experimental organic binders. This is an appreciable improvement over the so-far existing SVMs for LTCC, limited to closed structures such as thin membranes. An innovative industrial-grade potentially low-cost diagnostics multisensor for the pneumatic industry was developed, allowing the measurement of compressed air pressure, flow and temperature. The device is entirely mounted by soldering onto an electro-fluidic platform, de facto making it a true electro-fluidic SMD component in itself. It comprises additionally its own integrated SMD electronics, and thanks to standard hybrid assembly techniques, gets rid of external wires and tubings – this prowess was never achieved before. This opens the way for in situ diagnostics of industrial systems through the use of low-cost integrated sensors that directly output conditioned signals. In addition to the abovementioned developments, we propose an extensive review of existing Sacrificial Volume Materials, and we present numerous applications of LTCC to sensors and microsystems, such as capacitive microforce sensors, a chemical microreactor and microthrusters. In conclusion, LTCC is a technology adapted to the industrial production of microfluidic sensors and devices: the fabrication steps are all industrializable, with an easy transition from prototyping to mass production. Nonetheless, the structuration of channels, cavities and membranes obey complex rules; it is for the moment not yet possible to choose with accuracy the right manufacturing parameters without testing. Consequently, thorough engineering and mastering of the know-how of the whole manufacturing process is still necessary to produce efficient LTCC electro-fluidic circuits, in contrast with older techniques such as classical thick-film technology on alumina substrates or PCBs in FR-4. Notwithstanding its lack of maturity, the still young LTCC technology is promising in both the microelectronics and microfluidics domains. Engineers have a better understanding of the structuration possibilities, of the implications of lamination, and of the most common problems; they have now all the tools in hand to create complex microfluidics circuits

Capteur de basse force (~10-100 mN) à bas coût de production

But du projet : Dimensionner et réaliser des capteurs de force de l’ordre de 10 à 100 mN nominal Garder l’électronique de traitement du signal et les dimensions de la gamme de capteurs de force existante (MilliNewton du LPM) Utiliser des méthodes de production industrielles ou semi-industrielles qui garantissent un faible coût de productio

Integrated calorimetric microreactor in low-temperature cofired ceramic (LTCC) technology

Object of this work 1) Explore the feasibility of an LTCC microreactor • Chemical stability: compatible with HCl, NaOH, ... • Thermal stability to >100°C 2) Achieve a high degree of integration • Temperature measurement • Reactant flow measurement • Temperature control • Calorimetric chambe

Low-cost LTCC-based sensors for low force ranges

We have designed and fabricated a low-range (ca. 100 mN) thick-film piezoresistive force sensor with a cantilever beam fabricated in LTCC (Low Temperature Co-fired Ceramic). The beam was soldered onto a standard thick-film 25.4 x 12.7 mm signal conditioning base [1]. Switching from a classical Al2O3-based thick-film beam to LTCC allows design of a 3D structured beam with increased sensitivity of the piezoresistive bridge, yet largely conserved strength and stiffness. Another advantage of LTCC compared to alumina is a lower Young’s modulus (approx. 3 times lower), more suitable for the measurement of small loads

A Network Analysis Approach of the Venetian Incanto System

The objective of this paper was to perform new analyses about the structure and evolution of the Incanto system. The hypothesis was to go beyond the textual narrative or even cartographic representation thanks to network analysis, which could potentially offer a new perspective to understand this maritime system

Laser soldering of LTCC hermetic packages with minimal thermal impact

A novel laser soldering method for hermetic packaging of temperature sensitive devices such as organic electronics, micro- and nanostructures is presented in this work. The package combines a thermally optimized LTCC (Low Temperature Co-fired Ceramic) base with a glass lid. These two parts are soldered together by the use of a laser diode. The advantages of the laser soldered joint is its hermeticity to water and air in regard to glue and plastic, as well as the possibility to heat only the soldered joint. The power of the laser diode has to be controlled during the soldering process. We propose a solution based on temperature monitoring by the mean of a pyrometer. Heat transfer from the heated solder joint to the encapsulated device can be reduced by structuring the LTCC base, which also reduces the required optical power. Several schemes such as cavities under the joint and local thinning of the base are studied. Key words: Packaging, LTCC, laser soldering, thermal impac

Formulation and processing of screen-printing vehicles for sacrificial layers on thick-film and LTCC substrates

Ceramic technologies such as thick-film and LTCC (Low Temperature Cofired Ceramic) are excellent platforms for the fabrication of mesoscale devices such as sensors, actuators, microreactors and MEMS packaging. This work presents two alternative screen-printing vehicles for the processing of sacrificial materials and low-firing thick films: 1) a non-aggressive glycol-based vehicle for screen printing thick sacrificial layers onto thin LTCC, and 2) a "high non-evaporables" vehicle for mineral / carbon sacrificial materials allowing subsequent overprinting in the dried state. Their formulation, processing and applications are discussed with regard to the physical and chemical properties of the solvents, plasticisers and binders

Laser soldering of piezoelectric actuator with minimal thermal impact

Mechanical and electrical connecting of piezoelectric actuator is often done using conductive glue. Its advantage is not to heat the piezoelectric actuator during connection. But there are many disadvantages to gluing; the main one is curing time. Welding is another alternative, but when done in an oven, the temperature needed for this operation might destroy the heat sensitive actuator. The method described in this paper is laser soldering of piezoelectric actuator. The piezo actuator is mechanically and electrically connected to an alumina substrate by the use of tin solder heated by the mean of a laser diode. The advantage of the laser diode is its ability to selectively heat needed areas. Moreover, it is possible to control the energy brought to the system during the soldering process, thus reducing thermal impact on the piezoelectric actuator. Finally, the temperature can be monitored during the soldering process, allowing to control if the piezoelectric actuator was exposed to high temperature