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International audience; This paper presents the implementation of a single piece of macro-fiber composite (MFC) piezoelectric transducer as a multifunctional device for both strain sensing and energy harvesting for the first time in the context of an energy harvesting powered wireless sensing system. The multifunction device is achieved via time-multiplexing operation for alternating dynamic strain sensing and energy harvesting functions at different time slots associated with different energy levels, that is, when there is insufficient energy harvested in the energy storage for powering the system, the MFC is used as an energy harvester for charging up the storage capacitor; otherwise, the harvested energy is used for powering the system and the MFC is used as a strain sensor for measuring dynamic structural strain. A circuit is designed and implemented to manage the single piece of MFC as the multifunctional device in a time-multiplexing manner, and the operation is validated by the experimental results. The dynamic strains measured by the MFC in the implemented system match a commercial strain sensor of extensometer by 95.5 to 99.99 %, and thus the studied method can be used for autonomous structural health monitoring of dynamic strain.

International audience; New applications of embedded systems are envisioned in the context of aeronautics. However, the increasing burden of on-board cabling requires wireless solutions. Moreover, concerns such as safety or system lifetime often preclude the use of electrochemical energy storage. Ambient energy capture, storage and management are therefore key topics. In this paper we illustrate these concepts by describing an actual implementation in the engine harsh environment of an Airbus A380. A thermogenerator was used to harvest ambient energy and the electronics associated with it allows the local system being energy autonomous. All items were devised and tested in order to meet the criteria of DO-160G aeronautical standard. The set of equipment was mounted on aircraft, and submitted to tens of test flights during roughly a year, in very various flight conditions.

In recent years, wireless sensor networks (WSN) have been considered for various aeronautical applications to perform sensing, data processing and wireless transmission of information, without the need to add extra wiring. However, each node of these networks needs to be self-powered. Considering the critical drawbacks associated with the use of electrochemical energy sources such as narrow operating temperature range and limited lifetime, environmental energy capture allows an alternative solution for long-term, deploy and forget, WSN. In this context, thermoelectricity is a method of choice considering the implementation context. In this paper, we present hands-on experience related to on-going implementations of thermoelectric generators (TEG) in airliners. In a first part, we will explain the reasons justifying the choice of ambient energy capture to power WSN in an aircraft. Then, we will derive the general requirements applying to the functional use of TEG. Finally, in the last section, we will illustrate the above issues through practical implementations.

International audience; This paper presents an envisaged autonomous strain sensor device, which is dedicated to structural health monitoring applications. The paper introduces the ASIC approach that replaces the discrete approach of some of the main modules.

International audience; In the context of wireless sensors (WSs) autonomous in energy, this paper presents a single macro-fiber composite (MFC) piezoelectric transducer which is used for the first time as a multifunctional device as both sensor and energy harvester in a time-multiplexing manner. The MFC is used as an energy harvester to charge up a storage capacitor. When there is sufficient energy, the WS is powered up and the MFC is used as a sensor. A circuit was implemented to harvest energy from the MFC and use the MFC as a sensor. Experiment validation shows that the MFC has an accuracy of up to 97 % as sensor and the circuit harvests energy from the MFC at its maximum power point with up to 98 % efficiency.

This paper reports for the first time the experimental demonstration of a wireless sensor node only powered by an aeroacoustic energy-harvesting device, meant to be installed on an aircraft outside skin. Aeroacoustic noise is generated on purpose to serve as a means of converting mechanical energy from high velocity airflow into electrical energy. Results related to the physical characterization of the energy conversion process are presented. The proposed aeroacoustic transducer prototype, consisting in a rectangular cavity fitted with a piezoelectric membrane, is shown to deliver up to 2 mW AC power under Mach 0.5 airflow. Optimized power management electronics has been designed to interface with the transducer, including a self-powered Synchronized Switch Harvesting on Inductor (SSHI) interface circuit and an efficient buck-boost DC/DC converter. The design of micropower auxiliary circuits adds functionality while preserving high efficiency. This circuit stores energy in supercapacitors and is able to deliver a net output DC power close to 1 mW. A fully autonomous system has been implemented and tested, successfully demonstrating aeroacoustic power generation by supplying a battery-free wireless datalogger in conditions representative of an actual flight.

