Développement d'un système de détection en milieux gazeux d'espèces à risque pour le contrôle environnemental (application au monoxyde de carbone et à l'hydrogène) : Composants et systèmes micro-acoustiques

The detection of hazardous gas is a topical issue for the protection of persons. Besides, it represents a challenge linked to the storage of renewable energy. Simulation tools developed within the Time and Frequency Department attached to the FEMTO-ST Institute together with technological facilities available at MIMENTO center have enabled the development of SAW sensors providing answers to these issues. These Love wave’sbased sensors properties have enabled the detection of carbon monoxide in the ppm range. Similarly, hydrogen concentrations of the percent order has been measured by mean of Rayleigh wave’s based sensors. The efforts to optimize electro-acoustic devices have led to achieve delay lines built on quartz with insertion losses of 16 dB.Usually around 25 dB to 30 dB, the reduction of the insertion losses improves the potential of these sensorsin terms of autonomy and surface functionalization. Knowledge of the physical phenomena governing theoperation of these sensors represent the basis of their future development. Thus, different characterization and analysis techniques available in our institute have been carried out to reveal these phenomena. From there, the functionalization of sensor’s sensitives surfaces with metallic alloys and implementation of a chip separation method limiting the disturbance of the direct signal of the electro-acoustic devices, have been explored to improve the performance of the sensors. Based on the experimental results obtained in this thesis, the potential of elastic guided wave’s sensors applied to the detection of chemical quantities in gas phase can be established.In continuation of this study, two projects (P-AIR and SMARTY) dedicated to the control of the urban air quality have already been engaged.La détection de gaz potentiellement dangereux représente une problématique d’actualité pour la protectiondes personnes mais aussi un enjeu d’avenir pour le stockage des énergies renouvelables. Les outils desimulations développés au sein du Département Temps-Fréquence de l’Institut FEMTO-ST, associés aux outilstechnologiques proposés par la centrale MIMENTO ont permis la mise au point de capteurs SAW apportantdes réponses à ces problématiques. Ces derniers fondés sur les propriétés des ondes de Love ont ainsi permis ladétection du monoxyde de carbone dans la gamme du ppm. De même, la mesure de concentration d’hydrogènede l’ordre du pourcent a pu être réalisée par le biais de dispositifs s’appuyant sur les ondes Rayleigh. Les effortsfournis pour l’optimisation des dispositifs électro-acoustiques ont aboutis à la réalisation de lignes à retard surquartz affchant des pertes d’insertion de 16 dB. La limitation de ces pertes, généralement de l’ordre de 25 dB à30 dB sur quartz, augmente les potentialités de nos capteurs en terme d’autonomie et de fonctionnalisation desurface. La connaissance des phénomènes physiques gouvernant leur fonctionnement représente, à notre sens,la base de leur développement futur. De cette idée découle notre démarche d’identification et de compréhensionde ces derniers par le biais des différentes techniques de caractérisations et d’analyses disponible au sein denotre l’institut. Des pistes, telles que le recours à un alliage métallique pour la fonctionnalisation des surfacessensibles et la mise en œuvre d’une méthode de séparation des puces limitant les perturbations du signal directdes dispositifs électro-acoustiques, ont été explorées et ont permis d’améliorer la réponse des capteurs. Lepotentiel des composants à ondes élastiques guidée pour la détection de grandeurs chimiques en phase gazeusea pu être établi sur la base des résultats expérimentaux obtenus au cours de cette thèse. Dans la continuité decette dernière, deux projets de recherche (P-AIR et SMARTY) visant le contrôle de la qualité de l’air en milieuurbain ont d’ors et déjà été engagés

Development of a system for the detection of hazardous species in gases for environmental management (application to carbon monoxide and hydrogen) : Micro-acoustic components and systems

