Sensitivity optimization of micro-machined thermo-resistive flow-rate sensors on silicon substrates

We report on an optimized micro-machined thermal flow-rate sensor as part of an autonomous multi-parameter sensing device for water network monitoring. The sensor has been optimized under the following constraints: low power consumption and high sensitivity, while employing a large thermal conductivity substrate, namely silicon. The resulting device consists of a platinum resistive heater deposited on a thin silicon pillar ~ 100 $\mu$m high and 5 $\mu$m wide in the middle of a nearly 100 $\mu$m wide cavity. Operated under the anemometric scheme, the reported sensor shows a larger sensitivity in the velocity range up to 1 m/s compared to different sensors based on similar high conductivity substrates such as bulk silicon or silicon membrane with a power consumption of 44 mW. Obtained performances are assessed with both CFD simulation and experimental characterization

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Capteurs miniatures multi-paramètres pour la gestion des réseaux d'eau

Water is a vital element for every living being on the earth. Like many other dwindling natural resources, clean water faces a strong pressure because of human activity and the rapid growth of global population. The situation is so critical that clean water has been identified as one of the seventeenth sustainable development goals of the United Nations. Under these conditions, a sustainable management of water resources is necessary. For this purpose, a smart solution for water networks monitoring can be very helpful. However, commercially available solutions lack compactness, self-powering capabilities cost competitiveness, necessary to enable the large rollout over water networks. The present thesis takes place in the framework of a European research project, PROTEUS, which addresses these different problems by designing and fabricating a multi-parameter sensor chip (MPSC) for water resources monitoring. The MPSC enables the measurement of 9 physical and chemical parameters, is reconfigurable and self-powered. The present thesis addresses more precisely physical sensors, their design, optimization and co-integration on the MPSC. The developed device exhibits state of the art or larger performances with regard to its redundancy, turn-down ratio and power consumption. The present manuscript is split into two main parts: Part-I and Part-II. Part-I deals with non-thermal aspects of the MPSC, the pressure and conductivity sensor for instance, as well as the fabrication process of the whole device (Chapter 1 and 2). The background of environmental monitoring is presented in Chapter 1 along with the State of Art review. Chapter 2 describes fabrication methods of the MPSC. Preliminary characterization results of non-thermal sensors are also reported in this chapter. Chapter 3 and 4, included in Part-II, deal with thermal sensors (temperature and flow-rate). Chapter 3 describes the many possible uses of electric resistances for sensing applications. Finally, in chapter four, we focus on flowrate sensors before concluding and making a few suggestions for future worksL’eau est une ressource vitale, indispensable à la vie sur terre. A l’instar de nombreuses autres ressources naturelles, l’eau propre à la consommation est soumise à une forte pression à cause de l’impact de l’activité humaine d’une part et de l’augmentation continue de la population mondiale d’autre part. Une pression tellement forte que l’eau propre représente l’un des 17 objectifs de développement durable des Nations Unies. Dans ce contexte, une gestion rationnelle et durable de la ressource s’avère indispensable. Dans ce but, un système intelligent de supervision des réseaux d’eau potable peut s’avérer très utile. Les systèmes existant sont toutefois peu intégrés et compacts, nécessitent souvent une alimentation externe, et restent relativement chers pour un déploiement massif sur les réseaux. La présente thèse s’inscrit dans le cadre d’un projet de recherche européen, PROTEUS, visant à pallier ces différents problèmes en mettant au point un système de mesure pour la supervision de la ressource en eau permettant la mesure de 9 paramètres physico-chimiques, reconfigurable, et énergétiquement autonome. La contribution de la présente thèse à ce projet porte sur la conception et l’optimisation des différents capteurs physiques (conductivité électrique, pression, température et débit) ainsi qu’à leur co-intégration sur une même puce. Le système proposé montre des performances au moins égales à celle de l’état de l’art en ce qui concerne la robustesse, assurée par la redondance de nombreux éléments sensibles, le domaine de sensibilité et la consommation énergétique. Le présent manuscrit est par conséquent construit comme suit : le premier chapitre est une introduction générale à la supervision de grandeurs environnementales et à la puce multi-capteurs. Le second chapitre décrit la structure de la puce multi-capteurs ainsi que les méthodes de fabrication utilisées, avec une attention particulière accordée aux capteurs de pression et de conductivité électrique. Le troisième chapitre porte sur l’utilisation de résistances électriques pour la mesure de diverses grandeurs physiques, notamment la température. Le dernier chapitre s’attarde plus particulièrement sur l’utilisation de ce type de résistances pour la mesure de débit avant de conclure et de proposer des perspectives pour des travaux futur

Micro-fabricated thermal flow-rate sensors: the substrate material impact on the device performance and power consumption

International audienceWe report on micro-machined flow-rate sensors as part of autonomous multi-parameter sensing devices for water network monitoring. Three different prototypes of the flow-rate sensors have been designed, fabricated and experimentally characterized. Those sensors are made of identical micrometric platinum resistors deposited on different substrates, made of glass, silicon and micro-structured silicon, with and without insulation layers. The sensors are tested under the anemometric operating scheme. They are experimentally characterized under a water velocity range from 0 to 0.91 m/s. We show that the glass substrate device is more sensitive and less power-consuming under identical operating condition. We also show that, when silicon is needed as the substrate material, further optimization and design strategies are required. Experimental results are analyzed with respect to Computational Fluid Dynamics simulations with the Finite Element Metho

Design of micro-fabricated thermal flow-rate sensor for water network monitoring

International audienceWe report on micro-machined flow-rate sensors as part of autonomous multi-parameter sensing devices for water network monitoring. Three different versions of the flow-rate sensors have been designed, fabricated and experimentally characterized. Those sensors are made of identical micrometric platinum resistors deposited on two different substrates-glass and silicon with and without insulation layer. The sensors were tested under the anemometric operating scheme. They were characterized under a water velocity range from 0 to 3.68 m/s. We highlight the fact that the glass substrate device is more sensitive and less power-consuming than the silicon one under the identical operating condition, which requires further design strategies when using silicon as the substrate material. Experimental results are analyzed with respect to CFD simulations with the Finite Element Method

Ateliers et Travaux Pratiques sur le thème des Capteurs pour l’Eau

International audienc

Ateliers et Travaux Pratiques sur le thème des Capteurs pour l’Eau

International audienc

On the co-integration of a thermo-resistive flow-rate sensor in a multi-parameter sensing chip for water network monitoring

International audienceMotivated by the need for a multi-parameter sensing chip for water networks monitoring, we address here the specific case of a flow-rate sensor where the main challenge is the substrate material. Instead of using conventional low thermal conductivity materials such as glass, silicon has to be used. Indeed, a silicon substrate enables the co-integration of various kinds of sensors on the same chip as reported in this contribution. However, it increases the flow-rate sensor power consumption due to larger thermal leaks. We therefore design and study an optimized low power micro-machined thermal flow-rate sensor based on a silicon substrate and operating according to hot-wire anemometry. It can be considered as an alternative to other well established sensors for liquid flow-rate measurement when both the use of a silicon substrate and a low power consumption are needed