In this paper, we describe how the term telecommunications and its related concepts were introduced. We first recall that this term was coined in 1904 by Edouard Estaunié who was a French writer, known for his novels of character, and also by profession an engineer. . Dans ce papier nous décrivons la genèse du terme télécommunications, et des concepts associés. Nous rappelons que le mot a été inventé en 1904 par Edouard Estaunié, romancier et ingénieur, et nous expliquons le concept de cette création.

In this chapter, we will outline the principles implemented in order to obtain energy autonomy for an isolated system. To begin with, we will compare electrochemical and electrostatic energy storage, forms of technology which are at the heart of energy autonomy for wireless sensor networks. We will look at the architecture of systems based around harvesting ambient energy, we will consider the physical principles for the transducers used for energy capture, without forgetting the relevance of these systems in an aeronautical context. For the most part, the following chapter will focus on managing energy in electronic circuits. It should be noted that, for this current volume, we have limited ourselves to one application scope (aeronautics) within which we have chosen those structures which would appear to be the most relevant. For further information, we would direct the reader toward studies found.

In this chapter, we will present three builds, the purpose of this is to clearly illustrate what was developed in previous chapters. The first two builds were installed in a passenger plane and were tested in-flight, while the third system was more of a start toward a solution for energy autonomy that is more innovative than previous ones.

The large majority of energetically autonomous embedded systems are powered by a battery or an accumulator. Most often, using a non-rechargeable battery is proven to be financially unbeatable. So, for a manufacturer working on wireless sensors, an application consuming a total energy of less than 10 Wh over its lifespan will preferably be powered by a battery. For a total energy consumption that is initially much higher, it would be better to minimize the electronic consumption rather than implementing an energy harvesting and storage system. However, batteries have limitations when conditions such as lifespan, cost of maintenance and usage are demanding. Using a rechargeable storage component (rechargeable accumulator and/or supercapacitor associated with the harvesting of ambient energy) is then required. For some applications, particularly with strong temperature restrictions as in aeronautics (–40, + 80 °C) or operating over a very long period, rechargeable accumulators could not be used and storage should be established around an electrostatic-type component (capacitor or supercapacitor).

Although it is currently the subject of much discussion, in research laboratories as well as in the industrial world, the concept of wireless sensor networks is quite old. We will not pretend that it was the first instance of its implementation, but it is interesting to note, for example, the deployment from 1967 onward of such sensors by the American army during the Vietnam War1. This technology continues to be used in a military context, with miniaturized systems which fall into the bracket of Unattended Ground Sensors (UGS).

In this paper, we present the low cost fabrication process of a partial and thick silicon-on-insulator (SOI) substrate for mixed power integration (low and high voltage devices on the same chip). It is based on the Lateral Epitaxial Growth over Oxide process (LEGO). It is shown that the proposed process provides a crystalline quality compatible with a CMOS technology and high voltages devices.

International audience; We suggest an innovative architecture for an efficient energy generator devoted to the powering of a wireless sensor network deployed for Aircraft Health Monitoring. This battery-free generator captures energy from its environment (transient thermal gradients as a main source, and vibrations as a secondary source allowing early biasing of the generator) and stores this energy in ultracapacitors. In this way, this multi-source architecture benefits from the synergy between energy scavenging and harvesting: vibrations bring low but early and permanent energy. They also contribute to energy harvesting during cruise while thermal gradients have vanished. The use of active diodes and of a very low bias current of 10nA/branch allow achieving ultra-low power consumption, experimentally demonstrated on two different CMOS technologies. It is also proven that enough energy could be delivered to power the functions of a wireless sensor node.