La détection de gaz potentiellement dangereux représente une problématique d’actualité pour la protectiondes personnes mais aussi un enjeu d’avenir pour le stockage des énergies renouvelables. Les outils desimulations développés au sein du Département Temps-Fréquence de l’Institut FEMTO-ST, associés aux outilstechnologiques proposés par la centrale MIMENTO ont permis la mise au point de capteurs SAW apportantdes réponses à ces problématiques. Ces derniers fondés sur les propriétés des ondes de Love ont ainsi permis ladétection du monoxyde de carbone dans la gamme du ppm. De même, la mesure de concentration d’hydrogènede l’ordre du pourcent a pu être réalisée par le biais de dispositifs s’appuyant sur les ondes Rayleigh. Les effortsfournis pour l’optimisation des dispositifs électro-acoustiques ont aboutis à la réalisation de lignes à retard surquartz affchant des pertes d’insertion de 16 dB. La limitation de ces pertes, généralement de l’ordre de 25 dB à30 dB sur quartz, augmente les potentialités de nos capteurs en terme d’autonomie et de fonctionnalisation desurface. La connaissance des phénomènes physiques gouvernant leur fonctionnement représente, à notre sens,la base de leur développement futur. De cette idée découle notre démarche d’identification et de compréhensionde ces derniers par le biais des différentes techniques de caractérisations et d’analyses disponible au sein denotre l’institut. Des pistes, telles que le recours à un alliage métallique pour la fonctionnalisation des surfacessensibles et la mise en œuvre d’une méthode de séparation des puces limitant les perturbations du signal directdes dispositifs électro-acoustiques, ont été explorées et ont permis d’améliorer la réponse des capteurs. Lepotentiel des composants à ondes élastiques guidée pour la détection de grandeurs chimiques en phase gazeusea pu être établi sur la base des résultats expérimentaux obtenus au cours de cette thèse. Dans la continuité decette dernière, deux projets de recherche (P-AIR et SMARTY) visant le contrôle de la qualité de l’air en milieuurbain ont d’ors et déjà été engagés.The detection of hazardous gas is a topical issue for the protection of persons. Besides, it represents a challenge linked to the storage of renewable energy. Simulation tools developed within the Time and Frequency Department attached to the FEMTO-ST Institute together with technological facilities available at MIMENTO center have enabled the development of SAW sensors providing answers to these issues. These Love wave’sbased sensors properties have enabled the detection of carbon monoxide in the ppm range. Similarly, hydrogen concentrations of the percent order has been measured by mean of Rayleigh wave’s based sensors. The efforts to optimize electro-acoustic devices have led to achieve delay lines built on quartz with insertion losses of 16 dB.Usually around 25 dB to 30 dB, the reduction of the insertion losses improves the potential of these sensorsin terms of autonomy and surface functionalization. Knowledge of the physical phenomena governing theoperation of these sensors represent the basis of their future development. Thus, different characterization and analysis techniques available in our institute have been carried out to reveal these phenomena. From there, the functionalization of sensor’s sensitives surfaces with metallic alloys and implementation of a chip separation method limiting the disturbance of the direct signal of the electro-acoustic devices, have been explored to improve the performance of the sensors. Based on the experimental results obtained in this thesis, the potential of elastic guided wave’s sensors applied to the detection of chemical quantities in gas phase can be established.In continuation of this study, two projects (P-AIR and SMARTY) dedicated to the control of the urban air quality have already been engaged

Real Time Cascade Impactor Based On Surface Acoustic Wave Delay Lines for PM10 and PM2.5 Mass Concentration Measurement

In this research, Surface Acoustic Wave (SAW) sensors are combined with a cascade impactor to perform real time PM10 and PM2.5 mass concentration measurements. The SAW sensors consist of 125 MHz delay lines based on Love waves propagating on an AT-cut quartz substrate. The Love waves are guided on the substrate’s surface using a silica layer. SAW sensors themselves are not capable to discriminate particles by their size, therefore, particle separation based on aerodynamic diameter is achieved using a 3 Lpm dedicated cascade impactor. The latter was designed to integrate the SAW sensors which are monitored using a phase shift measurement. The collected particles impact on the acoustic sensor’s surface inducing a gravimetric effect that modifies the acoustic wave propagation conditions. The resulted phase shift allows the measurement of the mass deposited on the sensitive zone. The novel cascade impactor with SAW sensors as particle collecting stages is exposed to different aerosols in the 0–150 μg/m3 concentration range and proved to be able to detect and differentiate particles based on their size in real time. The system’s response was compared to a commercial optical counter based on light scattering technology and was found to be in good agreement with it

Development of Love Wave devices based on delay line configuration for the high detection and monitoring of carbon monoxide

International audienceCarbon Monoxide is produced by incomplete combustion. Its high toxicity and the lack of detection capability of human olfaction render CO a dangerous compound which is known as the silent killer. Therefore, there is the necessity to develop a device to detect the presence of low CO concentrations in indoor air. We here report on results obtained for CO detection by using SAW devices functionalized with new materials such as cobalt corroles. During the tests, CO sensors have been exposed to changes of several experimental parameters (temperature, flow, pressure, presence of analyte gas). In order to exclusively extract the information concerning CO adsorption, we used a specific differential setup comprising two SAW devices A minimum of 450ppb of CO concentration have been monitored and the experimentations have shown a great repeatability and stability of measurements. The test bench permits the regeneration of the trapping sites of CO allowing the reusability of the devices. These good results pave the way to the detection of other gas and even particles

Detection and Monitoring of Hydrogen using Palladium Film on SAW

International audienceWith predicted shortage of fossil energy resources and the increasing concern towards environmental pollution, hydrogen is seen as one of the most promising ways to store energy in automotive applications and consumer electronics. However, this odorless and colorless gas is highly explosive over 4% in air. Thus, the fast and accurate detection of hydrogen prior to the explosive concentration at room temperature is still a great problem. There are many methods of hydrogen detection and a comprehensive review can be found in the literature [1]. In this paper, thin palladium film is using as sensor material because of its well-known absorption properties relative to hydrogen. Phase variations of SAW devices using Rayleigh waves have been monitored versus various H2 flow. Moreover, a specific testing setup has been developed to follow hydrogen at atmospheric pressure and to allow regeneration of the sensor