The main feature of the thermomigration of Al/Si liquid droplets in silicon for the realization of isolation walls in bi-directional power devices is its low thermal budget. Therefore, it is compatible with the utilization of epitaxial substrates for innovative power devices, for example, with reduced on-state resistance. This paper describes the design and realization of a medium power SCR on epitaxy. After structure presentation and voltage blocking capability simulation, the specific issue of thermomigration on (1 1 1)-orientated epitaxial substrates is considered. Limitations to migration are found due to the off-axis cut necessary for good epitaxial growth. Electrical characterization exhibits great agreement with simulation, demonstrating the great potential of thermomigration as a low thermal budget technique for isolation walls processing for both standard structures and new devices on epitaxy.

In recent years, wireless sensor networks (WSN) have been considered for various aeronautical applications, including, among others, structural health monitoring (SHM) and fiight-tests. Each network node would allow performing sensing, data processing, and wireless transmission of information. Thus WSN permit (often new) functions without the need of adding extra wiring to an already large burden. However, these nodes need to be self-powered, many of the advantages of wireless sensor networking being lost if external (i.e. wired) power sources were used. For this purpose, batteries offer a high energy density at low cost. However, there are critical drawbacks associated with the use of batteries. First, environmental concerns and economical aspects associated with the replacement of primary batteries. Second, batteries may be prohibited since the wireless nodes are often implemented in locations without temperature regulation that could result both in a drastically reduced yield together with safety issues. Fortunately, batteries can be avoided through the use of environmental energy capture allowing a solution for long term, deploy and forget, WSN. However, environmental energy transducers, unlike batteries, are not energy reservoirs, and energy buffer storage is mandatory whatever the context. In this article we present hands-on experience related to ongoing - or prospective - implementations of energy harvesters in airliners.

National audience; The present work is related to the problem of energy autonomy within sensor networks embedded onboard aircrafts. More precisely, the design and experimental testing of an aeroacoustic energy transducer associated with dedicated power management electronics are described.

This paper reports the experimental demonstration of a wireless sensor node only powered by an aeroacoustic energy harvesting device, meant to be installed on an aircraft outside skin. New results related to the physical characterization of the energy conversion process are presented. Optimized interface electronics has been designed, which allows demonstrating aeroacoustic power generation by supplying a commercial wireless datalogger in conditions representative of an actual flight.

International audience; — In this paper we present hands-on experience related to on-going implementation in aircraft of power supply for a wireless sensor network deployed for aerodynamic flight tests. This autonomous battery-free power supply is capturing, managing and storing primary energy from the environment, using solar light and photovoltaic cells. For practical purposes, it is also equipped with an auxiliary power input. The specifications are detailed, the general architecture is presented and justified, and test results are discussed.

A model, using geometric optics, has been developed to calculate the illumination of a wafer inside a rapid thermal processor. The main parameters of the model are: the processing chamber geometry, the lamp number and location, the reflector characteristics, and the wafer temperature. Each incident light component, i.e., direct or reflected, is identified, its contribution to the illumination of the wafer is calculated through a 3D analytical model, and the corresponding contour maps are depicted. Then, the heat diffusion equation is numerically solved in two dimensions, and thermal maps of a Si wafer are given versus various experimental conditions, such as the effect of patterning the reflectors, of individually adjusting the electrical power applied to each lamp, and the impact of rotating the wafer or using crossed lamp banks. The latter method, while being easy to implement, is shown to give excellent thermal uniformity. >

International audience; This paper reports the testing of a new mechanism converting energy radiated from an acoustic source, i.e. a small cavity created on an aircraft outside skin and inducing high frequency oscillations of airflow passing over it. This acoustic noise is then converted into electrical energy. We have submitted in a wind tunnel a set of cavities to an airflow varying the Mach number, creating high sound levels. In a second set of experiments, we have submitted passive microphones to high acoustic levels and stored in capacitors the electrical energy collected at the microphone output. Finally, directions for future work are identified.

This paper describes a teaching experiment where students have to design a telecom system based on a wireless sensor network which specifications are power-oriented. Priority is given to an experimental hands-on approach.

This paper describes experimental results aiming at analyzing commercial Li-Polymer and Ni-MH batteries performances at extreme temperatures. A climatic test chamber has been used to simulate these conditions, in addition to simple electronic circuits for charging and discharging. Charge and discharge experimental curves of voltage and current versus time at different temperatures are given for temperatures ranging from −40°C to 80°C. Finally, the amount of charge stored to the batteries during the charge cycle at extreme temperature is presented.

This paper describes experiment results aiming at analyzing the ambient temperature effect on the lifetime of commercial Nickel-Metal Hydride (Ni-MH) secondary battery. In addition the paper presents the battery characteristics at extremely different ambient temperatures. To investigate this effect, a climatic chamber, has been used to simulate these conditions. Charge and discharge experimental curves of voltage versus time at different temperatures are given for temperatures ranging from −40°C to 80°C. Finally the batteries are retested at room temperature in order to study the temperature effect on the battery ageing.

A most promising technique for the design of energy efficient Radio Frequency (RF) transmitters is based on modulating the supply of the main Power Amplifier (PA) by a DC/DC converter. However, the slow time-response of DC/DC converters compared to the large bandwidth of the RF signal to transmit is an obstacle for application to broadband communications. In this paper, a digital signal processing structure enabling the use of bandwidth-limited DC/DC converters, and resulting in linear, efficiency-enhanced transmitter behaviour is presented. Models of the PA and DC/DC converters are used to validate the principle through simulation procedures.

A new method for creating deep junctions extending through the whole thickness of a wafer has recently been demonstrated. Applications are in the field of high power devices. The method uses the thermomigration of melted Al/Si droplets in silicon and allows function electrical isolation. This process requires a specific Rapid Thermal Processing equipment. The purpose of this paper is to discuss the control of the process by end-point detection, that is the optical in situ detection of the emergence of the melted alloy once thermomigration is completed. For this purpose, in situ laser reflectometry and video observation have been used. Experimental results are presented and discussed.

During rapid thermal processing, temperature non-uniformities are likely to occur because of increased thermal radiation from the wafer edges, or inappropriate illumination of the wafer. Up to now, despite the fact that the optical conditions of the wafer play a dominant role in temperature non-uniformity, little work about the effect of heating lamps and reflector arrangement on wafer illumination distribution has been published, if one compares with other topics related to Rapid Thermal Processing (RTP). Simulation software, using geometric optics, has therefore been developed to calculate the illumination of a wafer inside a RTP processing chamber. The main parameters of the analytical model are: (1) the processing chamber geometry, (2) the lamp number and location, and (3) the reflector characteristics. Each incident light component, i.e. direct or reflected, is identified, its contribution to the illumination of the wafer is calculated, and the corresponding contour maps depicted. Then, the heat diffusion equations is numerically solved in two dimensions, and 2D thermal maps of a 4' Si wafer are given vs. various experimental conditions, such as the effect of individually adjusting the electrical power applied to each lamp, and the impact of rotating the wafer.

Time Resolved Reflectivity (TRR) is first applied to the measurement of the solid phase epitaxial growth rate of As (60 keY 4. 1015 cm2) implanted (100) Si wafers. The thermal cycles consist of a fast heating phase (125C/s) followed by an isothermal plateau ranging between 520 and 624C. An activation energy of 2. 8 eV is found. TRR is then applied to temperature calibration vs. Germanium thin film melting point : it is demonstrated that reproducible results are given by the method and that it can replace thermocouples for optical pyrometer calibration. 1.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

PD (Proportional Integrated Derivative) controllers applied to temperature regulation in a rapid thermal processor are first presented. The setting method of the control parameters together with the corresponding experimental results is given. Evidence in favour of parameter dynamic adjustment is demonstrated. A new algorithm based upon parameter scheduling and providing enlarged control capability is then presented and tested with various wafers and processors. At last insights about closed loop self-tuning using Generalized Predictive Control algorithm are given and the corresponding results discussed. 1.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