Analysis of Palladium and Yttrium-Palladium alloy layers used for Hydrogen detection with SAW device

International audienceBecause of its physicochemical properties, hydrogen appears as an efficient source of energy for powering devices. Its abundance on earth and the simplicicty of the process needed for its extraction from water make this compound a promising solution for an increasing number of applications (energy production and storage, car industry, space, etc.). However, due to its unstable properties, a particular care must be dedicated to control gaseous leaks close to facilities using this resource. Surface Acoustic Wave (SAW) sensors consisting in Rayleigh-wave delay lines equipped with a sensitive overlay can be efficiently used to detect hydrogen. In this paper, we propose a SAW device exhibiting either pure palladium or palladium-yttrium alloy sensing area for the detection of hydrogen in standard environmental conditions. An X-ray diffraction analysis of these sensitive materials is also presented and correlated with the simultaneously acquired signal of our sensor. Mesurements of hydrogen in the 0.5-2 % concentration range diluted in nitrogen are presented. The effect of combining yttrium and palladium as sensing layer on the sensor response is reported and its interest for improving our sensor's sensitivity is finally discussed

Selective Detection of Hydrogen with Surface Acoustic Wave Devices Using Palladium Layer Properties

For an increasing number of applications, hydrogen represents a solution of the future as it is the most common element in the Earth. However, due to its unstable properties in gas phase, a particular care must be dedicated to control possible gaseous leaks close to tanks and facilities using this resource. In this paper, surface acoustic wave sensors are proposed for detecting gaseous hydrogen in standard environmental conditions (atmospheric pressure and room temperature). The proposed Surface Acoustic Wave sensors consists in two Rayleigh-wave delay lines built on Quartz, one equipped with a palladium overlay and the other exhibiting a free path between the two interdigited transducers. A specific gas test cell has been developed to test various sensor configurations submitted to hydrogen-composed atmospheres. A particular care was paid to avoid hydrogen leakage in the working environment and to perform the regeneration of the gas absorbing layer. The developed device allows for identifying different concentrations of hydrogen (in the 1-4 % range) diluted in nitrogen and is also able to detect hydrogen in current atmosphere. Surface Acoustic Wave devices exploiting hydrogen absorption capabilities of palladium thin films have been here used to make the detection and the identification of hydrogen concentrations in the 1-4 % range and the influence of outer parameters such as temperature and relative humidity variations on the sensor operation are also reported

Sensitivity of Surface Acoustic Wave Sensors Based LiNbO3 128° Y-X and at-Quartz to PM10 and PM2.5

International audienceParticulate matter (PM) was estimated to cause around 7 million premature deaths worldwide per year according to<br&gtWorld Health organization [1]. These particles can cause diseases leading to premature death [2]. Over the last decade, the monitoring of PM became an important issue on a worldwide scale.The miniaturization of the existing bulky systems has also become necessary to reduce their cost. To address this need, a new miniaturized system for PM monitoring was previously developed in our team [3].It takes advantage of both a 3 Lpm cascade impactor and surface acoustic waves (SAW) sensors to respectively separate and measure particles. The present study aims to compare the sensitivity of two SAW devices. The first exploits Love waves on an ATcut Quartz substrate and the second is based on Rayleigh waves from a LiNbO3 Y-X 128° substrates. The latter presents a high electromechanical coupling factor that could be exploited for the self-cleaning of the device after the measurement. This could allow overcoming the fouling issue faced with impactors that wouldn’t be solved with quartz based sensors which suffer from an insufficient electromechanical coupling

Covalent Organic Frameworks for the detection of CO

International audienceEvery year in the world, carbon monoxide (CO) is responsible for thousands of intoxications and hundreds of deaths. The detection (CO) at few ppm levels is thus a critical point for the control of the air quality. Corrole belongs to the family of porphyrinoids which is largely used for sensing applications [1]. We have shown that cobalt metallocorroles are able to bind carbon monoxide in the axial position with a high affinity even in the presence of nitrogen and dioxygen, the two main components of the atmosphere [2]. We have recently prepared sensing devices for low CO detection level (sub-ppm) using cobalt corroles deposited as films on a Surface Acoustic Wave device by spray coating [3]. Herein, we will describe the synthesis of new porous materials belonging to the Covalent Organic Frameworks (COF) family based on cobalt corroles (Figure 1). The two axial NH3 molecules can be easily removed to give the tetracoordinated cobalt corroles, as active species. Their synthesis and selective sorption properties for CO over N2 and O2 will be presented

Cobalt corroles for selective detection of carbon monoxide

International audienc