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The reflectivity of thin‐film platinum silicide was measured by means of a helium‐neon (He‐Ne) laser when samples of platinum films deposited on top of silicon wafers were annealed in a rapid thermal processor. This processor consists of two rows of tungsten‐halogen quartz lamps placed above and below a quartz processing chamber. The thermal cycles consisted of a fast heating (about 200 °C/s), followed by an isothermal plateau at temperatures ranging between 410 and 600 °C. Film reflectivities dropped in two stages, as a result of the reaction between platinum and silicon. This two‐stage drop was identified as due to the transformation of the platinum film, first into Pt2Si, and then into PtSi. The amounts of time required to complete the transformations were found to be in good agreement with the Arrhenius laws derived from the work of J. T. Pan and I. A. Blech [Thin Solid Films 113, 129 (1984)] on isothermal low‐temperature (220–330 °C) sintering of platinum films on silicon, who unambiguously establish...

This work deals with energy harvesting and storage to power aircraft embedded wireless sensors. First, we discuss the issue of powering wireless sensors in an aircraft and we present a state of the art of the various energy harvesting and storage technologies that could be used. Then, through the design and construction of two harvesters, we show the possibilities offered by this technology and we explain the design constraints imposed by the application to get a reliable and robust power supply. The first harvester is a photovoltaic power supply located on the upper surface of an A321’s wing supplying a wireless sensors belt nearby. The systems provides 2 watts to the load, works with cloudy weather and is highly resistant to negative temperature (-50°C) and low pressure (200hPa) that are met at aircraft cruising altitude. The second harvester is a thermoelectric power supply located in an A380 pylon supplying a structural health monitoring system. The harvester is highly resistant to high temperature (300°C) and severe vibrations of the installation area and manages to generate the required energy to supply the structural health monitoring sensors. Mechanical and electronic design steps and choices that led to both harvesters are detailed and discussed.; Ces travaux portent sur la récupération et le stockage d’énergie pour l’alimentation de capteurs sans fil dans un contexte aéronautique. Dans un premier temps, nous présentons la problématique particulière de l’alimentation des capteurs sans fil dans un tel domaine et dressons un état de l’art des différentes technologies de stockage et de récupération pouvant répondre à ce besoin. Dans un deuxième temps, à travers l’étude et la réalisation de deux récupérateurs, nous montrons les possibilités qu’apporte cette technologie et détaillons les contraintes de conception qu’impose le milieu afin d’obtenir une alimentation robuste et fiable. Le premier récupérateur présenté est une alimentation photovoltaïque située sur l’extrados de l’aile d’un A321 alimentant des bandes de capteurs sans fil proches. Le système fournit 2 watts, fonctionne par temps couvert et résiste aux températures fortement négatives (-50°C) et aux basses pressions (200hPa) qui sont rencontrées à l’altitude de croisière de cet appareil. Le deuxième récupérateur est une alimentation thermoélectrique placée dans le mât réacteur d’un A380 pour alimenter un système de capteurs dédié à la surveillance de l’état de structure. Le système résiste aux températures élevées (300°C) et aux importantes vibrations de la zone d’installation et produit l’énergie nécessaire à l’alimentation du système de capteurs. Les choix et les étapes de conception ayant menés aux deux systèmes sont détaillés, tant au niveau de l’assemblage mécanique que des circuits électroniques.

This work deals with energy harvesting and storage to power aircraft embedded wireless sensors. First, we discuss the issue of powering wireless sensors in an aircraft and we present a state of the art of the various energy harvesting and storage technologies that could be used. Then, through the design and construction of two harvesters, we show the possibilities offered by this technology and we explain the design constraints imposed by the application to get a reliable and robust power supply. The first harvester is a photovoltaic power supply located on the upper surface of an A321’s wing supplying a wireless sensors belt nearby. The systems provides 2 watts to the load, works with cloudy weather and is highly resistant to negative temperature (-50°C) and low pressure (200hPa) that are met at aircraft cruising altitude. The second harvester is a thermoelectric power supply located in an A380 pylon supplying a structural health monitoring system. The harvester is highly resistant to high temperature (300°C) and severe vibrations of the installation area and manages to generate the required energy to supply the structural health monitoring sensors. Mechanical and electronic design steps and choices that led to both harvesters are detailed and discussed.; Ces travaux portent sur la récupération et le stockage d’énergie pour l’alimentation de capteurs sans fil dans un contexte aéronautique. Dans un premier temps, nous présentons la problématique particulière de l’alimentation des capteurs sans fil dans un tel domaine et dressons un état de l’art des différentes technologies de stockage et de récupération pouvant répondre à ce besoin. Dans un deuxième temps, à travers l’étude et la réalisation de deux récupérateurs, nous montrons les possibilités qu’apporte cette technologie et détaillons les contraintes de conception qu’impose le milieu afin d’obtenir une alimentation robuste et fiable. Le premier récupérateur présenté est une alimentation photovoltaïque située sur l’extrados de l’aile d’un A321 alimentant des bandes de capteurs sans fil proches. Le système fournit 2 watts, fonctionne par temps couvert et résiste aux températures fortement négatives (-50°C) et aux basses pressions (200hPa) qui sont rencontrées à l’altitude de croisière de cet appareil. Le deuxième récupérateur est une alimentation thermoélectrique placée dans le mât réacteur d’un A380 pour alimenter un système de capteurs dédié à la surveillance de l’état de structure. Le système résiste aux températures élevées (300°C) et aux importantes vibrations de la zone d’installation et produit l’énergie nécessaire à l’alimentation du système de capteurs. Les choix et les étapes de conception ayant menés aux deux systèmes sont détaillés, tant au niveau de l’assemblage mécanique que des circuits électroniques.

SOI identifies a “silicon substrate / insulating film / thin silicon layer” structure. A lot of studies have been made since the 70's to obtain that kind of structures. The LEGO process is based on fusion and recrystallization of thick poly-silicon patterns on oxide, and provides localized SOI patterns on a silicon substrate. It has first been developed by G. Celler and al. in the 80's and is being reconsidered today because of new market demand for low cost partial SOI: the coexistence of control and power devices on the same chip for mixed power integration and with efficient electrical insulation. Following an overview of the existing techniques for the fabrication of SOI wafers, this thesis describes the LEGO process and the different optimizations that were performed to obtain monocrystalline SOI patterns up to 2mm². Then, we will present the fabrication of MOS devices on partial SOI substrates, and we will demonstrate that this LEGO process is compatible with completely functionnal devices showing the same electrical performances than on bulk silicon substrate. Finally, we will conclude on the possible applications of this process.; Le terme SOI (Silicon On Insulator) identifie une structure du type «substrat silicium / film isolant / couche mince de silicium». Depuis les années 70, de nombreux travaux ont été menés afin d'élaborer ce type de structures. Le LEGO (Lateral Epitaxial Growth over Oxide) est une technique basée sur la fusion et la recristallisation de motifs épais de silicium poly-cristallin sur oxyde, et qui permet d'obtenir des motifs localisés de SOI sur un substrat de silicium. Elle a été développée en premier lieu par G. Celler et al. dans les années 80 et est désormais reconsidérée à cause d'un nouveau marché pour les structures SOI partielles à faible coût, celui de l'intégration de composants de commande et de puissance sur une même puce avec une isolation diélectrique efficace.Après une présentation des différentes technologies permettant d'obtenir des substrats SOI, ce mémoire décrit plus particulièrement le procédé LEGO, et le travail d'optimisation qui a été mené sur ce procédé afin d'obtenir des motifs SOI monocristallins jusqu'à 2mm². Par la suite, nous abordons la fabrication de composants de type MOS sur SOI partiel, et nous démontrons que ce procédé permet d'accueillir des composants entièrement fonctionnels et présentant les mêmes caractéristiques électriques que sur substrat silicium massif. Enfin nous concluons sur les perspectives d'applications de ce procédé.